HK1176113A - Photosensor for position detecting device, position detecting device using same and position detecting method - Google Patents

Abstract

An object of the present invention is to provide a position detecting device using a reflection type photosensor, which assures a small size and low cost and enables detection of a long distance of about 10mm or more, and a position detecting method. The position of a moving body is detected by providing, on the moving body, a reflection plate(12) having reflecting surfaces (sa) and non-reflecting surfaces (sb) arranged alternately in a moving direction of the moving body, providing a light receiving element (8)of the reflection type photosensor(9) with, for example, two light receiving portions (8a and 8b)having different light receiving regions in the moving direction of the moving body, outputting output signals from these two light receiving portions (8a and 8b), and carrying out at least one calculation of adding, subtracting, dividing and function calculation of these two output signals.

Description

Photosensitive element for position detecting device, position detecting device using the same, and position detecting method

Technical Field

The present invention relates to a sensor for detecting a position and a movement amount of a moving object in an apparatus such as a camera using a reflection type photosensor, a position detection apparatus using the sensor, and a position detection method.

Background

Conventionally, for example, in a digital still camera, a camcorder, a monitoring camera, and the like, a lens is driven by using various actuators, and a position detection device is used to sense the position of the movable lens and the like.

For example, as a detection device for detecting the position and the movement amount of the focus lens, there are a type using a pulse generator as in the stepping motor system, and a type using an optical sensor or a magnetic sensor to detect the amount of change in an analog manner in the piezoelectric motor system, and examples of the former include japanese patent application laid-open No. 04-9712 (document 1), and examples of the latter include japanese patent application laid-open No. 05-45179 (document 2), japanese patent application laid-open No. 2002-357762 (document 3), japanese patent application laid-open No. 2006-173306 (document 4), and japanese patent application laid-open No. 2009-open No. 38321 (document 5).

The stepping motor system is a system in which the stepping motor system is rotated at each rotation angle corresponding to the number of generated pulses counted, and is generally used for applications requiring long-distance position detection, but since the motor does not rotate continuously, noise during rotation is large, and this noise causes sound interference during video recording, and there is a problem that responsiveness is slow.

For example, although a stepping motor system has been the mainstream of digital still cameras and the like, in recent years, a piezoelectric motor system has been used in which an optical sensor and a magnetic sensor are used for position detection because importance is attached to avoiding occurrence of noise during video recording, increasing the speed of autofocus, and downsizing of devices using the piezoelectric motor system.

Fig. 15A to 15B show a conventional position detecting apparatus using a general reflection-type photosensor, and as shown in fig. 5A, the reflection-type photosensor 1 is configured such that a light emitting element 3 is disposed in one recess partitioned by a light shielding wall 2, and a light receiving element 4 is disposed in the other recess. In addition, as shown in fig. 15B, at the light emitting/receiving surface S of the photosensor 1_LSide of, according to, the light emitting/receiving surface S_LThe reflector 5 is disposed in parallel with and movable in a line direction connecting the light emitting element 3 and the light receiving element 4. With this configuration, the light from the light emitting element 3 is reflected by the reflector 5 and input to the light receiving element 4, and the position and the moving distance of the reflector 5 (the moving object to which the reflector is attached) are detected based on the light receiving amount.

As an example of improving the performance of position detection and movement amount detection by using such a reflective photosensor, there is a technique disclosed in japanese patent laid-open No. 2006-173306 (document 4), and as an example of improving the linearity of an output signal, there is a technique disclosed in japanese patent laid-open No. 2009-38321 (document 5).

However, in the case of a digital still camera, a single-lens reflex camera, a camcorder, a monitoring camera, and the like of high magnification or high-end mode, in the case of lens position detection of a camera module for zoom function and long-distance detection, long-distance detection of 10mm or more with a high resolution of 5 μm or less is necessary, and detection is difficult in position sensing using a conventional reflection type photosensor.

On the other hand, in the position detection of the piezoelectric motor system in which the occurrence of noise is avoided during video recording, the speed of autofocus is increased, or the size of the application is reduced, a magnetic sensor is used, and an example of the magnetic sensor is disclosed in japanese patent application laid-open No. 2006-292396 (document 6). The magnetic sensor of document 6 is provided with a magnetic field generating member (magnet) in which S-poles and N-poles are alternately arranged, and 2 magnetic field detecting elements (MR elements or hall elements), and performs position detection by amplifying the outputs of the magnetic field detecting elements and performing arithmetic processing.

However, when the magnetic sensor is used, there are the following problems.

1) The system itself is large-sized.

2) Since a large number of magnets (magnetic field generating members) in which S poles and N poles are arranged are used, the total system cost becomes high.

3) Since the magnetic field is detected, it is difficult to improve the linearity of the signal.

4) When other magnetic forces are used in a device in which a magnetic sensor or the like is mounted, there is a possibility of erroneous operation due to the influence of a magnetic head (magnetic かぶり) or the like.

5) Since the output power of 2 magnetic field detection elements is low, amplification using an operational amplifier is required, and the cost of components for constituting the system becomes expensive.

6) Errors in the magnetic force obtained by magnetizing the S-pole and N-pole of the magnet are likely to occur, it is difficult to maintain the strength of the magnetic field constant, and the oxidation of the magnet deteriorates the performance.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide a sensor for a position detecting device using a reflection type photosensor which is small and inexpensive and can detect a long distance of 10mm or more with a resolution of 5 μm or less without using a magnetic sensor which is large in size and causes problems in detection accuracy, and a position detecting device and a position detecting method using the same.

In order to achieve the above object, a sensor for a position detection device according to the present invention includes: a reflecting part which alternately arranges the reflecting surface and the non-reflecting surface along the moving direction of the moving object; a reflection type photosensor device provided opposite to the reflection portion, having a light emitting element that emits light in a direction of the reflection portion, and a light receiving element that receives the light reflected by the reflection portion, the light receiving element of the reflection type photosensor device being provided with a plurality of light receiving portions having respective different light receiving areas in a moving direction of the moving object.

Preferably, the light receiving section of the light receiving element of the reflection type photosensor is formed such that an area of a light receiving region per unit length increases from a center portion of the light receiving section toward both ends in a moving direction of the reflection section, and the detection output linearly changes according to the moving amount of the moving object, or the light emitting section of the light emitting element is formed such that an area per unit length increases from a center portion of the light emitting element toward both ends in the moving direction of the reflection section, and the detection output linearly changes according to the moving amount of the reflection section.

The position detection device of the present invention includes: the position detection sensor according to the first aspect of the invention; and an arithmetic means for performing at least one of addition, subtraction, division, and function calculation based on the signals from the plurality of light-receiving units, and linearizing a relationship between a value obtained by the arithmetic operation and the position of the reflection unit.

Preferably, the light receiving device further includes a midpoint potential converting mechanism for translating the output values so that a midpoint potential of a change in the output value corresponding to a change in the position of the reflecting portion becomes 0 in a relationship between the output value obtained from each of 2 light receiving portions among the plurality of light receiving portions and the position of the reflecting portion, wherein the calculating mechanism performs the calculation of (A-B)/(A + B) when the output value of each of the 2 light receiving portions converted by the midpoint potential converting mechanism is A, B, and performs the calculation of (A + B)/(A-B) when A is not less than 0, B is not less than 0, A is not less than 0, and B is not less than 0, because linearity is easily obtained. That is, the output of the calculation for forming the triangular waveform in which the linear upper inclined portion and the linear lower inclined portion alternately appear can be obtained, the position detection can be performed over a long distance with high accuracy, and the output variation of the reflection type photosensor due to the temperature change can be eliminated.

The arithmetic mechanism further includes: setting means for setting a threshold value, which is an upper limit of a right rising curve and a lower limit of a right falling curve, which are critical values at which linearity of a curve is obtained, in the curve indicating a relationship between a position of the reflecting unit and an output value of each of the light receiving units obtained from each of 2 light receiving units; the statistical means of the number of times of reaching the threshold values of the upper limit and the lower limit can also detect the position of the moving object based on the statistics and the output obtained by the statistical means.

Further comprising: the position of the moving object can also be determined by approximating a relationship between output values obtained from 2 of the plurality of light receiving units and the position of the reflecting unit by sin- θ curves using phase angles θ corresponding to distances from a reference position, forming a midpoint potential converting mechanism that performs parallel translation so that a midpoint potential of each sin- θ curve becomes 0, and forming the 2 light receiving units so that a phase difference between the 2 signals becomes 90 degrees, setting the output value of each of the 2 light receiving units that have been parallel translated by the midpoint potential converting mechanism to A, B and setting an output value on a side where a phase advances by 90 degrees to a, and setting θ to arctan (B/a) by the arithmetic means.

Preferably, the plurality of light receiving sections have a third light receiving section formed such that an output of the third light receiving section and an output of one of the 2 light receiving sections are 180 degrees out of phase, and the midpoint potential calculating means for calculating the midpoint potential is formed by adding outputs of the 2 light receiving sections having the 180 degrees out of phase.

The position detection method of the present invention is characterized in that a reflecting portion for alternately arranging reflecting surfaces and non-reflecting surfaces with the same width along the moving direction of a moving object is fixed on the moving object; a reflection type photosensor provided opposite to the reflection portion and having a light emitting element and a light receiving element, the light receiving element of the reflection type photosensor being formed to have a plurality of light receiving portions which are different from each other along a moving direction of the moving object; and, the position of the moving object is detected by performing arithmetic processing on the outputs of the plurality of light-receiving sections that change with the movement of the moving object.

According to the present invention, for example, a reflecting portion in which reflecting surfaces and non-reflecting surfaces are alternately formed is attached to a moving object such as a movable lens of a camera, and an output signal corresponding to a distance close to a sinusoidal curve can be obtained by receiving a change state of light reflection from the reflecting portion by, for example, 2 light receiving sections (respectively different light receiving regions), and 2 signals having different phases of a periodic function close to a sinusoidal curve can be output by the 2 light receiving sections. Then, based on the 2 signals, a linear value operation (operation for obtaining a linear value) is performed, or the values of the linear portions in which the 2 signals change are accumulated (load calculation), whereby the position or the movement amount of the mobile object can be detected. Here, the linear value operation is an operation performed on the values of the light receiving sections such that the relationship between the position of the moving object and the values obtained by the light receiving sections is approximated to a straight line, and the values of the light receiving sections approximated to the straight line relationship are hereinafter simply referred to as "linear values", and the operation for obtaining the linear values is hereinafter simply referred to as "linear value operation".

Further, the reflective photosensor device is provided with a light receiving region or a light emitting region in which the detection output changes linearly in accordance with the amount of movement of the reflecting portion, and the area per unit length is wider from the center portion in the moving direction of the reflecting portion toward both ends, and by using such a reflective photosensor device, the linearity of 2 signals can be improved, for example.

Further, for example, by outputting 3 signals (a to C are output) by trisected light-receiving sections, calculating an intermediate potential from output signals a and C having a phase difference of 180 degrees, and performing linear value calculation from output signals a and B having a phase difference of 90 degrees, it is possible to obtain a midpoint potential at the same time at the time of linear value calculation, and even when the output signals vary due to temperature change or the like, it is possible to accurately detect the position and the movement amount of the moving object while the midpoint potential is kept constant.

According to the position detecting device of the present invention, since the reflecting portion is configured such that only the reflecting surface and the non-reflecting surface are alternately formed, the sensor can be formed at low cost and in a small size as compared with a plurality of magnetic field generating members in which S poles and N poles are arranged, and the linearity can be easily improved, and by forming the reflecting surface and the non-reflecting surface repeatedly in a large number, it is possible to perform excellent position sensing over a long distance of 10mm or more. Further, adjustment such as reduction in the width of the reflective surface and the non-reflective surface increases the gradient of the output, and high-resolution (high-accuracy) position detection of 5 μm or less can be realized. For example, if the widths of the reflective surface and the non-reflective surface are set to 300 μm or less, respectively, it is necessary to recognize a phase change of 180 degrees/30 degrees to 6 degrees in order to detect a change of 10 μm, but if the widths of the reflective surface and the non-reflective surface are set to 100 μm, it is sufficient to detect a phase change of 180 degrees/10 degrees to 18 degrees in order to detect a change of 10 μm, and a change of about 10 degrees can be sufficiently detected, so that a high resolution of 5 μm or less can be achieved. The zoom lens has the advantages that the zoom lens can be applied to camera modules which need a zoom function, such as a high-magnification or high-end mode digital still camera, a single-lens reflex camera, a camcorder and a surveillance camera which need position detection of more than 10mm, and can be applied to applications which need position detection in a long distance range with high precision.

In addition, problems when using magnetic sensors are eliminated. That is, without being affected by the magnetic head or the like, it is possible to prevent the occurrence of detection errors due to variations in the magnetization of the S-pole and N-pole of the magnet and variations in the magnetic field strength, and performance degradation due to oxidation of the magnet.

Further, by shielding a part of the light receiving region in the center of the light receiving section from light, linearity of the inclination of the rise and fall of the output waveform from the light receiving section can be improved, and detection accuracy can be improved.

Further, the sum and difference of the outputs from the 2 light-receiving sections formed in different regions are obtained, and the calculation processing for obtaining the ratio thereof is performed, whereby a curve of the calculation result with good linearity can be obtained.

By providing the third light-receiving section having a phase difference of 180 degrees to obtain the midpoint potential, it is possible to obtain the midpoint potential necessary for obtaining the linear characteristic necessary for the long-distance position detection at the same time at the time of detection, and there is an advantage that even if the midpoint potential level changes when the photosensor has temperature dependency or when the output signal from the photosensor fluctuates due to a temperature change, the result (linear characteristic) obtained by the calculation is not affected.

Drawings

Fig. 1 is a diagram showing a configuration of a position detection apparatus using a reflection type photosensor according to a first embodiment of the present invention.

Fig. 2A to 2D are diagrams showing configuration examples of the light receiving unit.

Fig. 3A to 3B are perspective views seen from the reflection portion side of the position detection device of the first embodiment shown in fig. 1, and perspective views seen from the photosensor side.

Fig. 4A is a diagram showing a detection example of the position detection device according to the first embodiment, fig. 4B is a diagram showing a midpoint potential of 0 in a simulation diagram of the light receiving element output, and fig. 4C is a diagram showing an example of a result of an arithmetic mechanism (linear value arithmetic output) for obtaining linearity.

Fig. 5A to 5C are graphs showing the results of the same processing as in fig. 4A to 4C performed with the structure of the light-receiving portion shown in fig. 2B.

Fig. 6 is a diagram showing the case where fig. 4B and 4C are superimposed and the extreme value of the output of the light receiving element is represented by ± 1 for convenience.

Fig. 7 is a diagram of an output of the light receiving portion when a part of the light receiving region is shielded as in fig. 2C and 2D in the first embodiment.

Fig. 8A to 8B are explanatory views showing a configuration of the position detecting device of the second embodiment and an example of the output and detection of the light receiving element at this time.

Fig. 9 is a diagram showing a configuration of a position detection device according to a third embodiment.

Fig. 10A to 10B are diagrams showing a configuration example of a light receiving element according to a third embodiment.

Fig. 11A to 11B are simulation diagrams of a configuration example of the position detection device and an output of the light receiving element of the third embodiment.

Fig. 12A to 12B are diagrams showing an example of the configuration of the reflection unit of the position detection device according to the third embodiment, and simulation and linear value calculation outputs of the light receiving element output associated with the reflection unit.

Fig. 13A to 13B are a configuration example of the reflection unit of the position detection device according to the third embodiment, and diagrams showing a relationship between the position of the reflection unit and a linear value calculation output when performing phase angle calculation.

Fig. 14A to 14B are diagrams showing the results when the midpoint potential is calculated by the position detection device of the third embodiment and the results when the midpoint potential is shifted.

Fig. 15A to 15B show a configuration of a conventional position detecting apparatus, and are a top view and a side view thereof.

Description of the symbols

1. 9 … reflective photosensitive device

3. 7 … light-emitting element

4. 8, 16, 17, 18, 24, 28 … light receiving element

5. 12 … reflection board (reflection part)

8a, 8b, 16a, 16b, 17a, 17b, 18a, 18b, 24a to 24c, 28a to 28c … light-receiving parts

14. 26 … arithmetic mechanism (Microprocessor)

19. 20 … light shading reflection film

22 … addition mechanism

Sa … reflective surface sb … non-reflective surface

Detailed Description

In fig. 1 to 3B, the configuration of a position detection apparatus using a reflection-type photosensor device of a first embodiment of the present invention is shown, in which a reflection-type photosensor device 9 having a light-emitting element 7 and a light-receiving element 8 is provided. That is, as shown in fig. 3A, the reflection type photosensor 9 is configured such that the light emitting element (LED)7 is disposed in one of the recesses 9a partitioned by the outer peripheral wall and the light shielding wall 9k, and the light receiving element (phototransistor) 8 is disposed in the other recess 9b, and the reflector (optical reflection section) 12 is disposed on the light emitting/light receiving surface side of the photosensor 9 so as to be parallel to the light emitting/light receiving surface and to move in the direction 100 substantially perpendicular to the arrangement direction (longitudinal direction in the drawing) of the light emitting element 7 and the light receiving element 8. The reflecting plate 12 is attached so as to move integrally with a moving object such as a lens.

In the reflecting plate 12, the reflecting surfaces sa and the non-reflecting surfaces sb in the shape of an extremely thin narrow stripe are alternately formed (vertical stripe), and in the embodiment, the width w1 of the reflecting surfaces sa and the non-reflecting width w2 are made equal (w) and w is formed to be about 300 μm. That is, the reflecting surface sa and the non-reflecting surface sa are preferably the same width. From the viewpoint of improving the detection accuracy (sensitivity), the width is preferably as narrow as possible. The non-reflection surface sb may be formed of a slit space. The reflector 12 can be easily formed with high accuracy by performing metal deposition or sputtering on transparent glass by using a general semiconductor lithography technique. When a resin is used as the base material, the surface portion may be roughened by etching or by press molding in the mold molding, in addition to metal plating.

Then, as also shown in fig. 2A, 2 light-receiving portions 8a, 8b, each of which has a light-receiving region divided so as to become a different region in the moving direction of the moving object, are formed on the light-receiving element 8 of the photosensor 9. In the present embodiment, as shown in fig. 2A and 2B, the interval d1 between the central portions of the 2 light-receiving sections 8a and 8B, and 16a and 16B is formed so that the phase difference between the received signals of the 2 light-receiving sections 8a and 8B becomes 90 degrees, and is usually set to w/2, but is not necessarily limited to w/2 depending on the shape of the light-receiving sections 8a and 8B, and the like. In addition, the 2 light receiving sections 8a and 8b are formed in the same area and the same shape. This is because, as described later, the output changes of the 2 light-receiving sections 8a and 8b due to the movement of the reflecting plate 12 are changed in the same manner, and the phase difference is 90 degrees. However, by designing the calculation means described later, if the linearity can be calculated without 90 degrees, such a limit is not necessary.

Further, in the first embodiment, there are: buffer amplifiers 13a and 13b for receiving outputs from the 2 light-receiving sections 8a and 8b of the light-receiving element 8, and an arithmetic unit (MPU)14 for performing a linear value arithmetic operation based on the outputs of the buffer amplifiers 13a and 13 b. The arithmetic means 14 may perform arithmetic operations by a microprocessor, or may use circuits such as an operational amplifier. Further, a midpoint potential conversion mechanism, not shown, for determining the center potential of the output change of each of the 2 light-receiving portions 8a and 8b when the reflection plate 12 moves, is provided, and the midpoint potential conversion mechanism is converted into an output change in which the midpoint potential is 0 point.

The midpoint potential conversion mechanism can make the midpoint potential 0 by, for example, a method of converting the midpoint potential into a digital value by an ADC, obtaining the midpoint potential by a microcomputer, and subtracting the midpoint potential from the output value obtained by the light-receiving portions 8a and 8b, or a midpoint potential conversion mechanism that performs offset (offset) processing of setting the DC level to 0 by the buffer amplifiers 13a and 13 b. When the output values of the 2 light-receiving sections 8a and 8B for converting the midpoint potential to 0 are A, B, and a is equal to or greater than 0, B is equal to or greater than 0, or a is less than 0 and B is less than 0, the operation of B ═ a-B)/(a + B) is performed, and a is equal to or greater than 0, B is less than 0, or a is less than 0, B is greater than or equal to 0, a ═ a + B)/(a-B) is performed, whereby a triangular waveform can be obtained in which a linear rising line and a linear falling line repeat with the movement of the reflection plate 12. In addition, by performing the calculation in which the measured values are included the same number of times in both the denominator and the numerator, even if the temperature characteristics of the reflective photosensor or the like fluctuate, the denominator and the numerator constitute the same change and are therefore eliminated.

Fig. 2B to 2D show another configuration example in place of the light receiving element 8. Note that fig. 1 is a perspective view of the reflection type photosensor 9 as viewed from the back side, but fig. 2A to 2D are drawn with the surfaces facing each other. In the light receiving element 16 of fig. 2B, 2 light receiving sections 16a and 16B each having a light receiving region elongated in the moving direction 100 of the moving object are arranged in a direction perpendicular to the moving direction 100 in a state in which the sections overlap. In this case, as described above, the interval d1 between the central portions of the 2 light-receiving units 16a and 16b is also formed so that the output is 90 degrees out of phase, as described above. The light receiving element 17 in fig. 2C has light receiving sections 17a and 17B that shield a part of the light receiving areas of the light receiving sections 8a and 8B in fig. 2A with a light shielding reflection film 19, and the light receiving element 18 in fig. 2D has light receiving elements 18a and 18B that shield a part of the light receiving areas of the light receiving sections 16a and 16B in fig. 2B with a light shielding reflection film 20. The light shielding reflection films 19 and 20 have polygonal outlines, but may have curved outlines, and may be appropriately selected based on the obtained output characteristics.

That is, the light receiving sections 17a, 17b, 18a, and 18b are provided with light receiving regions having areas per unit length wider from the center toward both ends in the moving direction of the reflector 12 by covering the active layers (light receiving regions) of the light receiving sections 8a, 8b, 16a, and 16b with the light shielding reflection films (a1 films) 19 and 20, as in the case of the above-described document 5 (jp 2009-. This can improve the linearity of the detection output of the photosensor 9. Also, in the embodiment, 2 light receiving sections are formed on 1 light receiving element 8, 16 to 18, but 2 light receiving sections 8a and 8b, 16a and 16b, 17a and 17b, 18a and 18b may be configured as light receiving elements, respectively.

On the other hand, similarly to the light receiving elements 17 and 18, the light emitting region of the light emitting element 7 may be partially covered with a light shielding film or the like, and the area per unit length may be increased from the center portion in the moving direction of the reflective plate 12 toward both ends, thereby improving the linearity of the detection output of the photosensor 9.

The first embodiment is constituted as described above, and according to this constitution, the results shown in fig. 4 can be obtained. That is, in the configuration of the first embodiment shown in fig. 4A, as shown in fig. 4B, the relative output a from the light-receiving section 8a of the light-receiving element 8 and the relative output B from the light-receiving section 8B when the midpoint potential is switched to 0 can be obtained, and these outputs A, B form waveforms in which a phase difference of 90 degrees (approximately corresponding to an interval of 0.15mm) is generated. Then, based on the outputs a and B, if the arithmetic means 14 performs arithmetic operations of B ═ a-B)/(a + B) and a ═ a + B)/(a-B) in accordance with the positive and negative of the above-described A, B, a triangular waveform repeating the upward inclined portion a and the downward inclined portion B with respect to the reflector coordinates can be obtained as shown in fig. 4C. That is, this calculation can obtain a detection output maintaining linearity.

If the relationship between the reflection plate 12 (reflection portion) and the reflection type photosensor 9 is determined, the relationship between the coordinates (position) of the reflection plate and the output A, B can be determined without any doubt, and at the time of formation of the position detection means, the relationship between the calculation output shown in fig. 4C and the coordinates of the reflection plate is known, and the relationship between the number of triangular waves and the coordinates of the reflection plate corresponding to the calculation output is stored in the memory in advance. As a result, when detecting which position the position of the reflecting plate 12 is actually at, the actual position can be detected from the look-up table stored in the memory based on the calculated output of the light-receiving units 8a and 8b measured and the value obtained by counting the number of times (which times) the straight line portions a and b pass at the time of measurement.

Further, by using the above-described arithmetic expression, the temperature characteristic of the reflective photosensor can be completely eliminated. That is, for example, when a is 0.4(V) and B is 0.1(V) without the influence of temperature, the value of the above formula (a-B)/(a + B) is 0.6, but on the contrary to this, if there is a fluctuation of 1 due to the influence of temperature, a is 0.44 and B is 0.11, but in this case, the calculated value is 0.6 and the fluctuation is partially eliminated. Therefore, it is not necessary to provide a circuit for monitoring and feeding back the temperature in the device by the thermistor and a special temperature characteristic eliminating circuit. Further, there is also considered a method in which the light receiving element 8 is formed such that the interval between the 2 light receiving sections 8a and 8B is a phase difference of 90 degrees, and therefore, when the change of the output signal obtained by performing the midpoint correction on the output B of the phase delay described above is approximated to a curve of sin θ, the output signal of a is sin (θ +90 °), so θ is calculated from the inverse function θ of the ratio B/a of the output signal sin (θ)/cos (θ) tan (θ), arctan (B/a), and the movement distance is calculated using the correlation between the reflection surface (or non-reflection surface) pitch and the angle θ of the reflection plate 12. The moving distance can be easily calculated by a method of obtaining the arithmetic expression of θ. In particular, when linearity is insufficient in the arithmetic expressions for a and b, good linearity can be obtained by the method of calculating the arithmetic expression for θ.

When the θ is obtained, as in the case of the above-described a and b, the relationship between the coordinates of the reflecting plate 12 and the angle θ is known in advance if the relationship between the reflecting plate 12 and the reflective photosensor 9 is determined, and the relationship is stored in a memory in advance, and the actual position of the reflecting plate 12 can be obtained by rotating the curve of tan θ several times (several times by the reflecting portion sa) and calculating the θ via the above-described function as described above. Instead of storing the relationship between θ and the position in the memory, a relationship between x, which is obtained by converting θ by a function of the width w of the reflecting surface sa, and the position may be stored in the memory, and the position may be determined from the value of x.

Fig. 5A to 5C show results obtained when the light receiving element 16 of fig. 2B is used, and in this case, as shown by the output from the light receiving portion 16a of the light receiving element 16, the output a when the midpoint potential is 0, the output from the light receiving portion 16B, and the output B when the midpoint potential is 0, an output having a waveform that causes a phase difference of 90 degrees can be obtained between the two. Then, based on these outputs a and B, by calculating B ═ a-B)/(a + B) and a ═ a + B)/(a-B) by an arithmetic mechanism (see fig. 1) constituted by a microcomputer in the same manner as in the example of fig. 1, a triangular waveform in which the linearity of a and B is maintained can be obtained as shown in fig. 5C.

Fig. 6 is a triangular waveform in which the output of the light receiving element 8 and the linear value calculation output of the first embodiment are superimposed, and the calculated values a and b sequentially repeat with respect to the movement distance (detection position) of the reflection plate 12. In this example, 1 triangular waveform corresponds to a movement distance of 0.3 mm.

In this example, since the triangular waveform repeats at a period of 0.3mm, for example, the calculated value of 0.15mm (bottom D1) and the calculated value of 0.45mm (bottom D2) are the same value, and it cannot be directly determined at which position the reflection plate is located. Because of this periodicity, the result is the same at the position x and the position (x +0.3) mm. However, in the range of 0 to 0.3mm, the calculated value a or b corresponds to the position of the reflecting plate, and therefore, the position can be determined from the calculated value by considering the number of times the vertex and the bottom pass.

That is, the acquisition and calculation of the signal of the reflecting plate 12 during movement are always performed. Therefore, the number of times of passing the bottom of the reflecting plate is counted and held, and the following formula is calculated and judged: the current position is (the position corresponding to the calculated value a (within 0.3 mm)) + (signal period (0.3mm) × statistics). The vertices U1, U2 … and the bottoms D1, D2 … are the points at which the signal A, B switches positive and negative, the bottom is the point at which the signal a switches from positive to negative or from negative to positive, and the vertices are the points at which the signal B switches from positive to negative or from negative to positive. The determination of the signal switching can be detected by an analog comparator circuit with a zero point as a reference, and the positive or negative determination can be made in the processor as a digital value after digital conversion.

Therefore, when the position detection device of the present embodiment is applied to a camera module having a zoom function, if the lens is returned to the origin (a state in which the zoom lens is accommodated) after the end or at the start of use, the amount of movement of the lens following the zoom operation can be known from the accumulated value of the statistics when the zoom function is used, and the current position of the lens can be known by storing the accumulated value of the statistics at the end of the zoom operation in a memory or the like. Further, it can be understood that the maximum movable position of the lens is achieved by changing the size of the reflecting surface sa of the reflecting plate 12 by widening it only at the end portion and by forming the output waves of the light receiving elements 8, 16 to 18 into different shapes only at the end portion.

In the present invention, since the amount of change (change per unit of movement) of a and b corresponding to the moving distance of the moving object can be increased, it is possible to perform very high-resolution position detection. That is, when detection with higher resolution is required, the inclination angles of the rise and fall of the output wavelength of the light receiving sections can be increased by optimally designing the light receiving pattern (the shape, size, arrangement, and the like of the 2 light receiving sections) and the configuration of the reflection plate 12 (the width of the reflection surface and the non-reflection surface, and the like) such that the amount of change in the calculated values a and b is increased in the calculated value waveform of fig. 6. As a result, the gradient of the calculated values a and b of the 2 output signals of the reflective photosensor 9 (the amount of change in the values of a and b corresponding to the movement distance) is increased, and high resolution can be obtained. In fig. 6, when the calculated values a and b are used, the upper and lower thresholds c are set₁、d₁By using the threshold value c₁And d₁The detection accuracy can be improved by the calculated values a and b therebetween.

In the case where the output D from the light-receiving section 17a is shown in fig. 7 and the light-receiving sections 17a, 17b, 18a, and 18b [ fig. 2C and 2D ] are represented by the light-receiving sections 17a, 17b, 18a, and 18b when the light-receiving section 17a is shielded as a part of the light-receiving region of the 2 light-receiving sections in the first embodiment, as shown in the figure, it can be confirmed that the linearity of the output waveform is improved on the top and bottom sides, as compared with the example a' of fig. 2A. That is, as shown in fig. 2C and 2D, the light receiving regions of the light receiving sections 17a, 17b, 18a, and 18b are partially blocked by the light blocking reflection films 19 and 20, and the areas per unit length are wider from the center of the light receiving sections in the moving direction of the reflecting sections toward both ends, that is, the linearity of the inclination in the extremum neighborhood of the output waveform can be improved.

Fig. 8A to 8B show a configuration of a second embodiment in which long-distance detection is performed instead of linear value calculation. That is, as shown in fig. 8B, in the portion marked in an elliptical shape by a broken line in the vicinity of the extremum of the output waveform (the apex/bottom portion), the change in the output signal is small, and accurate position detection cannot be performed, but if this portion is removed, it has linearity, and therefore, the position is detected by this linear portion. That is, although continuous position detection cannot be performed only with the signals of 1 light-receiving unit, as shown in fig. 8A, by providing 2 light-receiving units 8A and 8b and arranging the signal S2 having a different phase from the signal S1 so as to be shifted in phase by, for example, about 90, it is possible to detect the position by alternately using the straight portions of the two signals S1 and S2. In this case, the phase difference between the two light-receiving units 8a and 8b does not have to be 90 degrees, but the extreme values of the two signals S1 and S2 do not overlap each other, and the extreme value of one signal S1 is covered with the straight portion of the other signal S2, so that the phases are shifted.

The method of position detection in this example will be described with reference to fig. 8B. The threshold values d2 (lower limit) and c2 (upper limit) in which the signals S1 and S2 indicate a range in which linearity can be obtained are set in advance. Then, in the variation of e1 shown in fig. 8B, position detection is performed with the signal S1, and if the signal S1 reaches the upper threshold value c2, position detection is performed with S2 (e 2). Likewise, if the output of the signal S2 reaches the upper threshold c2, position detection is performed using the output of the signal S1 (e 3). Similarly, if the signal S1 reaches the lower threshold d2, the output of the signal S2 is switched to perform position detection, and by repeating the same, detection can be accurately performed even for a long distance. In this example, if the positions of the 2 light-receiving units 8a and 8b are fixed, the relationship between the detected positions and the output values of the signals is always constant, the relationship between the output values of the 2 signals and the distances is stored in advance, and the 2 signals S1 and S2 are counted by the addition circuit after passing through the upper threshold c2 and the lower threshold d2 several times, so that the accurate detection can be performed even for a long distance. Whether or not the threshold value is exceeded can be detected by a comparison circuit using the threshold value as a reference or a detection means based on comparison of a digital value in a processor. Accordingly, a calculation means for calculating a linear value is not required, and position detection can be performed with a simple configuration.

In the above-described embodiment, the light receiving regions of the light receiving elements 8, 16 to 18 are divided into 2, but the light receiving regions of these light receiving elements may be divided into 3 or more, linear value calculation may be performed based on 3 or more outputs in the first embodiment, and long-distance position detection may be performed at high resolution by accumulating 3 or more outputs in the second embodiment.

Next, a third embodiment will be explained.

In the case of performing the linear value calculation in the above embodiment, it is necessary to perform the calculation processing with the midpoint potential of the output signal from the light-receiving portion as a reference, but since the output voltage of the photosensor 9 has temperature dependency, the level of the midpoint potential changes due to a temperature change or the like, and when the calculation processing is performed in a state where the midpoint potential is shifted (fluctuated), linearity of the relationship between the value obtained from the calculation result and the distance is broken down.

The condition for obtaining normal linearity is satisfied by calculating 1/2 a value obtained by adding a Peak value and a Bottom value to each of the outputs a and B of the 2 light-receiving units 8a and 8B of the photosensor 9, obtaining the midpoint potential of each of the outputs a and B, and using the midpoint potential for the offset value (the amount of change in DC level) of each output to correct the midpoint potential. However, when the output signal of the reflection type photosensor 9 abruptly changes due to a factor such as a rapid change in the ambient temperature, the midpoint potential (for example, 0) to be originally provided as the operation expression may not be obtained as a normal value due to timing selection, and as a result, there is a possibility of a linear failure. Therefore, in the third embodiment, the intermediate potential is calculated, and the linear value operation is performed based on this.

Fig. 9 and fig. 10A to 10B show the configuration of the position detecting apparatus according to the third embodiment, in which the same reflecting plate 12(w1 ═ w2 ═ w) as in the first embodiment is arranged, and a reflection type photosensor 9 having a light emitting element 7 and a light receiving element 24 is provided. That is, the reflection type photosensor device 9 is constituted by the same configuration as that of the first embodiment, and is provided with a light receiving element 24 in place of the light receiving element 8. As shown in fig. 10A, the light receiving element 24 is also provided with 3 light receiving sections 24a, 24B, and 24C each having a light receiving area divided into different areas in the moving direction 100 of the moving object, and the 3 output signals (a to C) from the electric sensor 9 are designed so that the phase difference between the outputs of the 3 light receiving sections 24a, 24B, and 24C is 90 degrees, and the phase angle of the 3 output signals (a to C) is delayed by 90 degrees (output B) and 180 degrees (output C) from the reference signal (0 degree: output a).

Further, the apparatus has buffer amplifiers 25a, 25b, and 25c that receive outputs from the 3 light-receiving units 24a, 24b, and 24c, and an arithmetic unit (MPU)26 that determines a midpoint potential of the detection signal from the outputs of the amplifiers 25a, 25b, and 25c and performs a linear value operation. As the linear value calculation by the calculation means 26, calculation of B ═ a-B)/(a + B) and a ═ a + B)/(a-B), calculation of a phase angle θ of a signal obtained by a curve approximating a sine wave and θ ═ arctan (B/a), or the like can be applied, as in the first embodiment. At this time, the midpoint potential is obtained by shifting a value obtained by adding the amplifier 25a and the amplifier 25c to 0.

Fig. 10B shows another configuration example in place of the light receiving element 24, and the light receiving element 28 in fig. 10B is an element in which 3 light receiving sections 28a, 28B, and 28c, which are light receiving regions elongated in the moving direction 100 of the moving object, are arranged in a direction perpendicular to the moving direction 100 in a state in which they are partially overlapped. The light-shielding reflection film 19 described with reference to fig. 2C and 2D may be provided in the light-receiving portions 24a, 24b, and 24C and the light-receiving portions 28a, 28b, and 28C.

The third embodiment is constituted by the above structure, and according to this constitution, the results shown in fig. 11A, 11B, fig. 12A, 12B can be obtained. That is, in the configuration of the third embodiment shown in fig. 11A, as shown in fig. 11B, it is possible to obtain an output a ' from the light-receiving section 24a of the light-receiving element 24, an output B ' from the light-receiving section 24B, and an output C ' from the light-receiving section 24C, which form: the output B ' is delayed by 90 degrees and the output C ' is delayed by 180 degrees with respect to the output A ' (0 degrees) in terms of the phase angle. Then, based on the outputs a 'to C', the outputs at which the midpoint potential becomes 0 are respectively referred to as A, B, C, and the same linear value calculation as described above is performed by the calculation means 26. That is, the midpoint potential D is calculated using D ═ a '+ C')/2 based on the outputs a 'and C' having a phase difference of 180 degrees, and calculations of B ═ a-B)/(a + B) and a ═ a + B)/(a-B) are performed based on the outputs a and B when the midpoint potential is set to 0, in the same manner as in the first embodiment.

By this linear value calculation, as shown in fig. 12A, a triangular waveform in which the upper inclined portion a and the lower inclined portion b having linearity are repeated can be obtained. In the third embodiment, since the midpoint potential D is calculated, the midpoint potential (0V in the embodiment) in the linear value calculation does not vary even when the temperature changes, and is kept constant, and an accurate calculated value can be obtained. Further, according to the above-mentioned operational expression, as described in the first embodiment, the temperature characteristic of the photosensor 9 can be completely eliminated, and therefore, it is not necessary to provide a circuit for monitoring the temperature in the device by a thermistor and feeding back the temperature, and a special temperature characteristic eliminating circuit.

As shown in fig. 12A, the third embodiment is designed such that, in the reflection plate 12, the width of the reflection surface sa is 0.3mm, the width of the non-reflection surface sb is 0.3mm, and the output signal waveform of the reflection type photosensor 9 is obtained in 1 cycle amount by moving both 0.6 mm. That is, a movement of 0.6mm can be detected in 1 cycle of the signal waveform.

Fig. 13A to 13B show results obtained when an arithmetic expression for obtaining the phase angle θ of the signal with θ being arctan (B/a) is used as another linear value operation in the third embodiment. As described above, in the calculation for obtaining the linear value, there is also a method of using θ ═ arctan (B/a), and when the phase angle of the output signal is θ, the distance of movement of the reflecting plate 12 on the light emitting/receiving surface side of the movable photosensitive element 9 can be detected by correlating θ with the position (coordinate) of the reflecting plate 12.

The relationship between θ and the coordinates of the reflecting plate 12 is shown in fig. 13B. In this example, for example, the output signal of the photosensor 9 can be obtained by a movement of 0.6mm of the reflecting plate 12 composed of the reflecting surface sa of 0.3mm and the non-reflecting surface sb of 0.3mm, and in this case, since a relational expression of the movement of 0.6mm of the reflecting plate 12 to the phase angle of 360 degrees of the output signal holds, the position of the moving object can be detected by calculating the phase angle θ.

Next, the effect of calculating the midpoint potential will be described with reference to fig. 14A to 14B.

In the calculation of the third embodiment, a linear value is obtained by the calculation of the output signal A, B, but the value of the output signal A, B used in each calculation formula is not an absolute value but a relative value with respect to the midpoint potential D. That is, in order to perform position detection by the linear value operation, if the operation is not performed in a state where the midpoint potential of the output signal is always set to 0 in order to obtain synchronization of the output voltages, linearity required for position detection is lost.

In general, the output voltage of the reflection type photosensor 9 varies individually depending on the product, and also varies depending on the bias condition of the photosensor. In addition, since the photosensor has temperature dependency, the value of the midpoint potential D of the output signal is not a fixed value. In order to always obtain the midpoint potential D accurately, the amplitude of the output signals a 'and B' is monitored by an external LSI or the like, the value of the midpoint potential D is obtained by using the calculation formula a '/2 ═ B'/2 ═ D of the monitored value, and a ═ a '-D and B ═ B' -D are calculated.

In fig. 14B, the amplitude of the output signal varies from-1 to +1 to 0.5 to 2.5, and the above-described calculations of (a-B)/(a + B), (a + B)/(a-B) are performed regardless of whether the midpoint potential is shifted to 1.5V, and as a result, the calculated value of the waveform E is output. As a result, it is found that the value of the midpoint voltage D can be constantly monitored in synchronization with the detection of the output signal A, B so that stable linearity can always be obtained without causing system failure.

Fig. 14A shows the result of calculating the midpoint potential D, and the midpoint potential of the output A, B is always set to 0V by the calculation of the midpoint potential D, and thus the calculation result has a triangular waveform with high linearity and repetition. In the embodiment, since the output (signal) C is designed to advance by a phase angle of 180 degrees with respect to a, half values of a and C, that is, D is (a + C)/2, and normally represents the midpoint potential D of each output signal regardless of the fluctuation of the output A, B, C. That is, although the midpoint potential D can be calculated by the above-described calculation formula of D ═ Amax-Amin)/2 ═ B (Bmax-Bmin)/2, the midpoint potential D can be accurately calculated by the method using a and C having a phase difference of 180 degrees. Then, based on the output A, B, C obtained at the same time, the arithmetic operation means 26 performs the arithmetic operation of D ═ a + C)/2, and linearity can be generally secured in the linear value arithmetic operation.

According to the third embodiment, there is an advantage that, when the photosensor 9 has temperature dependency, the output signal from the photosensor 9 fluctuates due to a rapid temperature change, or the like, the linear characteristic obtained by the arithmetic expression is not affected even if the midpoint potential level changes.

Feasibility in industry

The present invention is applicable to, for example, a digital still camera, a single-lens reflex camera, a camcorder, a CCTV long-distance detection actuator and the like that require high-magnification zooming, as a position detection device and the like that perform long-distance detection with high resolution.

Claims (8)

1. A position detection sensor is provided with:

a reflection unit in which reflection surfaces and non-reflection surfaces are alternately arranged in a moving direction of a moving object;

a reflection-type photosensor device provided opposite to the reflection portion, having a light emitting element that emits light in a direction of the reflection portion, and a light receiving element that receives the light reflected by the reflection portion;

the light receiving element of the reflection type photosensor device is provided with a plurality of light receiving portions having respectively different light receiving areas in the moving direction of the moving object.

2. The position detecting sensor according to claim 1,

the light receiving section of the light receiving element of the reflection-type photosensor is formed such that the area of the light receiving region per unit length increases from the center of the light receiving section toward both ends in the moving direction of the reflection section, and the detection output changes linearly with the amount of movement of the moving object, or the light emitting section of the light emitting element is formed such that the area per unit length increases from the center of the light emitting element toward both ends in the moving direction of the reflection section, and the detection output changes linearly with the amount of movement of the reflection section.

3. A position detection device, comprising:

the position detecting sensor according to claim 1;

and an arithmetic means for performing at least one of addition, subtraction, division, and function calculation based on the signals from the plurality of light-receiving units, and linearizing a relationship between a value obtained by the arithmetic operation and the position of the reflection unit.

4. The position detection apparatus according to claim 3,

further, the optical pickup device further includes a midpoint potential conversion mechanism that makes the output value parallel so that a midpoint potential of a change in the output value corresponding to a change in the position of the reflection unit becomes 0 in a relationship between the output value obtained from each of 2 of the plurality of light-receiving units and the position of the reflection unit, and the arithmetic means makes the arithmetic means A, B the output value of each of the 2 light-receiving units converted by the midpoint potential conversion mechanism

When A is more than or equal to 0 and B is more than or equal to 0 or A is less than 0 and B is less than 0, the calculation of (A-B)/(A + B) is carried out,

when A is more than or equal to 0 and B is less than 0 or A is less than 0 and B is more than or equal to 0, the calculation of (A + B)/(A-B) is carried out.

5. The position detection apparatus according to claim 3,

the arithmetic mechanism further includes: setting means for setting a threshold value, which is an upper limit of a right rising curve and a lower limit of a right falling curve that are critical limits for linearity of a curve that represents a relationship between positions of the reflecting portions obtained from 2 of the plurality of light receiving portions and output values of the light receiving portions, respectively; a statistical mechanism of the number of arrivals of the threshold reaching the upper and lower limits,

then, the position of the moving object is detected based on the statistics and the output obtained by the statistics means.

6. The position detection apparatus according to claim 3,

further comprising: a midpoint potential converting mechanism for performing parallel translation so that a midpoint potential of each sin θ curve becomes 0, under the condition that a relationship between an output value obtained from each of 2 light receiving sections and a position of the reflecting section is approximated by each sin θ curve using a phase angle θ corresponding to a distance from a reference position,

the 2 light-receiving units are formed such that the phase difference between the 2 signals is 90 degrees, the output value of each of the 2 light-receiving units which are parallel-shifted by the midpoint potential converting mechanism is A, B, the output value on the side where the phase advances by 90 degrees is a, and the arithmetic means performs an arithmetic operation of θ ═ arctan (B/a).

7. The position detection apparatus according to any one of claims 3 to 6,

the plurality of light receiving sections have a third light receiving section formed such that an output of the third light receiving section and an output of one of the 2 light receiving sections are 180 degrees out of phase, and a midpoint potential calculating means for calculating the midpoint potential by adding outputs of the 2 light receiving sections having the 180 degrees out of phase is formed.

8. A position detection method is characterized in that,

a reflecting part for alternately arranging reflecting surfaces and non-reflecting surfaces with the same width along the moving direction of the moving object is fixed on the moving object; a reflection type photosensor provided opposite to the reflection portion and having a light emitting element and a light receiving element, the light receiving element of the reflection type photosensor being formed to have a plurality of light receiving portions which are different from each other along a moving direction of the moving object; and, the position of the moving object is detected by performing arithmetic processing on the outputs of the plurality of light-receiving sections that change with the movement of the moving object.