JPH05268164A - Signal transmitter between objects rotated relatively - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to reduce the number of light emitting devices and light receiving devices and perform reliable optical communication between two relatively rotating objects. [Structure] A plurality of light-emitting devices 11 are arranged on a circle C around a rotating body 10 which rotates around a rotary shaft 1, and one light-receiving device 21 is provided on a fixed body 20 directly below the circle C. The divergence angle θ of the projected light, the position of the light emitting device 11, the light receiving device 11 so that the region in which the light receiving device 21 relatively moves is covered by all the illumination areas D of the light that is projected from the plurality of light emitting devices 11. apparatus
21 and the distance L between the light emitting device 11 and the light receiving device 21
Determine. By providing a plurality of light emitting devices on the fixed plate 20 and one light receiving device on the rotating plate 10, full-duplex optical communication is also possible. In this case, the emission wavelengths of the two groups of light emitting devices are made different.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a signal transmission device for performing optical communication between two devices that rotate relative to each other.

[0002]

2. Description of the Related Art In machines and equipment including a rotating machine such as a filling machine and a capper in a filling and packaging facility, a detection signal from a sensor provided on the rotating body is transmitted to a fixed frame side or a fixed frame side. It is necessary to supply power and control signals from the side to the actuator mounted on the rotating body.

As a method for transmitting a signal between two relatively rotating objects, conventionally, there is a method using a slip ring or a rotary connector.

The slip ring system is a system in which a ring is fixed to a rotating shaft of a rotating body, a brush is provided on the fixed body, and the ring and the brush are always in contact with each other. The slip ring method has a problem in that the frictional force generated between the ring and the brush hinders the rotation of the rotating body and that the ring or the brush is worn to cause an error.

The rotary connector is constructed such that by enclosing mercury in the connector, the mercury is always kept in conduction regardless of the rotation of the rotating body.

A major problem common to these conventional signal transmission systems is that a ring-brush pair and a rotary connector must be provided for each type of signal to be transmitted. When the number of sensors and the number of actuators increase, the number of pairs of rings and brushes or the number of rotary connectors also increases, so that the size of the signal transmission unit becomes large. Further, these methods are easily affected by electromagnetic noise, and transmission errors are likely to occur.

In order to solve the above problems, there is known a device for optically transmitting a signal between two relatively rotating objects (for example, Japanese Utility Model Laid-Open No. 2-53641,
(Kaikaihei 2-55746).

In these optical signal transmission devices,
A large number of light emitting elements or light receiving elements are closely arranged in a ring shape, and one light receiving element or light emitting element is arranged so as to face these light emitting element groups or light receiving element groups in the close proximity. The light emitting element group or the light receiving element group is provided on one of the rotating body and the fixed body, and the light receiving element or the light emitting element is provided on the other. In some cases, instead of the light receiving element or the light emitting element, the end face of the optical fiber optically coupled to the light emitting element or the light emitting element is made to face the light emitting element group or the light receiving element group.

However, such an optical signal transmission device requires a large number of light emitting elements or light receiving elements.
Further, the light emitting element group or the light receiving element group and the light receiving element or the light emitting element facing the light emitting element group must be extremely close to each other, and high assembly accuracy is required.

Further, if bidirectional communication (full-duplex transmission) is to be performed simultaneously between the rotating body and the fixed body, the light emitting element groups or the light receiving element groups must be arranged in duplicate. However, a large space is required for these arrangements.

[0011]

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide an optical signal transmission device having a structure capable of reducing the number of light emitting and receiving elements used.

The present invention also provides a structure capable of increasing the distance between the light emitting element provided on either one of the relatively rotating objects and the light receiving element provided on the other.

The present invention further provides a structure in which the space required for arranging the light emitting and receiving elements is not large even in full-duplex transmission.

The optical signal transmission device according to the present invention for one-way communication comprises a set of optical communication devices including a light emitting device and a light receiving device. A light emitting device is provided on either one of the two relatively rotating supports, and the light emitting device is configured such that the emitted light has a spread. A light receiving device is arranged on the other of the two supports at a position for receiving the light emitted from the light emitting device.

The two relatively rotating supports may be either a rotating body and the other may be a fixed body, or both may be rotating bodies. In the latter case, the two supports may rotate in the same direction (though the rotation speeds are different) or they may rotate in opposite directions. The support may be a disc, a cylinder, or a rectangular parallelepiped, and its shape is arbitrary. The support may, of course, be part of a control device, an electronic device or any other electrical or mechanical device.

A plurality (preferably three or more) of at least one of the light emitting device and the light receiving device are provided, and these are arranged at intervals on a circumference centered on the relative rotation center. The light emitted from the at least one light emitting device is received by the at least one light receiving device at all the relative rotational angular positions of the two supports.

For example, a plurality of light emitting devices are arranged on one of the supports at substantially equal intervals on the circumference around the relative rotation center. One light receiving device is provided on the other support. The positions and the number of the plurality of light emitting devices are so arranged that the illumination area of the light having a spread emitted from the plurality of light emitting devices covers all the circular motion loci of the light receiving device due to the relative circular motion of the other support. The divergence angle of the emitted light and the position of the light receiving device are determined. The plurality of light emitting devices are simultaneously driven by the same signal. With this configuration, the light emitted from any one of the light emitting devices is always received by the light receiving device, and the signal is optically transmitted from the light emitting device side to the light receiving device side.

The number of light receiving devices may be one, or two or more. If two or more light receiving devices are provided, the number of light emitting devices will be reduced. Further, the OR signal of the output signals of the plurality of light receiving devices will be the received signal.

On the contrary to the above, a plurality of light receiving devices may be arranged at substantially equal intervals on the circumference, and one (or two or more) light emitting devices may be provided facing each other.

Thus, according to the present invention, a plurality of at least one of the light emitting device and the light receiving device are arranged at intervals on the circumference around the relative rotation center of the two supports. Since this is sufficient, it is possible to significantly reduce the number of light emitting devices and light receiving devices as compared with the conventional example described above. Further, since the diffused light is emitted from the light emitting device, the distance between the light emitting device and the light receiving device can be increased, and the light emitted from at least one light emitting device is always received by the at least one light receiving device. The optical communication can be performed without interruption. The present invention is particularly effective when the two relatively rotating supports are large. Further, according to the present invention, the communication using light is strong against electromagnetic noise.

When performing simultaneous two-way (full-duplex) communication, it is sufficient to provide two sets of the above-mentioned communication devices including a light emitting device and a light receiving device.

For example, one support may have a plurality of first
Light emitting device and at least one second light receiving device are arranged on the circumference, and the other support has at least one first light receiving device.
The light receiving device and the plurality of second light emitting devices are arranged on the circumference. Alternatively, at least one first light emitting device and a plurality of second light receiving devices are arranged on the circumference on one support, and at least one first light receiving device and at least one second light receiving device are provided on the other support. One second light emitting device is arranged on the circumference.

The light emitted from the first light emitting device is emitted by the first light receiving device, and the light emitted from the second light emitting device is emitted by the second light emitting device.
The respective light receiving devices receive the light. In this way, simultaneous bidirectional optical communication becomes possible. In order to avoid interference between the two sets of optical communication devices, it is preferable to use different wavelengths of light used in these optical communication devices.

According to the present invention, in the arrangement in which simultaneous two-way communication is performed, it is possible to arrange the light emitting and receiving devices along one circumference on each of the two relatively rotating supports. The installation space is relatively small.

Other features of the present invention will become apparent in the following description of the embodiments.

[0026]

Description of Embodiments First, a case of one-way communication will be described. Further, in this example, it is assumed that a plurality of light emitting devices are provided.

Referring to FIGS. 1 and 2, a rotary plate 10 is fixed to the rotary shaft 1. The rotary shaft 1 is rotated by a rotary drive device (not shown) such as a motor, and the rotary plate 10 is also rotated accordingly. The rotating shaft 1 is loosely passed through a hole formed in a fixed plate (frame or the like) 20 or is rotatably received by a bearing (not shown) provided in the fixed plate 20.

On the lower surface of the rotary plate 10, a plurality of light emitting devices 11 are arranged at equal intervals on a circle C centered on the rotation axis. In this embodiment, eight light emitting devices 11 are provided at 45 ° intervals. These light emitting devices 11 are connected to a communication control device 19 provided on the rotary plate 10 and are simultaneously driven by the same drive signal representing the data to be transmitted. Rotating plate 10
Considering that the rotation axis 1 is at the center of the
The number of is preferably 3 or more.

On the other hand, one light receiving device 21 and a communication control device 29 are provided on the fixed plate 20, and these are connected to each other. The light receiving device 21 has a circumference C in which the light emitting device 11 is arranged.
Is fixed at a position directly below (in a direction parallel to the rotation axis 1). However, it is not necessary to provide the light receiving device 21 directly under the circumference C, and it may be under the position slightly deviated from the circumference C inward and outward.

The light emitted from the light emitting device 11 spreads at a constant angle θ. The projected light with such a spread is
It can be easily obtained by directly projecting the emitted light of the light emitting element included in the light emitting device 11 or by giving an appropriate spread angle to the emitted light of the light emitting element using a lens system. The light emitted from each light emitting device 11 is a light receiving device.
An area to be illuminated on a plane (a plane parallel to the fixed plate 20) including the light receiving surface of 21 is indicated by a symbol D. When the light emitted from the light emitting device 11 has an isotropic spread, the illumination area D is a circle. The emitted light does not necessarily have to be isotropic, and the illumination area D may have an elliptical shape or any other shape.

What is important is that the illumination area of the plurality of light emitting devices 11 is drawn by the relative movement of the light receiving device 21 with the rotation of the rotary plate 10 (this is the same as the circumference C). ), The number and position of the light emitting device 11, the position of the light receiving device 21, the light emitting device 11 and the light receiving device.
21 and the spread angle θ of the projected light of the light emitting device 11
Is defined. As a result, the light receiving device
21 can always receive the light emitted from any one of the light emitting devices 11 regardless of the rotation of the rotary plate 10. It goes without saying that the illumination areas D of the light emitting device 11 may partially overlap each other.

In the arrangements shown in FIGS. 1 and 2, the radius of the circumference C is R, the distance from the light emitting device 11 to the light receiving device 21 is L, the number of light emitting devices 11 is N, and the illumination area D is a circle. In this case, the following equation should be almost satisfied.

[0033]

L / R = [tan (π / N)] / [tan (θ / 2)] Equation 1

FIG. 3 shows another arrangement example. Light receiving device
Two 21 are provided. In this case, the number of the light emitting devices 11 can be half (N / 2) that in the case of FIGS. 1 and 2. It suffices that either one of the light receiving devices 21 is always within the illumination area D of one of the light emitting devices 11. When the illumination area D has the same size as that shown in FIG. 2,
The two light receiving devices 21 may be arranged at an angular interval of 45 °.
The OR signal of the light receiving signals of the two light receiving devices 21 represents the received data.

FIG. 4 shows still another arrangement example. 1 to 3, the projection light of the light emitting device 11 is projected in a direction parallel to the rotation axis 1. In FIG. 4, the projected light of the plurality of light emitting devices 11 is projected toward the rotation axis 1, and the light receiving device 21 is inside the circumference C and is always one of the light emitting devices 11.
It is provided at a position where it can receive the projected light. In this arrangement example, the rotary plate 10 can be brought close to the fixed plate 20.

FIG. 5 shows another example of the rotating body and the fixed body. The rotating body 10A has a cylindrical shape and is rotatably arranged in a cylindrical space formed in the fixed body 20A. A plurality of light emitting devices 11 that emit light toward the outside are provided on the peripheral surface of the rotating cylindrical body 10A, and a light receiving device 21 is arranged in the space of the fixed body 20A so as to face the light emitting devices 11. ing. The light receiving device 21 always receives the projected light of at least one of the light emitting devices 11.

FIG. 6 shows an arrangement suitable for simultaneous bidirectional communication.

As shown in FIG. 1 or 2, the rotating plate 10
A plurality of first light emitting devices 11 are provided on the fixed plate 20
The respective light receiving devices 21 are provided. In addition, a plurality of second light emitting devices 22 are provided on the fixed plate 20 and one second light receiving device 12 is provided on the rotating plate 10. The positional relationship between the second light emitting device 22 and the second light receiving device 12 is exactly the same as the positional relationship between the first light emitting device 11 and the first light receiving device 21, and the fixed supporting member is the rotating plate. It is only reversed between the 10 and the fixed plate 20. That is, the second light receiving device
12 always receives the projection light from any of the second light emitting devices 22.

In the rotating plate 10, a plurality of first parts are arranged on the circumference C.
Light emitting device 11 and one second light receiving device 12 are arranged, and in the fixed plate 20, one first light receiving device 21 and a plurality of second light emitting devices 22 are arranged on one circumference. .. Since each of the rotating plate 10 and the fixed plate 20 needs to be provided with these light emitting and receiving devices on one circumference, the space for disposing these is only a region along one circumference, and it is sufficient that it is relatively narrow. ..

Needless to say, such simultaneous two-way communication is also possible in the arrangements shown in FIGS. 3, 4 and 5.

In order to prevent the occurrence of a communication error due to the interference of light, the wavelength of the light used in the optical communication in the first light emitting / receiving devices 11, 21 and the second light emitting / receiving device 22,
The wavelength of light used for optical communication in 12 may be different.

In the simplest case, the emission wavelength of the first light emitting device 11 and the emission wavelength of the second light emitting device 22 are made different. First
A filter is provided on the front surface of each of the second light receiving devices 21 and 12 to allow passage of only light in a narrow band centered on the wavelength of the projected light from the corresponding light emitting device. When the light emitting elements included in the first and second light emitting devices generate light in a wide wavelength band, it is preferable to dispose filters having different pass bands on the front faces of these light emitting devices.

FIG. 7 shows an example of the electrical configuration of the communication control device and the light emitting / receiving device in bidirectional communication. The communication control devices 19 and 29 have the same configuration, and the light emitting devices 11 and 22
Since the light receiving devices 12 and 21 have the same configuration, only the communication control device 19, the light emitting device 11 and the light receiving device 12 are shown in the block.

In the communication controller 19, a plurality of digital input signals are given to the input circuit 31 in parallel. The digital input signal is, for example, a sensor detection signal or an actuator control signal. These plural digital input signals are parallel / serial (P / S) conversion circuits.
32 is sampled at a constant cycle (this is called a cycle) and converted into a serial digital signal,
It is given to a plurality of light emitting devices 11 at the same time.

The light emitting device 11 includes an amplifier 13 for amplifying an input serial digital signal, and a light emitting diode (LED) as a light emitting element driven by the output of the amplifier 13.
14 and a lens system 15 for projecting the light emitted from the LED 14 by spreading the light at a constant angle θ. L
Pulsed light representing a serial digital signal is emitted from the ED 14 and is received by the light receiving device 21.

Similarly, under the control of the communication control device 29, pulsed light representing serial digital data is projected from the light emitting device 22 and is received by the light receiving device 12. The emission wavelength of the LED included in the light emitting device 22 is different from the emission wavelength of the LED 14 of the light emitting device 11.

The light receiving device 12 allows the passage of the light having the emission wavelength of the light emitting device 22 and blocks the light having the emission wavelength of the LED 14, the lens system 24 for condensing the light passing through the filter 23,
Photodiode (PD) (or phototransistor) 25, PD25 as a light receiving element for receiving the condensed light
An amplifier 26 for amplifying the received light signal and a binarization circuit 27 for binarizing or shaping the output signal of the amplifier 26 are provided.

Since the light projected from the light emitting device 11 or 22 is spread as described above, it does not always have a uniform light intensity in the illumination area D. Further, the light intensity is slightly higher in the portion where the adjacent illumination areas D overlap. Therefore, the level of the received light signal of the PD 25 is also not constant. Light emitting device 11 or 22
The light projected from is in the form of a pulse, and the presence or absence of the pulse or the level of the level represents 1, 0 of the binary signal, respectively.
In the binarization circuit 27, such a peak value varies depending on the positional relationship between the light emitting device and the light receiving device, but it is possible to clearly distinguish between the level representing 1 and the level representing 0 of the logical value. The received light signal is converted into a binary digital signal representing 1 or 0. The threshold level for level discrimination in the binarization circuit 27 is the lowest (or highest) level of the received light signals representing the logical value 1 and the highest level of the received light signals representing the logical value 0. It is set midway between the high (or low) level.

The received serial digital signal generated by binarizing in this way is converted into a parallel digital signal in the serial / parallel (S / P) conversion circuit 33, and further in the latch circuit 34 for one cycle. It is held for a period of, and is output to the outside through the output circuit 35. This output digital signal may be used to control the actuator and collect sensor data.

FIG. 8 shows the configuration of an electric circuit used in an arrangement configuration in which two light receiving devices 12 (21) are provided (for example, the arrangement configuration of FIG. 3).

The output signals of the two light receiving devices 12 are OR circuits 37.
To the S / P conversion circuit 33. Two photo detectors
Similarly, the output signal of 21 also becomes the reception data by taking the OR logic. Other configurations are the same as those shown in FIG.

FIG. 9 shows an input signal, a transmission signal, a reception signal and an output signal. The time axes of the central transmission and reception signals are shown enlarged.

The input signals A, B, C, D are sampled at time points t ₁ , t ₂ , t _3, etc. every cycle, converted into serial signals, and transmitted from the light emitting device. The light receiving signal from the light receiving device is converted into parallel signals A, B, C, D, and then taken into the next stage circuit as an output signal at times t ₁₁ , t ₁₂ , t _13, etc.

Although a plurality of light emitting devices are provided in the above embodiment, a plurality of light receiving devices may be provided and one light emitting device (or two or more light emitting devices) may be provided. In this case, the light projected from one light emitting device is arranged so that at least one of the plurality of light receiving devices can receive it, and the OR signal of the light receiving signals of the plurality of light receiving devices is used as the reception signal. ..

Further, in the above embodiment, one of the members that relatively rotate is the rotating plate and the other is the fixed plate, but both may be the rotating plates. The two rotary plates may rotate in the same direction or in different directions.

[Brief description of drawings]

FIG. 1 is a perspective view showing an arrangement example of a light emitting device and a light receiving device.

2A is a plan view showing the arrangement of the light emitting device and the light receiving device shown in FIG. 1, and FIG. 2B is a side view.

3A and 3B show another arrangement example of the light emitting device and the light receiving device, FIG. 3A being a plan view and FIG. 3B being a side view.

FIG. 4 shows still another arrangement example of the light emitting device and the light receiving device, (A) is a plan view and (B) is a side view.

FIG. 5 is a perspective view showing another example of a rotating body and a fixed body.

FIG. 6 is a side view showing an arrangement for performing bidirectional communication.

FIG. 7 is a block diagram illustrating an electrical configuration example of a communication device.

FIG. 8 is a block diagram illustrating another electrical configuration example of the communication device.

FIG. 9 is a time chart showing an input signal, a transmission signal, a reception signal and an output signal.

[Explanation of symbols]

 10 Rotating plate 10A Rotating body 11,22 Light emitting device 12,21 Light receiving device 20 Fixed plate 20A Fixed body

Claims (3)

[Claims] 1. A first light-emitting device that emits light that spreads to one of the two relatively rotating supports, and a first light-receiving device that receives light from the first light-emitting device to the other. A plurality of at least one of the first light emitting device and the light receiving device are respectively provided on the circumference around the relative rotation center and are spaced apart from each other. Signal transmission between relatively rotating objects, wherein light emitted from at least one first light emitting device is received by at least one first light receiving device at a relative rotational angular position apparatus. 2. A second light emitting device that emits a spreading light is further provided on the other support, and a second light receiving device that receives light from the second light emitting device is further provided on the one support. At least one of the second light-emitting device and the light-receiving device is arranged in a plurality around the circumference centered on the relative rotation center with a space between each other, and all of the two supports are arranged relative to each other. The relatively rotating object according to claim 1, wherein the light emitted from the at least one second light-emitting device is configured to be received by the at least one second light-receiving device in the rotational angular position. Signal transmission equipment between. 3. A wavelength of light used in optical communication between the first light emitting device and the first light receiving device, and a wavelength of light used in optical communication between the second light emitting device and the second light receiving device. The signal transmission device between relatively rotating objects according to claim 1 or 2, wherein the wavelength of light used is different.