JP2003047017A - Automatic convergence correction circuit of tri-color tube projection television - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform accurate convergence correction by directly detecting position information in a screen by an integrated sensor/screen structure to prevent a projected screen from being disturbed. SOLUTION: In the automatic convergence correction circuit, a photosensor unit is arranged at the center of the front of a screen, the photosensor unit is divided into four portions, the detection output of each small sensor is inputted to an arithmetic unit for adding and subtracting each detection output, the position of the photosensor unit is detected regarding horizontal and vertical directions based on the arithmetic result, the distance in convergence deviation to a position that is subjected to convergence adjustment in advance and to a detected photosensor unit position is obtained, and convergence correction is made based on the positional relationship.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection television, and more particularly to a novel structure of a position detecting sensor in an automatic convergence correction circuit of a three-tube projection television.

[0002]

2. Description of the Related Art A plurality of optical sensor units are arranged in an overscan portion on the rear surface of a screen of a three-tube projection television having projection tubes of R, G, and B colors, and the convergence is detected based on the detection output from the optical sensor units. Various correction schemes have been proposed.

FIG. 1 shows a first example of the prior art. This example is a projection television system including projection tubes 18r, 18g, and 18b and a screen 11, and a photoelectric conversion element provided at two locations on the periphery of the screen 11 detects a displacement from a reference position. Position detecting section 12 and a pattern generating section 15 for generating an alignment pattern toward a position on the screen where the position detecting section can receive light.
And the output of the position detector, the convergence yoke 17
Convergence correction unit 1 for controlling r, 17g, and 17b
4, a convergence correction device is disclosed.

In this example, a plurality of photoelectric conversion elements (phototransistors) are arranged at two positions on the long side and the short side of the peripheral portion of the screen, and the position data of the elements are obtained from the obtained detection output. After adjusting the dynamic convergence, the convergence that changes statically under the influence of temperature etc. is automatically adjusted. This example also discloses an example in which a CCD linear sensor is used as a photoelectric conversion element.

FIG. 2 shows a second example of the prior art. In this example, a storage unit 27 that stores correction data, and an address generation unit 26 that reads the correction data in the storage unit according to scanning.
A waveform creating unit 28 that creates a convergence correction waveform from the read correction data, and photodetector elements 22a to 22g arranged at a plurality of locations around the screen 21.
A / D that digitizes analog information from photodetector
Disclosed is an automatic convergence deviation correction system that includes a converter 29 and a calculation control unit 30 that creates convergence correction data based on information from a digitized photodetector.

In this example, eight photo-detecting elements are arranged in the overscan portion of the display screen as a sensor, and each uses one large-sized amorphous solar cell (about 10 × 10 mm square). The detection output from the detection element is converted into a digital value by the A / D converter and taken into the arithmetic control unit, the sensor position is calculated by a predetermined arithmetic processing, and the convergence deviation amount is estimated based on the calculated sensor distance. To perform convergence correction.

[0007]

However, in the method of the first example of the prior art, since the area of the position detecting section by the photodetecting elements provided at the two peripheral portions for detecting the position is small, these The output sensitivity detected from is insufficient.
Therefore, it is necessary to arrange a plurality of phototransistors in order to perform highly accurate convergence correction.

In the second method of the prior art, since the size of the sensor section is large, there is an advantage that sufficient sensor sensitivity can be obtained. However, after using the A / D converter and temporarily storing it in the memory, the position is stored. Performing detection calculation. That is, first, the state where the area of the entire sensor is irradiated with light is stored as the maximum sensor output, and then the sensor position is detected at the position of the alignment pattern at which the sensor output becomes half. Therefore, in this example, an A / D converter is required, and storage and calculation of two processing steps are required for position detection.

Further, since the position of the central part of the screen cannot be detected by these methods, the position of the central part of the screen is to be estimated by calculation from the position detection data of a plurality of optical sensor units arranged in the overscan part. However, there is a problem that the position detection is not always accurate.

Therefore, an object of the present invention is to arrange an optical sensor unit composed of four divided small sensors at an arbitrary position on the front surface of the screen, preferably in the central portion, and simplify the detection output of these small sensors. It is an object of the present invention to provide an automatic convergence correction circuit that can easily detect the position of an optical sensor unit only by moving the movement direction of an alignment pattern horizontally and vertically by performing addition / subtraction calculation processing with such a circuit configuration.

According to the present invention, since the optical sensor unit is arranged on the front surface of the screen, preferably in the central portion, it is possible to detect the position of the central portion of the screen as compared with the peripheral portion (overscan portion) on the rear surface of the screen as in the prior art. The accuracy is improved, a plurality of conventional photosensor units having a large size are not required, an A / D converter is not required, the processing steps are simplified, and the overall cost reduction can be achieved. .

As described above, the present invention is a system for detecting the position of the optical sensor unit arranged in the central portion of the screen. As will be described later in detail, the position of the black stripe provided on the front surface of the screen is utilized. As a photosensor unit, an amorphous screen solar cell is arranged between the black stripe and the diffusion layer, and the light component leaking from the diffusion layer is detected to detect the position of the central portion of the screen.

[0013]

In order to achieve such an object, according to the present invention, there is provided an automatic convergence correction circuit for a three-tube projection television, which is located at an arbitrary position on the front surface of the screen, preferably in the central portion. Placed in,
An optical sensor unit composed of four divided small sensors, and a calculation unit that inputs the detection output of each of the four divided small sensors and performs addition and subtraction calculation of each detection output, and the calculation result from the calculation unit is input. A microcomputer for instructing the movement direction of the alignment pattern and a non-volatile memory for storing the convergence correction data from the microcomputer. Based on the calculation result of the calculation unit, the position of the optical sensor unit is set in the horizontal and vertical directions. Is detected and the distance of the convergence deviation with respect to the position where the convergence is adjusted in advance and the detected position of the optical sensor unit is obtained, and the convergence is corrected based on the positional relationship between them.

Preferably, the arithmetic unit subtracts the sum of the detection outputs from the latter two small sensors from the sum of the detection outputs from the first two small sensors when the alignment pattern is moved in the horizontal direction. The first value and the first 2 when the alignment pattern is moved vertically.
A second value obtained by subtracting the sum of the detection outputs from the subsequent two small sensors from the sum of the detection outputs from the small sensors is obtained, and the position of the optical sensor unit is obtained from these values.

More preferably, the optical sensor unit is composed of stripe-shaped amorphous silicon solar cells arranged on a black stripe on the front surface of the screen.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 3 is a block diagram including an automatic convergence circuit according to the present invention. First, a normal digital convergence system adopted in a projection television will be described below.

The illustrated digital convergence control section (hereinafter, convergence controller) 300
Is a control unit for digital convergence correction. The convergence controller 300 has a built-in memory (RAM) (not shown) whose contents are read in synchronization with the horizontal synchronizing signal (H) and the vertical synchronizing signal (V) of the screen. Convergence correction data of grid points (eg, 13 rows × 16 columns = 208 points) on the screen are stored in the RAM from the nonvolatile memory (EEPROM) 500 via a local microcomputer (hereinafter, local microcomputer) 400 when the power is turned on. Is stored. In this case, there are a total of 6 sets of grid point data for horizontal and vertical convergence correction for each color of R, G, and B.

Each grid point data is obtained by a well-known interpolation calculation from adjacent grid points. The six sets of convergence correction data are the horizontal synchronization signal (H) and the vertical synchronization signal (V).
In synchronization with the above, each is converted into an analog signal by a D / A converter (not shown), and a convergence yoke (hereinafter, referred to as
(Also called CY). This analog signal is current-amplified by the CY amplifier 81, and further, each color projection tube 9
By supplying as a correction current to the horizontal and vertical convergence yokes 0 to 92, the geometric distortion of the screen,
And correct misconvergence. In this case, the convergence correction data is adjusted on the factory production line, and the EEPROM (500) is used as the convergence correction data.
Accumulated in. The screen thus corrected is projected on the screen 110 by each color projection tube.

Next, even after the convergence correction data has been adjusted at the factory as described above, the shipped set is subject to geometric distortion of the screen or aging due to aging or geomagnetic change in each household. Misconvergence shift occurs. In order to correct such distortion due to aging, etc., the position of the optical sensor unit and the position of convergence deviation are used by using the optical sensor unit arranged in the center of the front of the screen and the alignment pattern projected on the screen. It is detected, and the convergence deviation is corrected from the distance and the direction (vector) between them.

In the automatic convergence adjustment for automatically performing such correction, as shown in FIG. 3, the local microcomputer 400 receives an automatic adjustment instruction from the main microcomputer,
The instruction is sent to the convergence controller 300.
Upon receiving the instruction, the convergence controller 300 enters the automatic convergence adjustment mode, and the alignment pattern displays the on-screen display (OS).
D) through the video switcher 80 to the projection tubes 90-
It is added to the cathode of 92 and is projected on the screen 110.

As will be described later, the optical sensor unit in the center of the front surface of the screen generates a predetermined detection output when the alignment pattern is projected, and this detection output is amplified and subtracted by the arithmetic units 201 and 202 to be amplified and adjusted. The position of the optical sensor unit can be detected by inputting the calculation result to the digital convergence control section 300. As will be described later, assuming that there are four small sensors A, B, C, and D of the four-divided optical sensor unit, in the arithmetic unit 201, {(A + B) − (C +
D)} is calculated, and in the calculation unit 202, {(A +
C)-(B + D)} is calculated.

FIG. 4 is a block diagram of the main part of the screen of the projection television shown in FIG. Screen 110
Is a Fresnel lens 110a and a lenticular lens 1
It is composed of a diffusion layer 110d that constitutes 10b and 110c and a black stripe portion 110e that absorbs external light from the front surface.

FIG. 5 is a detailed structural diagram of a stripe-shaped amorphous silicon solar cell formed in the black stripe portion shown in FIG. As shown in the figure, the black stripe portion has a sandwich structure including a transparent electrode, amorphous silicon (α-Si), a metal electrode, and a black stripe on the diffusion layer 110d, and forms a stripe-shaped solar cell. . With such a structure, light leaking through the internal diffusion layer 110d is detected.

FIG. 6 shows a four-division sensor structure in which the screen of FIG. 3 is divided horizontally and vertically at the center of the screen when viewed from the front. The detection output is obtained from each solar cell of each small sensor A, B, C, D. The small sensor A is a collection of outputs of the striped solar cells on the upper left side of the screen. The small sensor C is a collection of the outputs of the solar cells on the upper right side of the screen. The small sensor B is a collection of outputs of the stripe-shaped solar cells on the lower left side of the screen.
The small sensor D is a collection of the outputs of the solar cells on the lower right side of the screen.

The output characteristics shown in the figure are the optical sensor unit 1
The range of 00 is the range of the solid line as shown {(A),
It is an S-shaped output characteristic when it is limited to (B), (C), (D)}. The parts other than the optical sensor unit 100 have a structure in which the amorphous silicon of FIG. 5 is used as an insulating layer. In addition, 101 is an electrode part.

The detection outputs from the small sensors A, B, C and D are subjected to addition / subtraction calculation by the arithmetic unit. That is, {(A +
B)-(C + D)} has a horizontal S-shaped output characteristic.
Also, {(A + C)-(B + D)} has an S-shaped output characteristic in the vertical direction.

FIG. 7 is a layout view of the optical sensor unit 100 and the alignment pattern. FIG. 7A shows the case of horizontal position detection, and the S-shaped characteristic shown in FIG. 6 when the alignment pattern 207 is moved in the horizontal direction. Is obtained.
Further, (B) is a case of vertical position detection, and when the alignment pattern 208 is moved in the vertical direction, the S-shaped characteristic shown in FIG. 6 is obtained.

As is apparent from the above, the automatic convergence correction circuit of the present invention makes it possible to detect the position of the optical sensor in the central portion of the screen, and to provide more accurate correction data than the conventional peripheral portion of the screen rear surface. Will be obtained. Further, as shown in FIG. 5, since the sensor is hidden behind the black stripe, the sensor arrangement is not visually noticeable from the outside.

Further, in the above embodiment, the structure in which the sensor is arranged in the center of the screen has been described. However, the arrangement of the optical sensor unit may be arranged at any position on the front surface of the screen so that the sensor output of that portion can be obtained. Can be

Further, although the example of the four-division sensor has been described above, a single sensor structure is also possible.

FIG. 8 is an overall processing flowchart of the convergence correction according to the present invention. This processing is performed by the local microcomputer 400 or the convergence controller 3
This is the process performed at 00. First, the digital convergence data is initialized at the time of shipment from the factory (S1). Next, for each color of R, G, B, the color of the alignment pattern is selected and displayed (S2). Next, the outputs of the small sensors A, B, C, D are measured (S3). The measuring method is shown in FIG. 9 described later. Next, it is determined whether or not the small sensor outputs have been measured for all R, G, and B colors (S4). When all colors are finished, EEPR
The difference between the factory-shipped sensor position measurement result stored in the OM (500) and the measurement result this time is calculated (S5). Next, the local microcomputer 400 creates digital convergence correction data based on this difference data (S6), and stores the data in the EEPROM (500) (S7). Further, by transferring this data to the convergence controller 300, the convergence correction is completed (S8).

FIG. 9 is a flow chart for measuring the output from the optical sensor unit according to the present invention. First, the location of the optical sensor unit 100 is detected (S1
1). However, this step is not necessary when it is clear that it is set in the center of the screen in advance. next,
The horizontal direction and the vertical direction are selected as the moving direction of the alignment pattern (S12). Next, the local microcomputer 400 reads the respective outputs of the arithmetic units 201 and 202 as the outputs of the sample hold circuits 205 and 206, and determines whether the detection output is "high" or "low" (S14). The sample and hold circuits 205 and 206 receive the output signals of the arithmetic units 201 and 203, hold the value, and "high" when the value exceeds a predetermined threshold value.
Is configured to output. Since the output of the arithmetic circuit changes as shown in FIG. 4 due to the movement of the alignment pattern, the movement of the alignment pattern first detects “high” and then “low”, so that the sensor can be easily detected. The center point of can be detected.

A specific description will be given of detection in the horizontal direction.
First, the movement of the alignment pattern is continued until the determination of "high" is made (S15). After that, "high" is detected by the movement of the alignment pattern, but the movement is further continued at this time (S15). After that, when the alignment pattern comes to the center of the sensor unit, the output of the sample hold circuit 205 becomes “low”. The movement distance of the alignment pattern at this time is stored in the RAM (S16), and the arithmetic unit is reset (S17). The same applies to the vertical direction. Further, it is again determined whether or not it is necessary to redo it in terms of measurement accuracy (S18). If it is necessary to start over, the process returns to step S11, and if not necessary, the measurement process of the optical sensor unit ends.

[0034]

As described above, according to the present invention,
By arranging the optical sensor unit on the front surface of the screen, preferably in the central portion, the accuracy of the central portion is improved as compared with the peripheral portion of the rear surface of the screen. further,
The sensor position can be detected by a simple process such as adding / subtracting the detection output of the optical sensor unit in the subsequent arithmetic unit, and the horizontal and vertical directions can be detected simply by changing the moving direction of the alignment pattern. Become. Furthermore, as a result of detecting the position of the small sensor in one processing step, high-speed processing is possible and an A / D converter is not required, resulting in a reduction in product cost.

[Brief description of drawings]

FIG. 1 is a first example of prior art.

FIG. 2 is a second example of the prior art.

FIG. 3 is a block diagram including an automatic convergence circuit according to the present invention.

FIG. 4 is a main part configuration diagram of a screen of the projection television shown in FIG.

5 is a detailed structural diagram of a stripe-shaped amorphous silicon solar cell configured in the black stripe portion shown in FIG.

FIG. 6 shows a four-division sensor structure in which the screen of FIG. 3 is divided horizontally and vertically at the center of the screen when viewed from the front.

7A and 7B are layout diagrams of the optical sensor unit and the alignment pattern of FIG. 6, where FIG. 7A is for horizontal position detection and FIG. 7B is for vertical position detection.

FIG. 8 is an overall processing flowchart of convergence correction according to the present invention.

FIG. 9 is a flowchart of a process of measuring an output from the optical sensor unit according to the present invention.

[Explanation of symbols]

70 ... Main microcomputer 80 ... Video switch 81 ... Convergence yoke amplifier 90-92 ... Projection tube 100 ... Optical sensor unit 110a ... Fresnel lens 110b, 110c ... Lenticular lens 110d ... Diffusion layer 110e ... Black stripe section 110 ... screen 201, 202 ... Arithmetic unit 205, 206 ... Sample and hold circuit 300 ... Digital Convergence Control 400 ... Local microcomputer 500 ... Non-volatile memory

Continued front page    (72) Inventor Kunihiro Yoshizawa             2-30-10 Taito, Taito-ku, Tokyo Taito Orie             Tontville LG Electronics Tokyo Lab             Inside the laboratory F-term (reference) 5C060 BA08 BC05 CE03 CF01 CG08                       CH07 CH19 GB02 GD01                 5C061 BB11 CC05 EE03

Claims (5)

[Claims] 1. A digital convergence control unit for inputting at least a horizontal synchronizing signal and a vertical synchronizing signal, performing convergence correction by a predetermined alignment pattern, and supplying a convergence yoke current, and the alignment pattern and the convergence yoke current. In an automatic convergence correction circuit of a three-tube projection television provided with a projection tube of each color of R, G, and B to be received and a screen for projecting an image from the projection tube of each color, the circuit is arranged at an arbitrary position in front of the screen. An optical sensor unit composed of four divided small sensors; an arithmetic unit for inputting the detection output of each of the four divided small sensors and performing an addition / subtraction calculation of each detected output; Input the calculation result, and the alignment pattern And a nonvolatile memory that stores convergence correction data from the microcomputer. Based on the calculation result of the calculation unit, the position of the optical sensor unit is set in the horizontal direction and the vertical direction. An automatic convergence correction for a three-tube projection television, characterized in that a distance that is detected and the convergence is adjusted in advance and a distance of the convergence deviation with respect to the detected position of the optical sensor unit is obtained, and the convergence is corrected based on the positional relationship between them. circuit. 2. The automatic convergence correction for a three-tube projection television according to claim 1, wherein the optical sensor unit is arranged at a central portion of the front surface of the screen, and the central portion serves as a four-division sensor. circuit. 3. The arithmetic unit, when moving the alignment pattern in the horizontal direction, calculates the sum of the detection outputs from the first two small sensors and the sum of the detection outputs from the second two small sensors. The subtracted first value and the sum of the detection outputs from the first two small sensors when the alignment pattern was moved in the vertical direction were subtracted from the sum of the detection outputs from the latter two small sensors. The automatic convergence correction circuit for a three-tube projection television according to claim 1, wherein the second value is obtained, and the position of the optical sensor unit is obtained from these values. 4. The automatic convergence correction circuit for a three-tube projection television according to claim 1, wherein the optical sensor unit is composed of striped amorphous silicon solar cells arranged on a black stripe on the front surface of the screen. 5. The automatic convergence correction circuit for a three-tube projection television according to claim 1, wherein a sample hold circuit for processing an output of the arithmetic unit is arranged between the arithmetic unit and the microcomputer.