JPH06165224A - Convergence deviation detecting device and method - Google Patents

Abstract

PURPOSE:To quantify a convergence deviation, to easily attain a convergence adjustment in a liquid crystal projector, detector which detects the difference of the scanning time of a luminous line. CONSTITUTION:This device is equipped with a screen 3 at which luminance sensors 7-10 are provided, and a video signal generator 5 which generates the luminous line which scans the screen 3 at a fixed speed. Moreover, the device is equipped with a deviation detector 4 which detects a difference between a time since the scanning of the luminous line is started until the light is detected by the luminance sensor at the time of driving one liquid crystal panel and a time since the scanning of the luminous line is started until the light is detected by the luminance sensor at the time of driving the other liquid crystal panel, by a video signal from the video signal generator 5. Then, a time difference since the scanning is started until the luminous line passes through a specific point on the screen 3 at the time of allowing the luminous line to scan the screen at the fixed speed by using the different liquid crystal panels indicates the deviation of a relative position between position between the liquid crystal panels, so that the convergence adjustment can be easily attained by adjusting the position of the liquid crystal panel based on the time difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector using a plurality of liquid crystal panels as light valves, and more particularly to the convergence adjustment of the plurality of liquid crystal panels.

[0002]

2. Description of the Related Art In a liquid crystal projector using three liquid crystal panels (so-called three-panel type), it is necessary to adjust the convergence of red, green and blue, but generally, the position of each liquid crystal panel is mechanically adjusted. It is done by doing.

As shown in FIG. 9, the convergence deviation is caused by two directions (x, x) parallel to each side of the liquid crystal panel 1.
y) and parameters such as the deviation of the rotation direction (θ) about the axis vertical to the liquid crystal panel surface are intricately entangled with each other, and conventionally, the adjuster actually adjusts them while looking at the image on the screen. Therefore, the adjuster requires skill and adjustment time is required, which is one of the major factors that hinder the improvement of productivity.

Further, when the number of pixels of the liquid crystal increases and the pixel pitch becomes finer as in the case of supporting high-definition, it becomes more difficult to make fine adjustment in pixel units by visual adjustment.

[0005]

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art as described above, and in order to facilitate the convergence adjustment of a liquid crystal projector, which requires a great deal of time and manpower, it is possible to adjust the convergence of the convergence. It is intended to provide a method for facilitating detection and a convergence deviation detecting device using the method.

Further, the present invention provides an adjusting method and an adjusting device for automating convergence adjustment using the above-mentioned convergence deviation detecting method.

[0007]

Therefore, the convergence detecting apparatus according to the present invention comprises a screen provided with a light detecting means, a signal generator for generating a bright line sweeping the screen at a constant speed, and the signal generator. From the start of the sweep of the bright line when one liquid crystal panel is driven by the video signal from the above until the photodetection means detects the light, and the start of the sweep of the bright line when the other liquid crystal panel is driven and the photodetection from the start of the sweep of the bright line A deviation detector that detects a difference from the time until the means detects light.

Further, the convergence adjusting device according to the present invention drives the convergence detecting device, a mechanism capable of adjusting the position of the liquid crystal panel, and the mechanism to eliminate the convergence deviation based on the detection result of the convergence deviation detecting device. Drive means for driving.

Further, the convergence deviation detecting method according to the present invention drives one liquid crystal panel to generate a bright line sweeping on the screen at a constant speed, and measures the time from the start of sweeping until passing a specific point on the screen. Then, drive another liquid crystal panel to generate a bright line sweeping at the same constant speed on the screen, and measure the time from the start of sweeping until passing through the same specific point as on the screen. The convergence deviation between the two liquid crystal panels is detected from the two time differences.

Further, the convergence deviation adjusting method according to the present invention drives one liquid crystal panel to generate a bright line sweeping at a constant speed on the screen, and measures the time from the start of sweeping until passing a specific point on the screen. Then, drive another liquid crystal panel to generate a bright line on the screen that sweeps at the same constant speed as the tip, and measure the time from the start of the sweep until it passes the same specific point as the tip on the screen,
The convergence deviation between the two liquid crystal panels is detected from the two time differences, and the position of the liquid crystal panel is changed based on the detection result.

[0011]

[Function] When the bright lines are swept at a constant speed using different liquid crystal panels, the time difference from the start of sweep to the passage of a specific point on the screen represents the shift in the relative position between the liquid crystal panels. Convergence can be adjusted by adjusting the position of the liquid crystal panel based on this time difference.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a convergence deviation detecting apparatus according to the present invention. In this figure, 2 is a liquid crystal projector, 3 is a screen, 4 is a convergence deviation detector, 5 is a video signal generator, 6 is a deviation amount display device, and 7 to 10 are luminance sensors.

The liquid crystal projector 2 receives the video signal from the video signal generator 5 and projects it on the screen 3. The video signal generated by the video signal generator 5 sweeps the screen 3 at a constant speed. Therefore, the liquid crystal projector 2 is arranged so that this bright line moves for each pixel of the liquid crystal panel.
The video signal generator 5 is supplied with the drive clock.

Further, the video signal generator 5 supplies a pulse indicating the start of the sweep and a pulse having a vertical period to the convergence deviation detecting device 4.

2 and 3 are timing charts for explaining this embodiment. The operation will be described below with reference to these drawings.

First, from the signal generator, a synchronizing signal as shown in FIG.
Entered in. In the liquid crystal projector 2, a clock of a pixel cycle for driving the liquid crystal as shown in FIG.
An image is displayed on the screen 3 according to the video signal.
(At first, all black). Here, the clock in FIG. 2B is based on the number of pixels in the horizontal direction (x direction in FIG. 9) of the liquid crystal panel, and N in the drawing is the number of pixels in that direction.

Now, as shown in FIG. 2C, the clock at the beginning of the horizontal period is set to 0, and the pulse is superimposed on the video signal in synchronization with the nth clock. n is appropriately determined according to the position of the brightness sensor. If this is continued for one field (for one frame if interlaced drive is used), a vertical line appears at a certain position on the screen.

In the next field, as shown in FIG.
The pulse superposition position is moved to a position corresponding to the (n + 1) th clock. Then, the vertical line shifts to the right by one pixel. Similarly, if the timing of superimposing the pulse is changed for each field, the vertical lines appear to move from left to right on the screen 3. (Fig. 2 (e) ~
(See (g)) The image signal, which is created as described above and represents the bright line that sweeps at a constant speed, is supplied to the liquid crystal projector 2. First, red and blue are optically cut off, or an electric signal is generated. Only the light that has passed through the green liquid crystal panel is displayed on the screen 3 by turning it off.

FIG. 3 (h) shows a clock having a vertical cycle.
(I) is a sweep start pulse. For explanation now,
The field in which the sweep starts is set to 1, and numbers are sequentially assigned from there, such as 2, 3, 4, ....

Suppose now that the luminance sensor detects light in the fifth field for the first time as shown in FIG. 3 (j). That is, at that time, the swept emission line passed over the sensor.

Next, only the light that has passed through the red liquid crystal panel is displayed on the screen 3. Then, when the same sweep is performed, it is assumed that the same luminance sensor detects light in the second field, as shown in FIG. Since the bright lines are swept from the left to the right one pixel at a time in one field, the convergence shift between the green liquid crystal panel and the red liquid crystal panel is 3 pixels at the position of the sensor.

Similarly, the blue liquid crystal panel is also swept, and at that time, if light is detected in the 7th field as shown in FIG. 3L, two pixels are moved to the right of the green liquid crystal panel. It means that they are out of alignment.

In this way, the relative convergence deviation of any one point on the screen 3 in the horizontal direction (x direction) can be detected.

The vertical (y-direction) shift is similarly set as follows.
The horizontal line may be swept vertically. N at the start of the sweep
If a bright line is generated on the line, the horizontal line can be swept in the vertical direction by sequentially generating the bright line on the (n + 1) th line and then on the (n + 2) th line in the next field. Similarly to the horizontal shift, the vertical shift can also be detected line by line depending on the timing of detecting light for red, green, and blue.

FIG. 5 shows an embodiment of the convergence deviation detector. In FIG. 5, 11 is an AND gate, 12
Is an inverter, 13 is a counter that is reset by the sweep start pulse supplied to the terminal 14, and counts the vertical cycle pulse supplied to the terminal 15, 16 to 23 are, when the output of the AND gate 11 becomes high level, It is a register that holds the value of the counter. Also, 24-29
Is a subtractor, 30 is a terminal to which a control signal for switching the registers 16 to 23 is input, and 31 to 34 are terminals to which detection signals of the luminance sensors 7 to 10 are input.

Next, the operation of the convergence deviation detector will be described, but in order to simplify the explanation, the explanation will be given by focusing on only the luminance sensor 7.

First, the control signal input to the terminal 30 is set to the low level to drive only the green liquid crystal panel to sweep the bright line. The counter is reset by the sweep start pulse and starts counting pulses in the vertical cycle. When the bright line passes over the luminance sensor 7, a detection signal is obtained at the terminal 31,
The counter value of the counter at that time is held in the register 16. Next, the control signal is set to a high level, and only the liquid crystal panel for another color, for example, red, is driven to sweep the bright line. Similarly to the above, when the bright line passes over the luminance sensor 7, the terminal 31 becomes high level, and the counter value at that time is held in the register 17 this time. Both registers 16, 17
The difference in the counter values of the is obtained at the output of the subtractor 24, which represents the green and red convergence deviation in the x direction.

In this way, by measuring the local convergence deviations at some points on the screen 3,
You can know the convergence deviation of the entire screen.

In the embodiment of FIG. 1, a total of four brightness sensors are mounted, one on each side of the screen 3. It is assumed that another color, for example, red, is displaced from green by 5 pixels to the left at the upper measurement point (luminance sensor 7) and 3 pixels to the right at the lower measurement point (luminance sensor 9). Figure 4
-Shown in (a). At this time, the difference between the register 16 and the register 17 in FIG.
Is +3.

As an adjustment procedure, first, the rotation direction (θ direction) is adjusted so that the vertical and vertical displacement amounts are the same and the same amount. This θ adjustment is performed by the difference between the output of the subtracter 24 and the output of the subtractor 26 in FIG.
The output of 8 should be minimized.

Thus, as shown in FIG. 4 (b),
It is assumed that there is a one-pixel shift to the left. Then, the convergence can be adjusted by making an adjustment in the x direction next.

If there is no factor of convergence deviation other than the x, y, and θ directions, when the adjustment in the x and θ directions is completed,
The deviations in the y direction at both points of the brightness sensors 8 and 10 are the same on the left and right. Therefore, if the adjustment in the y direction is performed, the convergence adjustment is completed. Similar to the x direction, the adjustment in the y direction can be performed by using the brightness sensors 8 and 10 based on the difference between the register 18 and the register 19 and the difference between the register 22 and the register 23 in FIG.

In the above embodiment, since the brightness sensor is used, the colors cannot be discriminated. Therefore, it is necessary to separately drive the red, green and blue liquid crystal panels to sweep the bright lines. However, since the color can be discriminated by using the color sensor, the convergence deviation at the point where the sensor is placed can be detected by only sweeping the white line once.

FIG. 6 shows an example of a convergence deviation detector when a color sensor is used. The color sensor is assumed to have three brightness sensors (for example, photodiodes) to which red, green, and blue color filters are attached, respectively. In this figure, 35 is a color sensor, 36, 37, 3
Reference numeral 8 is a buffer amplifier that converts the detection waveform of the sensor into a logic level. Further, 39 is reset by a sweep start pulse as in the embodiment shown in FIG.
A counter that starts counting vertical pulse, 40-4
Reference numeral 1 is a register that holds the value of the counter 39 when the sensor detects a bright line, and 43 and 44 are subtractors.

When a white bright line is swept in the vicinity of the color sensor 35, if there is no convergence deviation, red,
Bright lines are detected at the same time for both green and blue, and register 40-
The values of the counter 39 held in 42 are all constant. However, if there is a convergence deviation, the timing of detecting the bright line does not match between red and green or blue and green. Therefore, the values of the counter 39 held in the registers 40 to 423 are not the same, and the difference between the register 40 and the register 41 is red and green, and the difference between the register 41 and the register 42 is green and blue. It represents the relative convergence deviation in the direction.

If the deviation of the convergence is quantified as data, it can be fed back to the adjusting mechanism to enable automatic adjustment. In the liquid crystal projector 2, the convergence adjustment is mainly performed by mechanical means. That is, the position and orientation of the liquid crystal panel are changed by screws and the like. Therefore, if this adjustment is performed by a stepping motor or the like and the motor is controlled by the data of the convergence deviation measured as described above, the automatic adjustment system is realized. Figure 7
The situation is shown in. Reference numerals 43 to 45 are terminals to which data representing the convergence deviations in the x-direction, the y-direction, and the θ-direction, respectively, as described in the above embodiment are input. 46-4
Reference numeral 8 denotes a motor drive circuit which operates so that the motor rotates normally or reversely according to whether the deviation data is positive or negative. 49-51 are motors that can rotate in both forward and reverse directions. 52 is a liquid crystal panel, 53 is an adjusting pedestal, 54 is an x adjusting screw, 55 is a y adjusting screw, and 56 is a θ adjusting screw. The motor 49 adjusts the adjusting screw 54, the motor 50 adjusts the adjusting screw 55, and the motor 51 adjusts the adjusting screw 56. With this configuration, when the convergence deviation is detected, the motors 49 to 51 move accordingly,
Adjust the relative position of the LCD panel to correct the convergence shift.

When a color sensor is used as in the embodiment shown in FIG. 6, the sensor can also be used as a white balance detecting sensor. Therefore, it can also be used as a white balance adjustment system. FIG. 8 shows an embodiment in which the sensor is also used as a white balance detecting sensor. Incidentally, the same configurations as those of the embodiment of FIG.

In FIG. 8, reference numerals 57, 58 and 59 denote log amplifiers to which the detected voltage from the color sensor 35 is input.
When the input is v, the output is Log (v). 6
0 and 61 are subtractors, 62 and 63 are inverse log amplifiers, and if the input is Log (v), the output will be v. Now, the detection voltages from the color sensor 35 are Vr, Vg, red, green, and blue, respectively.
If Vb, the output of the log amp 57 is Log (Vr)
Similarly, the output of 58 is Log (Vg). Then, in the subtractor 60, Log (Vg) -Log (Vr) = Log
(Vg / Vr) is obtained, and by the reverse log amplifier 62, Vg / Vr, which is the ratio of the red detection output and the green detection output, is obtained.
You can know.

Similarly, the ratio of green to blue and Vg / Vr can be obtained. The white balance can be quantitatively known from the ratio of green to red and green to blue, and can be used as adjustment data.

[0041]

As described above, according to the convergence deviation detecting apparatus and the detection method of the present invention, the convergence deviation can be quantified, and the convergence adjustment in the liquid crystal projector 2 becomes extremely easy, which is useful for improving the productivity.

The bright line sweeping on the screen 3 is
Since each pixel is moved by one pixel of the liquid crystal panel (when sweeping in the x direction) or by one line of the liquid crystal panel (when sweeping in the y direction), it is possible to perform adjustment in pixel units. Therefore, even if the number of pixels of the liquid crystal increases and the pixel pitch becomes finer, adjustment is possible.

Further, when a color sensor is used, it is possible to measure the color temperature at the same time and it can be applied to a white balance adjusting system.

Further, according to the convergence deviation adjusting device and the adjusting method of the present invention, the convergence adjustment can be automated and its effect is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining a bright line generating operation of the present invention.

FIG. 3 is a view for explaining the operation of the convergence deviation detection device of the present invention.

FIG. 4 is a diagram illustrating a convergence adjustment procedure according to the present invention.

FIG. 5 is a view showing an embodiment of the convergence deviation detecting device of the present invention.

FIG. 6 is a view showing another embodiment of the convergence deviation detecting device of the present invention.

FIG. 7 is a view showing an embodiment of the convergence deviation adjusting device of the present invention.

FIG. 8 is a view showing still another embodiment of the convergence deviation detecting device of the present invention.

FIG. 9 is a view for explaining a convergence deviation of a liquid crystal panel.

[Explanation of symbols]

 2 Liquid crystal projector 3 Screen 4 Convergence deviation detector 5 Video signal generator 7, 8, 9, 10 Luminance sensor

Claims (9)

[Claims] 1. A device for detecting the convergence of a liquid crystal projector using a plurality of liquid crystal panels as light valves, comprising: a screen provided with a light detecting means; and a bright line sweeping the screen at a constant speed. Generated signal generator, the time from the start of the sweep of the bright line when one liquid crystal panel is driven by the video signal from the signal generator to the time when the light detection means detects light, and the other liquid crystal panel is driven. A convergence deviation detecting device comprising a deviation detector that detects a difference from the time from the start of sweeping the bright line to the time when the light detecting means detects light. 2. The convergence deviation detecting device according to claim 1, wherein two brightness detecting means are provided. 3. The convergence deviation detecting device according to claim 2, wherein the two brightness detecting means are arranged such that a straight line connecting the two brightness detecting means is perpendicular to the sweep direction of the bright line. Convergence deviation detection device. 4. A device for detecting the convergence of a liquid crystal projector using a plurality of liquid crystal panels as light valves, comprising a screen provided with color detection means, and a white bright line sweeping the screen at a constant speed. And a time period until the color detecting means detects light of a certain color and the light of another color is detected when at least two liquid crystal panels are driven by a video signal from the signal generator. A convergence deviation detection device comprising a deviation detector that detects a difference from the time until the deviation. 5. The convergence deviation detecting device according to claim 4, wherein the color detecting means is capable of individually detecting three colors of red, green and blue, and means for detecting a color temperature based on a detection output of each color is provided. A convergence deviation detecting device characterized by being provided. 6. The convergence deviation detecting device according to claim 1, a mechanism capable of adjusting the position of the liquid crystal panel, and a driving mechanism for eliminating the convergence deviation based on the detection result of the convergence deviation detecting device. Convergence deviation adjusting device comprising a driving means for driving. 7. A method for detecting the convergence of a liquid crystal projector using a plurality of liquid crystal panels as light valves, wherein one liquid crystal panel is driven to generate bright lines sweeping at a constant speed on a screen. , Measure the time from the start of sweep to passing a specific point on the screen, then drive another liquid crystal panel to generate a bright line on the screen that sweeps at the same constant speed as before. Convergence deviation detection method for measuring the time until it passes through the same specific point as in the above, and detecting the convergence deviation between the two liquid crystal panels from the difference between the two times. 8. A method for adjusting the convergence of a liquid crystal projector using a plurality of liquid crystal panels as light valves, wherein one liquid crystal panel is driven to generate bright lines sweeping at a constant speed on a screen. , Measure the time from the start of sweep to passing a specific point on the screen, then drive another liquid crystal panel to generate a bright line on the screen that sweeps at the same constant speed as before. The time until it passes through the same specific point as above is measured, the convergence deviation of the two liquid crystal panels is detected from the two time differences, and the position of the liquid crystal panel is changed based on the detection result so that the convergence deviation disappears. Convergence adjustment method to adjust. 9. The convergence deviation detecting method according to claim 7, wherein the bright line sweeping on the screen is moved by one pixel of the liquid crystal panel or one line of the liquid crystal panel for each field. Convergence deviation detection method.