JPS59178089A - Device for detecting vertical position deviation of video projector projected image - Google Patents

Abstract

PURPOSE:To detect a vertical position deviation by superimposing a position detecting pulse on a video signal and obtaining the timewise deviation of an output of the pulse signal by means of a photodetector referencing a cathode ray tube at a normal horizontal position. CONSTITUTION:Pulse signals S1-S3 for detecting position comprising plural pulses having nearly identical horizontal position at the horizontal blanking period are superimposed on a color video signal inputted from terminals t1-t3 and outputted from cathode tray tubes CRT1-CRT3. When the picture image by the cathode ray tube CRT2 is shifted downward and the picture image by the cathode ray tube CRT3 is shifted upward respectively, output signals S2'', S3'' of photodetectors PR2, PR3 are outputted by taking a time delayed by DELTAT2 and advanced by DELTAT3 respectively from the normal times T1, T2 extending from a vertical synchronizing signal VSYNC up to the center of the signals S1, S3 as a center. The DELTAT2 and DELTAT3 are timewise deviations representing the degree of vertical shift of the video image by the cathode ray tubes CRT2 and CRT3.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention provides one or more cathode ray tubes for each emission color corresponding to the three emission colors constituting a color image, and the information light of these anode ray tubes is transmitted through a magnifying lens. Alternatively, the present invention relates to a vertical position deviation detection device for a video projector projected image, which detects a vertical position deviation of a projected image on a screen via a Schmidt optical system.

Figure 1 (a) and (b) are top and front views showing an example of the above video projector, with red, green, and blue 1
Cathode ray tube CRT+, CRT that supports three emission colors
2. The information light from the CBr3 is projected onto the screen S to display a color image. Figure 2 (a,)
, (b) is a plan view and a front view showing another example of the video projector described above, in which multiple (in this case two) cathode ray tubes are used for each emission color to increase the brightness, that is, for red emission color. Corresponding cathode ray tubes CR14, CBr4, cathode ray tubes CRT2.corresponding to green emission color. CBr4, a cathode ray tube CRT3 corresponding to blue emission color. CRT6 is provided, and these cathode ray tubes CRTI, CIRT2,
..., CBr6 information light is projected onto the screen S and superimposed to display a color image.

In this way, in the video projector described above, the information light from the cathode ray tubes of each emission color is projected onto the same screen and superimposed, so the horizontal and vertical positions of the scanning lines of each color are -・Must be in compliance with the requirements. -, Conventional Id '1 In this case, a regulator is provided for each cathode female tube.1. Manual adjustments were made so that the scanning lines of other cathode ray tubes matched the scanning lines of the reference cathode ray tube. Therefore, it is time-consuming, and the FA''!-condition changes over time, causing mismatch between the scanning lines of the cathode rays and deteriorating the image quality.

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems, and an object of the present invention is to provide a vertical position deviation detection device for a video projector projected image, which detects the vertical position deviation of each cathode ray tube.

To avoid this problem, the present invention can be applied to a plurality of pulses whose horizontal positions are approximately the same in the horizontal blanking period of a plurality of consecutive scanning lines. These position detection pulse signals are generated in scanning line sections with different vertical positions for each cathode ray tube, and these position detection pulse signals are superimposed on the relevant video signal. A light-receiving element having a horizontally elongated light-receiving area that receives the optical output of each of these pulse signals for position detection is arranged in the corresponding section l on the screen of the pulse signal l-1 is the photoelectric conversion output of these light-receiving elements. Each cathode ray tube detects the normal position deviation in the vertical direction of the output of the position detection output knock pulse signal.

According to the present invention, the detected vertical position deviation is output to the vertical deflection circuit of each cathode ray tube, and the image from each cathode ray tube is controlled automatically so that it is positioned at the normal vertical position. This eliminates the need for manual adjustment, eliminates discrepancies in the scanned images of each cathode ray tube due to aging, and provides images of good quality at all times. .

Best mode for carrying out the invention The present invention will be described below with reference to drawings of embodiments.

FIG. 3 is a configuration diagram of an apparatus for detecting vertical positional deviation of an image projected by a video projector according to an embodiment of the present invention.

This embodiment uses the video projector shown in FIG.
I, CI T2. Screen S by cR'r
This is applied to a video projector that displays a color image by projecting and forming an image of information light. FIG. 4 is a timing chart z of signals of each part of FIG. 3. 1 is a Lupal signal generation circuit for position detection, as shown in Fig. 4, which is used for cathode ray tubes CRT+, CBr2, and CB, respectively
A position detection pulse signal Sl + S2 + S3 is generated to detect the entire vertical positional deviation of the image due to r3. These position detection signals Sl+S2+S
3 consists of a plurality of pulse signals generated at approximately the same horizontal position on a plurality of consecutive scanning lines during the horizontal blanking period, and the pulse signal section TW has a value slightly wider than the vertical variation range of each image. It also has a vertical synchronization signal VSYN
From C to each position detection signal Sl + S2 +
The time T1+T2+T3 to the center of S3 is set so that these position detection pulse signals Sl+S2 and S3 do not overlap with each other in time.

This position detection path signal generation circuit 1 can be easily constructed from a counter circuit, a monostable multivibrator, etc. 2-digit position detection pulse signal S+,
This is a clock pulse generator circuit that generates clock pulses for determining the timing of generation of S2+33. 3
is the red tap input from terminal t1! - A position detection pulse signal superimposition circuit that superimposes a position detection pulse signal Sl on an image signal and outputs the resultant cathode intestinal tract CRTIK. 4 is terminal t2
The green video signal P input from the position detection pulse signal S
This is a position detection pulse signal superimposition circuit that superimposes the pulse signal 2 and outputs it to the polar ray tube CRT2.

Reference numeral 5 denotes a position detection pulse signal superimposition circuit which superimposes a position detection pulse signal SA on the blue video signal inputted from the terminal t3 and outputs the same to the cathode ray tube C'RT3. P.R.

P, R2, PR3 are position detection pulse signals S, respectively.
, S2 + S3 A light-receiving element having a horizontally elongated light-receiving area (straddling multiple scanning lines to increase resolution), which receives the optical output of S2 + S3, and receives the pulse signal for position detection shown in Figure 1. It is arranged vertically at the right end of the screen S corresponding to the time TI + T2 + T3 of S+ + S2 + S3. Therefore, each cathode ray tube CRT1. CRT2.

Normal case 1 where there is no vertical positional deviation in the image captured by CRT3
+ T2 + T3 as the center 1, and the A position detection pulse signal S1. Position detection output pulse signals S4', S2', and S3' having a pulse signal interval of 'rs' are obtained by photoelectrically converting the optical outputs of S2 and S3. , it's ox,
The image from the cathode ray tube CRT2 is shown below, and the cathode ray tube CRT2
If the images from 3 are shifted upward, the position detection output pulse signal 82'' of the light receiving elements PR2 and PR3
.

83'' is output based on the time T2 and T3 in the above normal case, each delayed by ΔT and advanced by ΔT3.In other words, the direct response of these ΔT2+ΔT3 is the image produced by the cathode ray tubes CRT2 and CRT3. This is a temporal deviation that indicates the degree of vertical deviation (positional deviation).

6 is the time deviation ΔT1.6 of the position detection output pulse signals of the light receiving elements PRI, PR2, PR3. This is a vertical position deviation calculation circuit that calculates ΔT2+ΔT3, and FIG. 5 shows the temporal deviation ΔT1 of the position detection output pulse signal of the cathode ray tube CRT+.
FIG. 2 is a circuit diagram of an example for determining The counter CT becomes active at the same time as the vertical synchronization signal VSYNC is output, and starts counting the clock pulses CLK.

The retriggerable monostable multi-by-break RM uses the position detection output pulse signal 81', (81'') as a trigger pulse, and uses a bar/l/
The pulse signal of Step 4 is output, and the subsequent pulse signal is obtained. Since the counter CT stops the counting operation when this consecutive pulse signal is applied, its count output is converted from the vertical 1st period signal VSYNC to the position detection output pulse signal s,' (S, ") represents the time T+'(T+") at the moment when it is output. Count output of this counter CT u D/A converter DAC
Digital/analog conversion is performed. Es.

is the position detection output pulse signal S when the position deviation is zero],
Time Ts (Ts/2) until '(Sl") is output
The count value of the clock pulse CLK between
It is an analog voltage (constant). D/A converter D
By determining the difference between the AC output and the voltage Es1 using the differential amplifier DA, the position detection output pulse signal 81'(Sl"
) is obtained. other temporal u
ml difference ΔT2. ΔT3 is obtained in exactly the same manner.

The time deviation ΔTl + ΔT2 + ΔT3 (7) signal obtained by this vertical position 1 difference calculation circuit 6 is for each cathode ray tube C.
RT+, CRT2°.

The position detection pulse signals Sl, S2, and S3 may differ in horizontal position by l/-1° as long as they do not overlap each other in the vertical direction. Needless to say, the present invention can also be applied to a video projector having a plurality of cathode ray tubes for each emission color.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are a plan view and a front view showing an example of a video projector that is the object of the present invention, and FIG.
). (l) is a plan view and a front view showing another example of a video projector which is a subject of the present invention, and FIG. The configuration diagram, Figure 4, shows the vertical synchronization signal and horizontal synchronization signal 1 position detection pulse signal. A timing chart of the position detection output pulse signal, and FIG. 5 is a circuit diagram of an embodiment of the vertical position deviation calculation surface. CRT+, CRT2. CRT3...Cathode ray tube, P
R+, PR2, PR3... Light receiving element, 1 Pulse signal generation circuit for position detection, 2... Clock pulse generator, 3, 4, 5 Pulse signal superimposition circuit for position detection, 6
...Vertical position deviation calculation circuit. (Q) (b) z l Picture C) - (a) (b) Second evil

Claims (1)

[Scope of Claims] One or more cathode ray tubes are provided for each of the three emission colors constituting a color image, and information light from these cathode ray tubes is transmitted through a magnifying lens or a Schmidt optical system to a screen. In a video projector that displays a color image by projecting and forming an image on the screen, the horizontal blanking period of multiple scanning lines that are continuous toward the floor is slightly longer than the range of variation in the vertical position of the image produced by each cathode chamber tube. a position detection pulse signal generation circuit that generates a position detection pulse signal consisting of a plurality of pulses having approximately the same horizontal position in a set line section having a different vertical position for each cathode ray tube; a position detection pulse signal superimposition circuit that superimposes a pulse signal on the video signal; and a position detection pulse signal superimposition circuit that is arranged within a corresponding section of the screen of each of the position detection pulse signals and receives the optical output of each of the position detection pulse signals. , a light receiving element group having a horizontally elongated light receiving area, and each cathode ray tube outputting a position detection output pulse signal obtained by photoelectrically converting the optical output of each of the position detection pulse signals received by each of the light receiving elements. 1. A vertical position deviation detection device for an image projected by a video projector, comprising: a vertical position deviation calculation circuit for determining a temporal deviation with reference to when the image is in a normal position.