JPH07143506A - Projection display device - Google Patents

Abstract

PURPOSE:To provide a projection display device for automatically performing the various kinds of convergence, geometrical or gamma corrections concerning a device for correcting a projection display. CONSTITUTION:This device is provided with a reflection plane 3 installed on a transmissive screen 16, test signal generation part 11 for generating a test signal on the transmissive screen 16, image pickup part 2 for picking up an image projected on the reflection plane 3 by supplying the test signal to a projector 17, position detection part 5 for detecting the leading value and inclination of a signal from the image pickup signal of the image pickup part 2, error calculation part 6 for calculating a display position and an inclination error for each color from the output signal of the position detection part 5, and correct signal generating part 7 for preparing a convergence, geometrical distortion or gamma correcting waveform corresponding to the display area of the test signal from the output of the error calculation part 6, and high-precision automatic adjustment is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for performing various corrections of a one-body type projection display, and more particularly to a projection display device for automatically performing various corrections of convergence, geometric distortion and gamma.

[0002]

2. Description of the Related Art Generally, a projection type display (video projector) for magnifying and projecting in a screen by using three projection tubes (hereinafter abbreviated as CRT) that emits three primary colors is a C
Incident angle to the screen of RT (hereinafter referred to as "concentration angle")
Is different for each CRT, color shift, focus shift, deflection distortion, and luminance change occur on the screen. These various corrections adopt a method in which an analog correction waveform is created in synchronism with the horizontal and vertical scanning periods, and the size and shape of this waveform are changed for adjustment, but there is a problem in terms of correction accuracy. is there. Further, since various corrections are manually observed by visually observing deviations on the screen, there is a problem that adjustment time is required.

Therefore, as a method with high convergence accuracy, a digital convergence device described in Japanese Patent Publication No. 59-8114 and a method for automatically correcting deflection distortion are disclosed in Japanese Patent Publication No. 3-38797. Tokkyo 1-4
The automatic convergence correction device disclosed in Japanese Patent No. 8553 discloses a method for detecting a convergence error and a correction method therefor.
Japanese Patent Laid-Open No. 63-48987 discloses a convergence error correction method disclosed in Japanese Patent No. 549993 and a method for automatically detecting and correcting a convergence error of a projection display.
The method disclosed in the convergence error correction apparatus for a projection display of Japanese Patent Publication is disclosed.

FIG. 20 is a block diagram of a conventional projection type display device capable of automatic correction. In FIG. 20, 101 is a display device for which the convergence is to be adjusted, 1
Reference numeral 02 is a signal generator that generates a signal for convergence adjustment, 103 is a signal switcher that switches the signal, 104 is an image pickup device that picks up the display screen of the display device 101, and 105
Is an image processing device for calculating the center of gravity and detecting a misconvergence error, and 106 is a controller for controlling the signal generating device 102, the signal switching device 103 and the image processing device 105.

The operation of the projection type display device configured as described above will be described below. First, the signal generator 10
2 produces a low frequency repeating pattern shown in FIG. In FIG. 21, x is the horizontal direction of the screen, y
Is the vertical direction of the screen. This repetitive pattern is displayed on the display device 101 by the signal switch 103. The displayed repeated pattern is imaged by the image pickup device 104, and the head position (hereinafter referred to as the center of gravity position) of the peak of each waveform is calculated by the image processing device 105. This is R (red),
The misconvergence error is detected by performing the waveform for each color of G (green) and B (blue), and detecting the difference between their barycentric positions.

The calculation of the position of the center of gravity will be described in detail.
First, the signal of the repetitive pattern picked up by the image pickup device 104 is A / D converted, and the digital data is linearly interpolated. This figure is shown in FIG. Hi in this figure
(x) is the data of the repeated pattern. Here, only one data of the repetitive pattern has been described, but the same applies to other repetitive patterns.

The position of the center of gravity is obtained by the following quadratic curve approximation. D = {hi (x) - (A · x 2 + B · x + C)} 2dx integral range of the equation is determined by threshold hTH. Where A · x ² + B · x + C is an approximate quadratic curve,
The coefficients are determined so as to minimize the above equation. That is, D /
A = 0, D / B = 0, D / C = 0, and the position of the center of gravity x0
Is x0 =-(B / 2A).

As described above, the barycentric position is calculated for each color of R, G, and B by performing the quadratic curve approximation for each repeated pattern, and the difference between the barycentric positions is detected. By using this as the amount of misconvergence error and performing the convergence correction of the display device, the automatic convergence correction can be performed.

FIG. 23 is a block diagram of a conventional projection type display device capable of various automatic adjustments. In FIG. 23, the projection device 111 includes a projector for each color, that is, an R projector 112, a G projector 113, and a B projection K device 114, and the light of each color is projected onto the projection screen 115, and each of the projectors 112 to 114. Is formed on the projection screen 115. At this time, the auxiliary screen 11 is placed on the non-imaging surface.
6, the non-imaged image on the auxiliary screen 116 is detected by the photo sensor 114, and the convergence error information existing in this image is obtained by calculating the matrix centroid error value as described in FIG. Then, the convergence error on the projection screen 115 is obtained from the convergence error information existing in the non-imaged image, and the convergence of the projection display device is automatically adjusted by this.

[0010]

However, in the projection type display device having the conventional structure as described above, the image pickup means for detection can be incorporated into the display device to perform integrated automatic correction. Since you can only adjust the static convergence correction of
There is a problem that complicated adjustment and time are required to adjust the entire screen.

Further, since the barycentric position of the low frequency signal waveform in the area obtained by dividing the entire display screen in the horizontal direction N and the vertical direction M is calculated by the quadratic approximation, complicated processing is required in the image processing section. Therefore, there is a problem that the circuit scale becomes very large and the adjustment time becomes very long.

Further, since the image processing is performed by the low frequency signal which is line-symmetrical to the angled waveform, there is a problem that the position detection sensitivity and accuracy of each level are changed due to the image receiving gamma characteristic of the image display apparatus, and the correction accuracy is lowered. Had.

In view of the above point, the present invention provides a reflecting surface on a transmissive screen that is projected and displayed by a projection optical system, picks up image light from the reflecting surface, and calculates an error value for each color. A one-body projection display device that can drastically reduce the adjustment time by creating and automatically correcting a correction waveform for correcting the convergence of the entire screen, geometric distortion, brightness and focus based on this calculated signal The purpose is to provide.

[0014]

SUMMARY OF THE INVENTION A first aspect of the present invention is to provide a reflecting surface setting means for providing a reflecting surface on a transmissive screen, and a signal generating means for generating a mountain-shaped test signal at a predetermined position on the display screen. An image pickup unit that supplies the test signal to a display device and picks up an image displayed on the reflection surface; and a position detection unit that detects a leading value and a slope of the signal from the image pickup signal from the image pickup unit, Error calculating means for calculating the display position / tilt error for each color from the detection signal, and correction for creating convergence, geometric distortion, and gamma correction waveform corresponding to the display area of the test signal from the output signal of the error calculating means It is the structure provided with the waveform creation means.

In a second aspect of the present invention, a light source that emits image light of each color, a projection optical system that magnifies and projects the image light from the light source onto a transmissive screen surface by a projection optical system, and the transmissive screen are provided. This is a configuration including a transmission unit that transmits only the image light from the projection optical system.

Further, according to a third aspect of the invention, a transmissive means for allowing the transmissive screen to transmit only the image light from the projection optical system,
A signal generating means for generating a mountain-shaped test signal at a predetermined position on the display screen, and supplying the test signal to the display device,
Image pickup means for picking up a reflection image from the rear surface of the transmission screen of the projection optical system, position detection means for detecting the head value and inclination of the signal from the image pickup signal from the image pickup means, and each color from the output signal of the position detection means An error calculating means for calculating a display position / tilt error for each, and a correction waveform creating means for creating a convergence, a geometric distortion, and a gamma correction waveform corresponding to the display area of the test signal from the output signal of the error calculating means. It is a configuration provided.

[0017]

According to the first aspect of the present invention, the reflecting surface is installed on the transmissive screen projected and enlarged by the projection optical system, and the image light from the reflecting surface is imaged to calculate the error value for each color. , This calculation signal automatically creates and corrects the correction waveform for correcting the convergence, geometric distortion and gamma of the entire screen, so that various complicated adjustments are unnecessary and the adjustment time can be greatly shortened. .

According to the second aspect of the invention, in a display device for projecting and enlarging and displaying an image on a transmissive screen by using a projection optical system, a unidirectional transmissive screen for transmitting only image light from the projection optical system. With this configuration, external light such as illumination light and unnecessary light does not enter the projection optical system.
A high-contrast image display can be realized.

According to the third aspect of the present invention, in a display device for projecting and enlarging and displaying an image on a transmissive screen by using a projection optical system, a unidirectional transmissive screen for transmitting only image light from the projection optical system. The reflected image light from the back side of the transmissive screen is imaged to calculate the error value for each color, and the correction signal for correcting the convergence, geometric distortion and gamma of the entire screen is automatically calculated by this calculation signal. Since the image is created and corrected, various complicated adjustments are not required, and the adjustment time can be significantly shortened and high contrast display can be performed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the basic configuration of a projection display device according to the first embodiment of the present invention.

In FIG. 1, reference numeral 1 is a test signal for adjustment corresponding to an image adjustment point of the projector 17 in convergence adjustment, 2 is an image pickup section for picking up an image of the reflecting surface 3, and 3 is a front surface of the transmissive screen 16. A reflection surface 4 is provided, 4 is an observer for observing the image light from the transmissive screen 16, 5 is a position detection unit that calculates position information from data of an image pickup signal from the image pickup unit 2, and 6 is position detection An error calculation unit that detects a convergence error from the output of the unit 5, a correction signal generation unit 7 that generates a correction signal for convergence correction from the output of the error calculation unit 6, and a correction signal generation unit 8 A control unit for controlling the deflection unit 9 (DY) and the auxiliary deflection unit 10 (convergence yoke = CY) of the CRT according to the generated correction signal, 12 is a switch for switching between a video signal and a test signal, 1 Is a drive circuit for driving the CRT 14 of the projector 17, 15 is a projection lens for projecting the image projected on the CRT 14 onto the transmissive screen 16, and 20 is a test signal generating section for generating a test signal for convergence adjustment. .

The structure of the projection type display device of the present embodiment having the above-mentioned structure will be described below with reference to FIG. FIG. 2 shows a configuration of a rear projection type video projector 18 using the transmissive screen 16, FIG. 2 (a) shows a set configuration, and FIG. 2 (b) shows an optical configuration.

In FIG. 2A, the image light from the CRT 14 is enlarged and projected by the projection lens 15 and is transmitted through the transmission screen 1.
6 is enlarged and projected. The mirror 19 provided between the transmissive screen 16 and the projection lens 15 is an optical reflection means for shortening the depth of the set having an integral structure. In order to detect the image light from the reflecting surface 3 provided on the front surface of the transmissive screen 16, a mirror surface 19 is provided as shown in FIG.
The image light is picked up by the image pickup device 2A installed on the non-imaging surface.

As shown in FIG. 2B, the image light from the CRT 14 and the projection lens 15 is projected at a right angle on the surface of the transmissive screen 16. As shown in FIG. 2 (a), as an image sensor installation method, a window for imaging is opened in the center of the mirror 19 surface, and the image sensor 2 A is installed in this detection window, and The reflected image light is captured.

The operation of the projection type display apparatus of the first embodiment thus constructed will be described with reference to FIGS. 3 and 4.

The convergence adjusting test signal 1 is projected on the reflecting surface 3 provided on the front surface of the transmissive screen 16. Here, the convergence error detection is performed for each of the R, G, and B CRTs, but since the adjustment operation is the same, only G will be described here. The test signal of this embodiment is shown in FIG. As can be seen from FIGS. 3A and 3B, the test signal has a quadrangular pyramid shape when the screen 16 is the bottom surface and the signal level direction is the height direction. In order for the test signal displayed on the screen to be linear in the level direction as described above, gamma correction in the display device is required. The test signal generator 11 considering the gamma correction will be described below.

Generally, the relationship between the input signal voltage (E) of the CRT and the light emission output (L) can be approximated by the following equation L = k · E ^r . The index γ of the input voltage (E) in this equation represents the gamma characteristic of the CRT, and this value is generally γ = 2.2.
Becomes Since this gamma characteristic is an amount that is uniquely determined for the CRT, in the test signal generator 11, for example, R
If the test signal voltage (E) is converted into E ^−r using the OM, the light emission output (L) becomes L = k · E, which is linear with respect to the input. In the following description of the geometric distortion / convergence correction using the quadrangular pyramid-shaped test signal, the description will proceed assuming that the gamma characteristic has been corrected.

First, a method of controlling the reflecting surface will be described. The block diagram of the rear projection type projector-18 of FIG. 4 is used. FIG. 4A shows a display screen in which the test signal is displayed on the transmissive screen 16 in the case of the normal screen display.
In addition, when the automatic adjustment is performed in FIG. 4B, since the reflective surface 3 is installed on the front surface of the transmissive screen 16, the display image is not displayed, but as shown in FIG. Is projected. The test signal from the reflecting surface 3 is detected and various corrections are performed.

As described above, the reflecting surface is provided when the correcting operation is performed, and the reflecting surface is removed when the correcting operation is completed, and the reflecting surface is used as the screen protection cover surface. When receiving a signal source having a different aspect ratio in FIG. 4C, it is used as a shutter function for the outer frame of the display area. As shown in the top view of the projector in FIG. 4D, the reflective surface is housed in the reflective surface roll section 20, and the reflective surface 3 from the reflective surface roll section 20 is the transmissive screen 1.
It has a structure to be installed in front of 6.

A method of controlling the reflecting surface 3 will be described with reference to (Table 1).

[0031]

[Table 1]

In Table 1, the control method in the correction mode has a reflective surface as shown in FIG. 4 (b) during correction and no reflective surface after correction as shown in FIG. 4 (a). . The control method in the reception mode is as shown in FIGS. 4 (a) and 4 (c) when there is no reflection surface, or when the signal is discriminated and the aspect ratio is detected to use as a shutter function. (b)
It is used as a protective cover for the screen with a reflective surface as shown in.

Next, a method for detecting the position of geometric distortion and convergence will be described. For the explanation, the position detector 5 of FIG.
The block diagrams showing the detailed configuration of FIG. 6, FIG. 7, FIG. 8, and FIG. 9 are used. In FIG. 5, 21 is a CCD camera that captures the test signal 1 projected on the reflecting surface 3, and 22 is a CC.
An A / D converter for A / D converting the image pickup signal from the D camera 21, 23 a frame memory for storing the image data from the A / D converter 22, 24 a differential filter for obtaining the difference between the imaged test signals , 25 is a linear region calculation unit that obtains a linear portion of the test signal from the output of the difference filter 24,
Reference numeral 26 is a center-of-gravity position calculation unit that calculates the center-of-gravity position of the test signal from the output of the linear region calculation unit 25, and reference numeral 27 is an error detection circuit that detects an error for each color from the center-of-gravity position signal from the center-of-gravity position calculation unit 26.

A method of calculating the barycentric position of the test signal will be described below. In the present embodiment, the CCD camera 21 is used as the image sensor of the image capturing unit 2 for the sake of explanation, but even an image capturing device having a slow pulse response speed such as a photodiode has a high accuracy because it is a test signal of a low frequency component as described above. Needless to say, the above can be detected and corrected, and can also be realized by detection on a non-imaging surface where the focus is deviated.

There are three reasons for the detection by the CCD camera 21. First, when the information of the entire screen is taken in and the geometric distortion is corrected, the geometric distortion of the detection system, which is the image sensor, cannot be ignored, so the element must have less than 1% distortion. Secondly, even on a display screen having a different scanning frequency of the display device, the scanning is converted to a specific scanning frequency of the image pickup system, so that subsequent image processing can be performed under constant conditions. Thirdly, since the monitoring distance of the focal length can be dealt with by changing the optical lens, it is possible to deal with various display devices. The CCD camera is used for the above reasons.

In the position detecting section 5, a high-accuracy position is detected even in a system with a low detection accuracy in which the current type black and white CCD of about 380,000 pixels and the sample frequency of the A / D converter 22 are processed at about 14.32 MHz. Detection is required.
In the A / D converter 22 of FIG. 6A, the sampling frequency fsap =
The photoelectric conversion signal converted at 14.32 MHz (sampling period 70 ns) is shown, and the center of gravity position which is the apex of the photoelectric conversion signal at this time is present at the sample point S7. In FIG. 6B, the position of the center of gravity, which is the apex of the photoelectric conversion signal, exists between the sampling points S6 and S7. In this case, since the sample points are coarse, highly accurate position detection cannot be performed. Therefore, the position of the center of gravity is calculated by linear approximation from the voltage of the sample point near the position of the center of gravity, and the position can be detected with high accuracy.

As shown in FIG. 6C, the linear approximation data of the data D4 to D6 of the rising sampling points S4 to S6 of the photoelectric conversion signal and the falling sampling points S9 to S6 of the photoelectric conversion signal.
By calculating the intersection of the straight line approximation data of the data D9 to D7 of S7, it is possible to calculate the center of gravity position with high accuracy even in a system with coarse detection accuracy.

The solid line in FIG. 7A shows the actual test signal, and the broken line shows the signal obtained by interpolating the sampling signal from the CCD camera by the low pass filter (LPF). As can be seen from FIG. 7 (a), rounding of the apex portion of the test signal occurs due to the low sampling frequency, and when the barycentric position is obtained from the CCD output signal, the actual barycentric position is point A. However, the point A'is mistakenly determined to be the center of gravity of the test signal. In order to eliminate such a detection error, the position of the center of gravity is calculated. The calculation of the position of the center of gravity is performed by extending the linear portion excluding the rounded portion and setting the intersection of the extended portions as the position of the center of gravity. That is, on the data, the test signal data as shown by the solid line in FIG.

The calculation of the center of gravity position is performed by dividing the data into a plurality of correction areas corresponding to the respective test signals as shown in FIG. 3 and calculating the center of gravity position for each area. Although the following description of the arithmetic processing is performed only for one area, the same arithmetic processing is performed for other areas.

As the first step of the arithmetic processing, an operation for detecting only the linear portion of the test signal data is performed excluding the rounding area by sampling. This is performed by detecting the difference signal of the image data of the test signal by the difference filter 24. When the image data of the test signal shown in FIG. 7A is input to the differential filter 24, the output data is as shown in FIG. 7B. Further, from the output data, the linear area calculation unit 25 detects the data difference signal, that is, the periods A and B in which the slope of the test signal is constant. Here, the period when the slope is 0 is ignored.

Hereinafter, only the image data within the periods A and B are valid and the barycentric position is calculated. Here, the position of the center of gravity is calculated by extending the linear periods A and B on the data and using the test signal at this intersection as the center of gravity. As shown in FIG. 7B, when this calculation of the position of the center of gravity is performed, the data DA (corresponding address nA) from the highest vertex of the linear part A, the inclination of the linear part A, and the linear part B If the data DB (corresponding address nB) from the most apex and the inclination of the linear portion B are β, the center of gravity position x can be determined by the following equation. x = nA + (DB−DA−β · (nB−nA)) / (α−β) Thus, by determining the position of the center of gravity by linear extrapolation,
For example, even when the CCD camera is coarsely sampled, it is possible to detect the position of the center of gravity with a high precision of a sampling period or more.

The center of gravity obtained as described above is expressed as coordinates on the address map corresponding to each pixel of the CCD. For example, FIG. 8 shows an address map when a black and white CCD camera having 380,000 pixels is used. As shown in FIG.
This address map has 768 horizontal points (x1 to x76
8), and is composed of addresses of 493 points (y1 to y493) in the vertical direction. FIG. 8B shows a partially enlarged view of the address map when the center of gravity position (black circle ●) of the test signal is calculated. As shown in FIG. 8B, the position of the center of gravity is represented as a point on the address map, such as (x = 12.7, y = 11.3). Similarly, the position of the center of gravity of the test signal corresponding to each correction area on the display screen is mapped on this address map.

In order to improve the detection accuracy of the barycentric position detection, it is necessary that many linear regions exist in the signal component. This will be described with reference to FIG. FIG. 9A shows a secondary test signal such as a conventional SIN ² waveform, and FIG. 9B shows a quadrangular pyramidal test signal of this embodiment. When these test signals are cut by the horizontal scanning lines ln (n = 1 to 5), the characteristics are like mountain-like characteristics, but in the case of the conventional test signals, since they have secondary waveforms, Since the quantization error differs depending on the signal level, the optimum quantization cannot be performed and the detection accuracy will be reduced. On the other hand, in the test signal of the quadrangular pyramid of the present embodiment, since the signal is linear, it is possible to perform highly accurate calculation by selecting the optimum number of quantization bits.

Next, a method of detecting an error value from the gravity center position calculation signal obtained as described above will be described. When calculating the convergence error, as shown in the waveform diagram of FIG. 10A, the G signal is treated as a reference signal, and the R signal calculates the error value of t1 in the left direction and the B signal calculates the error value of t2 in the right direction. .

Further, when calculating the geometric distortion error, FIG.
As shown in 0 (b), a specific sample point S20 is treated as a reference signal, and an error value of t3 for the R signal to the left, t4 for the G signal to the left, and t5 for the B signal to the left is calculated. . The calculation of the barycentric position and the error value is managed by the information corresponding to the address of the sample point. Therefore, as the reference signal for calculating the geometric distortion error, for example, 768 points in the horizontal direction (x
1 to x768), and addresses obtained by equally dividing 493 points (y1 to y493) in the vertical direction are treated as reference signals.

After detecting the position of the test signal as described above,
The error calculation circuit 27 calculates the error for each color.
A correction signal for geometric distortion / convergence is generated from the calculated error information by the correction signal generation unit 7, and the control unit 8 of the projector 17 is controlled so that the error becomes 0 by this correction signal.

The correction signal generating section 7, the deflecting section 9 and the auxiliary deflecting section 10 perform the same operations as those of a general color television receiver, and therefore their explanations are omitted. The correction signal generator 7
It is needless to say that the correction points and the detection points (the positions of the adjustment test signals) need to be the same, and therefore the positions and the number of the adjustment test signals change depending on the correction method such as analog or digital.

Thereafter, the same processing is performed for R and B as well, whereby the geometric distortion / convergence correction (hereinafter referred to as a convergence operation) is completed. Further, in the present embodiment, the case where the black-and-white CCD camera is used to sequentially display the test signals has been described, but if the color CCD camera is used, the test can be performed in a short time.

Next, the emission characteristic diagram of FIG. 11 and the test signal of FIG. 12 will be used to explain the method of improving the detection accuracy of the detection of the center of gravity in the position detecting section 5 and the gamma correction. As described in the present embodiment, a large number of linear regions exist in the signal component, and by selecting the optimum number of quantization bits, highly accurate calculation can be performed.

FIG. 11 is a projector 17 for displaying a large screen using red, green and blue (hereinafter abbreviated as R, G and B) CRTs.
FIG. 3 is a light emission characteristic diagram of R, G, and B of FIG. 12 (a) shows a waveform of a quadrangular pyramid-shaped test signal similar to that in FIG. 2, and FIG. 12 (b) shows photoelectric conversion of the quadrangular pyramid-shaped test signal of FIG. 12 (a) affected by saturation of the phosphor. The waveform of the scanning line cross section of the signal is further shown in FIG.
2 (c) shows the waveform of the video signal applied to the CRT cathode electrode. As can be seen from FIG. 11, in contrast to the linear characteristic of G, the emission characteristic of B has a non-linear region above a certain level of the beam current.

The cause of the non-linear region is the saturation of the B phosphor in the large current region. As can be seen from this figure, the characteristics of the photoelectric conversion output obtained by imaging the quadrangular pyramidal test signal displayed on the display device by the imaging unit by the saturation characteristics of the phosphor are, for example, when viewed in the scanning line cross section of the test signal, As shown by the solid line in FIG. 12 (b), it has a saturation characteristic in the high luminance region. In order to correct this saturation characteristic, the drive circuit 1
The gamma correction circuit in 3 performs gamma correction of the video signal as shown by the solid line in FIG.

As a result, the signal displayed on the display screen is
As shown by the broken line in FIG. 12 (b), the signal has a linear characteristic at each signal level, which enables more accurate detection.

Next, the gamma correction operation will be described in detail.
There are two types of gamma correction: CRT gamma and gamma correction due to saturation of the phosphor. Since the CRT gamma has been described above, the gamma correction associated with the saturation of the phosphor will be described here. As can be seen from FIG. 12, the characteristics of the photoelectric conversion output obtained by imaging the quadrangular pyramidal test signal displayed on the display device by the imaging unit due to the saturation characteristics of the phosphor are, for example, when viewed in the scanning line cross section of the test signal, 12
(b) As shown by the solid line, it has a saturation characteristic in the high-luminance region. In order to correct this saturation characteristic, the position detection unit 5 is shown in FIG.
The error with respect to the linear characteristic as shown by the broken line is calculated, and the gamma correction circuit in the drive circuit 13 is controlled so as to eliminate this error, and gamma correction is performed. The calculation of the error in this gamma correction will be described in detail with reference to FIGS.

FIG. 12C shows 1 of data obtained by A / D converting the photoelectric conversion output signal having the linear characteristic shown by the broken line in FIG. 12B.
The second-order difference, FIG. 12D, is the first-order difference of the photoelectric conversion output signal having the saturation characteristic due to the phosphor shown by the solid line in FIG. 12B. FIG. 12 (e) is a quadratic difference of the linear characteristic signal, and FIG. 12 (f) is a quadratic difference of the saturation characteristic signal.
For simplification of the description in FIGS. 12C to 12F, the difference data is taken only on one side of the apex of the signal in FIG. 12B, but the difference data for the entire region of the signal may be used. , And the following discussions are the same as those using FIGS. 12 (c) to 12 (f).

Comparing FIG. 12 (e) and FIG. 12 (f), the sum of the absolute values of the data of the second-order differences of the signals having the saturation characteristics shown by the solid line in FIG. 12 (b) is It can be seen that the value becomes larger than the sum of the absolute values of the data of the second-order difference of the signal having the linear characteristic shown by the broken line in FIG. The position detector 5 and the error calculator 6 calculate the sum of the absolute values of the secondary difference data due to the saturation characteristic of the phosphor as the gamma characteristic error. Further, the correction signal generator 7 supplies this gamma error to the gamma correction circuit in the drive circuit 13, and the gamma correction circuit outputs the test signal waveform supplied to the CRT as shown by the solid line in FIG. Modulate and perform gamma correction. As a result, the signal displayed on the display screen has a linear characteristic at each signal level as shown by the broken line in FIG. 12 (b), and the chromaticity in all areas from low luminance to high luminance is kept constant. You can

As described above, according to this embodiment, the reflecting surface is installed on the transmissive screen which is projected and displayed by the projection optical system, and the image light from the reflecting surface is picked up to obtain the error value for each color. The calculation signal is used to automatically create and correct the correction waveform to correct the convergence, geometric distortion, and gamma of the entire screen, so various complicated adjustments are not required and the adjustment time is greatly reduced. Can be realized.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 13 is an optical configuration diagram of the projection type display device in the second embodiment of the present invention.

In FIG. 13, reference numeral 28 denotes a unidirectional transmission surface that transmits only the image light from the CRT 14. It should be noted that the same operations as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

First, the unidirectional transmission surface of this embodiment will be described. In FIG. 13A, the image light from the CRT 14 is enlarged and projected by the projection lens 15 and enlarged and projected on the transmissive screen 16. The unidirectional transmission surface 28 provided between the transmission type screen 16 and the projection lens 15 has a CR
It is a unidirectional transmission means for transmitting only the image light from T14 to the transmission screen 16. Generally, in order to minimize reflection on the surface inside the set in which the projection optical system is housed, a black surface treatment with low reflectance is applied.

On the back surface of the transmissive screen, a part of the image light is projected due to diffused reflection on the surface, but it is in a very bright state because external light from the front surface is mostly incident. Therefore, the unidirectional transmitting surface 28 is configured to prevent unnecessary light such as external light from entering the set, suppress diffused reflection due to the unnecessary light in the set, and prevent a decrease in contrast.

14 and 15 and 16 are used to describe the unidirectional transmission surface 28 of this embodiment in detail. First, the configuration when the light transmittance of the liquid crystal device is used will be described with reference to FIG. A pair of electrodes S, C
FIG. 14 shows a block diagram of a basic drive circuit of a liquid crystal device 78 having the above, and FIG. 15 shows its drive waveform.

The drive circuit shown in FIG. 14 has an exclusive OR (E
XC.OR) gate 77 with a duty ratio of 5
By applying a 0% rectangular wave to one input of the EXC.OR gate 77 and one electrode C of the liquid crystal device 78 and the output of the EXC.OR gate 77 to the other electrode S, an AC voltage applied to the liquid crystal is applied. In accordance with the on / off signal vsig shown in FIG. 15A, becomes ± (VDD-VSS), 0 as shown in FIG. 15D. Further, this operation is shown in FIG.

Since the liquid crystal is bidirectional and responds to the effective value, the pulse duty ratio of the liquid crystal drive is 100% during the ON period of the liquid crystal applied voltage vC-vS shown in FIG. 15 (d).
This is static drive. FIG. 16 shows a characteristic diagram of light transmittance with respect to the applied voltage of the liquid crystal. As shown in Fig. 16, the operating voltage (VDD-VSS) for static drive
Can be set to a high value above the saturation voltage Vsat, and TN (Twis
ted Nematic) and GH (Guest-Host) method,
For example, it is 2 to 5V. It can be seen that the light transmittance can be controlled by controlling the applied voltage in this way.

As described above, the case in which the liquid crystal is applied as the unidirectional light transmitting means has been described. However, a magic mirror for transmitting light in the unidirectional direction or thin film optics is used for reflection. It can also be realized by controlling the transmittance.

As described in the first embodiment, in order to automatically adjust the display device, it is sufficient that the unidirectional transmission surface can control transmission and reflection.

As described above, according to the present embodiment, in the display device which projects and enlarges and displays the image on the transmissive screen by using the projection optical system, the single direction in which only the image light from the projection optical system is transmitted. By using a transmissive screen, external light such as illumination light or unnecessary light does not enter the projection optical system, so that high-contrast image display can be realized.

Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 17 is a block diagram of a projection type display device according to the third embodiment of the present invention.

In FIG. 17, reference numeral 29 is a transmissive / reflective surface that transmits or reflects the image light from the CRT 14. In addition,
The same elements as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In terms of optical configuration, it is provided at the same position as the unidirectional transmission surface 28 of the second embodiment described in FIG.
In the third embodiment, the unidirectional transmission surface described in the second embodiment is provided with a reflecting means for reflecting only a part of the light to perform the automatic adjustment described in the first embodiment. .

First, in order to describe the installation position of the optical transmission / reflector in detail, the optical configuration diagram of FIG. 18 is used. FIG. 18 basically has a configuration in which a transmission / reflection surface 29 of an optical transmission / reflector is provided in place of the unidirectional transmission surface of the second embodiment described in FIG. In FIG. 18, a transmissive / reflective surface 29 is provided between the lens 15 and the transmissive screen 16, and a reflected image from the transmissive / reflective surface 29 is captured by the image sensor 2A.
Is being imaged. With the optical configuration shown in FIG. 18, since detection is performed on the image plane, highly accurate detection and correction can be realized.

Table 2 is used to describe the operation and configuration of the transmissive screen 16 and transmissive / reflective surface 29 configured as shown in FIG. 18 in detail.

[0071]

[Table 2]

In Table 2, the display surface is the screen surface,
The control surface means an optical control surface, and two methods are conceivable: a transmission method in which light in a single direction is transmitted through the control surface and a transmission / reflection method in which transmission and reflection are controlled. Transmission method is second
This is a system in which the unidirectional transmission surface 28 described in the above embodiment is used as a control surface and a reflection surface is provided on the transmission screen surface which is the display surface.

The transmissive / reflective method is an application of the liquid crystal described in the second embodiment, and the transmissive / reflective surface 29 is used as a control surface by utilizing the liquid crystal shutter function, and the display surface is used as an original transmissive screen. It is a method. In the transmissive method and the transmissive / reflective method, the unidirectional transmissive surface 28 and the transmissive / reflective surface 29 are controlled in transmissivity by the liquid crystal shutter function using liquid crystal as described in the second embodiment. As shown in (Table 2), the method can be divided depending on where the reflection surface is provided.
Therefore, the reflected light detected by the image sensor 2A is captured by the image sensor 2A as reflected light from the control surface in the transmissive / reflective mode and from the display surface in the transmissive mode.

As the transmission / reflection system, as shown in FIG. 18, for example, a liquid crystal plate is provided as a transmission / reflection surface 29 at the image forming position on the screen 16 and the reflected light of the image formed from the liquid crystal plate is reflected. The image is captured by the image capturing unit 2. The operation of the liquid crystal plate can be realized by using it as a transmissive body during normal image projection and as a reflective body during adjustment.

FIG. 19 shows a transmissive system in which the transmissive screen 16 and the reflective surface have the same structure. As shown in FIG. 19, the transmissive screen 68 is composed of a Fresnel lens 67 and a lenticular 66 and a black stripe 79 for improving the contrast ratio in order to widen the viewer's favorite area.
Black stripe 7 which has a low transmittance in
By providing the reflecting surface 80, which is coated with a reflecting material, on the incident surface of the image light 9 of FIG.

Further, the material of the optical reflection surface can be realized by using a reflecting material or a diffusing material used in a general transmission type or reflection type screen. The optical reflection means can be realized by applying an oxide paint such as zinc, aluminum or magnesium as a white screen as an oil-based paint, or by mixing a pearl-like powder with a paint and applying it as in a pearl white screen. You can also apply aluminum powder like a silver screen,
It can be realized by spraying milky white glass particles like a bead screen.

As the optical means of the transmitting / reflecting surface, the case where liquid crystal or various reflecting materials are applied has been described, but a magic mirror for transmitting light in a single direction,
It can also be realized by applying thin film optics to control reflection and transmittance.

The operation of detecting the reflected light from the transmitting / reflecting surface 29 and performing the automatic adjustment in this way is the same as the operation described in the first embodiment, and the description thereof will be omitted.

As described above, according to this embodiment, in the display device which projects and enlarges and displays an image on the transmissive screen by using the projection optical system, the single direction in which only the image light from the projection optical system is transmitted. Compensation for correcting the convergence, geometric distortion and gamma of the entire screen by calculating the error value for each color by capturing the reflected image light from the back side of the transmission screen and calculating the error value for each color. Since the waveform is automatically created and corrected, various complicated adjustments are not required, and the adjustment time is greatly shortened and high contrast display is possible.

Although the projection type display device using the CRT has been described in this embodiment for easy understanding, it goes without saying that other display devices are also effective.

Further, in the present embodiment, the case where an integral type or a two-body type video projector is used as the projection type display device has been described, but a direct view type display device other than that may be used.

Further, although the case where the CCD camera is used as the image pickup device for detecting the image light is described in the present embodiment, other two-dimensional or one-dimensional detection device may be used.

In this embodiment, the case where the image pickup device for detecting the image light is set on the mirror surface of the projection optical system to pick up an image is described. However, it may be set at any position between the lens and the screen. Good.

In the present embodiment, the case where the monochrome CCD camera is used has been described, but it is also possible to project the test signals of the three primary colors at the same time and use the color CCD camera for the image.

In this embodiment, the case of correcting the convergence, the geometrical distortion and the gamma as the position detection of the display device has been described, but other position detection errors may be performed.

Further, in the present embodiment, when the horizontal and vertical barycentric position of each region is calculated by linear approximation from a quadrangular pyramidal photoelectric conversion signal whose rising and falling from the image pickup means changes substantially linearly However, the calculation may be performed by non-linear approximation as long as simple approximation can be performed.

In the present embodiment, the case where the test signal is a quadrangular pyramid-shaped mountain-shaped signal has been described, but any other signal may be used as long as it is a signal whose slope changes linearly.

In this embodiment, the image receiving gamma of the display device has been described as being corrected on the test signal generating side. However, gamma correction is performed in the loop of test signal generation-image display-imaging-centroid position detection. It goes without saying that it is good if it exists.

Further, although the case where the liquid crystal device is used as the device for controlling the light transmittance is described in the present embodiment, other light control elements may be used.

In this embodiment, the case where the transmittance in a single direction is controlled has been described. However, the brightness may be corrected by controlling the transmittance of the optical system for each screen area.

In this embodiment, the unidirectional transmitting surface and the transmitting / reflecting surface are installed on the screen surface which is an image forming surface. However, the non-image forming surface between the lens and the screen is arranged. May be installed.

[0092]

As described above, according to the first aspect of the present invention, the reflecting surface is installed on the transmissive screen projected and enlarged by the projection optical system, and the image light from the reflecting surface is picked up. By calculating the error value for each color and automatically creating and correcting the correction waveform to correct the convergence, geometric distortion and gamma of the whole screen by this calculation signal, various complicated adjustments are not required The adjustment time can be shortened. Further, since the reflecting surface is used as a shutter for the outer frame of the display area and a protective cover for the screen, it is very effective in a projector having a one-piece structure.

When the display screen is viewed from the bottom and the signal level direction is viewed from the height direction, a linear signal for calculating the center of gravity can be set to a wide linear area by creating a test signal having a quadrangular pyramid shape. The position can be detected with high accuracy. Further, the calculation processing speed can be increased by calculating the position of the center of gravity of the leading value from the linear portion of the image pickup signal by linear approximation calculation.

According to the second invention, in the display device for projecting and enlarging and displaying the image on the transmissive screen by using the projection optical system, the unidirectional transmission for transmitting only the image light from the projection optical system. By using the mold screen, external light such as illumination light and unnecessary light does not enter the projection optical system, and thus high contrast image display can be realized.

Further, according to the third invention, in the display device for projecting and enlarging and displaying the image on the transmissive screen by using the projection optical system, the unidirectional transmission for transmitting only the image light from the projection optical system. Compensation waveform for compensating the convergence, geometric distortion and gamma of the whole screen by calculating the error value for each color by capturing the reflected image light from the back surface of this transmission screen Since it is automatically created and corrected, various complicated adjustments are not required, and it is possible to greatly reduce the adjustment time and achieve high contrast display. In particular, it is a very effective means for a one-body type video projector, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of a projection type display device according to a first embodiment of the present invention.

FIG. 2 is an optical configuration diagram of the same embodiment.

FIG. 3 is a diagram showing a test signal for detection of the embodiment.

FIG. 4 is a configuration diagram for explaining an operation of a reflecting surface of the embodiment.

FIG. 5 is a detailed block diagram of a position detector of the embodiment.

FIG. 6 is a waveform chart for explaining the operation of detecting the position of the center of gravity of the embodiment.

FIG. 7 is a waveform chart for explaining the operation of detecting the position of the center of gravity of the embodiment.

FIG. 8 is a view for explaining the operation of calculating the position of the center of gravity of the embodiment.

FIG. 9 is a waveform diagram of a test signal for explaining the operation of calculating the center of gravity of the embodiment.

FIG. 10 is a waveform diagram for explaining the error detection operation of the same embodiment.

FIG. 11 is a light emission characteristic diagram of an RGB CRT of the projector of the embodiment.

FIG. 12 is a diagram showing a test signal of the same example.

FIG. 13 is an optical configuration diagram of a projection display apparatus according to a second embodiment of the present invention.

FIG. 14 is a block diagram for explaining an operation of transmittance control according to the same embodiment.

FIG. 15 is a waveform chart for explaining the operation of the transmittance control of the same example.

FIG. 16 is a characteristic diagram for explaining the operation of transmittance control of the example.

FIG. 17 is a block diagram of a projection type display device according to a third embodiment of the present invention.

FIG. 18 is an optical configuration diagram of the same example.

FIG. 19 is a diagram showing a configuration of a transmissive screen and a reflective surface of the same example.

FIG. 20 is a block diagram showing a configuration of a conventional projection display device.

FIG. 21 is a diagram showing an adjustment test signal of a conventional projection display device.

FIG. 22 is a diagram showing the operation of calculating the center of gravity of a conventional projection display device.

FIG. 23 is a block diagram showing the configuration of a second conventional projection display device.

[Explanation of symbols]

 1 Adjustment test signal 2 Imaging unit 3 Reflection surface 4 Observer 5 Position detection unit 6 Error calculation unit 7 Correction signal generation unit 12 Switch 16 Transmissive screen 17 Projector 25 Linear region calculation unit 26 Center of gravity position calculation unit 27 Error detection circuit 28 Unidirectional transmission surface 29 Transmission / reflection surface

Claims (8)

[Claims] 1. A display device for projecting and enlarging and displaying an image on a transmissive screen using a projection optical system, a reflective surface installation means for providing a reflective surface on the transmissive screen, and a predetermined screen for the display screen. A signal generating means for generating a mountain-shaped test signal at a position, an image capturing means for supplying a test signal from the signal generating means to a display device, and capturing an image projected on the reflecting surface; and the image capturing means. Position detecting means for detecting the leading value and inclination of the signal from the image pickup signal from, error calculating means for calculating display position and inclination error for each color from the output signal of the position detecting means, and output signal of the error calculating means To a correction waveform creating unit that creates a convergence, geometric distortion, and gamma correction waveform corresponding to the display area of the test signal, and corrects the display device with the correction waveform from the correction waveform creating unit. Projection display device which is characterized in that the so that. 2. The projection type display apparatus according to claim 1, wherein the image pickup means installs an image pickup device on an optical reflection surface provided between the light source of the projection optical system and the screen to pick up an image. 3. The projection display apparatus according to claim 1, wherein the reflecting surface installing means installs the reflecting surface when performing the correcting operation, and removes the reflecting surface when the correction is completed. 4. The reflection surface installation means uses a shutter surface outer frame shutter function when receiving signal sources having different aspect ratios, and the reflection surface is used as a screen protection cover. Projection display device. 5. The signal generating means and the position detecting means generate at least one quadrangular pyramid-shaped pattern when the display screen is viewed from the bottom and the signal level direction is viewed from the height direction.
2. The projection display device according to claim 1, wherein the head position and the inclination are detected from the image pickup signal having the inclination of a straight line. 6. The projection display apparatus according to claim 1, wherein the error calculating means obtains the position of the leading value from the linear portion of the image pickup signal by approximate calculation. 7. A light source for emitting image light of each color, a projection optical system for magnifying and projecting the image light from the light source onto a transmissive screen surface by a projection optical system, and an image from the projection optical system for the transmissive screen. A projection type display device comprising a transmitting means for transmitting only light. 8. A display device for projecting and enlarging and displaying an image on a transmissive screen using a projection optical system, transmissive means for allowing the transmissive screen to transmit only image light from the projection optical system, and the display screen. A signal generating means for generating a mountain-shaped test signal at a predetermined position, and a test signal from the signal generating means are supplied to a display device to pick up a reflection image from the back surface of the transmission screen of the projection optical system. Means, position detection means for detecting a signal start value and inclination from the image pickup signal from the image pickup means, error calculation means for calculating display position / tilt error for each color from the detection signal, and the error calculation means Correction waveform creating means for creating a convergence, geometric distortion, and gamma correction waveform corresponding to the display area of the test signal from the output signal, and the correction waveform from the correction waveform creating means In projection display apparatus is characterized in that so as to correct the display device.