JP2001086526A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of a detector to detect an offset of convergence. SOLUTION: Detection mirrors 14-21 are placed around a screen 2 and ends of the screen 2 requiring a photo sensor 4 and the detection mirrors 14-21 reflect a pattern video image light to measure a convergence offset projected from cathode ray tubes 8, 9, 10, the photo sensor 4 placed at a prescribed position receives this reflected light to read position information of electron beams corresponding to each color and to detect the convergence offset.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device capable of detecting a convergence shift amount and automatically correcting the convergence shift, and more particularly to a system for automatically correcting a convergence shift. The present invention relates to an optical structure for detecting a convergence deviation amount.

[0002]

2. Description of the Related Art As one form of a large-screen display device, there is a method of projecting a picture of a cathode ray tube on a screen to display a picture of 40 inches to 70 inches. In this method, since a cathode ray tube is used, the display raster positions of red, blue, and green on the screen are shifted due to the influence of geomagnetism or the like, so that convergence may occur. The convergence includes static convergence and dynamic convergence.

The correction of the static convergence deviation is described in Japanese Patent Application Laid-Open No. 64-34090. In this publication, two optical sensors are arranged at the lower part and the side part of the screen, and by displaying a pattern signal, a red, green, and blue pattern with respect to a reference position are displayed.
A shift amount of the display position is detected, a correction amount is obtained from the shift amount, and the display position of the cathode ray tube is corrected to correct static convergence. Also, JP-A-63
Japanese Patent Publication No. -131681 describes that optical sensors are provided at four positions on the upper, lower, left, and right ends of a screen to detect a deviation amount of convergence and similarly correct static convergence.

The correction of dynamic convergence is described in Japanese Patent Laid-Open Publication No. Hei 7-336704. Optical sensors are provided at eight positions at the upper, lower, left and right end portions and the peripheral portion of the screen, and the amount of convergence is detected to detect dynamic convergence. Correcting convergence.

[0005]

In order to automatically correct static convergence, only two optical sensors are required as disclosed in the above publication. However, the deviation of convergence due to a change in terrestrial magnetism or a deformation of the cabinet is not sufficient only by static correction, but requires automatic correction of dynamic convergence over the entire screen. In such a case, eight optical sensors are required by adding four optical sensors at the corners in addition to the four optical sensors at the periphery of the screen, that is, at the top, bottom, left and right ends. However, in the case of a configuration using eight optical sensors, the cost increases greatly, and some solution is required.

An object of the present invention is to provide a projection display apparatus which solves the above-mentioned drawbacks and reduces the cost of a detection apparatus for detecting the amount of convergence deviation.

[0007]

In the present invention, detection mirrors are installed at the four corners of the screen and the upper, lower, left and right ends of the screen where an optical sensor is required, and the convergence deviation amount displayed from the CRT can be reduced. The pattern image to be measured is reflected by the detection mirror. The position information of the reflected light is read by one optical sensor provided at a predetermined position, and the convergence deviation amount is detected.

In order to achieve the object of the present invention, in the first aspect, light from a plurality of cathode ray tubes displaying images of different colors is projected onto a screen via a plurality of projection lenses, and In a projection display device in which a cathode ray tube is equipped with a convergence coil for correcting convergence of each color image projected on the screen, a plurality of detection mirrors arranged around the screen, and the detection mirror And an optical sensor for receiving the reflected light of the convergence coil, and a correction current flowing through the convergence coil is controlled by an output from the optical sensor.

In the first invention, the optical sensor is disposed near one of the plurality of projection lenses and the plurality of cathode ray tubes, and the detection is performed such that light from the detection mirror is incident on the optical sensor. Place the mirror. It is preferable that the angle of attachment of the detection mirror is approximately half the angle of view of the projection lens. In the first invention, the detection mirror may be constituted by a light reflecting element and a lens portion of a Fresnel lens. Further, in the first invention, the detection mirror is constituted by a concave mirror. The concave mirror may be constituted by a flat plate concave mirror in which a flat plate is formed in a concave shape, or the concave mirror may be constituted by a prism cylindrical concave mirror having a prism provided with a concave mirror so that the cabinet can be attached as it is, without giving an angle to the cabinet. May be. Further, in the first invention, a holding frame for holding the screen may be provided, and a projection for attaching the detection mirror may be provided around the holding frame.

According to a second aspect of the present invention, three CRTs of red, green, and blue having a convergence coil attached to a neck portion, and an image displayed on a fluorescent screen of the three CRTs are projected. In a projection type display device having a projection lens of three books and a screen for projecting images projected by the three projection lenses, a plurality of detection mirrors are arranged around a periphery of the screen, and the plurality of detection mirrors It is configured to dispose an optical sensor on which a plurality of reflected light beams are incident.

In the second invention, the detection mirror may be arranged at a predetermined angle to the surface of the screen. Further, the optical sensor is disposed near any one of the three projection lenses and the three cathode-ray tubes, and an angle of attachment of the detection mirror with respect to a surface of the screen is set to about の of an angle of view of the projection lens. It is preferable to set it near. In the second invention, the detection mirror may be constituted by a concave mirror. Further, in the second invention, the optical sensor is disposed near any one of the three projection lenses and the three cathode ray tubes, and the plurality of detection mirrors are concave mirrors,
The angle at which the detection mirror is attached to the surface of the screen may be about half the angle of view of the projection lens. Further, the curvature of the concave surface may be set so that the focal length of the concave mirror is substantially equal to the projection optical distance determined by the projection lens.

In the second invention, the plurality of detection mirrors may be constituted by a plane mirror and a Fresnel lens. Also, the second
In the invention, the optical sensor includes the three projection lenses and the three projection lenses.
A screen frame is fixed to the screen, placed near any one of the CRTs of the book, a projection is provided around the screen frame in the direction of the optical axis from the projection lens, and the projection is optically reflected. A structure in which a film having a function is provided may be employed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the projection type display device according to the present invention will be described below with reference to the drawings by using some embodiments. First, an embodiment of a projection display device according to the present invention will be described with reference to FIG. FIG. 1A is a front view showing an embodiment of a projection display apparatus according to the present invention, and FIG. 1B is a partial cross-sectional view taken along line A1-A2 in FIG. Is shown. The embodiment shown in FIG. 1 shows an example in which the present invention is applied to a rear projection type CRT display device.

In the figure, the projection type display device comprises:
Cabinet 1, screen 2, mirror 3, optical sensor 4, red, green, blue projection lenses 7, 5, 6, red, green, blue CRTs 8, 9, 10, red, green, blue convergence correction coil 11 , 12, 13 and detection mirrors 14-21. In a normal use state, the image displayed on the fluorescent screen of the cathode ray tubes 8 to 10 is enlarged and projected by the projection lenses 5 to 7, and the image light is
The light is reflected by the mirror 3 and forms an image on the screen 2. Since the red, green, and blue cathode ray tubes have slightly different optical positions with respect to the screen 2, the display positions of red, green, and blue on the screen 2 are shifted. In this projection display device, the convergence correction coils 11 to 13 mounted on the necks of the cathode ray tubes 8 to 10 are used.
This deviation is corrected by applying a desired current to the screen 2 to realize an image without convergence deviation on the screen 2.

Hereinafter, the convergence correction coils 11 to 1
The current flowing through 3 will be described with reference to FIG. FIG.
FIG. 2 is a block diagram showing a convergence correction circuit of the projection display device. In a normal use state, data necessary for correction is stored in advance in the first memory 32 for raster alignment. When this data is read out by the CPU 31, a correction waveform is generated by the DA converter 34, amplified by the amplifier 35, and drives the convergence correction coil 13. Thereby, the convergence can be corrected.

Next, a description will be given of a correction in the case where a deviation occurs in convergence due to some factor, for example, a change in the geomagnetism due to a change in the installation direction, a deformation of the cabinet 1 due to a change in time, or the like. Detection mirrors 14 to 21
Are arranged in the overscan area around the screen 2. When light from the cathode ray tubes 8 to 10 hits the detection mirrors 14 to 21, the light is arranged to be incident on the optical sensor 4 via the mirror 3. First, in a state where the convergence is appropriate, for example, at the time of shipment at a factory, the convergence correction current output from the CPU 31 is changed, and the detection mirrors 14 to 21 are changed.
The red, green, and blue light signals at
Red, green, and blue raster position information is obtained by input to the CPU 31 via the AD converter 30 and stored in the second memory 33.

Since this projection type display apparatus uses a raster scan type CRT display, in FIG. 1, the detection mirrors 16, 17, 18, 15, 19 are arranged in order from the upper left position of the screen 2. , 1
Light signals are received in the order of 4, 20. The CPU 31 controls the sampling of the AD converter 30 so as to match the reception timing of the optical signal. Also, red, green,
Since the blue light signal cannot be detected at the same time, raster position information of each color is obtained in the order of red first, then green, and finally blue. The raster position information of each color can be obtained by detecting the position of the electron beam corresponding to each color by the horizontal synchronization signal. Therefore,
Only data from the detection mirror corresponding to the position of this beam is taken out.

If the convergence deviation occurs for some reason, the raster position information of red, green, and blue is obtained in the same manner, and is compared with the value stored in the second memory 33. Get. The CPU 31 updates the correction data stored in the first memory 32 based on the difference data so that a correct convergence state is obtained. After updating the correction data corresponding to each color, the correction data is read out by the CPU 31 and the DA converter 34
, A correction waveform is generated, amplified by the amplifier 35, and drives the convergence correction coils 11 to 13, so that a normal operation is performed, and it is possible to display an image with convergence.

In the projection type display device of the embodiment, the position of the beam for each color is obtained by calculating the position of the center of gravity from the position data from the detection mirrors 15, 17, 19 and 21 near the center of the screen. If the detection mirrors 15, 17, 19, and 21 are used to determine the position of the electron beam corresponding to each color at the corners of the screen, the accuracy will deteriorate. To solve this,
The detection mirrors 14, 16, 18, and 20 are used to determine the beam position of the corner portion, and the beam position of each color can be similarly determined. In this embodiment, the optical sensor 4 may be arranged only near the projection lens 5 of the cathode ray tube 9 or may be arranged near each of the projection lenses 5 to 7.

Next, the detection mirrors 19 and 21 will be described with reference to FIG.
And the positional relationship between the optical sensors 4 will be described. FIG. 3 is a side view showing the positional relationship between the detection mirror and the light sensor in FIG. 1, and shows the projection type display device shown in FIG. 1 except for the mirror 3, the red and blue CRTs and the projection lens. . In the figure, arrows 38 and 39
Represents light rays projected from the projection lens 5, reflected by the detection mirrors 21 and 19, and reaching the optical sensor 4. An angle 42 sandwiched between arrows 38 and 39
Is the angle of view of the projection lens 5. Also, angles 40, 41
Indicates the mounting angles of the detection mirrors 21 and 19 with reference to the plane formed by the screen 2. The angles are expressed as α42, α40, and α41. Since the optical sensor 4 and the projection lens 5 are arranged close to each other, approximately α
40 = α41 = α42 / 2. If α42 is large, the projection optical distance is short, and the offset amount of the optical sensor 4 with respect to the optical axis cannot be ignored, the mounting angle is appropriately corrected. Assuming that the correction amount is β, α40 = α42 /
2-β, α41 = α42 / 2 + β.

Next, some embodiments of the detection mirror will be described with reference to FIG. FIG. 4A is a side view showing a positional relationship between the detection mirror and the light sensor shown in FIG. 3, and FIGS. 4B to 4D are side views showing examples of the detection mirror. is there. FIG. 4 shows an embodiment of the detection mirror 21, but can be applied to other detection mirrors. Since the image projected from the projection lens 5 is formed on the screen 2, the image light is reflected by the detection mirror, and the image light reaching the optical sensor 4 is slightly diffused.
For this reason, it is desirable that the image light can be collected again by the detection mirror.

The reflection surface of the detection mirror 21 shown in FIG. 4B is formed in a concave shape so that the light reflected by the detection mirror 21 can be focused on the sensor 4.
Since the detection mirror 21 is configured such that a concave mirror is provided on a flat plate, it is hereinafter referred to as a flat plate concave mirror. FIG. 4 (c)
The detection mirror 21 shown in FIG. 3 has a concave reflecting surface so that light can be easily focused on the sensor 4 and can be easily mounted near the screen 2 and on the cabinet 1. The prism is provided with a concave mirror so that it can be attached as it is without giving an angle to the prism. For this reason, it is hereinafter referred to as a prismatic concave mirror.

The detection mirror 21 shown in FIG. 4D has a two-piece structure composed of a plane mirror 22 and a part of a Fresnel lens 23. 4A, 4B, and 4C can be used as the detection mirror 21. For example, even if a combination of a plane mirror and a convex lens is used, it can be appropriately used as long as it is a light collecting method. As a result, in the optical sensor 4, an optical signal having a good S / N can be obtained.

Next, referring to FIGS. 5 and 6, FIG.
The detection mirror 21 using a plane mirror and a part of the Fresnel lens shown in FIG. FIG. 5 is a side view showing a part of the plane mirror and the Fresnel lens. In the figure, 60, 6
Numeral 2 denotes light rays projected from the projection lens 5 and incident on the plane mirror 22. Light rays 60 and 62 are refracted by the Fresnel lens 23, respectively, are totally reflected by the plane mirror 22, and are refracted by the Fresnel lens 23 again. , Rays 61, 6
3 and heads in the direction of the optical sensor 4. Due to this light condensing effect, an optical signal with a good S / N can be obtained in the optical sensor.

Referring now to FIG. 6, the detection mirror shown in FIG. 4D or FIG.
And a case using a Fresnel sheet will be described. FIG. 6 is a side view showing a configuration of a lenticular sheet, an optical reflection element (a plane mirror), and a Fresnel lens sheet. In the figure, in a CRT type projection display device, the screen 2 is generally composed of a lenticular sheet 64 and a Fresnel sheet 65. In this configuration, an optical reflecting element (for example, a plane mirror or the like) is provided on the side of the incident light near the lenticular sheet 64.
66 and 67 are arranged to have the function of the plane mirror 22 shown in FIG. Further, the lens shape of the surface of the peripheral portions 68 and 69 of the Fresnel sheet 65 facing the optical reflection element is configured to have the same function as the Fresnel lens 23 in FIG. 4D. Thereby, the light reflected by the optical reflection element 22 is refracted by the lens portions of the ends 68 and 69 of the Fresnel sheet 65,
The light can be collected on the sensor 4. In this embodiment, the optical reflection element 66 is attached to the end of the lenticular sheet 64, and the reflected light can be condensed by the lens function of the end of the Fresnel sheet 65, so that a simple, low-cost convergence is achieved. A deviation detecting device can be realized.

The screen frame to which the detection mirror is attached will be described below with reference to FIGS. FIG. 7 is a front view showing another embodiment of the projection type display apparatus according to the present invention, and is a view showing an example of a mounting structure of the detection mirrors 14 to 21 and is different from our display apparatus shown in FIG. The difference is that a screen frame 50 is added.

FIG. 8 is a perspective view showing one embodiment of the screen frame shown in FIG. The detection mirrors 14 to 21
Although the configuration may be such that the screen 2 is directly attached to the cabinet 1 in FIG. 1, the screen 2 may be temporarily attached to the screen frame 50 and the screen frame 50 may be attached to the cabinet 1 in order to simplify the attachment of the screen 2. In the case of such a structure, as shown in FIG.
It is conceivable to attach the screen frame 50 to the cabinet 1 after attaching the detection mirrors 14 to 21 in advance. When the screen frame 50 is integrally formed of a material such as plastic, a projection having a shape corresponding to the detection mirrors 14 to 21 is provided in advance, and an optical reflection material such as aluminum is used as a detection mirror element on the surface. By providing the film 51 by gluing or the like, it is possible to realize a low-cost projection display device in which the screen 2 is easily attached.

Next, a description will be given of an apparatus for detecting a deviation amount of static convergence. FIG. 9 is a front view showing still another embodiment of the projection display apparatus according to the present invention.
As shown in the figure, the amount of deviation of the static convergence is detected by arranging detection mirrors 15, 17, 19, and 20 near the center of each periphery of the screen 2 to detect the amount of deviation of each color beam. Can be. Therefore, in this case, four detection mirrors are sufficient. This static convergence deviation amount detection device also operates as described with reference to FIGS. 1 and 2 and can use the embodiment described with reference to FIGS. When the amount of deviation of the static convergence is detected, the number of detection mirrors can be further reduced as compared with the case where the amount of deviation of the position of the electron beam corresponding to each color of dynamic convergence is detected.

As described above, according to the present invention, the convergence deviation amounts of red, green, and blue can be detected by combining a plurality of detection mirrors provided at the periphery of the screen and one optical sensor. The convergence correction data can be updated based on the calculated convergence deviation amount. Images can be realized. Further, since only one optical sensor is required, the cost can be kept very low.

[0030]

As described above, according to the present invention, a plurality of detection mirrors provided in the peripheral portion of the screen and a single optical sensor detect the convergence deviation amounts of red, green and blue. As a result, the cost can be kept very low.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a projection display apparatus according to the present invention and a partial cross-sectional view taken along line A1-A2.

FIG. 2 is a block diagram showing a convergence correction circuit of the projection display device.

FIG. 3 is a side view showing a positional relationship between a detection mirror and a light sensor in FIG.

FIG. 4 is a side view showing a positional relationship between a detection mirror and a light sensor, and a side view showing an embodiment of the detection mirror.

FIG. 5 is a side view showing a part of a plane mirror and a Fresnel lens.

FIG. 6 is a side view showing a configuration of a lenticular sheet, an optical reflection element (a plane mirror), and a Fresnel lens sheet.

FIG. 7 is a front view showing another embodiment of the projection display apparatus according to the present invention.

FIG. 8 is a perspective view showing one embodiment of the screen frame shown in FIG. 7;

FIG. 9 is a front view showing still another embodiment of the projection display apparatus according to the present invention.

[Explanation of symbols]

1 cabinet, 2 screen, 3 mirror, 4
Optical sensor, 5, 6, 7: Projection lens, 8, 9, 10: CRT, 11, 12, 13: Convergence correction coil, 14, 15, 16, 17, 18, 19, 20, 21
... detection mirror.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoharu Nagiri 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Within the AV Division of Hitachi, Ltd. F term in Hitachi Image Information System Co., Ltd. (reference) 5C060 BA02 BA07 BC05 CE01 CF01 GA02 GB02 GB07 GD01 HB24 HB26 JA01 JB06

Claims (16)

[Claims] 1. A method of projecting light from a plurality of CRTs displaying images of different colors on a screen via a plurality of projection lenses, wherein the plurality of CRTs converge the images of the respective colors projected on the screen. In a projection display device equipped with a convergence coil for correcting the light, a plurality of detection mirrors arranged around the screen, and an optical sensor for receiving reflected light from the detection mirror are provided, and the light A projection display device, wherein a correction current flowing through the convergence coil is controlled by an output from a sensor. 2. A projection display apparatus according to claim 1, wherein said optical sensor is arranged near one of said plurality of projection lenses and said plurality of cathode ray tubes, and light from said detection mirror is applied to said optical sensor. A projection display device, wherein the detection mirror is arranged so as to be incident. 3. The projection display device according to claim 2, wherein the angle of attachment of said detection mirror is set to substantially half of the angle of view of said projection lens. 4. The projection type display device according to claim 1, wherein said detection mirror comprises a light reflecting element and a lens portion of a Fresnel lens. 5. The projection display device according to claim 1, wherein said detection mirror is constituted by a concave mirror. 6. The projection type display device according to claim 5, wherein said concave mirror is a flat plate concave mirror formed by forming a flat plate into a concave shape. 7. The projection type display device according to claim 5, wherein said concave mirror is a prism having a concave mirror provided on a prism so that the cabinet can be directly attached without giving an angle to the cabinet. Projection display device. 8. The projection display apparatus according to claim 1, further comprising: a holding frame for holding said screen; and a projection for mounting said detection mirror around said holding frame. . 9. A red, green, and blue CRT with a convergence coil attached to a neck portion, three projection lenses for projecting an image displayed on a fluorescent screen of the three CRTs, and In a projection type display device having a screen for projecting images projected by three projection lenses, a plurality of detection mirrors are arranged around a periphery of the screen, and a plurality of reflected lights reflected by the plurality of detection mirrors are provided. A projection type display device, wherein an optical sensor to which light is incident is arranged. 10. The projection display apparatus according to claim 9, wherein said detection mirror is disposed at a predetermined angle with respect to a surface of said screen. 11. A projection display apparatus according to claim 10, wherein said optical sensor is arranged near one of said three projection lenses and three cathode ray tubes, and said detection mirror is attached to a surface of said screen. A projection display device, wherein the angle is about half the angle of view of the projection lens. 12. The projection display apparatus according to claim 9, wherein said detection mirror is a concave mirror. 13. The projection display apparatus according to claim 9, wherein said optical sensor comprises said three projection lenses and three optical lenses.
It is arranged near any one of the CRTs, and the plurality of detection mirrors are concave mirrors, and the mounting angle of the detection mirror with respect to the surface of the screen is about 1/2 of the angle of view of the projection lens. A projection display device characterized by the above-mentioned. 14. The projection type display device according to claim 13, wherein the curvature of the concave surface is set such that the focal length of the concave mirror is substantially equal to the projection optical distance determined by the projection lens. A projection display device characterized by the above-mentioned. 15. The projection display apparatus according to claim 9, wherein said plurality of detection mirrors are constituted by a plane mirror and a Fresnel lens. 16. The projection type display device according to claim 9, wherein said optical sensor comprises said three projection lenses and three optical lenses.
A screen frame is fixed to the screen, placed near any one of the CRTs of the book, a projection is provided around the screen frame in the direction of the optical axis from the projection lens, and the projection is optically reflected. A projection display device comprising a film having a function.