JPH08304751A - Liquid crystal projection device - Google Patents

Abstract

PURPOSE: To write a handwritten character on a screen on which a video is projected, to add another material to the screen and to record data inserted later on the screen. CONSTITUTION: In this liquid crystal projection device, white light emitted from a light source 3 is transmitted through a transmission type liquid crystal display board 2 where a picture is displayed according to a video signal and the video is projected on the screen 9 by using a projection optical lens system 4 in front of the display board 2. A half reflection mirror 11 is arranged between the display board 2 and the lens system 4, the video reflected on the screen 9 is reflected in a direction other than the direction of the display board 2 by the mirror 11, and the reflected light is picked up by an image pickup means and made a signal, which is compared with the video signal transmitted to the display board 2 to obtain a difference. After the difference signal is amplified, it is synthesized with the original video signal transmitted to the display board 2 and the synthesized signal is recorded or printed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projection device for displaying a projected image on a screen using a transmissive liquid crystal display plate, and more particularly to detecting reflected light from the screen and converting it into a signal to perform various kinds of signal processing. The present invention relates to a liquid crystal projection device.

[0002]

2. Description of the Related Art A conventional liquid crystal projection device 1A
15, the light source 3, the transmissive liquid crystal display plate 2 arranged in front of the light source 3, the optical lens system 4 arranged in front of the liquid crystal display plate 2, and the liquid crystal display plate 2 are driven. Circuit system 6A for 5 is a cooling fan. An image signal created by a personal computer 8 or the like provided separately from the liquid crystal projection device 1A is sent to the circuit system 6A via the interface cable 7, and the liquid crystal display panel 2 is driven by the circuit system 6A. As a result, an image is displayed on the liquid crystal display board 2.

In the liquid crystal projection device 1A thus constructed, the white light A emitted from the light source 3 is incident on the liquid crystal display plate 2 and transmitted through the liquid crystal display plate 2 displaying an image. The image light B becomes image light B, and when the image light B passes through the optical lens system 4, it becomes image light on the screen 9 as projection light C.

[0004]

In such a conventional liquid crystal projection device, the explainer unilaterally projects the material created by the personal computer 8 or the like on the screen 9 when the presentation device is used for presentation. It was something to do. Therefore, in addition to the material displayed on the screen 9, it is not possible to add other materials or leave them as recorded data. In this case, it is often seen that the people receiving the explanation are only listening, not actively exchanging opinions and debating.

In the liquid crystal projection device disclosed in Japanese Utility Model Laid-Open No. Sho 63-180829, a half mirror is arranged in front of a light source, and an original is illuminated by the light transmitted through the half mirror, and a television camera is provided. It has been proposed that the image of the TV camera can be sent to the liquid crystal display board via the liquid crystal drive circuit, but this liquid crystal projection device sends the television signal and the image pickup signal of the original sent separately. There is a problem that operations such as combining and and writing handwritten characters on the screen where the image is displayed cannot be performed.

The present invention has been proposed in order to solve the problems of the above-mentioned conventional techniques, such as writing handwritten characters on a screen projecting an image,
Another object of the present invention is to provide a liquid crystal projection device which can be attached with another material and can record data inserted later.

[0007]

In order to achieve this object, a liquid crystal projection device according to the present invention uses a transmissive liquid crystal display panel displaying an image of white light emitted from a light source according to a video signal. In a liquid crystal projection device for transmitting and projecting an image on a screen using a projection optical system in front of the transmission type liquid crystal display plate, a semi-reflection mirror is arranged between the transmission type liquid crystal display plate and the projection optical system. Then, the image reflected from the screen is reflected in a direction other than the transmissive liquid crystal display board by this semi-reflection mirror,
The reflected light is imaged by the image pickup means and converted into a signal.

Further, the liquid crystal projection apparatus according to the present invention compares the signal obtained by picking up the reflected light by the image pick-up means with the video signal sent to the transmissive liquid crystal display panel, takes a difference, and obtains this difference signal. It is configured to be combined with the original video signal sent to the transmissive liquid crystal display panel after being amplified.

Further, the liquid crystal projection apparatus according to the present invention is configured to detect the trapezoidal distortion of the image projected on the screen based on the signal obtained by picking up the reflected light by the image pickup means.

Further, in the liquid crystal projection device according to the present invention, the projection optical system is tilted vertically, the device body is tilted vertically, or the screen is tilted, using a signal obtained by detecting the trapezoidal distortion. Is used to correct the trapezoidal distortion.

Further, the liquid crystal projection apparatus according to the present invention is configured to detect the focus of the image projected on the screen by the signal of the reflected light taken by the image pickup means.

Further, the liquid crystal projection apparatus according to the present invention is configured to drive the projection optical system to automatically focus the projected image on the screen by using the signal which has detected the above-mentioned focus matching. .

Further, the liquid crystal projection apparatus according to the present invention is configured to detect the color misregistration of the signals of the red, green and blue components by the signal obtained by imaging the reflected light by the image pickup means.

Further, the liquid crystal projection apparatus according to the present invention adjusts an optical system, a transmissive liquid crystal display panel, etc. by utilizing a signal obtained by detecting a color shift of the red, green and blue component signals. It is configured to correct the color shift.

[0015]

According to the above construction, the signal obtained by picking up the reflected light by the image pickup means and the video signal sent to the transmissive liquid crystal display panel are compared to obtain a difference, and the differential signal is amplified and then the transmissive type is obtained. By combining with the original video signal sent to the liquid crystal display board, the combined signal can be stored or printed out.

Further, it is possible to perform trapezoidal distortion correction, focus correction, and color misregistration correction by using a signal obtained by picking up the reflected light by an image pickup means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of a liquid crystal projection device according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the liquid crystal projection device of the present invention. In this figure, the liquid crystal projection device 1 includes a light source 3, a transmissive liquid crystal display plate 2 arranged in front of the light source 3, a semi-reflective mirror 11 arranged in front of the liquid crystal display plate 2, and a semi-reflective mirror. 11, an optical lens system 4 arranged in front of the image forming lens 11, an image forming lens 12 through which light reflected by the semi-reflecting mirror 11 at a right angle to the optical axis passes, and a CCD camera as an image pickup means arranged in front of the image forming lens 12. 10 and a circuit system 6. The circuit system 6 includes a main circuit 6a, a liquid crystal drive circuit 6b, and a CCD drive circuit 6c. Figure 2
Shows the configuration of the main circuit 6a.

The image data created by the personal computer 8 or the like is received by the signal processing circuit 61 in the main circuit 6a of the liquid crystal projection device 1 through the interface cable 7, and then the liquid crystal drive circuit 6b.
And the liquid crystal display panel 2 is driven.

In the liquid crystal projection device 1 thus constructed, the white light A emitted from the light source 3 becomes the image light B by passing through the liquid crystal display plate 2 on which an image is displayed. Passes through the semi-reflective mirror 11,
The projection light C becomes the projection light C through the optical lens system 4 and the screen 9
Projected on. Further, the reflected light D reflected from the screen 9 reaches the semi-reflecting mirror 11 via the optical lens system 4 again, and is reflected by the semi-reflecting mirror 11 in the direction in which the CCD camera 10 is provided. CCD
An image is formed on the camera 10. In the CCD camera 10, the incident reflected light D is converted into an image pickup signal (this signal is referred to as data b).

This data b is sent to the main circuit 6a via the CCD drive circuit 6c. In the main circuit 6a, the difference circuit 62 compares the original image data a and the data b sent from the personal computer 8 to the liquid crystal display panel 2 and extracts the difference data c. The difference data c is additional image data such as handwritten characters written on the screen 9 and attached materials in addition to the image projected on the screen 9. The data c is amplified by the amplifier circuit 63 to improve the image quality, and then added to the original image data a by the synthesizing circuit 64 to obtain an image signal without deterioration (referred to as data d). be able to.

Next, the operation of making a presentation using the liquid crystal projection device will be described. As shown in FIG. 3, the image data a created on the personal computer 8 is sent to the liquid crystal projection device 1, and a video 20 similar to the image 20 on the personal computer 8 is projected on the screen 9.

It is assumed that a presentation or the like is performed based on the image 20 on the screen 9. At this time, in addition to the projected image 20, handwritten characters 21 and handwritten images such as changed items may be added on the screen 9 or the material 22 may be pasted. In such a case, the entire image on the screen 9 is displayed on the C screen in the liquid crystal projection device 1.
The data is captured by the CD camera 10 and the above-mentioned data conversion is performed to obtain the final data d.

This data d is sent to the personal computer 8, saved on the personal computer 8 and displayed on the screen of the personal computer 8 as shown in FIG. The display image 23 can be printed by the printer 13 and can be distributed to attendees as a material during the conference. The print image of the printer 13 is set to 23.

Next, a means for further improving the image quality by capturing the image on the screen 9 into the liquid crystal projection device will be described. If the optical axis of the liquid crystal projection device and the projection surface of the screen 9 are not in a vertical relationship, they will cause trapezoidal distortion.

As shown in FIGS. 5A and 5C, if the optical axis of the liquid crystal projection device 1 and the screen 9 are vertical, a distortion-free image can be obtained. The output of the CCD camera 10 at this time has the same waveform for the data S1 at the uppermost stage and the data S1 at the lowermost stage of the image as shown in FIG.

On the other hand, if the screen 9 is tilted forward with respect to the optical axis of the liquid crystal projection device 1 as shown in FIGS. 6A and 6C, the projected image has a trapezoidal outline. Then, the output of the CCD camera 10 is, as shown in FIG. 2B, the lowermost data S2 rather than the uppermost data S1.
Is wider.

On the contrary, as shown in FIGS. 7A and 7C, the screen 9 is arranged with respect to the optical axis of the liquid crystal projection device 1.
If is tilted backward, the projected image has an inverted trapezoidal outline. Then, the output of the CCD camera 10 has a narrower width in the lowermost data S2 than in the uppermost data S1, as shown in FIG.

The CCD camera 1 is in the state described above.
After detecting the trapezoidal distortion based on the image pickup signal from 0, the angle of the screen 9 is changed, the attitude of the liquid crystal projection apparatus main body is changed, or the attitude of the optical lens system 4 is changed to correct the optical axis. To do.

Next, a mechanism for changing the attitude of the liquid crystal projection device body will be described. In the chassis base 100 of the liquid crystal projection device 1, as shown in FIG. 8, a vertical shaft 106 having a screw formed therein is fitted as a foot component into a nut 107 fixed to the chassis base 100. A driven gear 105 is fixed to the upper ends of the upper and lower shafts 106 and meshes with the idle gear 104. The idle gear 104 has a motor 10
The drive gear 103 attached to the No. 2 meshes.

With this structure, the drive gear 103 on the motor 102 side rotates to rotate the idle gear 104, and the driven gear 105 rotates accordingly. When the driven gear 104 rotates, the upper and lower shafts 106 also rotate and move up and down by the nut portion. This movement changes the amount of feeding the foot component 101 with respect to the chassis base 100. Such a mechanism for feeding out the foot component 101 is provided on the front left and right of the chassis base 100.

The signal from the CCD camera 10 is supplied to the main circuit 6a.
To the trapezoidal distortion detection circuit 65, and when the trapezoidal distortion is detected, the motor 102 is rotated in a predetermined direction to change the attitude of the liquid crystal projection device body, and when the distortion is eliminated, the motor 102 is stopped. By configuring, trapezoidal distortion can be automatically corrected.

It is also possible to use the output signal of the CCD camera 10 to automatically control the focus. In this case, as shown in FIG. 9, a black-and-white vertical stripe test pattern TP1 is projected from the liquid crystal projection device 1 onto the screen 9, and the reflected light is captured by the CCD camera 10 and converted into a signal. CC out of focus
As shown in FIG. 11A, the output signal from the D camera 10 has a falling and rising edge of the signal waveform between the black level and the white level.

In such a case, the output signal of the CCD camera 10 is sent to the focus detection circuit 66 of the main circuit 6a, and the motor 32 of the focus drive mechanism as shown in FIG. The focus ring 30 is driven via the idle gear 31.
Then, as shown in FIG. 11B, a point where the output signal from the CCD camera 10 becomes a rectangular wave is searched for and focused.

Further, in the liquid crystal projection device of the type in which the transmissive liquid crystal display plate is composed of the three primary color liquid crystal display plates for red, the liquid crystal display plate for green and the liquid crystal display plate for blue, the color image is projected on the screen 9. The technique of superimposing each color is sophisticated, and it is possible to detect the color shifts of these three colors (pixel shifts of the three-color liquid crystal display panel) from the signals of the CCD camera and adjust the color matching.

FIG. 12 shows the structure of a general three-plate type liquid crystal projection device. In this figure, the white light emitted from the light source 40 is a dichroic mirror (color separation optical system) 41,
42, 43 depending on blue light R1, green light R2, red light R
It is separated into three and is passed through a blue liquid crystal display plate 44, a green liquid crystal display plate 45, and a red liquid crystal display plate 46, respectively. The image light of each color passing through the liquid crystal display plate of each color is reflected by the mirrors 47, 4
The light is guided to the optical lens system 53 via the semi-reflection mirror 51 by 8, 49 and 50. The projection light emitted from the optical lens system 53 is projected on the screen 9 as a color image. The reflected light from the screen 9 returns through the optical lens system 53, is reflected by the semi-reflection mirror 51, and is captured by the CCD camera 52.

In order to detect a color shift with this three-plate type liquid crystal projection device, a vertical stripe test pattern TP2 is projected on the screen 9, and the reflected light is guided to the CCD camera 52 by the semi-reflective mirror 51, and red, green and Signal is divided into blue components. When there is a color shift, a shift also occurs in each color output signal of the CCD camera 10 as shown in FIG. 13. Therefore, the shift of this signal is detected, and the liquid crystal display board 44,
It can be used for color misregistration correction of 45 and 46. When the color misregistration is correctly corrected, the color output signals of the CCD camera 14 overlap each other as shown in FIG. The color misregistration may be corrected by adjusting the optical system.

[0037]

As described above, according to the present invention, it is possible to add handwritten characters and materials to the image projected on the screen at the time of giving a presentation, etc. Rather, there is an advantage that a listener participation type presentation can be performed. In addition, there is an advantage that a high-quality image without distortion, in focus, and without color shift can be projected on the screen.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a liquid crystal projection device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a main circuit.

FIG. 3 is a perspective view showing how a projected image on a screen is used and a presentation is performed.

FIG. 4 is a perspective view showing a state in which handwritten character information and attached materials are combined with a projected image and displayed on a personal computer or printed out.

FIG. 5 is an explanatory diagram showing a state in which no trapezoidal distortion is generated on the screen.

FIG. 6 is an explanatory diagram showing a state in which trapezoidal distortion is generated due to the forward tilt of the screen.

FIG. 7 is an explanatory diagram showing a state in which trapezoidal distortion occurs due to the rearward tilt of the screen.

FIG. 8 is a perspective view showing a mechanism for tilting the liquid crystal projection device body up and down to correct the trapezoidal distortion.

FIG. 9 is a perspective view showing a state in which vertical stripes are projected on a screen to detect a focus shift.

FIG. 10 is a perspective view showing a focusing mechanism.

FIG. 11A is a waveform diagram showing a state where the focus is deviated,
(B) is a waveform diagram in a state where the focus is in agreement.

FIG. 12 is a perspective view showing a configuration of a three-panel liquid crystal projection device.

FIG. 13 is a waveform diagram showing a state where color misregistration occurs.

FIG. 14 is a waveform diagram showing a state in which color misregistration is corrected.

FIG. 15 is a configuration diagram showing a configuration of a conventional liquid crystal projection device.

[Explanation of symbols]

1 Liquid Crystal Projection Device 2 Transmissive Liquid Crystal Display Plate 3 Light Source 4 Optical Lens System 5 Fan 6 Circuit System 6a Main Circuit 6b Liquid Crystal Driving Circuit 6c CCD Driving Circuit 7 Interface Cable 8 Personal Computer 9 Screen 10 CCD Camera 11 Semi-Reflecting Mirror 12 Imaging Lens 13 Printer 20 Projected image on the screen 21 Handwritten characters 22 Material pasted on the screen 23 Composite image by image data obtained by adding the image created on the personal computer and the image added on the screen 30 Focus ring 31 Idle gear 32 Motor 33 Motor gear 40 Light source 41, 42, 43 Dichroic mirror 44 Blue liquid crystal display plate 45 Green liquid crystal display plate 46 Red liquid crystal display plate 47, 48, 49, 50 Mirror 51 Semi-reflection Mirror 52 CCD camera 53 Optical lens system 61 Signal processing circuit 62 Difference circuit 63 Amplifier circuit 64 Composite circuit 65 Trapezoidal distortion detection circuit 66 Focus detection circuit 100 Chassis base 101 Foot parts 102 Motor 103 Drive gear 104 Idle gear 105 Followed gear 106 Upper and lower shafts 107 nuts

[Procedure amendment]

[Submission date] August 25, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 11

[Correction method] Change

[Correction content]

FIG. 11

Claims (8)

[Claims] 1. White light emitted from a light source is transmitted through a transmissive liquid crystal display panel displaying an image by a video signal, and is projected on a screen by using a projection optical system in front of the transmissive liquid crystal display panel. In a liquid crystal projection device that projects an image, a semi-reflective mirror is arranged between the transmissive liquid crystal display plate and the projection optical system, and the image reflected from the screen is reflected by the semi-reflective mirror except the transmissive liquid crystal display plate. The liquid crystal projection device is characterized in that the reflected light is reflected in the direction of, and the reflected light is imaged by an imaging means and converted into a signal. 2. A signal obtained by picking up the reflected light by an image pickup means and a video signal sent to the transmissive liquid crystal display plate are compared to obtain a difference, which is amplified and then sent to the transmissive liquid crystal display plate. The liquid crystal projection device according to claim 1, wherein the liquid crystal projection device is synthesized with an original video signal that is generated. 3. The liquid crystal projection device according to claim 1, wherein a trapezoidal distortion of an image projected on a screen is detected by a signal obtained by imaging the reflected light by an imaging means. 4. The trapezoidal distortion is corrected by tilting the projection optical system in the vertical direction, tilting the apparatus main body up or down, or tilting the screen by using the signal in which the trapezoidal distortion is detected. The liquid crystal projection device according to claim 3. 5. The liquid crystal projection device according to claim 1, wherein the focus of the image projected on the screen is detected by a signal obtained by imaging the reflected light by an imaging means. 6. The liquid crystal projection device according to claim 5, wherein the projection optical system is driven to automatically focus the projection image on the screen by using the signal in which the focus match is detected. . 7. The liquid crystal projection device according to claim 1, wherein a color shift of signals of red, green, and blue components is detected by a signal obtained by imaging the reflected light by an imaging means. 8. The color misregistration is corrected by adjusting an optical system, a transmissive liquid crystal display panel, and the like using a signal obtained by detecting a color misregistration of the red, green, and blue component signals. The liquid crystal projection device according to claim 7.