JPH1188806A - Liquid crystal projector with camera for painting and calligraphy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to execute optimum overscanning without narrowing an image pickup area of a camera and to finely display a picture based on an input signal by switching an enlargement ratio for the input of a video signal and that for the input of a camera image in accordance with an input video signal. SOLUTION: The same signal as a switching signal to be supplied to a selection circuit is supplied to an enlargement processing circuit 70. An enlargement controller controls the reading of a video signal stored in a memory 8 based on the switching signal and controls multiplication coefficients to be supplied to respective multipliers so that enlargement signal processing is executed by an enlargement ratio corresponding to a video signal inputted from the circuit 4. When a camera input signal and a video signal correspond to an NTSC type and the display resolution of a liquid crystal panel 11 corresponds to an SVGA, enlaregement processing can be respectively executed in an enlargement ratio based on overscanning at the time of inputting a video signal and in an enlargement ratio based on just-scanning at the time of inputting a camera input singal and fine images can be respectively displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention integrally comprises a document camera for photographing a document or the like and a liquid crystal projector for enlarging and projecting an image based on an image signal taken by the document camera. The present invention relates to a liquid crystal projector with a document camera, and more particularly to a liquid crystal projector with a document camera suitable for performing enlarged display without damaging the effective pixels of the liquid crystal panel even when a video input such as another video reproduction signal is made.

[0002]

2. Description of the Related Art In recent years, the adoption of digitization of image signal processing has expanded its application range, and input image signals, which are subject to image processing, have become increasingly finer year by year.
For this reason, devices equipped with an image signal processing circuit are required to further increase the data processing capacity required for image processing compared to conventional devices, and any video source can perform image processing corresponding to the input video signal. It is also desired to expand the data processing capacity so that the data processing can be performed.

In response to such demands, recently, as a device equipped with an image processing circuit, instead of a conventional overhead projector, a projection display device using a document camera and a liquid crystal panel (hereinafter, referred to as a liquid crystal projector). ) And a liquid crystal projector with a document camera, which are integrally formed, are widely used.

This liquid crystal projector with a document camera obtains an imaged video signal captured by a documentary camera that captures a document or the like, and then performs predetermined signal processing on the obtained imaged video signal to obtain a liquid crystal in the liquid crystal projector. An image based on the captured video signal is formed on the panel, and the formed image is magnified and projected using an optical system such as a magnifying projection lens, so that an image of the imaging target can be projected. Unlike traditional overhead projectors,
There is an advantage that it is possible to easily image and display an image without writing a document or the like to be imaged. For this reason, liquid crystal projectors with a document camera are widely used, for example, for demonstrations or displays at various event venues.

A liquid crystal projector with a document camera has a function of capturing and displaying not only an image signal picked up by the document camera but also an output image signal from a personal computer or a reproduction signal from a VTR or the like. Some have. In such a liquid crystal projector with a document camera, in order to normally display an image of an input video signal, image signal processing corresponding to each video input source must be performed.

Normally, the resolution of a liquid crystal panel provided in a liquid crystal projector is determined by the number of pixels, and a resolution corresponding to the display resolution of an input video source is used. Currently, the mainstream liquid crystal panel is SVGA (800 horizontal pixels × 60 vertical pixels).
0 pixels) corresponding to a display screen of an input video source, from VGA (640 horizontal pixels × 480 vertical pixels) to XGA (1024 horizontal pixels × 768 vertical pixels), SXG
A (high resolution display such as A (1280 horizontal pixels × 1024 vertical pixels)) having high display resolution is also being commercialized.

Here, considering a case in which a video reproduction signal of the current NTSC system is taken in and displayed by using a liquid crystal projector with a document camera equipped with a liquid crystal panel compatible with SVGA, which is currently mainstream, for example, As shown in FIG. 5, it is necessary to perform an enlargement process on an input video signal by image signal processing in a liquid crystal projector so as to increase the number of horizontal / vertical pixels and the number of lines, and project the input image signal. That is, an input video signal (video reproduction signal) of the NTSC system having a display resolution of 640 pixels horizontally × 480 pixels vertically is
S whose display resolution is 800 pixels horizontally x 600 pixels vertically
In order to display on a VGA-compatible liquid crystal panel, at least a 1.25-fold enlargement process is required.

FIG. 4 is a block diagram showing an example of a conventional liquid crystal projector with a document camera capable of performing projection after performing enlargement processing so as to increase the number of horizontal and vertical pixels and the number of lines as described above. Note that, for simplification of description, description of optical system means such as a light source lamp and a projection lens which are originally mounted in the liquid crystal projector will be omitted.

In FIG. 4, a video signal input terminal 2 is connected to a reproduced signal from, for example, a VTR, that is, the current NTS.
A video signal of the C system is supplied, and the input video signal is supplied to the selector circuit 4. This selector circuit 4 includes:
A captured video signal (hereinafter, video signal) captured by the document camera 3 is also supplied. The selector circuit 4 performs a switching operation based on a switching control signal (hereinafter, referred to as a switching signal) supplied from a control circuit (not shown) via a switching signal input terminal 1, and performs video processing on one of the input video signals. Supply to circuit 5.

At this time, the camera 3 output signal and the input terminal 2
Assuming that the input video signal from the LCD is of the NTSC type and the liquid crystal panel 11 mounted on the liquid crystal projector is of the SVGA compliant type, the output signal of the selector circuit 4 Is subjected to signal processing, and is decoded into an RGB signal.
It is supplied to a digital converter (hereinafter, referred to as an A / D converter) 6.

In the A / D converter 6, one horizontal cycle period is digitized by 780 samples, converted into a digital video signal, and supplied to an enlargement processing circuit 70. In this case, the number of effective samples in this digital video signal is 780 × 0.83 ≒ 640 for the horizontal effective sample and 483 (≒ 480) for the vertical effective sample.

The enlargement processing circuit 7 performs the above-described enlargement signal processing on the input video signal using the memory 8. Thus, by increasing the number of pixels and the number of lines in the input video signal, the input video signal can be converted into an SVGA signal corresponding to the high resolution of the liquid crystal panel 11.

For example, the enlargement processing circuit 7 generates five samples from four samples while performing weighted averaging in both the vertical and horizontal directions as shown in FIG. That is, by performing an interpolation process on each sample using a predetermined interpolation coefficient, 4
Five samples can be generated from the sample. Therefore, by performing such expanded signal processing, the horizontal effective sample is changed from 640 to 800 samples, and the vertical effective sample is changed from 480 to 600 samples. Image data can be obtained.

Output data of the enlargement processing circuit 7 is a digital-to-analog converter (hereinafter referred to as a D / A converter).
9 and is converted to an analog signal by the D / A converter 9 before being supplied to the drive circuit 10. The drive circuit 10 starts driving based on the supplied input signal, so that an image based on the supplied input signal is formed on the liquid crystal panel 11. Thereafter, an image formed on the liquid crystal panel 11 is projected by light emitted from a light source lamp (not shown), and this image light is enlarged and projected by a projection lens (not shown) and projected on a screen or the like.

However, in the NTSC standard, the horizontal and vertical effective scanning rates are determined according to the standard. However, the actual video signal may not satisfy this, and the effective scanning line may be insufficient. In particular, in the case of a reproduction signal of a VTR or the like, inconvenience that a video is disturbed such as a flaw such as a white horizontal line can be seen at a lower portion of a screen due to switching of helical scan or the like. For this reason, a general television receiver or the like performs overscan of several percent to hide it outside the effective area of the screen. Therefore, in the case of the liquid crystal projector with a document camera having the above configuration, for example, if the enlargement ratio by the enlargement processing circuit 7 is set to 1.33 times, the overscan ratio becomes (1.33 / 1.25-1) × 100 = 6.4%, which makes it possible to hide such flaws outside the effective area of the screen. However, in a liquid crystal projector with a document camera having such a function of performing enlargement processing, the selector circuit 4 switches to a video signal from the document camera 3, and the video signal satisfies the NTSC standard. In this case, if the enlargement processing is performed at the above-described overscan rate, the imaging area of the document camera 3 is reduced as a result.
There is a problem that it is not possible to perform an enlarged image signal process compatible with a video reproduction signal and a captured video signal from a document camera.

[0016]

As described above, in the conventional liquid crystal projector with a document camera, the input video source can be switched between a video signal input and an image pickup input by the document camera. Enlarged image signal processing cannot be performed at an enlargement ratio corresponding to the source switching. In other words, at the time of video input, normal video can be displayed and the imaging area of the camera can be made normal by overscanning. However, when an imaging signal is input from a document camera, the same overscanning is performed. Therefore, even if the effective scanning area is made normal, the imaging area of the document camera is reduced, and as a result, there is a problem that it is not possible to perform a compatible enlarged signal processing of these input video sources. .

Accordingly, the present invention has been made in view of the above-mentioned problems, and an enlargement ratio between a video signal input and a camera input can be switched in accordance with an input video signal so that an image pickup area of a camera can be changed. An object of the present invention is to provide a liquid crystal projector with a document camera that can perform optimal overscan without narrowing and can display an image based on an input signal in an excellent manner.

[0018]

According to a first aspect of the present invention, there is provided a liquid crystal projector with a document camera, comprising: a video signal from a camera integrated with a liquid crystal projector having a liquid crystal panel; A signal and a video signal having the same format can be selectively switched to be input, and the number of pixels based on the input signal is driven in order to drive the liquid crystal panel configured with a larger number of pixels than the format of these input signals. In a liquid crystal projector with a document camera having an enlargement conversion function of performing an enlargement conversion process to the number of pixels according to the liquid crystal panel, a switching circuit for selectively switching and inputting an image signal and a video signal from the camera. , For an input signal from the switching circuit,
An enlargement processing circuit capable of changing and enlarging the enlargement signal at a predetermined enlargement ratio and outputting the enlargement ratio, and controlling the switching by the switching circuit and the enlargement ratio by the enlargement processing circuit in conjunction with each other. And control means for performing enlarged signal processing at an enlargement ratio according to the input signal selected by the circuit. According to the first aspect of the present invention, the enlargement processing function selects an image pickup video signal from a camera integrated with a liquid crystal projector having a liquid crystal panel and a video signal having at least the same format as the image pickup image signal. The number of pixels based on the input signal is enlarged and converted into the number of pixels corresponding to the liquid crystal panel in order to drive the liquid crystal panel composed of a larger number of pixels than the format of the input signal by switching and inputting the signals. I do. In this case, the control means controls the switching by the switching circuit and the enlargement rate by the enlargement processing circuit in conjunction with each other, and controls the enlargement signal processing at the enlargement rate according to the input signal selected by the switching circuit. I do. This makes it possible to switch the enlargement ratio between when a document camera is input and when a video signal is input,
Enlarged signal processing can be performed at an optimal enlargement ratio according to the input video signal.

According to a second aspect of the present invention, there is provided the liquid crystal projector with a document camera according to the first aspect, wherein the image signal and the video signal from the camera are NTSC video signals. It is characterized by being a signal.

According to the second aspect of the present invention, the operation is the same as that of the first aspect of the present invention. For example, it is assumed that an image signal from a camera and the video signal are NTSC video signals. Further, assuming that the liquid crystal panel is compatible with SVGA, the control means:
The control can be performed so that the enlarged signal processing is performed at a magnification of 1.25 times when a captured video signal is input from the camera and at a magnification of 1.33 times when a video signal is input. As a result, even when the video signal is a reproduction signal from a VTR, overscan can be performed, and in the case of a camera input, it is possible to perform just-scan such that the effective scanning rate is not insufficient. ,
Obtain compatibility of enlarged signal processing.

According to a third aspect of the present invention, there is provided the liquid crystal projector with the document camera according to the first aspect, wherein the image signal and the video signal from the camera are PAL type images. It is characterized by being a signal.

According to the third aspect of the present invention, even when the image signal and the video signal from the camera are PAL system image signals, they operate in the same manner as the first and second aspects. Thus, it is possible to perform the enlargement signal processing at the optimum enlargement ratio.

A liquid crystal projector with a document camera according to a fourth aspect of the present invention has a video signal from a camera integrated with a liquid crystal projector having a liquid crystal panel and has at least the same format as this video signal. A video signal can be selectively switched to be input, and the number of pixels based on the input signal is adjusted according to the liquid crystal panel in order to drive the liquid crystal panel configured with a larger number of pixels than the format of the input signal. In a liquid crystal projector with a document camera having an enlargement signal processing circuit for performing an enlargement conversion process to the number of pixels, a switching circuit for selectively switching and inputting an image pickup video signal from the camera and the video signal is provided. The processing circuit includes a memory for storing an input signal from the switching circuit, and a read signal from the memory for one horizontal period. 1 a horizontal period delay circuit for cast,
Multiplication results of both the first and second multipliers for multiplying the output signal from the one horizontal period delay circuit and the read signal from the memory by different multiplication coefficients, respectively, and the first and second multipliers A first adder for adding and outputting the sum, and 1 for delaying an addition signal from the first adder for each pixel.
A pixel delay circuit, third and fourth multipliers for multiplying the output signal from the one-pixel delay circuit and the addition signal from the first adder with different multiplication coefficients, respectively, and the third and fourth multipliers A second adder for adding and outputting both multiplication results of the multipliers, and a switching control by the switching circuit, a write / read control of the memory, and a multiplication coefficient of the first to fourth multipliers. The enlargement processing control that enlarges the image at the enlargement ratio according to the input signal by controlling the multiplication coefficient in response to the switching control of the switching circuit while changing the reading method of the memory. And means.

According to the fourth aspect of the present invention, an image signal from a camera integrally provided in a liquid crystal projector having a liquid crystal panel is provided by an enlarged signal processing circuit function.
At least this imaging video signal and a video signal having the same format are selectively switched and input, and based on the input signal to drive the liquid crystal panel configured with a larger number of pixels than the format of the input signal. The number of pixels is enlarged and converted to the number of pixels corresponding to the liquid crystal panel.
In this case, the enlargement processing control means can perform switching control by the switching circuit, write / read control of the memory, and control of multiplication coefficients of the first to fourth multipliers. In addition to the above, by performing the control of the multiplication coefficient in response to the switching control of the switching circuit, it becomes possible to perform the enlargement conversion processing at the enlargement ratio according to the input signal. This makes it possible to switch the enlargement ratio between the case of inputting a document camera and the case of inputting a video signal, as in the first aspect of the invention. Processing can be performed.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of a liquid crystal projector with a document camera according to the present invention. FIG. 1 is a block diagram showing an entire configuration in which an optical system is omitted, and FIG. FIG. 3 is a block diagram illustrating a specific configuration example of an enlargement processing circuit used in one device. In FIG. 1, the same reference numerals are given to the same components as those in the apparatus shown in FIG. 4, and the optical system means such as a light source lamp and a projection lens which are originally mounted in the liquid crystal projector will be described. The description is omitted for simplification.

As shown in FIG. 1, in the liquid crystal projector with a document camera according to the present invention, even when the input is switched to a video signal from the current NTSC type document camera 3, an enlargement ratio suitable for the camera input is obtained. , A switching signal from a control unit (not shown) is supplied to the enlargement processing circuit 70 in addition to the selector circuit 4 via the switching signal input terminal 1a so that the enlarged image signal processing can be performed. I have. Therefore, the switching signal supplied via the switching signal input terminal 1a is supplied to the select circuit 4 and the enlargement processing circuit 70.

A video signal input terminal 2 is supplied with, for example, a reproduced signal from a video, that is, a video signal of the current NTSC system, and supplies the input video signal to a selector circuit 4. The selector circuit 4 is also supplied with a video signal captured by the document camera 3. The selector circuit 4 performs a switching operation based on a switching signal supplied from a control circuit (not shown) via a switching signal input terminal 1a,
One of the input video signals is supplied to the video processing circuit 5.

At this time, the camera 3 output signal and the input terminal 2
It is assumed that the input video signal from the LCD is of the NTSC system and that the liquid crystal panel 11 mounted on the liquid crystal projector is of the SVGA compliant type. Then, the output signal of the selector circuit 4 is subjected to predetermined signal processing by the video processing circuit 5 and is decoded into an RGB signal.
It is supplied to the D converter 6.

In the A / D converter 6, one horizontal cycle period is digitized by 780 samples, converted into a digital video signal, and supplied to the enlargement processing circuit 70. In this case, the number of effective samples in this digital video signal is 780 × 0.83 ≒ 640 for the horizontal effective sample and 483 (≒ 480) for the vertical effective sample.

The enlargement processing circuit 70 uses such an existing NT
When the input video signal of the SC system is supplied, the expanded signal processing of 1.25 times is performed using the memory 8 as described in the related art (see FIGS. 5 and 6). Thus, by increasing the number of pixels and lines in the input video signal, the NTSC video signal is converted into an SVGA signal corresponding to the high resolution of the liquid crystal panel 11, that is, from 640 to 800 horizontal effective samples and from vertical effective samples. 480 samples to 1.25 from 600 samples
It is possible to convert the image data to SVGA-compatible image data that has been enlarged twice.

However, when the video input signal is a reproduction signal from a VTR, the overscan is performed with the enlargement ratio set to, for example, 1.33 times in order to hide the noise generated at the lower part of the screen. At this time, if the video input is switched to the video input from the document camera 3 and if this video signal is of the NTSC system, the enlargement processing is performed at the same enlargement ratio and the The scanning is performed, and as a result, the imaging area of the document camera 3 is reduced.

However, unlike the conventional enlargement processing circuit 7, the enlargement processing circuit 70 of this embodiment can perform enlargement processing in place of the optimum enlargement ratio according to the input video signal.

The specific configuration of the enlargement processing circuit in this embodiment will be described in detail with reference to FIG.

As shown in FIG. 2, in the enlargement processing circuit 70, an input terminal 71 for receiving an output signal from the A / D converter 6 shown in FIG. And another input terminal 72 for capturing.

The digital video signal captured by the input terminal 71 is supplied to the memory 8 first. Memory 8
Is capable of writing or reproducing the supplied digital video signal, and its writing / reading control is controlled by a magnification controller 72.

The output data of the memory 8 is supplied to the 1H delay circuit 7
3 and a multiplier 75. One delay circuit 73 delays the input data by one horizontal period and supplies the result to multiplier 74. The multipliers 74 and 75 are configured such that the multiplication coefficient k is controlled by the enlargement ratio controller 72, and performs multiplication with the input data using the multiplication coefficient k determined to be multiplied by this control. Output multiplication result. In this case, the multiplication coefficient of the multiplier 75 is (1−k). The multiplication result of each of the multipliers 74 and 75 is supplied to an adder 76,
After being subjected to addition processing (arithmetic processing) by the adder 76, it is supplied to the one-sample delay circuit 77 and the multiplier 79.

One-sample delay circuit 77 receives input data,
That is, the line data is output after being delayed for each sample. The output data of the one-sample delay circuit 77 is
The signal is supplied to a multiplier 78. These multipliers 78 and 79
Also, the multiplication coefficient k is controlled by the enlargement ratio controller 72. The multiplication coefficient k is multiplied with the input data using the multiplication coefficient k determined by this control, and the multiplication result is output. In this case, the multiplication coefficient of the multiplier 79 is (1−k). The multiplication results of the multipliers 78 and 79 are supplied to an adder 80, which performs addition processing (arithmetic processing) by the adder 80, and then outputs the result to a D / A converter 9 shown in FIG. Supplied.

Therefore, according to the enlargement processing circuit 70 having the above configuration, the enlargement ratio for performing the input enlargement processing can be switched according to the switching of the video signal. That is, when the input is switched to the video signal input from the document camera 3 by the control of the multiplication coefficient k by the enlargement ratio controller 72, the enlargement ratio is set to 1.25 times the normal value.
When switching to a video signal input where a playback signal from R may be supplied, the magnification can be switched so as to be 1.33 times, that is, an optimal over-range according to the input video signal. A scan rate can be obtained.

Thereafter, the output data of the enlargement processing circuit 70 is supplied to the D / A converter 9 to be converted into an analog signal, and then supplied to the drive circuit 10.
The drive circuit 10 starts driving based on the supplied input signal, so that an image based on the supplied input signal is formed on the liquid crystal panel 11. Thereafter, an image formed on the liquid crystal panel 11 is projected by light emitted from a light source lamp (not shown), and this image light is enlarged and projected by a projection lens (not shown) and projected on a screen or the like.

Next, the operation will be described in detail with reference to FIG.

FIGS. 3A and 3B are explanatory diagrams for explaining the operation. FIG. 3A shows an enlargement processing operation when processing is performed at an enlargement ratio of 1.25 times, and FIG. 3B shows 1.33. 9 illustrates an enlargement processing operation when the enlargement processing is performed at a double enlargement ratio.
Note that the enlargement process is originally performed for two dimensions in the vertical and horizontal directions. However, for simplicity, one dimension will be described, and the input video signal will be of the current NTSC system. The following description is based on the assumption that a SVGA-compatible device having a high display resolution is used.

Now, it is assumed that the input selection mode of the liquid crystal projector with a document camera shown in FIG. Then, the selector circuit 4 operates the document camera 3 based on a switching signal from a control unit (not shown).
Is controlled so as to take in the video signal from the.

In this case, in the enlargement processing circuit 70, the input video signal is of the NTSC system and the liquid crystal panel is
Since it has a display resolution compatible with VGA, the enlargement process is performed at an enlargement ratio of 1.25 under the control of the enlargement ratio controller 72.

For example, as shown in FIG. 3A, in the enlargement processing circuit 70, under the control of the enlargement ratio controller 72, the same pixel is read out once every four pixels (line) I from the memory 8. As a result, the magnification itself becomes 1.2
Although the image is magnified five times, the diagonal lines and the like become jagged. Therefore, as shown in the figure, a weighted average is performed between the output of the memory 8 and the data delayed by one pixel (line) as shown in the figure. . As a result, the output data becomes smooth and necessary for displaying on the liquid crystal panel 11.
It is possible to obtain an SVGA signal that has been subjected to the enlargement processing at a magnification of 25 times, and as a result, it is possible to display well without reducing the imaging area of the document camera 3.

Next, it is assumed that the input selection mode is selected for video input. Then, the switching of the selector circuit 4 is controlled based on a switching signal from a control unit (not shown) via the video signal input terminal 2 so as to take in a reproduction signal from, for example, a VTR.

In this case, since the input video signal is of the NTSC system, the effective scanning rate may be insufficient. Also, due to the reproduction signal, noise or the like may be generated at the lower part of the screen. Therefore, in the enlargement processing circuit 70, 1.33 is controlled by the enlargement ratio controller 72 in order to eliminate such inconvenience.
By performing the enlargement processing at the enlargement ratio of 6.4%, an overscan of 6.4% is performed.

For example, as shown in FIG. 3B, in the enlargement processing circuit 70, the same pixel is read out once every three pixels (line) I from the memory 8 under the control of the enlargement ratio controller 72. Thereafter, as shown in the figure, a weighted average is performed between the output of the memory 8 and the data delayed by one pixel (line). As a result, the enlargement process is performed at a magnification of 1.33 times, which is necessary for displaying the image on the liquid crystal panel 11 without reducing the imaging area of the document camera 3, and 6.
A 4% overscanned SVGA signal can be obtained. As a result, the noise generated at the lower part of the screen can be hidden outside the effective area of the screen, so that the video based on the input reproduction signal can be displayed well.

Therefore, according to the present embodiment, as described above, by using the enlargement processing circuit 70 for controlling the enlargement ratio to be switched in accordance with the switching of the input video signal, for example, an overscan is incorporated at the time of video input. The enlargement process can be performed at the same enlargement ratio, and the enlargement process can be performed at the enlargement ratio at which the effective scanning ratio is not insufficient when the document camera is input. Accordingly, it is possible to realize a compatible liquid crystal projector with a document camera capable of inputting a video and a camera.

In this embodiment, an image based on a video signal or an image based on an input video signal from a document camera, such as a document, is displayed as a still image. It may be configured to display an image.

In this embodiment, in the enlargement processing circuit 70, the method of reading the memory 8 by the enlargement ratio controller 72 and the 1H delay circuit, one sample delay circuit, a plurality of multipliers, a plurality of adders, and the like are used. By controlling the weighting method based on the circuit group to be configured, it is possible to set the number of times as much as 1 to 2 times in principle. Therefore, the input video signal and the output of the document camera 3 are PAL
The present invention is also applicable to the system and the SECAM system.

In this embodiment, the display resolution of the liquid crystal panel has been described as being compatible with the SVGA. However, the present invention is not limited to this. The XGA (1024 horizontal pixels) having a higher definition display resolution is not limited to this. , 768 pixels (vertical).

Further, in this embodiment, the switching of the input video signal and the change of the enlargement ratio by the selector circuit 4 may be controlled so as to be automatically performed by a switching control signal by a control means (not shown). Alternatively, the operation may be performed manually by a user operating control means (not shown).

[0054]

As described above, according to the present invention, it is possible to narrow the image pickup area of a camera by making it possible to switch the enlargement ratio between a video signal input and a camera input according to an input video signal. It is possible to perform enlargement processing at an optimum enlargement ratio without any problem, and as a result, an image can be displayed favorably by either a camera input or a video signal input. As a result, it is possible to realize a liquid crystal projector with a document camera compatible with an unconventional camera input and video input.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a liquid crystal projector with a document camera according to the present invention.

FIG. 2 is a block diagram showing a specific configuration example of an enlargement processing circuit of FIG. 1;

FIG. 3 is an explanatory diagram for explaining an operation.

FIG. 4 is a block diagram showing an example of a conventional liquid crystal projector with a document camera.

FIG. 5 is an explanatory diagram of a case where a display resolution is enlarged from an NTSC system to an SVGA system.

FIG. 6 is an explanatory diagram for explaining an enlargement process.

[Explanation of symbols]

 1a: Switching signal input terminal, 2: Video signal input terminal, 3: Document camera, 4: Selector circuit, 5: Video processing circuit, 6: A / D converter, 8: Memory, 9: D / A converter Reference numeral 10: drive circuit, 11: liquid crystal panel, 70: enlargement processing circuit, 72: enlargement ratio controller, 73: 1H delay circuit, 74, 75, 78, 79: multiplier, 77: one sample delay circuit, 76, 80 ... adder, 81 ... output terminal.

Claims (4)

[Claims] 1. An image pickup video signal from a camera integrally provided in a liquid crystal projector having a liquid crystal panel, and a video signal having at least the same format as the image pickup video signal can be selectively switched and input. A document having an enlargement conversion function of enlarging and converting the number of pixels based on an input signal to the number of pixels corresponding to the liquid crystal panel in order to drive the liquid crystal panel having a larger number of pixels than the format of these input signals. In a liquid crystal projector with a camera, a switching circuit for selectively switching and inputting an image pickup video signal from the camera and the video signal; and performing an enlargement signal process on the input signal from the switch circuit at a predetermined enlargement ratio. And an enlargement processing circuit capable of changing the enlargement ratio, and switching between the switching circuit and the enlargement ratio by the enlargement processing circuit. And a control means for controlling the operation of the switching circuit and performing an enlargement signal processing at an enlargement ratio according to the input signal selected by the switching circuit. 2. The liquid crystal projector with a document camera according to claim 1, wherein the video signal and the video signal from the camera are NTSC video signals. 3. The liquid crystal projector with a document camera according to claim 1, wherein the imaged video signal from the camera and the video signal are PAL video signals. 4. An image pickup video signal from a camera integrally provided in a liquid crystal projector having a liquid crystal panel, and a video signal having at least the same format as the image pickup video signal can be selectively switched and inputted. In order to drive the liquid crystal panel composed of a larger number of pixels than the format of these input signals, an enlarged signal processing circuit for enlarging and converting the number of pixels based on the input signal into the number of pixels corresponding to the liquid crystal panel is provided. In a liquid crystal projector with a document camera, a switching circuit is provided for selectively switching and inputting an image pickup video signal from the camera and the video signal, and the enlargement signal processing circuit stores an input signal from the switching circuit. A memory, and 1 for delaying a read signal from the memory by one horizontal period
A horizontal period delay circuit; first and second multipliers each multiplying an output signal from the one horizontal period delay circuit and a read signal from the memory by a different multiplication coefficient; and the first and second multiplications. A first adder that adds and outputs the multiplication results of the two adders, a one-pixel delay circuit that delays an addition signal from the first adder for each pixel, and an output from the one-pixel delay circuit Third and fourth multipliers for multiplying a signal and an addition signal from the first adder by different multiplication coefficients, respectively, and adding and outputting the multiplication results of both the third and fourth multipliers A second adder for performing switching control by the switching circuit, writing / reading control of the memory, and control of multiplication coefficients of the first to fourth multipliers. Change and the switching circuit By controlling the multiplication coefficient in response to exchange control, document camera LCD projector, characterized in that the enlargement processing control unit, in the configuration to expand conversion processing enlargement ratio corresponding to the input signal.