JP2000020697A - Overhead projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a scanner function in an OHP(overhead projector) for performing enlarged projection of an opaque original. SOLUTION: Image signals of R, G, B obtained by a CCD camera 5 are converted into pieces of image data through an A/D conversion circuit 8 and written in memories 9a to 9c. Pieces of the image data in the memories 9a to 9c are converted into analog signals through D/A conversion circuits 12a to 12c, the image signals are converted into optical information and projected on a screen by a projection display 13. Pieces of the image data stored in the memories 9a to 9c are transmitted to a computer 30 by an interface control circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead projector, and more particularly to an overhead projector capable of enlarging and projecting an opaque document as it is.

[0002]

2. Description of the Related Art Recently, an overhead projector (hereinafter, referred to as OHP), which is capable of enlarging and projecting an opaque document as it is without using a conventional transparent sheet, as a presentation device used for a conference or a lecture at a university. (For example, Japanese Patent Application Laid-Open No. 7-1047)
No. 13). In this technique, a document is imaged by a TV camera, and the imaged content is projected on a screen by a projection display device. The OHP captures an image by illuminating a document surface of a document set face down on a document mounting glass with illumination inside the OHP. Such a configuration is employed because an image can be captured without being affected by external light.

[0003]

However, the above-mentioned OHP does not have a scanner function, and has a problem that data of an imaged original cannot be output to an external device such as a computer. . SUMMARY An advantage of some aspects of the invention is to provide an overhead projector that can output data of a captured document to the outside.

[0004]

According to the present invention, there is provided an image pickup means for reading an original, an A / D conversion means for converting an image signal output from the image pickup means into a digital signal, and an output signal from the A / D conversion means. A memory for storing image data, a D / A converter for converting the image data output from the memory into an analog signal, a projection display apparatus for inputting the image signal output from the D / A converter, Interface control means for transmitting the image data stored in the memory to an external device. The image signal thus obtained by the imaging means is input to the projection display device via the A / D conversion means, the memory, and the D / A conversion means, whereby the contents of the document are projected on the screen. Then, the interface control unit communicates with the external device, and transmits the image data stored in the memory to the external device.

[0005]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the first embodiment of the present invention.
It is a block diagram of OHP which shows Embodiment of this invention. This O
The HP includes an imaging lens 2, a three-color separation color filter 3 for separating light information from the original 1 into three primary color information, a motor 4 for rotating the filter 3, and a CCD camera 5 serving as imaging means for converting incident light into an electric signal. A signal processing circuit 6 for converting the output signal of the CCD camera 5 into an image signal; a transmittance correction amplifier 7 for correcting the amplitude of the image signal; and an A / D conversion circuit 8 for converting the image signal from the amplifier 7 into a digital signal. ,
Memories 9a to 9c for converting R, G, and B image data sequentially output from the A / D conversion circuit 8 into simultaneous signals;
A memory control circuit 10 for performing write / read control of the memories 9a to 9c, an interface control circuit 11 for transmitting image data stored in the memories 9a to 9c to an external device, and an analog signal for transmitting image data from the memories 9a to 9c D / A conversion circuits 12a to 12c for converting into D / A
A projection type display device 13 converts image signals output from the conversion circuits 12a to 12c into optical information and projects the optical information on a screen or the like (not shown).

In the OHP according to the present embodiment, the original 1 is placed face down on a glass original table (not shown), and the document surface of the original 1 is imaged by the CCD camera 5. At this time, the document surface of the original 1 is illuminated by original illumination (not shown).

A three-color separation color filter 3 for separating light information from the original 1 having passed through the imaging lens 2 into three primary color information of red (R), green (G) and blue (B) is driven by a motor 4. It rotates in front of a CCD camera 5 serving as an imaging unit. When this is viewed from the imaging lens 2 side as shown in FIG. 2, the color filter 3 is a filter cell 3 that transmits only the red light component.
1, a filter cell 32 transmitting a blue light component and a filter cell 33 transmitting a green light component.

When the color filter 3 rotates, the light passing through the imaging lens 2 and entering the CCD camera 5 changes sequentially in red, blue, and green. In this way, the light information from the document 1 is separated into three primary color information. The signal output from the CCD camera 5 when the light that has passed through the color filter 3 enters the CCD camera 5 is subjected to signal processing such as amplification and band adjustment by a signal processing circuit 6 and converted into an image signal. The image signals are red, blue,
The signal is obtained by sequentially taking in each of the green components. However, the amplitude of the image signal is different for each color because the light transmittance differs between the filter cells 31 to 33.

Therefore, the transmittance correction amplifier 7 performs gain correction for each color based on the gain correction amount corresponding to the transmittance of each color, and makes the amplitude of the image signal uniform. The image signal thus gain-corrected is converted from an analog signal to a digital signal by the A / D conversion circuit 8. Under the control of the memory control circuit 10, the R image data is written into the memory 9a, and the G image data is written into the memory 9b.
And the B image data is written to the memory 9c. In this way, the image data of R, G, and B are stored in the memories 9a to 9a.
By storing the data once in the memory 9c and reading it out, it can be converted into a simultaneous signal.

Subsequently, D / A conversion circuits 12a to 12c
Converts the R, G, and B image data output from the memories 9a to 9c into analog image signals, and outputs the analog image signals to the projection display device 13. Next, the drive circuit 14 in the projection type display device 13 includes the D / A conversion circuit 1.
The R, G, and B image signals from 2a to 12c are converted into liquid crystal drive signals and output to liquid crystal panels 15a to 15c, respectively.

In this way, an image relating to the R component of the document 1 is displayed on the liquid crystal panel 15a, an image relating to the G component is displayed on the liquid crystal panel 15b, and an image relating to the B component is displayed on the liquid crystal panel 15c. On the other hand, light emitted from the lamp 16 is guided to the dichroic mirror 18 by the cold mirror 17. The cold mirror 17 transmits harmful infrared rays and reflects only visible light.

The dichroic mirror 18 includes a lamp 16
Only the green light in the visible light reflected by the cold mirror 17 and reflected by the cold mirror 17 is reflected, and the total reflection mirror 19 reflects this green light and makes it incident on the liquid crystal panel 15b. at the same time,
The dichroic mirror 18 transmits non-green light from the cold mirror 17 and makes the light enter the dichroic mirror 20. The dichroic mirror 20 reflects only the blue light of the light from the dichroic mirror 18 and makes the light enter the liquid crystal panel 15c.

The dichroic mirror 21 combines the light by reflecting the light transmitted through the liquid crystal panel 15c and transmitting the light transmitted through the liquid crystal panel 15b. The red light transmitted through the dichroic mirror 20 enters the liquid crystal panel 15a. Then, the total reflection mirror 22 reflects the light transmitted through the liquid crystal panel 15 a and makes the light enter the dichroic mirror 23.

Next, the dichroic mirror 23 combines the light by reflecting the light from the dichroic mirror 21 and transmitting the light from the total reflection mirror 22. The light from the mirror 21 is light obtained by combining green light and blue light, and the light from the mirror 22 is red light. Thus, by combining these lights, the original white light of the lamp 16 is obtained.

Finally, the total reflection mirror 24 reflects this light and the projection lens 25 projects it. Thus, the image signal is converted into optical information by the projection display device 13 and projected on the screen 26. In the liquid crystal panel 15a,
Since the R component relating to the character or figure portion of the original 1 is displayed, the incident red light cannot pass through this portion, and the red light passes only through a white background portion in the original. Similarly,
Also in the liquid crystal panels 15b and 15c, green light and blue light pass only through a white background portion of the document.

Accordingly, the light passing through the liquid crystal panels 15a to 15c is combined by the dichroic mirrors 21 and 23, so that the white portion of the document becomes white light. That is, the original 1 having black characters and a white background can be projected on the screen 26. In this way, the opaque plain paper original 1 can be enlarged and projected with high clarity without copying it onto a transparent film.

On the other hand, SCSI (Small Computer Systems)
Interface), an interface control circuit 11 conforming to a digital interface standard such as RS-422 or RS-232C is connected to a computer 30 as an external device via a transmission cable 29. Then, the interface control circuit 11 sends out the R, G, B image data stored in the memories 9a to 9c to the transmission cable 29 in accordance with the digital interface standard.

The computer 30 exchanges data with the interface control circuit 11 according to the digital interface standard, and receives image data sent from the interface control circuit 11. In this way, the image data of the imaged original 1 is transferred to the computer 3.
0, and the computer 30 can use the received data as graphic data.

It should be noted that in the present embodiment, the image pickup of the original 1
In each process of display (projection) by the projection display device 13 and data transmission by the interface control circuit 11,
Although the R, G, and B image signals are handled so as to enable color display, the present invention may be applied to a monochrome image signal (in this case, one memory and one D / A conversion circuit are used).

[0020]

According to the present invention, by providing an image pickup means, an A / D conversion means, a memory, a D / A conversion means and a projection type display device, the contents of a document can be projected on a screen, By providing the interface control means, the image data stored in the memory can be transmitted to an external device. As a result, in addition to the OHP function for enlarging and projecting an opaque original as it is, a scanner function for outputting data of a captured original to an external device can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of an OHP showing a first embodiment of the present invention.

FIG. 2 is a plan view of a three-color separation color filter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Original document, 2 ... Imaging lens, 3 ... 3 color separation color filter, 5 ... CCD camera, 6 ... Signal processing circuit, 7 ... Transmittance correction amplifier, 8 ... A / D conversion circuit, 9a-9c ... Memory, 10 ... Memory control circuit, 11 ... Interface control circuit, 12a to 12c ... D / A conversion circuit, 13 ... Projection display device, 29 ... Transmission cable, 30 ... Computer.

Claims (1)

[Claims] An imaging unit that reads an original; an A / D conversion unit that converts an image signal output from the imaging unit into a digital signal; a memory that stores image data output from the A / D conversion unit; D / A conversion means for converting the image data output from the memory into an analog signal, a projection display apparatus receiving the image signal output from the D / A conversion means as input, and image data stored in the memory And an interface control means for transmitting the data to an external device.