JPH06186924A - Liquid crystal display device for ohp - Google Patents

Abstract

PURPOSE:To provide a liquid crystal display device for an OHP capable of freely carrying and using it for a user. CONSTITUTION:When data in a floppy disk are displayed on a liquid crystal panel, first of all, the data in the floppy disk are read out in sector unit (S71). Then, whether the readout data are the compressed data or not is discriminated (S72). When the compressed data, when the data of (00) or (FF), the data are expanded to the original data from the number of bytes where the data stored next continue to transfer to a screen data buffer (S73). When not the compressed data, the readout data are transferred to the screen data buffer as it is (S74). Thereafter, whether the readout of the data by one picture are ended or not is discriminated (S75), and when the readout of the data by one picture are ended, liquid crystal panel display processing (S13-S17) are executed, and the data stored in the screen data buffer are DMA-transferred at every one line to be displayed on the liquid crystal panel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an OHP (over head pro)
liquid crystal display device for a projector.

[0002]

2. Description of the Related Art A projection device (OH) for enlarging and projecting a document printed or copied on a transparent film and displaying it on a screen.
P: over head projector) is widely used in companies and schools.

Recently, since a document, a graph, etc. are often created by using a word processor, a personal computer, etc., when these documents are used as OHP originals, they are first output to a paper by a printer and then a copying machine. It was necessary to make a copy for OHP film, and the work for that was complicated when the number of documents increased.

Therefore, a liquid crystal display device for an OHP has been considered in which a liquid crystal panel is placed on a light source of an OHP and data created by a personal computer is displayed on the liquid crystal panel to directly project the data on the screen. .

[0005]

However, since the OHP liquid crystal display device that has been conventionally considered is configured to be used by connecting to a personal computer, for example, when the OHP is used in another conference room. Each time, all of these devices had to be carried, and it was not possible for the user to carry and use them freely.

Further, in the conventionally considered liquid crystal display device for OHP, since TN liquid crystal or the like is used, it can be used for a transmission type OHP, but when it is used for a reflection type OHP, the light transmittance of the liquid crystal is increased. Since the light is low, there is a problem that a portion that is originally displayed as white and becomes white becomes blackish, and a projected image with sufficient brightness cannot be obtained.

Further, when explaining materials and the like using the OHP, articles other than manuscripts created on a personal computer, for example, articles related to the theme at that time, which are published in newspapers or magazines, are displayed on the spot. However, there has been no conventional OHP liquid crystal display device capable of such a display.

An object of the present invention is to provide a liquid crystal display device for an OHP which a user can freely carry and use. Another object of the present invention is to provide a liquid crystal display device that can be used in both a transmissive OHP and a reflective OHP.

[0009]

FIG. 1 is a diagram for explaining the principle of the present invention. The reading means 1 reads image data such as characters and figures. The storage unit 2 stores the data read by the reading unit 1.

The liquid crystal panel 3 displays the data stored in the storage means 2. The recording medium drive means 4 writes the data stored in the storage means 2 to the recording medium and reads the data recorded in the recording medium. The recording medium driving means 4 is, for example, a floppy disk drive for writing and reading a floppy disk.

[0011]

Since the OHP liquid crystal display device of the present invention is provided with the recording medium driving means 4 for writing and reading data to and from a recording medium, for example, a floppy disk, it is an external device such as a personal computer. The data created in step 1 can be read and displayed on the liquid crystal panel 3. Therefore, it is not necessary to connect the liquid crystal display device to an external device such as a personal computer, and the liquid crystal display device can be freely carried and used.

Further, since printed characters, figures, etc. can be read by the reading means 1 and the read data can be projected on the screen on the spot, it becomes easier to use. Also, by using a phase change liquid crystal in the liquid crystal panel,
Since no polarizing plate is required, the light transmittance is increased, and a liquid crystal display device that can be used in both transmissive and reflective OHPs can be provided.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is an external view of a liquid crystal display device for OHP according to an embodiment of the present invention.

On the upper surface of the main body of the liquid crystal display device, there are provided a status display section 11 for indicating the operating status and a keyboard section 12 for designating the operating status and the display screen. A disc insertion slot is provided. In addition, a 640
Liquid crystal panel 14 composed of × 400 dots phase change liquid crystal
And a handy scanner 15 for reading characters, figures, etc.
And are connected. In addition, optional remote control 1
6 can be used.

FIG. 3 shows the status display section 11 and the keyboard section 1.
2 is an enlarged view of FIG. The status display unit 11 indicates the operating status of the liquid crystal display device, for example, which mode the system is in, such as a manual screen data display mode, a data capture mode from the handy scanner 15, and a screen data storage mode. Operation number display section 1 that displays the operation number
1a, a scene number display section 11b for displaying a screen number of screen data, and an LE that lights up when the liquid crystal display device is in operation
It is composed of a D11c and an LED 11d that lights up when an abnormality occurs.

The keyboard section 12 includes a ten-key for inputting numerical values 0-9, an input key operated for confirming an operation number set by the ten-key, and a front key operated for displaying a previous screen during manual operation. It consists of an end key that is operated to end the operation being executed.

Next, the circuit configuration of the liquid crystal display device will be described with reference to FIG. The CPU 21 controls each part of the circuit according to various processing programs stored in the ROM 22, and exchanges data with each interface circuit described later, writes data to the RAM 26, and reads data. The CPU 21 has a built-in timer 37, and the timer 37 monitors the interval time and the like in the program.

Key input interface (KYE IF) 23
Outputs a key operation signal from the keyboard unit 12 to the data bus. Handy Scanner Interface 24
Converts a signal for one line read by the handy scanner 15 into parallel data and outputs the parallel data to the data bus.

Floppy disk controller (FD
C) 25 is a floppy disk drive (FDD) 3
The operation of the FDD3 is controlled at the time of reading.
The serial data output from 3 is converted into parallel data and output to the data bus, and the parallel data output onto the data bus during writing is converted into serial data and output to the FDD 33.

The LCDIF 27 is a PIO which controls the transfer of parallel data, and latches the data on the data bus and outputs it to the liquid crystal panel 14. The phase transition liquid crystal used in the liquid crystal panel 14 is composed of, for example, a mixed liquid crystal of a nematic liquid crystal and a cholesteric liquid crystal or a chiral nematic liquid crystal, and undergoes a cholesteric-nematic phase transition,
In addition, the liquid crystal has a positive dielectric anisotropy.

By using a phase change liquid crystal for the liquid crystal panel 14, a high light transmittance can be obtained, and a reflective OH
It is possible to realize an OHP liquid crystal display device that can be used even in P.
Also, the line interface 28 outputs the data from the RS232C line received via the DR / RV 29 to the data bus, and at the same time, outputs the data on the data bus to the DR / RV 29.
To the RS232C line via.

The LEDIF 30 is a circuit for driving the above-mentioned LED 11c indicating that the operation is in progress and the LED 11d indicating that the device is in an abnormal state. Further, the buzzer IF 31 is a buzzer (not shown) when an abnormal condition occurs.
Is a circuit for driving to notify the user.

The DMA controller (DMAC) 32 is
It is a circuit for controlling DMA transfer that directly transfers data between devices without going through the CPU 21. Incidentally, the liquid crystal display device of this embodiment has an optional light receiving unit 34,
The remote controller IF35 and RGBCRTIF36 can be mounted in the main body. By mounting these circuits, the infrared remote controller can control the operation of the device and the image displayed on the external CRT can be displayed on a floppy disk. It becomes possible to take in.

Since this liquid crystal display device has a function of writing and reading to and from a floppy disk, if this device and OHP are provided, the data recorded on the floppy disk is displayed on the liquid crystal panel 14, and the data is displayed. It can be projected on the screen. Therefore, the structure of the device is simplified, and a small OHP liquid crystal display device that can be freely carried and used by the user can be realized.

Next, in the liquid crystal display device having the above-mentioned structure, the processing contents when displaying the data read by the handy scanner 15 on the liquid crystal panel 14 will be described with reference to the flow charts of FIGS.

First, the read size set by the user is read in step S1 of FIG. Here, the reading size is a code set by the user according to the size of the area to be read by the scanner 15, and as shown in FIG. 5, it is 4 of “01”, “02”, “03”, “04”. There are different types of codes.

For example, when the area size is in the range of 50 × 25 mm, the reading size is “01”, the resolution of the scanner 15 is 400 DPI, the scanning direction of the scanner 15 is vertical, and the area size is 105 × 67 mm. When it is within the range, the reading size is "02" and the resolution of the scanner 15 is 200DP
I, the scan direction is vertical. Also, the size of the area
If it is within the range of 128 x 80 mm, set the scan size to "0
3 ", resolution is 200 DPI, scan direction is horizontal, and when the area size is in the range of 160 x 100 mm, read size is" 04 ", scanner 15 resolution is 200 DPI, and scan direction is horizontal.

In the next step S2, it is determined whether or not the read size is "01". "01" as reading size
If is set, the process proceeds to step S3, the screen data for one screen of the liquid crystal panel 14 is read by the handy scanner 15, and the screen data is stored in the screen data buffer (not shown) of the RAM 26. At this time,
When the user has instructed to invert the screen data, the data read by the scanner 15 is inverted and stored in the screen data buffer.

If the read size is not "01" in the determination in step S2, the flow advances to step S4 to determine whether the read size is "02". When "02" is set as the reading size, the data for one screen of the liquid crystal panel 14 is stored in the reading screen data buffer from the scanner 15, but at this time, the dot data of a multiple of 4 of the vertical line is read out and discarded. Data other than the above is stored in the screen data buffer. As a result, the dot data in the Y-axis direction is compressed to 3/4. When the user instructs the screen data to be inverted, the read data is inverted and stored in the screen data buffer.

Further, the data stored in the screen data buffer in step S6 is thinned out by 2 dots per byte. As a result, the dot data in the X-axis direction is compressed to 3/4.

If the read size is not "02" in the determination in step S4, the process proceeds to step S7 in FIG. 6 to determine whether the read size is "03". When "03" is set as the reading size, step S8
The data for one screen of the liquid crystal panel 14 is read, the dot data in multiples of 3 in the scanning direction is read and discarded, and the other data is stored in the screen data buffer. As a result, the dot data in the Y-axis direction (in this case, the scan direction is the horizontal direction) is compressed to 2/3.

Further, in step S9, the data in the screen buffer is thinned out by 3 dots per 1 byte. As a result, the dot data in the Y-axis direction (vertical direction) orthogonal to the scanning direction is compressed to 5/8.

Then, in step S10, the data in the screen data buffer is vertically / horizontally converted. This is because when the read size is "03", the scan target is scanned in the horizontal direction, so the screen buffer stores 90 ° rotated data. This is for reversing and restoring the original data.

If the read size is not "03" in the determination in step S7, it is "04", so step S11
Proceeding to step 1, the scanner 15 reads data for one screen of the liquid crystal panel and sets it in the screen data buffer. At this time, dot data that is a multiple of 2 in the scan direction is discarded and the other data is stored in the screen data buffer. As a result, the dot data in the X-axis direction (in this case, the scanning direction is the horizontal direction) is compressed to 1/2.

Further, in step S12, the data in the screen data buffer is thinned out by 4 dots per byte. As a result, the dot data in the Y-axis direction (vertical direction) is compressed to 1/2. After that, the process proceeds to step S10 described above, and vertical / horizontal conversion of the screen buffer is performed.

After steps S3 and S6 of FIG. 5 or step S10 of FIG. 6, the process proceeds to the liquid crystal panel display process of FIG. 7A. In this liquid crystal panel display processing, first, step S1
At 3, the temperature of the temperature sensor provided on the liquid crystal panel 14 is read. Here, the temperature of the liquid crystal panel 14 is detected because the temperature of the liquid crystal panel 14 changes due to the heat from the light source of the OHP in the use state. Therefore, an appropriate speed according to the temperature of the liquid crystal panel 14 at that time is detected. This is for writing data.

Next, in order to erase the afterimage of the liquid crystal panel 14,
In step S14, the entire surface of the liquid crystal panel 14 is once set in a scattering state, and then in step S15, the entire surface is set in a transmitting state. Then, in step S16, the screen data in the screen data buffer is transferred to the L level for each line (80 bytes) by the DMAC 32.
The data for one screen read by the scanner 15 is displayed on the liquid crystal panel 14 by DMA transfer to the CD interface 27. Further, in step S17, the liquid crystal panel 14
Is kept in that state and the display state is held.

Next, the processing contents when the digital RGB data output from the personal computer is displayed on the liquid crystal panel 14 will be described with reference to the flowchart of FIG.

RG output from the personal computer (hereinafter referred to as a personal computer) in step S21 of FIG.
Start capturing B data. The RGB data fetched in step S22 is written in the screen data buffer.
Next, in step S23, it is determined whether or not the trigger key has been pressed.

Here, it is determined whether or not the trigger key is pressed because the phase change liquid crystal has a slow writing speed and therefore the received data cannot be displayed on the liquid crystal panel 14 in parallel with the data reception. This is because the RGB data is temporarily stopped and the liquid crystal panel 14 is caused to display the data taken into the screen data buffer.

If the trigger key is not pressed, the process returns to step S22 to continue writing the data to the screen data buffer, and when the trigger key is pressed, the process proceeds to step S24 to stop the RGB data acquisition. Further, the RGB capture flag is turned on in step S25, and the above-described liquid crystal panel display processing (S13 to S17) is performed.
To execute.

Next, the processing for storing the data displayed on the liquid crystal panel 14 in the floppy disk will be described with reference to the flow charts of FIGS. First, in step S31 of FIG. 9, it is determined whether the data displayed on the liquid crystal panel 14 is the RGB data imported from the personal computer. If it is RGB data, step S3
Go to 2 and store RGB data from the personal computer RGB
Screen data buffer is selected, and if it is not RGB data, the process proceeds to step S33, and the scanner screen data buffer for storing the data from the handy scanner 15 is selected.

In the next step S34, a free area of the floppy disk inserted in the floppy disk drive is searched, and in step S35, it is determined whether or not there is a free area. If there is no free area, step S36.
After displaying an error message, the process ends.

On the other hand, if the floppy disk has a free area, it is determined in step S37 whether or not the current writing is the first writing, and if it is the first writing, the identifier of the compressed data is determined in step S38. set. Further, the address of the empty area searched in step S39 is set as the data transfer destination address.

At this time, if the data displayed on the liquid crystal panel 14 has already been written to the floppy disk and the current writing is the second or later writing, the process proceeds to step S40 and the address of the empty area is set. Set as the data transfer address.

Next, in step S41, it is determined whether or not there is unstored data. Here, the unstored data is the data that could not be written due to insufficient remaining capacity of the write buffer (buffer that stores data for one sector of the floppy disk) in the previous writing. It is temporarily stored in the compression work area by the processing described later.

If there is unstored data in the determination in step S41, the compressed data stored in the compression work area and the value of the compression counter (described later) are set in the write buffer in step S42. After that, the unstored data flag is cleared in step S43.

Next, in step S44, it is determined whether or not the end flag which is set when the reading of the data for one screen is completed. If the end flag is not turned on, one byte of data is read from the selected screen data buffer in step S45, and steps S46 and S47 are performed.
Then, it is determined whether the data is "00H" or "FFH".

If the data read from the screen data buffer is "00H" or "FFH", the process proceeds to FIG. 10 (step S48 in FIG. 10). In step S48 of FIG. 10, how many bytes of the same data continue is searched, and the number of continuous data is counted by the compression counter.

Then, in step S49, the liquid crystal panel 14
It is determined whether or not the search for the data for one screen has been completed, and if the search for the data for one screen has been completed, the end flag is turned on in step S50, and then the process of A in FIG. The process proceeds to step S56 and subsequent steps).

Further, if another data appears while searching for how many bytes of the same data continue, and the search for the data for one screen has not been completed, the process shown in FIG.
The process proceeds to A (No. 1) (the process after step S56).

In the process of A in FIG. 11, first, in step S5.
At 6, it is determined whether the remaining capacity of the write buffer is 1 byte or less. In this embodiment, it is determined whether the remaining capacity of the write buffer is 1 byte or less. In this embodiment, when the data read from the screen data buffer is "00H" or "FFH", how many bytes of the same data are This is because the compression counter counts whether or not they are continuous, and the compressed data of "00H" or "FFH" and the count value of the compression counter are stored in the floppy disk as one set of data. That is, in order to store the compressible data in the floppy disk, at least the remaining capacity of 2 bytes is required in the write buffer.

Therefore, when the remaining capacity of the write buffer is 1 byte or less, the unstored flag is turned on in step S57, and the compressed data (1 byte) of "00H" or "FFH" and the compression counter in step S58. Value (1 byte) and is temporarily stored in the compression work area.

On the other hand, when the remaining capacity of the write buffer is 2 bytes or more, the process proceeds to step S61 and the compressed data and the value of the compression counter are set in the write buffer.
Then, in step S62, it is determined whether or not the write buffer is full.

When the write buffer becomes full as a result of setting the compressed data and the value of the compression counter in the write buffer, or when the compressed data and the value of the compression counter are saved in the compression work area in step S58, The compression counter is cleared in step S59, and step S60.
Write the data in the write buffer to the corresponding sector of the floppy disk. Further, in step S61, it is determined whether or not the writing is normally performed. If the writing is normally performed, the process returns to the process of C of FIG. 9 (the process of step S34 and thereafter) to search the empty area of the floppy disk. Write the next data.

As a result, the data in which "00H" or "FFH" continues for many bytes is 2 in total of the data of "00H" or "FFH" and the 1-byte data indicating the number of continuous bytes.
Since it can be represented by byte data, it is possible to obtain a high compression rate for data in which white dots and black dots are likely to be continuous, such as image data. Moreover, in this case, since the data is compressed only when all 1 bytes are "0" or "1", the process of compressing and expanding the data becomes simple.

The compressed data temporarily stored in the compression work area and the value of the compression counter are set in the write buffer by the processing of step S42 described above when the processing of C in FIG. 9 is executed, and then the floppy disk. Written in.

Returning to FIG. 11, if the write buffer is not full in the determination in step S62, the compression counter is cleared in step S63, and then it is determined in step S64 whether or not the end flag is turned on.

If the end flag is not turned on, that is, the write buffer has a sufficient memory capacity, and 1
When the screen data has not been read,
Returning to the processing of B in FIG. 9 (processing after step S45 in FIG. 9), the next data is read from the screen data buffer and the above processing is repeated.

If the end flag is turned on in the determination in step S64, it is determined in step S65 whether or not the remaining capacity of the write buffer is 1 byte or less. If the remaining capacity of the rat buffer is not less than 1 byte, it is indicated in step S66 that the end of the data for one screen is "00,0".
2-byte data (end mark) of "0" is set in the write buffer.

Then, in step S67, the data in the write buffer is written in the corresponding sector of the floppy disk, and in the next step S68, it is determined whether or not the writing has been normally performed. If there is an abnormality, the process returns to step S67 to write again to the floppy disk, and if OK, a specific area of the screen data is taken out as title data by the title write processing of step S69, and that data is stored in the title storage area. To do.

When the remaining capacity of the write buffer is 1 byte or less as determined in step S65, that is, when the compressed data and the number of consecutive bytes of the data are written in the write buffer, the remaining capacity of the write buffer is 1 byte. If the end flag is turned on at that time, the process proceeds to step S60 described above, and after writing the data in the write buffer to the floppy disk, C in FIG.
Perform the following processing.

In the processing of FIG. 9C, a new free area of the floppy disk is secured, and at this time, step S44.
Since the determination of whether the end flag of is on is YES,
The process of D in FIG. 11 (step S65) is executed. In the process of D in FIG. 11, the 2-byte end mark is written in the corresponding sector as described above.

Returning to FIG. 9, if the data read out in the determinations of steps S46 and S47 is data other than "00H" and "FFH", then FIG. 10 (step S51 in FIG. 10).
Proceed to.

If the read data is data other than "00H" and "FFH", data compression is not performed.
In step S51, the read data is set as it is in the write buffer, and in the next step S53, it is determined whether or not the reading of the data for one screen is completed.

If the reading of the data for one screen has not been completed, the process directly proceeds to step S54 and it is determined whether or not the write buffer is full. At this time, if the reading of the data for one screen is completed, the end flag is set in step S53 and then the process proceeds to step S54.

If it is determined in step S54 that the write buffer is full, the process of E in FIG. 11 (step S in FIG. 11) is performed.
In step 60), the data for one sector in the write buffer is written to the floppy disk.

If the write buffer is not full, it is determined in step S55 whether or not the end flag is on. If the end flag is not on, the flow returns to (step S45) in FIG. 9 to read the next data.

If the end flag is on at this time, the process of D in FIG. 11 (processes after step S65) is executed, and the end marks of "00" and "00" are added to the end of the data of one screen. Add and write to a floppy disk.

Next, the processing for displaying the data of the floppy disk on the liquid crystal panel 14 will be described with reference to the flowchart of FIG. First, step S in FIG.
At 71, the data on the floppy disk is read out in sector units. In the next step S72, it is determined whether the data read from the floppy disk is compressed data.

In the OHP liquid crystal display device of this embodiment,
When the data displayed on the liquid crystal panel 14 is stored in the floppy disk, it is stored in the data format as shown in FIG.

A 32-byte header is provided at the beginning of each screen data, and information indicating whether or not the data is compressed data is provided at the beginning of the header (for example, "00H" when there is no compression, compressed data In the case of, "80H") is stored. Screen data is stored following the header, and has a fixed length of 32 Kbytes for uncompressed data and a variable length for compressed data.

Returning to FIG. 12, in the determination of step S72,
If the screen data read from the floppy disk is compressed data, the compressed data is decompressed and transferred to the screen data buffer in step S73. When decompressing the compressed data, if the data is "00" or "FF", the number of consecutive bytes of the data stored next is decompressed to the original data. For example, if the read data is "00,08", "00" is converted into data in which 8 bytes are continuous.

If the data read from the floppy disk is not compressed data (for example, data created by a personal computer, etc.), the read data is transferred to the screen data buffer as it is in step S74.

Then, in step S75, it is determined whether or not the data for one screen has been read. If the data for one screen has not been read, the process returns to step S71 to read the next data on the floppy disk.

When the data for one screen has been read, the above-mentioned display processing (S13 to S17) of the liquid crystal panel is executed, and the data stored in the screen data buffer is DMA-transferred for each line (80 bytes). To display on the liquid crystal panel 14.

In the above embodiment, "00H", "FF"
The data was compressed and recorded on the floppy disk only when "H" data was continuous, but the compression method is not limited to this and other methods may be used. You may record it.

The medium for recording the data is not limited to the floppy disk but may be another recording medium such as an optical disk or a magneto-optical disk.

[0079]

According to the present invention, image data such as characters and figures can be recorded on a recording medium such as a floppy disk, and the data can be read and displayed on a liquid crystal panel, so that an OHP original is prepared. There is no need. Further, since this liquid crystal display device only needs to have at least the reading and writing functions of the recording medium, the structure of the device can be simplified and miniaturized, and the liquid crystal display device which can be freely carried and used by the user can be realized. Further, by providing the image data reading means, necessary data can be read and projected on the spot.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an external view of a liquid crystal display device of an example.

FIG. 3 is an enlarged view of a display unit and a keyboard unit.

FIG. 4 is a circuit configuration diagram of an example.

FIG. 5 is a flowchart (1) for displaying data read by a handy scanner on a liquid crystal panel.

FIG. 6 is a flowchart (2) for displaying data read by a handy scanner on a liquid crystal panel.

FIG. 7 is a flowchart (3) for displaying data read by a handy scanner on a liquid crystal panel.

FIG. 8 is a flowchart for displaying RGB data of a personal computer on a liquid crystal panel.

FIG. 9 is a flowchart (1) for storing the data displayed on the liquid crystal panel in a floppy disk.

FIG. 10 is a flowchart (2) for storing the data displayed on the liquid crystal panel in a floppy disk.

FIG. 11 is a flowchart (3) for storing the data displayed on the liquid crystal panel in a floppy disk.

FIG. 12 is a flowchart for displaying data of a floppy disk on a liquid crystal panel.

FIG. 13 is a diagram showing a structure of screen data.

[Explanation of symbols]

 1 reading means 2 storage means 3 liquid crystal panel 4 recording medium driving means

Claims (2)

[Claims] 1. A reading means (1) for reading image data, a storage means (2) for storing the data read by the reading means (1), and a display for displaying the data stored in the storage means (2). A liquid crystal panel (3), and a storage medium driving unit (4) for writing the data stored in the storage unit (2) to a recording medium and reading the data from the recording medium. Do O
Liquid crystal display device for HP. 2. A recording medium driving means for writing data to a recording medium and reading data from the recording medium, and a phase transition liquid crystal panel for displaying the data read from the recording medium. LCD device for OHP.