JP2617101B2 - Color liquid crystal display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interface circuit for a color liquid crystal display device, and more particularly, to a light-weight, small-sized, and small-sized device using only interface signals of a CRT display device frequently used in personal computers and the like. The present invention relates to a color liquid crystal display device having an interface circuit which can be replaced with a simple liquid crystal display device.

<< Summary of the Invention >> The present invention uses an interface signal of a CRT display to store and read independent color display data in an independent RAM. The present invention relates to a color liquid crystal display device which can convert the display data into a mixture of blue and blue and provide an interface circuit capable of color display with a drive circuit configuration equivalent to the conventional one.

<< Conventional Technology >> Liquid crystal display devices have characteristics of low profile, low voltage and low power consumption, and have recently been put to practical use as display terminal devices such as personal computers and word processors using large dot matrix panels. Today, LSI circuits have been developed that can replace CRTs and can be directly connected to CRT interfaces as portable personal computers.Manufacturers of OA equipment have developed interface circuits dedicated to liquid crystal displays using gate arrays. And have caused significant demand for liquid crystals. However, these liquid crystal display devices are 640 × 200
Although it is necessary to have a display capacity that replaces CRTs such as dots,
Since it is a monochrome monochrome display, it is insufficient as a display device, for example, in the case of graphic display. The simple matrix display panel uses one or two of the red, green, and blue color display data to simply display ON and OFF. The charm was not enough.

<< Problems to be Solved by the Invention >> As described above, the interface circuit of the conventional liquid crystal display device has been less attractive because it has a monochrome display, but in recent years a color liquid crystal display device has been developed. It is an object of the present invention to provide an interface circuit capable of performing color display using a color CRT interface signal and applicable to a liquid crystal display device.

<< Example >> Next, an example of the present invention will be described. FIG. 1 is a configuration diagram showing the entire color liquid crystal display device of the present invention. In FIG. 1, Hsyc is a horizontal synchronizing signal, Vsyc.
Is a vertical synchronization signal, and DR, DG, and DB are display data signals of red, green, and blue, respectively. CK is a clock signal. A Y-axis display area control circuit 1 counts the horizontal synchronizing signal Hsyc and determines a display area in the Y-axis direction. The X-axis area control circuit 3 is a control circuit that counts the clock signal CK and determines a display area in the X-axis direction. 1 /
The octalization counter circuit 5 divides the frequency of the clock signal CK in the display area of the X-axis and the Y-axis by 1/8 to obtain a runner signal φ ₁
Output circuit. The shift registers 6, 7, 8 store the display data D
R, DG, circuit takes in shifting the serial signal DB to the clock signal phi _2, the latch circuits 9, 10 and 11, the output signal of the shift register 9, 10, 11, circuits for temporarily storing . The shift registers 12, 13, 14 include the latch circuits 9,
The output signals of 10, 11 are converted to the respective shift clock signals φ ₄ ,
A circuit that shifts bit by bit according to φ ₅ and φ ₆ . AND
The circuits 15, 16, 17 and the OR circuit 18 are provided with the shift registers 12, 1
Select gate circuit for selectively extracting 3, 14 output signals. The shift register 19 is a circuit for shifting the output signal of the selection gate circuit. A latch circuit 20 is a circuit that temporarily stores the output of the shift register 19 and outputs mixed-color display data in parallel. Frame signal generation circuit 23
Is a circuit that generates a frame signal. The shift clock generator 24 is a circuit for generating a shift clock for sequentially transferring mixed color display data input to the X electrode drive circuit 27. The latch clock generator 25
A circuit for generating a latch signal for latching data input to the electrode drive circuit 27 and the Y electrode drive circuit 29; The AC signal circuit 26 is a circuit for switching the polarity of drive signals of the X electrode drive circuit 27 and the Y electrode drive circuit 29 in order to drive the color liquid crystal panel 28 into AC. Color LCD panel 28
Is a liquid crystal panel with red, green, and blue filters attached to transparent electrodes. X electrode drive circuit 27 and Y electrode drive circuit 2
Reference numeral 9 denotes a circuit for driving the X electrode and the Y electrode of the color liquid crystal panel 28, respectively. The configuration is as described above.

Next, the operation of the embodiment of the present invention will be described. The Y-axis display area control circuit 1 is reset by the vertical synchronizing signal Vsyc, counts the horizontal synchronizing signal Hsyc as a clock signal, counts until the count value reaches a set value, for example, 400, and calculates the Y-axis effective display area time. The signal is output to the AND circuit 4.

The X-axis display area control circuit 3 is reset by the horizontal synchronization signal Hsyc, counts using the clock signal CK as a clock, counts until the count value reaches a set value, in other words, 640, and displays the effective display area time in the X-axis direction. AND signal
Output to the circuit 4. Therefore, the AND circuit 4 generates the clock signal φ ₂ in the effective display area in the Y-axis and X-axis directions.
Occurs.

The red, green and blue color display data DR, DG and DB are respectively
Input to the shift registers 6, 7, 8 and the clock signal φ
₂ is stored while being shifted by 1 bit.
The output signals of the shift registers 6, 7, 8 are input to the latch circuits 9, 10, 11 and are temporarily stored. Latch signal phi ₁ for this is the, the clock signal phi ₂ 1/8
The carry signal is divided by the conversion counter circuit 5. The output signal of the latch circuit 9, 10 and 11, a latch signal phi ₁ the signal phi ₃ inverted by the inverter 21, is parallel to the transfer to the shift register 12, 13 and 14. Wherein each color display data transferred to the shift register 12, 13 and 14, the shift clock phi _4, phi _5, by phi ₆ 1
The data is shifted for each bit and input to the AND circuits 15, 16, and 17, respectively. The ring counter 22 receives the clock signal φ
_This is a ternary ring counter that receives the output of a multiplication circuit 30 using a PLL circuit that oscillates at a frequency three times as high as ₂ , and outputs clock signals φ ₄ , φ ₅ , and φ ₆ in a time series and performs the shift operation. It becomes a shift clock signal for the registers 12, 13, and 14.

Therefore, the OR circuit 18 sequentially shifts the shift registers 12, 13,.
From 14, color display data of red, green, blue, red,... Colors are sequentially and selectively output. The output signal of the OR circuit 18 is input to the shift register 19, is stored is shifted every clock signal since the clock signal phi ₂ and the shift clock signal. Latch circuit 20, the, the output signal of the shift register 19, a parallel manner by the latch signal phi _1, latches, and outputs the color display data are mixed into the X-electrode driving circuit 27. The shift clock generator 24 shifts the color display data of the latch circuit 20 to the shift register of the X-electrode drive circuit 27 by using a clock signal φ ₆ to shift parallel 8-bit mixed color display data.
A shift clock signal is generated by a counter that divides by 1/8. The latch clock generator 25 is constituted by a counter for dividing the carry signal of the shift clock generator 24 into 1/80, and the mixed color display data shifted to the shift register of the X electrode drive circuit 27 is 640 × 3.
When a dot occurs, a latch signal is generated in a latch circuit built in the X electrode drive circuit 27. On the other hand, when the vertical synchronization signal Vsyc is input, the frame signal generation circuit 23
The frame signal is supplied to the shift register of the electrode drive circuit 29. The frame signal generating circuit 23 is constituted by a one-shot multivibrator, and the frame signal becomes a data signal for the Y electrode driving circuit 29.
The latch signal from the latch clock generator 25 is input to the Y electrode drive circuit 27 as a data shift clock signal to shift data. The X electrode driving circuit 27 and the Y electrode driving circuit 29
A drive circuit for driving the X electrode and the Y electrode is generated. When the data is “1”, a selection signal is generated mutually, and when the data is “0”, a non-selection signal is generated and driven. .

As described above, according to the present invention, the display data of red, green, and blue of the conventional CRT display can be directly substituted for the color liquid crystal panel, and a P / S conversion circuit and a selection gate circuit are added. Thus, it can be handled in the same manner as the conventional monochrome liquid crystal display system configuration. Also, the system configuration with P / S conversion circuit, select gate circuit, 1/8 counter, and ring counter
It is logical and can be colored by an extremely simple circuit configuration.

<< Effects of the Invention >> As described above, according to the present invention, color display of liquid crystal can be easily performed by using an interface signal of a CRT display. And an attractive display device such as a flat display terminal. In addition, since the same driving circuit as that for monochrome can be used, a great effect is obtained such that it is not necessary to develop a driving circuit dedicated to color.

[Brief description of the drawings]

 FIG. 1 is a circuit diagram showing one embodiment of the present invention. 1 Y-axis display area control circuit 2 X-axis display area control circuit 5 1/8 counter circuit 6, 7, 8, 12, 13, 14 shift register 9, 10, 11, 20 ... Latch circuit 23 ... Frame signal generation circuit 24 ... Shift clock generator 25 ... Latch clock generator 26 ... AC signal circuit 27 ... X electrode drive circuit 28 ... Color liquid crystal panel 29 ... Y electrode drive circuit

Claims (1)

(57) [Claims] An X-axis electrode and a Y-axis electrode are arranged in a matrix, and a color liquid crystal panel in which red, blue, and green filters are colored, an X-electrode driving circuit for driving the X-axis electrode, and a Y-axis electrode. Y-axis electrode drive circuit for driving the axis electrode, each S / P conversion circuit group for converting red, blue, and green serial display data into parallel data, and time-shifting the parallel-converted data. And a selection gate circuit for selectively taking out the output of the shift register group, and a second S / P conversion circuit for converting serial data of the selection gate circuit into parallel data. A color liquid crystal display device having an interface circuit, wherein an output of the second S / P conversion circuit is used as a display input of the X electrode drive circuit.