JP3269081B2 - Liquid crystal drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal driving device for driving a liquid crystal used in, for example, a liquid crystal television receiver.

[Prior Art] It is known that, when driving a liquid crystal, increasing the frame frequency of driving improves the contrast.

FIG. 3 shows a liquid crystal driving device in which the driving frame frequency is increased in order to improve the display contrast in the conventional liquid crystal driving, and FIG. 4 is a timing chart showing the operation state of the liquid crystal driving device in FIG. It is a chart.

First, the receiving circuit 1 extracts a video signal Sv, a horizontal synchronizing signal φH, and a vertical synchronizing signal φV from the received television signal. The video signal Sv is supplied to the A / D converter 3 by the horizontal synchronizing signal φH.
And the vertical synchronizing signal φV are sent to the control circuit 2.
The control circuit 2 receives a start signal ST, a clock signal φs, a latch signal φn, an inversion signal φF, a switching signal SEL, address designation signals AD1, AD2, a read / write signal R / W from the input horizontal synchronization signal φH and vertical synchronization signal φV. Generate various timing signals such as shift registers 5, 8, 9 and drive circuit
6, 10 and 11, a switching circuit 4, outputs to the memories A and B, etc., and generates a plurality of types of liquid crystal driving voltages VLC to generate driving circuits 6, 10, and 11.
Output to

On the other hand, the A / D converter 3 converts the input video signal Sv into k-bit digital video data E and outputs the k-bit digital video data to the memories A and B. Signal AD1, AD2 and read / write signal R / W
, The even fields (n, n + 2, n + 4,...) Of the video data E
..) Are stored in the odd field (n + 1, n + 3,...).
..) Is read by the memory B.

Next, the video data of n fields read into the memory A is n + 1 fields, and the speed at the time of writing is 2
2 times, that is, twice as fast as normal video data, and is read out twice as an output signal EA.
Similarly, the video data of the (n + 1) th field read into the memory B is the (n + 2) fields, and is read twice at twice the writing speed, that is, twice as fast as the normal video data. , As an output signal EB to the switching circuit 4. The output signals EA and EB input to the switching circuit 4 are switched every field time by a switching signal SEL from the control circuit 2, become data DAB, output to the shift register 5, and synchronized with the clock signal φs of the control circuit 2. And stored in the shift register 5. The data DAB stored in the shift register 5 is latched every 1 / 2H (horizontal scanning period) by the latch signal φn from the control circuit 2 in the segment drive circuit 6, and is driven by the inversion signal φF to perform AC driving. The level is shifted to the liquid crystal drive voltage VLC whose polarity is inverted, and the segment electrodes of the liquid crystal display panel 7 are driven.

Further, the common side of the liquid crystal display panel 7 is
1H (horizontal scanning period) from the start signal ST is input to the shift registers 8 and 9 and the clock signal φn outputs 1 / 2H
Since the shift register is sequentially shifted every (horizontal scanning period), the output signals X'1 to X 'from the shift registers 8 and 9 are shifted.
120 and X'121 to X'240 are added to the corresponding common electrode drive circuits 10 and 11 to drive two common electrodes respectively. The common electrode driving circuits 10 and 11 are connected to each of the output signals X'1 to
A liquid crystal driving voltage VLC that inverts the polarity so that AC driving is performed by an inversion signal φF corresponding to X'120, X'121 to X'240.
Is applied to the common electrode of the liquid crystal display panel 7, and the common electrodes are driven two by two.

[Problems to be Solved by the Invention] As described above, the selection time of the common electrode of the liquid crystal display panel at one time is 1/2 and the selection frequency is doubled, so that the contrast is improved. However, in this conventional liquid crystal driving device, the transfer speed of the shift register must be doubled, and the memory capacity needs to be two fields, which causes a rise in cost.

Therefore, the present invention has been made in view of the above circumstances, and it is possible to use as little memory as possible and to increase the frame frequency of liquid crystal driving without increasing the data transfer speed to the segment electrode driving circuit. It is an object to provide a liquid crystal driving device.

[Means and Actions for Solving the Problems] A series of video data is read every other horizontal scanning period.
A storage means having a capacity of 2 fields × the number of data bits, a video data read by a half field after the video data of a half field read into the storage means, and a video data not passing through the storage means. Switching means for alternately outputting every one horizontal scanning period, and outputting a liquid crystal drive voltage based on data not passing through the storage means during one horizontal scanning period;
A segment electrode driving unit that outputs a liquid crystal driving voltage based on data from the storage unit in the next one horizontal scanning period, and a scanning electrode corresponding to video data that does not pass through the storage unit in the one horizontal scanning period; In the next one horizontal scanning period, a common electrode driving unit that scan-drives another scanning electrode corresponding to the data from the storage unit and drives two common electrodes at a time is provided. 1/2
The segment electrodes are driven by alternately outputting video data stored in a memory having a capacity of the field × the number of data bits every other horizontal period and raw video data not passing through the memory every one horizontal period. The common electrodes corresponding to the video data are driven two by two.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a liquid crystal driving device according to an embodiment of the present invention, and FIG. 2 is a timing chart showing an operation state and data contents of the liquid crystal driving device of FIG.

First, the receiving circuit 1 extracts a video signal Sv, a horizontal synchronizing signal φH, and a vertical synchronizing signal φV from the received television signal. The video signal Sv is supplied to the A / D converter 3 by the horizontal synchronizing signal φH.
And the vertical synchronizing signal φV are sent to the control circuit 12, respectively.
The control circuit 12 receives a start signal ST ₀ , a clock signal φs, a latch signal φn, an inversion signal φF, an output inhibition signal INH1,2, a switching signal SEL ₀ , an address designation signal AD from the input horizontal synchronization signal φH and vertical synchronization signal φV. In addition to generating various timing signals such as read / write signal R / W, and outputting the signals to shift registers 15, 18, 19, drive circuits 16, 20, 21, switching circuit 14, memory M, output control circuits 22, 23, etc. A plurality of types of liquid crystal drive voltages VLC are generated and output to drive circuits 16, 20, and 21.

On the other hand, the A / D converter 3 converts the input video signal Sv into k-bit digital video data E and outputs the k-bit digital video data E to the memory M. The video data E is read every 1H (horizontal scanning period) according to the signal R / W.

Next, the video data for 1/2 field read into the memory M is read out after 1/2 field according to the address designation signal AD and the read / write signal R / W from the control circuit 12, and the video data Ec Switching circuit 14 as
Is output to A / D converter 3 input to switching circuit 14
Video data E from the memory M and video data Ec from the memory M
Becomes outputted alternately data Dco accordance switching signal SEL ₀ from the control circuit 12 in this switching circuit 14, is input to the shift register 15. And this data Dco is the control circuit 1
The data is stored in the shift register 15 in synchronization with the second clock signal φs. Data Dc stored in this shift register 15
O is level-shifted to the liquid crystal drive voltage VLC which is latched every 1H (horizontal scanning period) by the latch signal φn from the control circuit 12 in the segment drive circuit 16 and inverts the polarity so that the AC drive is performed by the inversion signal φF. Then, the segment electrodes of the liquid crystal display panel 7 are driven.

Further, the common side of the liquid crystal display panel 7 is
The start signal ST ₀ of 2H (horizontal scanning period) from the input to the shift register 18, 19 IH by a clock signal φn
The data is sequentially shifted in the shift register every (horizontal scanning period). Therefore, each output signal from the shift registers 18 and 19 is always output to the output control circuits 22 and 23 so that the common electrode drive circuits 20 and 21 drive two common electrodes respectively. , 23 are horizontal synchronizing signals φH
According to the output inhibit signals INH1, 2 which are inverted every 1H (horizontal scanning period) in synchronization with
Output signals X'1 to X'120, X'121 from shift registers 18, 19
To X′240 are added to the corresponding common electrode drive circuits 20 and 21, respectively. The common electrode drive circuits 20 and 21 are connected to each output signal X'1
To X'120 and X'121 to X'240, the liquid crystal driving voltage V whose polarity is inverted so that AC driving is performed by the inversion signal φF.
The level is shifted to LC and applied to the common electrode of the liquid crystal display panel 7 to drive the common electrodes two by two.

In the present embodiment, the video data stored every other horizontal scanning period in the memory having the capacity of 1/2 field × data bit number and the raw video data
The segment electrodes are driven alternately every horizontal scanning period, and the common electrodes corresponding to the video data are driven two by two.
May be stored in a memory having a capacity of (field × data bit number) every a-1 horizontal scanning period, and a common electrodes corresponding to video data may be driven by a lines.

[Effects of the Invention] As described above, according to the present invention, video data stored every other horizontal scanning period in a memory having a capacity of フ ィ ー ル ド field × data bit number and a raw video not passing through the memory Since the segment electrodes are driven by alternately outputting data every horizontal scanning period and the common electrodes corresponding to the video data are driven two by two, a memory having a smaller capacity than the conventional one is used. And a liquid crystal driving device in which the driving frequency is doubled without increasing the data transfer speed of the segment electrode driving circuit.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a block diagram showing a circuit configuration of a liquid crystal driving device.
FIG. 3 is an explanatory diagram showing the contents of the waveforms and data of each part in FIG. 1, FIG. 3 is a structural explanatory view showing an example of a conventional liquid crystal driving device, and FIG. 4 is the waveform and data contents of each part in FIG. FIG. M: memory, 1: receiving circuit, 3: A / D converter, 7
… Liquid crystal display panel, 12… Control circuit, 14… Switching circuit, 15, 18, 19… Shift register, 16… Segment drive circuit, 20, 21… Common electrode drive circuit, 22, 23… Output control circuit.

Claims (1)

(57) [Claims] 1. A storage means having a capacity of 1/2 field.times.data bits for reading a series of video data every other horizontal scanning period; Switching means for alternately outputting video data read two fields later and video data not passing through the storage means every one horizontal scanning period; and a liquid crystal drive voltage based on data not passing through the storage means in one horizontal scanning period. A segment electrode driving unit that outputs and outputs a liquid crystal driving voltage based on data from the storage unit in the next one horizontal scanning period; and a scanning electrode corresponding to video data that does not pass through the storage unit in the one horizontal scanning period. Driving, and in the next one horizontal scanning period, common electrode driving means for scanning and driving another scanning electrode corresponding to data from the storage means and driving two common electrodes at a time. A liquid crystal driving device which is characterized by comprising a.