JPS62250776A - Driving method for liquid crystal display - Google Patents

Abstract

PURPOSE:To prevent the occurring of a flicker even when a jumping scanning is executed by repeating successively the operation to impress an electric potential except a video signal to the liquid crystal for displaying of the next row to be jumped and making into the picture by one field after a television signal is impressed to the liquid crystal for the displaying of one row. CONSTITUTION:To an input terminal 1 by an input changeover signal phis, when phis is a 'H' level, a constant direct current electric potential 7 is connected and when the phis is a 'L' level, a video signal 6 is connected and an input changing-over circuit 8 to control like that is added. In the first field, phi1v is inputted to a shift register 4, and for phiv1, phiv2..., the video signal 6 is inputted to an input terminal 1, a driving pulse is generated. In the second field, to a liquid crystal cell connected to an odd number line, the constant direct current electric potential 7 is impressed, and the video signal is impressed to the liquid crystal cell connected to the even number line. Thus, the periodicity of the change comes to be one field, the oscillation of the transmission factor of the light comes to be 60Hz, and therefore, the flicker does not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of driving a liquid crystal display device for receiving television images.

[Conventional technology]

The conventional method for driving a liquid crystal display device is disclosed in Japanese Patent Application Laid-Open No. 60-569.
8, the polarity of the video signal applied to the liquid crystal was inverted every field or frame.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, when performing interlaced scanning in a liquid crystal display device with a large number of scanning lines, the polarity of the video signal must be reversed every frame in order to drive the liquid crystal with variable current. .

Figure 5 shows the conventional liquid crystal display V? , and FIG. 4 is a timing chart of the circuit of FIG. 3. FIG.

In Fig. 3, 1 is an input terminal to which a television video signal is supplied, and the signal from this input terminal 1 is transmitted through each switching element M, , M, , . . . , into a line in the vertical (Y-axis) direction. L1 * IJl m...
・Supplied to Lm. Note that m is a number corresponding to the number of pixels in the horizontal (X-axis) direction. In addition, m-stage shift register 2
Clock signals φ, H1φ, H having m times the horizontal frequency are supplied to this shift register, and active pulse signals φH1, φH, . ...φHm is supplied to each control terminal of the switching elements M1 to Mm.

In addition, each line L1 to LJII has switching elements Mn, M, 1°, each consisting of, for example, an H channel FET.
...Mn, I J@I M! ! ...' Mn,
++HM@fn + M@m ・"M One end of nm is connected. Note that n is a number corresponding to the horizontal scanning line. The other end of this switching element Mtt...Mna+ is connected to each liquid crystal cell "o + O □...Connected to the common potential 3 through Cnm.

A seven-stage shift register 5 is provided in the front panel, and a horizontal frequency clock signal φ1v,
φ and V are respectively supplied, and this shift register 4.5
1 drive pulse signal φv8. which is sequentially scanned by clock signals φIv, φ, V from each output terminal of φIv, φ, V. φV,...
・φvn is each row of switching elements Mll to Mnm in the X-axis direction (M, 1 to M, rn) + (Mtt to Mt
m) −=(Mn, ~Mnm) are respectively supplied to the control terminals. Note that the shift register 2 has a low potential (V
ssx) and high potential (VDDX), and the shift register 4.5 is also supplied with low potential (Vssy) and high potential (VDDX).
D7) is supplied.

In this circuit, a lock signal as shown in A in FIG. 4 is input to the shift register 2, a driving pulse shown in FIG. 4C is outputted from the shift register 2, and the shift register 4.5 is φ1v, φ shown in FIG. 4B,
V are respectively input, and the drive pulse shown in the fourth diagram is output from the shift register 4.5. At this time, φ1v and φ
! V is φ in the first field to perform interlaced scanning,
A clock signal is applied to the shift register 4 to select the odd-numbered scanning line, and in the second field, φ2
A clock signal is applied to v to operate the shift register 5, select an odd-numbered scanning line, and output a driving pulse.

And φv1. When φH1 is output, switching elements M and 1' (st to Min are turned on, and a loop of input terminal 1 → M1 → L, → MIS → Ctt → common potential 3 is formed, and the voltage is applied to the liquid crystal cell Ctt. The tU difference between the input terminal 1 and the common potential 3 is supplied to the liquid crystal cell 011. In this way, one load corresponding to the television video signal is written to each liquid crystal cell from 11 to Cnm, and the By changing the light transmittance of each liquid crystal cell using a charge bond, the writing of the first field and the second field is combined to display one frame of one television image.

By the way, when displaying with a liquid crystal, AC lJA'#J is generally used to improve its reliability and lifespan. In the case of this conventional example, the polarity of the video signal is inverted every frame and input to the input terminal 1, resulting in the waveform shown in FIG.

When a liquid crystal cell is driven once with such a circuit and signal configuration, for example, the light of C11 and C A comparison of changes in transmittance over time is shown in FIG. In this case, if the switch '11'=llllnm is a unipolar switch such as an N-channel transistor, a difference occurs between the write state and the charge retention state depending on the polarity of the charge imprinted on the liquid crystal cell. Figure 11g6 shows this kind of situation, and shows that when the video signal has a negative polarity with respect to the common potential 3, the writing state is good compared to the positive polarity video signal, and the holding state is poor. It shows. In Figure 6, the change in light transmittance of the liquid crystal cell C11 is shown by the solid line 1 in the figure.
0, the change in light transmittance of the liquid crystal cell C□ is shown by the broken line 1
This shows that it will be like 1.

In FIG. 6, the size of the shaded area indicates the filter that blocks light, and the change in light transmittance is 10, 111.
- It is shown that when added, the light transmittance changes as shown in FIG. The original variation in FIG. In Hiroa, it fluctuates in a cycle where one period is 2 frames (4 fields). - In the video No. 18 of Man Television, 1 field is sent in a cycle of 60H2, so it changes in 4 fields as shown above. In one cycle, the frequency was 15 Hz, and the light transmittance oscillated at that frequency, resulting in flicker and a significant decrease in image quality.

The purpose of the invention is to solve these problems, and its purpose is to provide a high-quality liquid crystal display device that does not cause flicker even when interlaced scanning is performed.

[Means for solving the problem] (a) Input the television video signal to the panel section in which display liquid crystal cells are arranged in a matrix 1))
In a liquid crystal display device that performs interlaced scanning by shifting the rows in which the television signal is input in the first and second fields, (c) the television signal and the potential of the video signal other than the video signal corresponding to the video signal of the television; (d)
After applying the television signal to the display liquid crystal cells for one row, (e) sequentially repeating the operation of applying a potential other than the video signal to the display liquid crystal cells of the next row to be skipped;
It is characterized by having a screen for each field.

〔Example〕

In the present invention, a video signal 6 and a potential 7 other than the corresponding video signal are switched and supplied to the input terminal 1 in FIG. 1, and the liquid crystal cell connected to the skipped scanning line is , which applies a potential other than the above-mentioned video signal, and FIGS. 1 and 2 show an uninvented embodiment in which a potential other than the above-mentioned video signal is applied during the horizontal retrace period of the television video signal.
One equation for writing a constant DC potential as a potential is shown. (Hereinafter, the first position other than the video signal will be explained as a constant DC potential.) In Fig. 1, when the input switching signal φB is applied to the input terminal 1, and when φ8 is at the rHJ level, a constant DC potential 7 is applied to the input terminal 1.
is connected to input terminal 1, and when φ day is at rLJ level, an input switching circuit 8 is added to control the video signal 6 to be connected, and at the same time switches M1...Mn
The θR gate θ can be turned on from the outside.
8. Add θ,...θn. The all-on terminal 9
The input switching signal φ8 is applied to the input switching signal φ8. When each signal is inputted to such a circuit configuration at the timing shown in FIG. 2, the input terminal 1 has a waveform in which the video signal 6 and the constant DC potential 7 shown in FIG. 8 are switched. Although various combinations of the video signal and the constant DC potential are possible, in this embodiment, as shown in FIG.
On the other hand, the following description will be made assuming that the video signal 6 has a negative polarity and that the constant DC potential 7 has a positive polarity.

In the first field, φ and V are in the shift register 4.
φvl, φV, . . . generate drive pulses when the image signal 6 is input to the input terminal 1, and the liquid crystal cells connected to the odd-numbered lines 011+0
11...' 01m I Cst * Cst "'
The video signal 6 is sequentially written into Csm"'. At this time, during each horizontal retrace period, no driving pulse is generated from the shift register 4, and the shift register 5 to which φ and V are input.
A drive pulse is generated in synchronization with the horizontal retrace period in which a constant DC potential 7 is input to the input terminal 1 from 1i! to the even-numbered line. d has been done. Lol! j, crystal cell C□
.

C1t...C, m I a, 11 a411 ・”
a4'm +++ C! The negative DC potential 7 is sequentially written to nm.

In the second field, the phases of φ, V and φ, V are opposite to the first field, and the liquid crystal cells connected to the odd-numbered lines have a constant DC potential of 7.
is applied, and a video signal is applied to the liquid crystal cells connected to the even-numbered lines.

The temporal change in the light transmittance of the liquid crystal cell in this 1@intuition is as shown in FIG.

In FIG. 9, the size of the area of the hatched portion indicates the amount of light blocked, and similarly to FIG. 6, the solid line 10 indicates the change in the liquid crystal cell CIt, and the broken line 11 indicates the change in the liquid crystal cell CII. When this change in light transmittance is added by f10 and '11, it becomes as shown in Figure 10. The periodicity of this change is 1 field, and the vibration of light transmittance is 60Hz, so flicker is reduced. Does not occur.

The embodiment of the present invention has been described above using a method in which a constant DC potential is input during the horizontal retrace period. While reading and storing the video signal, the previously stored video signal and a constant DC potential are written line by line for each horizontal scanning period, and the same method is used when writing.
l 1. +, . . . The stored contents corresponding to Lm are switched to switch M1. M.

...A similar effect can be obtained even if a video signal and a constant DC potential are applied by turning on Mm at the same time and writing line-sequentially.

〔Effect of the invention〕

As described above, according to the present invention, a single DC potential is input to the liquid crystal cell to be skipped, where there is no video signal, and by mutually driving it with the normally sent video signal, the interlaced scanning is performed. This has the effect that flicker does not occur even when By using the above driving method, it is possible to realize a high-quality liquid crystal display device with an increased number of scanning lines.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the method for driving a liquid crystal display device of the present invention. FIG. 2 is a timing chart of each signal showing an embodiment of the method for driving a liquid crystal display device of the present invention. FIG. 5 is a circuit configuration diagram showing a conventional method for driving a liquid crystal display device. FIG. 4 shows a conventional liquid crystal display II7. Timing chart of each signal showing the drive and method of ii. FIG. 5 is a diagram of input signals to a conventional liquid crystal display device. FIGS. 6 and 7 are state diagrams showing changes in light transmittance due to the conventional driving method. FIG. 8 is a diagram of input signals to the liquid crystal display device in the present invention. FIGS. 9 and 10 are state diagrams showing changes in light transmittance according to the driving method of the present invention. 1... Input terminal to the liquid crystal display device 2.415... Shift register 3... Common potential 6... Video (IJ signal 7°°° Potential other than video signal (-DC z position) 8...
・Switching circuit 9...All-on terminal 10.11...Light transmission ratio of liquid crystal cell or higher Applicant: Seiko Epson Shishiki Co., Ltd. Once in a while'' ■Figure 2 Figure 3 Figure 5

Claims (1)

[Scope of Claims] (a) A line in which a television video signal is input to a panel section in which display liquid crystal cells are arranged in a matrix, and (b) a line in which a television signal is input in the first field and the second field. In a driving method for a liquid crystal display device that performs interlaced scanning by shifting the image signal, the method comprises: (c) having a television signal and a potential other than a video signal corresponding to the video signal of the television, and (d) converting the television signal into one line. After applying the voltage to the display liquid crystal cell for 10 minutes, the operation of (e) applying a potential other than the video signal to the next display liquid crystal cell to be skipped is sequentially repeated to form a screen for one field. A method for driving a liquid crystal display device.