JP3270077B2 - Driving method of liquid crystal television - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the driving of a liquid crystal television.
More particularly, the present invention relates to a driving method for performing high-resolution display without using a field memory or an arithmetic device.

[0002]

2. Description of the Related Art Various systems have been put into practical use as driving methods for liquid crystal televisions. The configuration of the main part of the LCD television and the conventional drive mainly focusing on the scanning method are described below.
The operation method will be described. FIG. 5 is a block diagram of a general example of the configuration of a liquid crystal television. In the figure, for example, R, G, and B video signals 201 from a chroma circuit are input to an A / D converter 203, and are sequentially digitized by a control signal generated by a timing generator 204 based on a synchronization signal 202. The signal is input to the signal electrode drive circuit 206 and output to the signal electrode of the liquid crystal display device 207. On the other hand, the scan electrode signals applied to the scan electrodes of the liquid crystal display device 207 are sequentially output from the scan electrode drive circuit 205 according to the control signal from the timing generator 204.

As a scanning method of a display image in a liquid crystal television having such a configuration, a scanning electrode corresponding to one field is provided on a liquid crystal panel, and the same scanning electrode is used in an even field and an odd field (half resolution). Solution) is most often used. In this method, the displayed data is {(Dn) + (Dn + 1)} /
2, {(Dn + 2) + (Dn + 3)} / 2, {(Dn + 4) +
(Dn + 5)｝ / 2,..., And the vertical resolution is reduced by half. Here, Dn, Dn + 1...
This is data in units of the horizontal cycle. Here, the horizontal cycle is
A horizontally scanned video signal is input to a liquid crystal television, and refers to the period of the horizontal scanning.

On the other hand, there is a method of displaying an image in the same manner as interlaced scanning (hereinafter, referred to as interless scanning) used in a television using a CRT. here,
Interlaced scanning means that 1 is sequentially sent to the even field.
Data Dn + 1, Dn + 3 of one horizontal cycle unit sequentially transmitted in odd fields so as to fill the spaces between the scanning lines for displaying the data Dn, Dn + 2, Dn + 4,.
, Dn + 5,..., And scan one frame of data into Dn, Dn + 1, Dn + 2, Dn + 3, Dn + 4.
, Dn + 5,... That is, in the liquid crystal television, 1 which is a double of one field.
This is a method in which scanning electrodes for a frame are prepared, two scanning electrodes are displayed as one set, and the even and odd fields are shifted by one.

FIG. 4 shows the relationship between displayed data and scanning lines in this system. In FIG. 4, in the first field, the scanning electrodes are m and m + 1, m + 2 and m + 3, m + 4 and m +
.., And in the second field, m + 1
, M + 2, m + 3 and m + 4, m + 5 and m + 6... In this case, the number of divisions of the liquid crystal display device is the same as that of the above-mentioned display method, and the data to be displayed are {(Dn) + (Dn + 1)} / 2 in sequence.
{(Dn + 1) + (Dn + 2)} / 2, {(Dn + 2) + (D
n + 3)｝ / 2, {(Dn + 3) + (Dn + 4)} / 2,
{(Dn + 4) + (Dn + 5)} / 2,..., And although the number of scanning lines increases, the resolution is not improved so much because the data of the preceding and following lines are mixed.

Further, since there is a correlation between the data in the vertical direction and the data, there is a method in which a computing unit 601 with a line memory is provided as shown in FIG. For example, the data between Dn and Dn + 2 is calculated and displayed as {(Dn) + (Dn + 2)} / 2. This method uses a TFT (Thin Film T)
tranistor), MIM (Metal Insu)
The present invention is also applied to a display device using an active display element such as a lateral metallizer or a diode ring.

Incidentally, in a simple matrix type liquid crystal display device which performs time division driving with the number of divisions n, the maximum possible value of the ratio α between the maximum Vmax and the minimum Vmin of the voltage applied to the pixel of interest is expressed by the following equation 1. . According to this, since the number of divisions approaches 1 when the number of divisions n increases, the steepness of the transmittance characteristic of the liquid crystal becomes a problem, which means that contrast cannot be obtained with ordinary liquid crystals. In a liquid crystal display device using an active element represented by MIM, control of a pixel of interest is performed by a voltage value of the pixel within a selected time, so that the above-described restriction by the number of divisions is eliminated.

[0008]

(Equation 1)

In order to obtain a display with a higher resolution, there is a method using a field memory. FIG. 7 is a block diagram of a display system of a liquid crystal television having a field memory. The data of the previous field stored in the field memory 701 is read and displayed twice on the liquid crystal display device 207, and the A / D converter 2
03 is stored in the field memory 701. Since the data is displayed twice, the display time becomes longer,
The display resolution is improved.

[0010]

However, in the above-described method using the field memory, in addition to increasing the number of memory components, data for two fields must be transferred to the liquid crystal driving device in one field time. A circuit for reading out data and transferring data is required. In addition, the method using interpolation requires high-speed data processing,
Inconveniences such as an increase in components such as a memory for storing data for interpolation and a D / A converter are caused. An object of the present invention is to solve the above-mentioned problems and to provide a driving method for a liquid crystal television in which the resolution in the vertical direction is improved without using a field memory or an interpolation arithmetic circuit.

[0011]

In order to achieve the above object, in a method of driving a liquid crystal display device according to the present invention, a liquid crystal television having a liquid crystal display device having one frame of scanning electrodes together with signal electrodes. In a liquid crystal television driving method for displaying an image in which one frame is composed of two fields, a period in which each of the scanning electrodes is selected is set to 1/1 / the horizontal cycle of the video signal.
At time 2, all the scanning electrodes are sequentially scanned in one field, and a data signal corresponding to the video signal is transmitted to the video signal.
The timing when the horizontal period of the signal e switches to the next horizontal period
To the signal electrode, and the scan electrode signal is applied one by one.
The middle point of the selection period is the horizontal period of the video signal.
Characterized the this <br/> be controlled to switch the same timing as the. Also, a method of driving the liquid crystal display device of the present invention
The method has a scanning electrode for one frame together with a signal electrode.
Video signals to an LCD television equipped with a
Signal, and one frame consists of even fields and odd fields.
Display an image consisting of two fields
In the method for driving a liquid crystal television, the scanning electrodes
Is selected to be a half of the horizontal cycle of the video signal.
Time, and sequentially scan all scan electrodes in one field.
A data signal corresponding to the video signal,
At the timing when the horizontal period of the next horizontal period switches
The scan electrode signal is applied to every other signal electrode.
The middle of the selection period is the switching of the horizontal period of the video signal
The timing is controlled to be the same as
Selection of even-numbered scan electrode signals
A data signal corresponding to the video signal at an intermediate point in the period
And in the odd field,
At an intermediate point in the selection period of the scan electrode signal, the video signal
Switching the data signal corresponding to the signal
You .

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a timing chart of the driving signal of the present embodiment, and FIG.
Is a block diagram of a main part of a liquid crystal television, and FIG. 3 is a configuration diagram of a liquid crystal display device. The liquid crystal display device used in this embodiment is a device having a switching element composed of an MIM as shown in FIG. In the figure, 301 is a scanning electrode, 302
Are signal electrodes, which are not shown, but are provided on opposing surfaces of a substrate sandwiching a pair of liquid crystals. Reference numeral 303 denotes an MIM element, which is turned on when a selection pulse is output and turned off in other cases, and controls the liquid crystal pixel indicated by 304. Therefore, it is not affected by the increase in the number of divisions due to the increase in the number of scan electrodes. The configuration of the liquid crystal television of FIG. 2 is basically the same as the configuration of FIG. 5, but the timing generator uses a different timing.

In FIG. 1, the left half signal waveform is an even field, and the right half signal waveform is an odd field waveform. 2A shows a video signal. The video signal (a) input to the liquid crystal television is converted into a digital signal by the A / D converter 203 in FIG. 2 and transferred to the signal electrode drive circuit 206. This data is used as output data in the next horizontal period. Meanwhile, data is held in the signal electrode drive circuit 206. (B) shows the data held by the signal electrode drive circuit 206. From the signal electrode drive circuit 206, a signal obtained by pulse-width-modulating the above-mentioned held data according to the gradation is output to each signal electrode.
(C) shows the signal electrode output data output to the signal electrode.

Further, m-2, m-1, m, and m + 1 indicate scanning signals applied to the scanning electrodes. Here, the timing of the signal electrode output data and the scanning signal is a feature of the present invention, and is as follows. That is, the update of the data of the signal electrode signal is at the center of the selection period of the scan electrode signal and at the timing of every other scan electrode, and the switching position is shifted by one in the even field and the odd field. . In FIG. 1, in the even field, the data signal is switched from Dn-2 to Dn at an intermediate point of the scanning signal m-1, and the scanning signal m +
The data signal is switched at the intermediate point of 1. In the odd field, the data signal is switched from Dn-3 to Dn-1 at the intermediate point of the scanning signal m-2, and the data signal is switched at the intermediate point of the scanning signal m next. Accordingly, the pulse width modulation data (c) must be output from the signal electrode IC so as to be completed in a half cycle of the selection pulse. Further, the liquid crystal display device has one
Since the number of scanning electrodes for a frame is 480 (for example, 480), the scanning signal electrodes are controlled so that a time selection pulse of half of 1H is output. From the above, the cycle of the signal (c) is 1/1 of the horizontal cycle (1H) of the video signal (a).
It is output to the signal electrode at 4 times.

In the liquid crystal display device controlled as described above,
For example, the m-th scanning electrode is (Dn
+ Dn) / 2 data is (Dn-1) in the odd field.
+ Dn + 1) / 2 data will be displayed. Since the liquid crystal responds to the effective value of the applied voltage, in such a case, the average voltage is displayed. Dn-1, Dn,
Since the data of Dn + 1 is continuous data in the vertical direction, each data has a correlation. Therefore, the data Dn can be obtained by interpolation from the data of Dn-1 and Dn + 1, and can be expressed as DnＤ (Dn-1 + Dn + 1) / 2. From the above, the m-th display data is Δ (Dn + D
n) / 2 + (Dn-1 + Dn + 1) / 2｝ / 2 ≒ Dn. Similarly, the (m + 1) th scanning electrode is Dn + 1,
The (m + 2) th scan electrode represents the data of Dn + 2. In this embodiment, a liquid crystal display device having a switching element made of MIM is used.
Needless to say, the same effect can be obtained in the case of a liquid crystal display device using STN having a sharp liquid crystal characteristic as a liquid crystal material.

[0016]

As is apparent from the above description, according to the present invention, a liquid crystal television having a high resolution in the vertical direction can be realized with a simple configuration without using a field memory or an interpolation arithmetic circuit.

[Brief description of the drawings]

FIG. 1 is a timing chart of a drive signal according to an embodiment of the present invention.

FIG. 2 is a block diagram of a liquid crystal television according to an embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of the liquid crystal display device according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram of a conventional driving method.

FIG. 5 is a block diagram of a conventional liquid crystal television.

FIG. 6 is a block diagram of a conventional liquid crystal television using an arithmetic unit with a line memory.

FIG. 7 is a block diagram of a conventional liquid crystal television using a field memory.

[Explanation of symbols]

 201 Video Signal 202 Synchronization Signal 203 A / D Converter 204 Timing Generator 205 Scan Electrode Drive Circuit 206 Signal Electrode Drive Circuit 207 Liquid Crystal Display 301 Scan Electrode 302 Signal Electrode 303 MIM Element 305 Liquid Crystal Pixel

Claims (2)

(57) [Claims] A video signal is input to a liquid crystal television provided with a liquid crystal display device having scanning electrodes for one frame together with signal electrodes, and a liquid crystal television displaying an image in which one frame is composed of two fields. In the driving method , a period for selecting each of the scan electrodes is set to a half of a horizontal period of the video signal, and all the scan electrodes are sequentially scanned in one field to correspond to the video signal. A data signal,
When the horizontal period of a signal switches to the next horizontal period
The scan electrode signal is applied to the signal electrode ,
The same timing as the switching of the horizontal period of the video signal
A driving method for a liquid crystal television, wherein the driving is controlled so that 2. A scan for one frame together with a signal electrode.
Liquid crystal television with a liquid crystal display device with electrodes
A video signal is input, and one frame is composed of even and odd fields.
An image consisting of two fields, a few fields
In the method of driving a liquid crystal television for displaying, a period in which each of the scanning electrodes is selected is a horizontal period of the video signal.
The scanning period is set to a half of the period , all the scanning electrodes are sequentially scanned in one field, and a data signal corresponding to the video signal is transmitted to the video signal.
When the horizontal period of a signal switches to the next horizontal period
The scan electrode signal is applied to the signal electrode ,
The same timing as the switching of the horizontal period of the video signal
And the even numbered scan electrodes in the even field.
Corresponding to the video signal at an intermediate point during the signal selection period.
A data signal is switched, and in the odd field, an odd-numbered scan electrode
Corresponding to the video signal at an intermediate point during the signal selection period.
LCD televisions characterized by switching data signals
Drive method .