JP2003084729A - Liquid crystal display device, source driver, method for driving source driver, program, and medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a flickering of vertical lines appearing on a liquid crystal screen. SOLUTION: This liquid crystal display device has a source driver IC chip 4 having two systems of sample-hold circuits for reading the information to be written to a liquid crystal element in one horizontal period and writing the read information onto the liquid crystal element in the next one horizontal period, and while the one sample-hold circuit performs reading, another sample- hold circuit performs writing, and while the one sample-hold circuit performs the writing, another sample-hold circuit performs the reading, and the number of switching times of two systems of the sample-hold circuits with each other is always even or odd in respective field periods or respective frame periods.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, a source driver, a source driver driving method, and a program used as a display device of a television monitor, video equipment such as car navigation, and information equipment such as computer. , And media.

[0002]

2. Description of the Related Art In recent years, the ratio of liquid crystal display devices has been rapidly expanding in various applications such as AV, OA, vehicle-mounted and information communication.

The demands for medium-thin, thin, lightweight, and low-cost are becoming stronger, and a source driver IC chip for driving liquid crystal and a gate driver IC chip are formed on a glass substrate on which active elements are formed. By directly mounting the C
OG (chip on glass) type liquid crystal display devices are becoming popular.

The structure and operation of such a conventional liquid crystal display device will be described.

In FIG. 3, which is a block diagram of a conventional liquid crystal display device, 1 is a counter electrode glass substrate, 2 is a pixel electrode glass substrate, 3 is a gate driver IC chip, 4 is a source driver IC chip, 5 is a power source and various types. Control signal wiring, 6 is output wiring of the gate driver IC chip 3 and the source driver IC chip 4, 7 is a flexible wiring board, and 8'is a drive circuit for outputting OEH signals having different numbers in odd and even fields.

The pixel electrode glass substrate 2 is used as a substrate on the TFT array side, and the counter electrode glass substrate 1 is arranged so as to face the pixel electrode glass substrate 2, and liquid crystal is sealed between these glass substrates. The display area is formed. A non-display area is formed between the outer circumference of the display area and the outer circumference of the pixel electrode glass substrate 2, and the gate driver IC chip 3 and the source driver IC chip 4 are mounted on the non-display area.

The gate driver IC chip 3 and the source driver IC chip 4 are the gate driver IC chip 3
Also, via the output wiring 6 of the source driver IC chip 4, it is also connected to the electrodes in the display area.

A flexible wiring board is provided on the input side of the gate driver IC chip 3 via the power supply and various control signal wirings 5, and on the input side of the source driver IC chip 4 via the power supply and various control signal wirings 5. 7 are connected by an ACF (anisotropic conductive film) composed of conductive particles and an adhesive. Then, a signal for driving the gate driver IC chip 3 and the source driver IC chip 4 and a power supply voltage are supplied from the outside, and a character is displayed on the liquid crystal display cell to which the output of the gate driver IC chip 3 and the source driver IC chip 4 is connected. Alternatively, an image is displayed.

Now, the role of the gate driver IC chip 3 is to serve as a vertical scanning driver, which receives the control pulse (STV, CPV) from the driving circuit 8'as an input and which is used for each liquid crystal panel in one vertical period (1V). That is, a pulse having one horizontal period (1H) width is sequentially output to the gate line.

The source driver IC chip 4 plays a role of a driver for applying a horizontal scanning and a video signal (RGB) to a control pulse (STH, STH,
CPH, OEH) and video signal as input, first 1H
Image information corresponding to each pixel in the horizontal direction of the panel in the period is sampled and held, and the held information is line-sequentially output to each source line of the liquid crystal panel in the next 1H period, and new image information is generated. It is to sample. Thereafter, such sampling operation and hold operation are repeated.

Here, such a sample hold operation will be described with reference to the timing charts shown in FIGS.

FIG. 5A is an explanatory diagram of the waveform of the start pulse (vertical synchronizing signal) STV input from the drive circuit to the gate driver IC chip, and FIG. 5C is a clock pulse (horizontal synchronizing signal) CPV. 3 is an explanatory diagram of waveforms of FIG.

The STV is taken in at the rising edge of CPV, and starting from this, the first pulse of 1H width is output. A voltage is applied to the uppermost gate line of the liquid crystal panel by this pulse, and the TFT in the display area is turned on. After that, scanning is sequentially performed from top to bottom, and a pulse having a 1H width is supplied to each gate line in a 1V scanning period (each rising interval of CPV is drawn slightly narrower in the drawing). Is actually 1 H. Also, the even field is composed of 262 H and the subsequent vertical blanking period, and the even field is composed of 263 H and the subsequent vertical blanking period).

FIG. 5D is an explanatory diagram of the waveform of the output enable signal OEH input from the drive circuit to the source driver IC chip.

At each rising edge of the output enable signal OEH, switching between the two systems of sample and hold circuits A and B in the source driver IC chip is performed, and immediately before 1H.
The video signal sampled and held during the period is output (each rising edge of OEH is slightly narrower in the drawing, but is actually 1H).

Now, FIG. 5B is an explanatory diagram of the waveform of the voltage VCOM applied to the counter electrode of the liquid crystal, and FIG.
FIG. 4 is an explanatory diagram of a waveform of a video signal (RGB).

These are 262 in the even field and 263 in the odd field, which are inverted every 1H and 1
It is also reversed for each V. Below the VCOM waveform is the A system,
This shows switching of the system of the sample hold circuit having two systems of the B system (see FIG. 5B), and the switching operation is continued in synchronization with the OEH signal from the time the power is turned on to the time the power is turned off.

It should be noted that it is uncertain whether the system A or the system B will be started immediately after the power is turned on, and here, for convenience, the system A is started.

Further, STV and VC of the conventional liquid crystal display device
4A to 4D, which are explanatory diagrams of the OM and the liquid crystal output waveform in each field, FIG. 4A to FIG.
The transitions of the expanded waveform of VCOM and the liquid crystal output and the liquid crystal output waveform in the odd even field are shown when there is an offset due to the characteristic difference between the system and the B system.

In the liquid crystal display device having such a structure,
As described with reference to FIG. 5, the system of the sample hold circuit of the video signal output from the source driver IC chip 3 is that if the first line starts from the A system in the even field, it ends in the B system. , 1 for odd fields
The line starts with the A series and ends with the A series.

Therefore, the first line of the next even field starts with the B system and ends with the A system. Then, the first line of the next odd field starts in the B system and ends in the B system.

The second and subsequent lines can be similarly considered.

In this way, in the conventional liquid crystal display device,
The sample hold circuits were switched in the order of A system, A system, B system, B system, A system ....

[0024]

However, the start pulse STV is supplied as shown in FIG. 4A, and the A-system and the B-system of the sample-hold circuits of the two systems of the source driver IC chip 4 have a characteristic difference. I have, A
System offset is -10 mV, B system offset is +20 m
In the case of V, the actual output with respect to the output expected value of each system shown by the dotted line becomes as shown by the solid line in consideration of the offset amount of each system as shown in FIG. Further, when only the actual liquid crystal output is extracted, it becomes as shown in FIG.

Therefore, when the liquid crystal output of the first line in each field is extracted, it becomes 4V as shown in FIG. 4 (d).
It becomes a cycle (4 vertical cycles), and the brightness difference according to the offset changes and appears at 15 Hz, and it becomes more noticeable as vertical line flickering on the screen when the halftone pattern is displayed (as will be described later, VCOM Considering the switching of the polarity of the liquid crystal output corresponding to the switching of A, A-, A +, B-, B +, A
-, A +, B-, B +, ...

In consideration of the above conventional problems, the present invention makes it possible to make vertical line flickering appearing on a liquid crystal screen inconspicuous, a source driver, a source driver driving method, a program, and a program. It is intended to provide a medium.

[0027]

[Means for Solving the Problems] The first invention (Claim 1)
Corresponding to) is provided with a source driver having two systems of a sample hold circuit for reading information to be written in the liquid crystal element in one horizontal period and writing the read information in the liquid crystal element in the next one horizontal period, When the sample and hold circuit of 1 is performing the reading, the other sample and hold circuit is performing the writing, and when the one of the sample and hold circuits is performing the writing, the other sample and hold circuit is In the liquid crystal display device in which the reading is performed, the number of times the sample hold circuits of the two systems are switched is always an even number or an odd number in each field period or each frame period.

A second aspect of the present invention (corresponding to claim 2) is a sample for reading information to be written in a liquid crystal element in one horizontal period and writing the read information in the liquid crystal element in the next one horizontal period. In a source driver having two hold circuits, when one of the sample and hold circuits is performing the reading, the other of the sample and hold circuits is performing the writing, and one of the sample and hold circuits is performing the writing. The other sample-hold circuit is performing the reading, and the number of times of switching between the sample-hold circuits of the two systems is always even or odd in each field period or each frame period in the source driver. is there.

A third aspect of the present invention (corresponding to claim 3) is a sample for reading information to be written in a liquid crystal element in one horizontal period and writing the read information in the liquid crystal element in the next one horizontal period. A method for driving a source driver having two hold circuits, comprising the step of performing the reading by one of the sample and hold circuits and the writing by the other sample and hold circuit; A step of performing the reading by the other sample-hold circuit while writing, and a step of making the number of times of switching between the sample-hold circuits of the two systems always even or odd in each field period or each frame period. It is the driving method of the source driver.

According to a fourth aspect of the present invention (corresponding to claim 4), in the source driver driving method according to the third aspect of the present invention, one of the sample and hold circuits performs the reading operation while the other of the sample and hold circuits performs the reading operation. The step of performing the writing, the step of performing the writing by the other sample and hold circuit while performing the writing by one of the sample and hold circuits, and the number of times of switching between the two systems of sample and hold circuits are set for each field period. Alternatively, it is a program for causing a computer to execute all or some of the steps which are always even or odd in each frame period.

According to a fifth aspect of the present invention (corresponding to claim 5), in the method of driving a source driver according to the third aspect of the present invention, one of the sample and hold circuits performs the reading operation while the other of the sample and hold circuits performs the reading operation. The step of performing the writing, the step of performing the writing by the other sample and hold circuit while performing the writing by one of the sample and hold circuits, and the number of times of switching between the two systems of sample and hold circuits are set for each field period. Alternatively, the medium is a medium that carries a program for causing a computer to execute all or part of the steps that are always even or odd in each frame period, and is a medium that can be processed by the computer.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) First, the configuration of the liquid crystal display device according to the present embodiment will be described with reference to FIG. 1 which is a configuration diagram of the liquid crystal display device according to the first embodiment of the present invention.

The liquid crystal display device according to the present embodiment is characterized in that it is even-odd (for example, by inserting an OEH signal in the blanking period in order to adjust the sample hold circuit for writing at the beginning of each field). The point is that the even numbers of the OEH signals in several fields are made uniform, which will be described later in detail.

In FIG. 1, 1 is a counter electrode glass substrate,
Reference numeral 2 is a pixel electrode glass substrate, 3 is a gate driver IC chip forming a gate driver, 4 is a source driver IC chip forming a source driver, 5 is a power supply and various control signal wirings, 6 is a gate driver IC chip and a source driver IC Output wiring of the chip, 7 is a flexible wiring board, and 8 is a drive circuit that outputs an OEH signal in which the numbers are even in an even-numbered field (the drive circuit 8 is different from the conventional drive circuit 8 ').

The pixel electrode glass substrate 2 is used as the substrate on the TFT array side, and the counter electrode glass substrate 1 is arranged so as to face the glass substrate, and liquid crystal is sealed between these glass substrates to provide a display. A region is formed. A non-display area is formed between the outer circumference of the display area and the outer circumference of the pixel electrode glass substrate 2, and the gate driver I is formed on the non-display area.
The C chip 3 and the source driver IC chip 4 are mounted.

The gate driver IC chip 3,
The source driver IC chip 4 is also connected to the electrodes in the display area via the output wiring 6 of the gate driver IC chip 3 and the source driver IC chip 4.

The input side of the gate driver IC chip 3 is flexible through a power supply and various control signal wirings 5, and the input side of the source driver IC chip 4 is flexible through a power supply and various control signal wirings 5. The wiring board 7 is connected by an ACF (anisotropic conductive film) composed of conductive particles and an adhesive. Then, a signal for driving the gate driver IC chip 3 and the source driver IC chip 4 and a power supply voltage are supplied from the outside, and the liquid crystal display cell to which the output of the gate driver IC chip 3 and the source driver IC chip 4 is connected, Characters or images are displayed.

Next, the OEH in the odd and even field
The operation of the liquid crystal display device of the present embodiment will be described with reference to FIG. 2A, which is an explanatory diagram of a liquid crystal output waveform when the number of signals is even. While the operation of the liquid crystal display device of the present embodiment is described, an embodiment of the source driver driving method of the present invention will also be described.

When the number of OEH signals in the even-numbered even field is even, the sample hold circuit system for the video signal output from the source driver IC chip is, as described above, the first line from the A system in the even field. If it starts, it ends in the B system, so in the odd field, the first line starts in the A system and ends in the B system. Therefore, the first line of the next even field also starts with the A system and ends with the B system. Then, the first line of the next odd field is also A
It starts with the system and ends with the system B.

In this way, all the 1st lines become the A system, and the polarity switching of the liquid crystal output corresponding to the switching of VCOM is added by + and- (note that the polarity inversion drive is V
COM wave number is odd in each field), switching of the sample hold circuit is A-,
A +, A-, A +, A- are shown in FIG.
As shown in (a), the cycle is repeated at 2V. Therefore, the brightness difference according to the offset changes and appears at 30 Hz, and it is possible to make the vertical line flicker on the screen inconspicuous even when the halftone pattern is displayed.

Of course, as shown in FIG. 2B, when the number of OEH signals in the odd-even field is made to be an odd number, the sample-hold circuits are switched between A-, B +,
It is expressed as A-, B +, A-, and is repeated in a 2V cycle. Therefore, the brightness difference according to the offset is
Since it changes and appears at 30 Hz, it is possible to make the vertical line flicker on the screen inconspicuous even when the halftone pattern is displayed.

As shown in FIG. 2 (c), in the case of the conventional driving method, since the number of OEH signals in the even-numbered field is not uniform, the sample hold circuit is switched between A-, A +, B-, It is expressed as B + and A-, and is repeated in a 4V cycle. Therefore, the brightness difference according to the offset changes and appears at 15 Hz, and is apt to be noticeable as vertical line flickering on the screen when the halftone pattern is displayed.

Of course, the structure shown in this embodiment is an example, and it goes without saying that the type of the display area may be another type of panel such as an active matrix type or a simple matrix type.

In the above, the first embodiment has been described in detail.

The number of times of switching between the two systems of sample and hold circuits of the present invention is always an even number or an odd number in each field period in the above-described embodiment. However, the present invention is not limited to this, and the number of times of switching between the sample and hold circuits of the two systems of the present invention may be always an even number or an odd number in each frame period.

Further, the switching between the two systems of sample and hold circuits according to the present invention is performed in the above-described embodiment by determining whether the number of output enable signals for switching between the two systems of sample and hold circuits is even or odd. The same was done during the field period. However, the present invention is not limited to this, and the switching between the sample and hold circuits of the two systems of the present invention may be performed so that it is always even or odd in each field period or each frame period.

In short, the liquid crystal display device of the present invention has two systems of sample hold circuits for reading the information to be written in the liquid crystal element in one horizontal period and writing the information read in the liquid crystal element in the next one horizontal period. It has a source driver, and when one sample and hold circuit is reading, the other sample and hold circuit is writing, and when one sample and hold circuit is writing, the other sample and hold circuit is reading. In the liquid crystal display device, the number of times of switching between the sample hold circuits of the two systems is always even or odd in each field period or each frame period.

A source driver having two systems of sample hold circuits for reading the information to be written in the liquid crystal element in one horizontal period and writing the information read in the next horizontal period in the liquid crystal element. When the sample and hold circuit is reading, the other sample and hold circuit is writing, and when one of the sample and hold circuits is writing, the other sample and hold circuit is reading. Needless to say, the present invention includes a source driver in which the number of times of switching between the sample hold circuits is always even or odd in each field period or each frame period.

The invention is a program for causing a computer to execute the functions of all or part of the above-described liquid crystal display device of the present invention and the source driver (or devices, elements, circuits, sections, etc.). It is a program that works in cooperation with a computer. Of course, the computer of the present invention is not limited to pure hardware such as a CPU, but may include firmware, OS, and peripheral devices.

Further, the present invention is a program for causing a computer to execute all or part of the steps (or steps, operations, actions, etc.) of the above-described source driver driving method of the present invention, It is a program that operates in cooperation with a computer.

It should be noted that some means (or devices, elements, circuits, sections, etc.) of the present invention and some steps (or steps, operations, actions, etc.) of the present invention are performed by a plurality of these means or It is meant to refer to some means or steps in a step, or to some functions or some operations in one means or step.

Also, some devices (or elements, circuits, parts, etc.) of the present invention mean some devices of the plurality of devices, or some means of one device. (Or, an element, a circuit, a part, etc.) or a part of the functions of one means.

A computer-readable recording medium in which the program of the present invention is recorded is also included in the present invention. Further, one usage form of the program of the present invention may be a mode in which the program is recorded in a computer-readable recording medium and operates in cooperation with the computer. Further, one usage form of the program of the present invention may be a mode in which the program is transmitted through a transmission medium, read by a computer, and operates in cooperation with the computer. The recording medium includes a ROM and the like, and the transmission medium includes a transmission medium such as the Internet and light, radio waves, sound waves and the like.

The configuration of the present invention may be realized by software or hardware.

The invention is also a medium carrying a program for causing a computer to execute all or part of the functions of all or part of the above-mentioned liquid crystal display device and source driver of the present invention. Is a medium that is readable by and that executes the functions in cooperation with the computer.

Further, the present invention is a medium carrying a program for causing a computer to execute all or some of the steps of all or some of the steps of the above-described source driver driving method of the present invention. The readable and readable program is a medium for performing the operation in cooperation with the computer.

As described above, according to the present invention, for example, the display area portion, the liquid crystal driving gate driver IC chip for vertically scanning the display area portion, and the first horizontal (1H) period of horizontal scanning. In the horizontal direction of the panel, sampled and held circuits for sampling the image information corresponding to each pixel in the next 1H period and outputting (holding) the sampled image information are provided for each output terminal in two systems. Then, the liquid crystal driving source driver IC chip that outputs the video information to the display area portion every 1H period, each of the gate driver IC chips, and the source driver I.
A power source for the C chip, various control signal wirings, a non-display area in which the output wirings of the gate driver IC chip and the source driver IC chip are arranged, and the gate driver I
In a liquid crystal display device having a flexible wiring board on which bus wirings for supplying various control signals and power supply voltage to the C chip and the source driver IC chip are arranged, there are two systems of sample and hold circuits built in the source driver IC chip. The liquid crystal display device is characterized in that the number of output enable signals (OEH) of 1H cycle for performing the switching is set so as not to be different between odd and even fields.

Further, according to the present invention, for example, the number of output enable signals (OEH) of 1H cycle for switching the sample hold circuits of two systems built in the source driver IC chip does not differ in odd even fields. Thus, the above-mentioned drive circuit for a liquid crystal display device is provided.

In short, in the liquid crystal display device of the present invention, the display area portion, the liquid crystal driving gate driver IC chip for vertically scanning the display area portion, and the first horizontal (1H) period for horizontal scanning. In the horizontal direction of the panel, sampled and held circuits for sampling the image information corresponding to each pixel in the next 1H period and outputting (holding) the sampled image information are provided for each output terminal in two systems. The liquid crystal driving source driver IC chip that outputs the video information to the display area every 1H period, the gate driver IC chips, the power source of the source driver IC chip, various control signal wirings, and the gate. The non-display area portion in which the output wirings of the driver IC chip and the source driver IC chip are arranged, the gate driver IC chip and the source driver IC chip In a liquid crystal display device equipped with a flexible wiring board on which bus wirings for supplying various control signals and power supply voltage to the driver IC chip are arranged, switching between two systems of sample hold circuits built in the source driver IC chip is performed. It is characterized in that the number of output enable signals (OEH) of 1H cycle to be performed is made uniform so as not to be different in an odd even field. From the above,
It is possible to realize a liquid crystal display device capable of making the 15 Hz vertical line flicker appearing on the screen inconspicuous when the halftone pattern is displayed due to the characteristic difference between the sample hold circuits of the two systems of the source driver IC chip.

[0061]

As is apparent from the above description,
INDUSTRIAL APPLICABILITY The present invention has an advantage that vertical line flickering appearing on a liquid crystal screen can be made inconspicuous.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a liquid crystal display device according to a first embodiment of the present invention.

2A is an explanatory diagram of a liquid crystal output waveform when the number of OEH signals in an odd-even field according to the present invention is even, and FIG. 2B is an odd number of OEH signals in an odd-even field according to the present invention. Explanatory diagram of the liquid crystal output waveform when aligned (c); Explanatory diagram of the conventional liquid crystal output waveform when the number of OEH signals in the even-numbered field is not aligned

FIG. 3 is a block diagram of a conventional liquid crystal display device.

FIG. 4A is an explanatory diagram of a waveform of a conventional start pulse (vertical synchronization signal) STV, and FIG. 4B is a conventional voltage VC applied to a counter electrode of liquid crystal.
Explanatory diagram of the actual output waveform with respect to the expected output value affected by the OM waveform and offset (c); Explanatory diagram of the actual waveform of the actual liquid crystal output in each field (d); , Explanatory drawing of the waveform of the actual liquid crystal output of the first line in each field

5A is an explanatory diagram of a waveform of a start pulse (vertical synchronization signal) STV input to the gate driver IC chip, and FIG. 5B is an explanatory diagram of a waveform of a voltage VCOM applied to a counter electrode of liquid crystal (c). ); Explanatory diagram of waveform of clock pulse (horizontal synchronizing signal) CPV input to gate driver IC chip (d); Explanatory diagram of waveform of output enable signal OEH (e); Video signal (R, G, B video signal) ) Illustration of RGB waveforms

[Explanation of symbols]

1 Counter Electrode Glass Substrate 2 Pixel Electrode Glass Substrate 3 Gate Driver IC Chip 4 Source Driver IC Chip 5 Power Supply and Various Control Signal Wiring 6 Gate Driver IC Chip and Source Driver IC
Chip output wiring 7 Flexible wiring board 8 Drive circuit that outputs OEH signals with even numbers in even-numbered fields

Claims (5)

[Claims] 1. A source driver having two systems of a sample hold circuit for reading information to be written in a liquid crystal element in one horizontal period and writing the read information in the liquid crystal element in the next one horizontal period, When the sample and hold circuit of 1 is performing the reading, the other sample and hold circuit is performing the writing, and when the one of the sample and hold circuits is performing the writing, the other sample and hold circuit is In the liquid crystal display device, the reading is performed, and the number of times the sample hold circuits of the two systems are switched is always even or odd in each field period or each frame period. 2. A source driver having two systems of a sample hold circuit for reading information to be written in a liquid crystal element in one horizontal period and writing the read information in the liquid crystal element in the next one horizontal period, When one of the sample-hold circuits is performing the reading, the other sample-hold circuit is performing the writing, and when one of the sample-hold circuits is performing the writing, the other sample-hold circuit. Is performing the reading, and the number of times of switching between the sample and hold circuits of the two systems is always an even number or an odd number in each field period or each frame period. 3. A driving method of a source driver having two systems of a sample hold circuit for reading information to be written in a liquid crystal element in one horizontal period and writing the read information in the liquid crystal element in the next one horizontal period. There is a step of performing the writing by the other sample and hold circuit while performing the reading by one of the sample and hold circuits; and a step of performing the writing by the one of the sample and hold circuits and the other sample and hold circuit by the other sample and hold circuit. A method of driving a source driver, comprising: a step of performing the reading; and a step of making the number of times of switching between the sample hold circuits of the two systems always even or odd in each field period or each frame period. 4. The method of driving a source driver according to claim 3, wherein one of the sample and hold circuits performs the reading while the other of the sample and hold circuits performs the writing, and one of the sample and hold circuits. And performing the reading by the other sample and hold circuit while performing the writing, and a step of always setting the number of times of switching between the sample and hold circuits of the two systems to be an even number or an odd number in each field period or each frame period. A program that causes a computer to execute all or part of the. 5. The method of driving a source driver according to claim 3, wherein one of the sample and hold circuits performs the reading while the other of the sample and hold circuits performs the writing, and one of the sample and hold circuits. And performing the reading by the other sample and hold circuit while performing the writing, and a step of always setting the number of times of switching between the sample and hold circuits of the two systems to be an even number or an odd number in each field period or each frame period. Is a medium that carries a program for causing a computer to execute all or part of the above, and is a computer-processable medium.