JP2002341840A - Liquid crystal display device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve the problem that the luminance difference between black display in an effective display area and that in an ineffective display area is conspicuous in the case of input of an image signal which has the number of effective display scanning lines smaller than the number of display capability scanning lines of a liquid crystal panel. SOLUTION: The liquid crystal display device is provided with a scanning line number discrimination circuit 14 which detects the number of scanning signal lines to be used for display of the image data signal and a scanning speed varying circuit 15 which controls the period of a scanning clock signal in order to display the image data signal and prescribed data in the effective display area and the ineffective display area respectively, and the period of the scanning clock signal in the ineffective display area is so controller that the period on the effective display area side may be longer than that on the opposite side.

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 and a program used when it is necessary to change the aspect ratio of a screen depending on an image signal to be displayed on a display such as a television or a personal computer.

[0002]

2. Description of the Related Art First, referring mainly to FIG. 6 which is a block diagram of a conventional liquid crystal display device, the structure of a conventional liquid crystal display device used for a display which needs to change the aspect ratio of a screen according to a signal to be displayed. Will be described.

In a conventional liquid crystal display device, when an image signal of m effective display scanning lines is input, the number of scanning lines n (>) is increased.
m) A signal line drive circuit 62 for driving a signal line of a normally black type active matrix liquid crystal panel 61 having a display capability and a scan line drive circuit 63 for driving a scan line of the liquid crystal panel 61 are connected to each other. The scanning line number identification circuit 64 for identifying the effective display scanning line number of the image signal to be displayed and the high-speed scanning of the liquid crystal panel 61 are activated, and at the same time, the output scanning voltage is set to the TFT during the blanking period of the image signal.
And a high-speed scanning control circuit 65 for controlling the ineffective display area to be displayed in black by fixing to an off level that does not turn on.

Next, the operation of such a conventional liquid crystal display device will be described with reference to FIG. 7 which is a signal waveform diagram for explaining the operation of the conventional liquid crystal display device.

In FIG. 7, reference numeral 71 denotes an image signal input to a signal line driving circuit 62 (see FIG. 6) comprising an image valid period 72 and a blanking period 73; This is a scan clock pulse signal input to the scan line drive circuit 63 (see FIG. 6) including the high-speed scan pulse portion 76.

When an image signal having m (<n) display data is input, the liquid crystal panel 11 (see FIG. 6)
The invalid display area of (nm) scanning lines other than the effective display area of m scanning lines above must be displayed in black or the like.

However, the image signal blanking period 7
3 (see FIG. 7) is shorter than the period required to scan the number of scanning lines (nm), so that when one black display is sequentially performed at the standard scanning speed, scanning for one frame is completed. Before that, the image signal of the next frame is input, and normal display cannot be performed.

Therefore, when the scanning line number identification circuit 64 (see FIG. 6) identifies the input of an image signal having display data of m scanning lines, the blanking period 73 of the image signal.
In (see FIG. 7), the cycle of the scanning clock signal 74 (see FIG. 7) is switched at high speed by the high-speed scanning control circuit 65 (see FIG. 6), and scanning is completed before the image signal of the next frame is input. On the other hand, in the high-speed scanning pulse portion 76 (see FIG. 7), the scanning voltage is
Is fixed to an off level at which the TFT does not turn on, and the vertical scanning is performed at a higher speed than the normal scanning while keeping the TFT in the off state.
For one, m scanning lines of images are displayed.

As described above, in the conventional liquid crystal display device, when an image signal of the number m of effective display scanning lines, which is smaller than the display capability of the liquid crystal panel n, is inputted, the image signal of the next frame is inputted. In order to complete the scan before the input, the cycle of the scan clock signal 74 is switched.

[0010]

However, in the above-mentioned conventional liquid crystal display device, a luminance difference occurs between black displayed in the effective display area and that displayed in the invalid display area.

The present invention has been made in consideration of such a conventional problem as described above, and for example, when an image signal having an effective display scanning line number smaller than the display capability scanning line number of the liquid crystal panel is input, an effective display area is provided. It is an object of the present invention to provide a liquid crystal display device and a program which can make the luminance difference between the black display of the invalid display area and the black display of the invalid display area less noticeable.

[0012]

Means for Solving the Problems The first invention (claim 1)
Means for detecting the number of scanning signal lines to be used for displaying an image data signal input from the outside on the liquid crystal panel; and the detected number is the total number of the scanning signal lines. If the number is less than (1) displaying the image data signal in an effective display area provided on the liquid crystal panel having a scanning signal line to be used for displaying the image data signal; In order to display predetermined data in an invalid display area provided in the liquid crystal panel having a scanning signal line that is not used for displaying a signal, a period of a scanning clock signal used when sequentially scanning the scanning signal line is set. Control means for controlling, the period of the scanning clock signal of the scanning signal line for scanning the invalid display area, the scanning clock signal of the scanning signal line of the effective display area side Write phases is said effective display region to be greater than the period of the scan clock signal on the opposite side of the scanning signal lines, the control means is a liquid crystal display device which performs continuously the control.

According to a second aspect of the present invention (corresponding to claim 2), a detecting means for detecting the number of scanning signal lines to be used for displaying an image data signal input from the outside on a liquid crystal panel; When the detected number is smaller than the total number of the scanning signal lines, (1) an effective display area provided in the center of the liquid crystal panel having a scanning signal line to be used for displaying the image data signal; Displaying the image data signal, and (2) displaying predetermined data in two invalid display areas provided above and below the liquid crystal panel having scanning signal lines not used for displaying the image data signal, Control means for controlling a period of a scan clock signal used when sequentially scanning the scan signal lines, wherein the scan means performs at least one scan of the two invalid display areas. The cycle of the scan clock signal of the signal line is such that the cycle of the scan clock signal of the scan signal line above and below the invalid display area is larger than the cycle of the scan clock signal of the central scan signal line of the invalid display area. The control means is a liquid crystal display device that performs the control continuously.

According to a third aspect of the present invention (corresponding to claim 3), the scanning of a scanning signal line for displaying predetermined data in the two invalid display areas is performed by using an image data signal input from the outside. The liquid crystal display device of the second aspect of the present invention, which is performed simultaneously during the blanking period.

According to a fourth aspect of the present invention (corresponding to claim 4), the period of the scanning clock signal of the scanning signal line for scanning the effective display area is the same as that for scanning the invalid display area. The liquid crystal display device according to the first or second aspect of the present invention, which is longer than the period of the scanning clock signal of the scanning signal line.

A fifth invention (corresponding to claim 5) provides a liquid crystal display device according to the first invention, wherein a scanning signal line to be used for displaying an image data signal inputted from the outside on a liquid crystal panel is provided. Detecting means for detecting the number, if the detected number is less than the total number of the scanning signal lines,
(1) scanning the image data signal in an effective display area provided on the liquid crystal panel having a scanning signal line to be used for displaying the image data signal; and (2) scanning not using the image data signal for display. Control means for controlling a period of a scan clock signal used when sequentially scanning the scan signal lines in order to display predetermined data in an invalid display area provided in the liquid crystal panel having signal lines; and Is a program for causing a computer to function as all or part of the above.

A sixth aspect of the present invention (corresponding to claim 6) is a liquid crystal display according to the second aspect of the present invention, wherein a scanning signal line to be used for displaying an externally input image data signal on a liquid crystal panel is provided. Detecting means for detecting the number, if the detected number is less than the total number of the scanning signal lines,
(1) displaying the image data signal in an effective display area provided at the center of the liquid crystal panel having a scanning signal line to be used for displaying the image data signal; and (2) using the image data signal for display. In order to display predetermined data in two invalid display areas provided on the upper and lower sides of the liquid crystal panel having no scanning signal lines, the period of the scanning clock signal used when sequentially scanning the scanning signal lines is changed. This is a program for causing a computer to function as all or a part of control means for controlling.

[0018]

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 of the present embodiment will be described with reference to FIGS. FIG. 1 shows the first embodiment.
3 is a block diagram of the liquid crystal display device in FIG. FIG.
FIG. 5 is a signal waveform diagram for describing an operation of the liquid crystal display device according to the first embodiment. FIG. 3 is an explanatory diagram of a display area of the liquid crystal panel 11 according to the first embodiment. FIG. 8 is a detailed explanatory diagram of the liquid crystal panel 11 according to the first embodiment.

In FIG. 1, reference numeral 11 denotes a normally black type liquid crystal panel having a display capability of n scanning lines and displaying black when no voltage is applied to the liquid crystal element 85 (see FIG. 8). Are signal lines 82 of the liquid crystal panel 11 (FIG. 8).
Signal line driving circuit for driving the liquid crystal panel 1
A scanning line driving circuit that drives one scanning line 83 (see FIG. 8), and a scanning line number identification circuit 14 that identifies the number of effective display scanning lines of an input image signal. Further, when the scanning line number identification circuit 14 identifies m scanning lines number less than the display capability of the liquid crystal panel, a scanning voltage 27 (see FIG. 2) is applied to an invalid area between (nm) lines. Is fixed to an off level at which the TFT 84 (see FIG. 8) provided in each liquid crystal element 85 of the liquid crystal panel 11 is not turned on (that is, a level for performing black display without applying a signal from the signal line driving circuit 12). At the same time, the scanning speed is changed in several steps (continuously) to control the scanning line driving circuit 13.

In FIG. 2, reference numeral 21 denotes an image valid period 22 and a blanking period 23.
The waveform of an input image signal (that is, an image signal having display data of m scanning lines) input to (refer to FIG. 1), 24 is a scanning line drive composed of a normal scanning pulse portion 25 and a scanning pulse variable portion 26 A waveform of a scanning clock for causing the circuit 13 (see FIG. 1) to perform scanning, and 27 is a waveform of a scanning voltage.

In FIG. 3, reference numeral 31 denotes an effective display area for displaying image data inputted on the liquid crystal panel 11,
32 is an invalid display area.

In FIG. 8, one end of a liquid crystal element 85 is connected to a signal line 82 via a TFT 84, and one end is connected to a scanning line 83.

Next, the display capability of the liquid crystal panel 11 The liquid crystal display according to the present embodiment in the case where the image signal 21 (see FIG. 2) having m effective display scanning lines less than the scanning line number n is input. The operation of the device will be described. In addition,
An example of the liquid crystal display method of the present invention will be described while describing the operation of the liquid crystal display device of the present embodiment.

The scanning line number discriminating circuit 14 discriminates that the number of effective display scanning lines is m (<n) by looking at the input image signal 21 and determines the result of the discrimination as the scanning speed variable circuit 1.
5 is output.

The scanning speed variable circuit 15 operates by receiving an output from the scanning line number discriminating circuit 14 and operates in the blanking period 23 (see FIG. 2) of the image signal 21 (see FIG. 2).
The scanning speed of the invalid display area 32 (see FIG. 3) by the scanning line drive circuit 13 is varied in several steps so that scanning is completed before the image signal of the next frame is input. . Note that the scanning speed variable circuit 15 fixes the scanning voltage 27 (see FIG. 2) to the off level in the invalid display area 32 between (nm) lines during this period, and supplies the signal line driving circuit to the liquid crystal panel 11. Control is performed such that black display is performed without applying a signal from the control unit 12.

That is, in this embodiment, when the scanning speed is switched from (1) the image effective period 22 (see FIG. 2) to the blanking period 23, the scanning speed is increased several times (continuously) from the normal scanning pulse. The scanning pulse is switched to (2) the blanking period 23 to the image valid period 22
When switching to the normal scanning pulse, control is performed such that the scanning is switched from the high-speed scanning pulse to the normal scanning pulse in several steps (continuously).

Thus, in the blanking period 23, scanning of (nm) invalid display areas 32 is completed (by so-called simultaneous writing of upper and lower invalid display areas).
Since the TFT 84 (see FIG. 8) is in the off state, the signal line 82 (see FIG. 8)
No new voltage is applied to the terminal on the scanning line 83 side, and the above-described off-level is applied to the terminal on the scanning line 83 side (the invalid display area 32 is not Black display is performed by such control.)

At this time, the difference in luminance between the black display in the effective display area and the black display in the invalid display area can be made less noticeable than in the above-described conventional case. The reason will be described below.

That is, when the time for writing the signal voltage to the liquid crystal element 85 is shortened, the characteristics of the liquid crystal element 85 as shown in FIG. Due to the characteristics, it is difficult for the signal voltage to be applied to both ends of the liquid crystal element 85 to reach a required level. Then, because of the characteristics of the liquid crystal element 85 as shown in FIG.
Does not decrease sufficiently, and a luminance difference occurs between black display in the effective display area 31 (see FIG. 3) and that in the invalid display area 32 (see FIG. 3) (normally black type). In a liquid crystal display device, signal writing is not performed from a signal line in order to perform black display,
Such a difference in luminance can also occur due to the effect of charges remaining in a capacitor (not shown) connected in parallel to the liquid crystal element.)

However, in the present embodiment, the time for writing the signal voltage to the liquid crystal element 85 is gradually changed by changing the scanning speed in the blanking period 23 (see FIG. 3) in several steps. Therefore, it is possible to make the luminance change between the effective display area and the invalid display area less noticeable to the human eye.

Of course, such an effect is achieved by using a normally white type liquid crystal panel in which each TFT must be turned on to perform black writing from a signal line to a liquid crystal element in order to perform black display in an invalid display area. It makes sense in some cases.

In the liquid crystal display device of the present invention, in the above-described embodiment, the scanning clock of the scanning signal line for scanning at least one (actually, both) of the two invalid display areas. The signal period is continuously controlled such that the period of the scanning clock signal of the scanning signal line above and below the invalid display area is larger than the period of the scanning clock signal of the scanning signal line at the center of the invalid display area. It was a liquid crystal display device. Such control is to complete the display in the invalid display area without greatly changing the cycle of the scan clock signal for scanning the invalid display area from the cycle of the scan clock signal for scanning the valid display area. The scanning of the scanning signal lines performed to display predetermined data in the two invalid display areas is particularly effective when the scanning is performed simultaneously during a blanking period of an externally input image data signal.

However, the liquid crystal display device of the present invention is not limited to this, and the period of the scan clock signal of the scan signal line for scanning the invalid display area is not limited to the scan clock signal of the scan signal line on the effective display area side. The liquid crystal display device may be continuously controlled so that the period of the scanning clock signal of the scanning signal line on the side opposite to the effective display area is longer than the period of the scanning clock signal. Such control is also effective, for example, when the invalid display area is provided only on one of the upper and lower sides (after all, the luminance change near the boundary between the valid display area and the invalid display area is made inconspicuous). Just be able to do that).

Further, the detecting means of the present invention is the scanning line number discriminating circuit 14 in the present embodiment described above, but is not limited to this. In short, the liquid crystal panel of the image data signal inputted from the outside is used. Any means may be used for detecting the number of scanning signal lines to be used for display on the display.

The control means of the present invention is the scanning speed variable circuit 15 in the above-described embodiment, but is not limited to this. In short, the number of detected lines is larger than the total number of scanning signal lines. (1) displaying the image data signal in an effective display area provided on a liquid crystal panel having a scanning signal line to be used for displaying the image data signal;
(2) A scan clock signal used when sequentially scanning the scan signal lines to display predetermined data in an invalid display area provided on a liquid crystal panel having a scan signal line not used for displaying an image data signal. Any means may be used as long as it is a means for controlling the period.

The predetermined data of the present invention is data for performing black display in the above-described embodiment, but is not limited thereto, and may be, for example, character data in a data broadcasting service. You may.

The present invention provides all or a part of the above-described liquid crystal display device of the present invention (or device, element,
This is a program for causing a computer to execute the functions of circuits, units, and the like, and is a program that operates in cooperation with the computer. Of course, the computer of the present invention is not limited to pure hardware such as a CPU,
It may include firmware, an OS, and peripheral devices.

The present invention also provides a program for causing a computer to execute all or some of the steps (or steps, operations, actions, and the like) of the above-described liquid crystal display method of the present invention. It is a program that works in cooperation.

Note that some of the means (or devices, elements, circuits, units, etc.) of the present invention, and some of the steps (or steps, operations, functions, etc.) of the present invention, It may mean some means or steps within a step, or some functions or some operations within one means or step.

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

The present invention also includes a computer-readable recording medium on which the program of the present invention is recorded. Further, one usage form of the program of the present invention may be a form in which the program is recorded on a computer-readable recording medium and operates in cooperation with the computer. One usage 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, light, radio waves, and sound waves.

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

As described above, the present invention has a display capability of, for example, n scanning lines, and each pixel is provided with a switching element, and when no voltage is applied to this switching element, the display state is black. A normally black type active matrix liquid crystal panel, a signal line driving circuit for applying an image signal to a pixel via the switching element to the liquid crystal panel, and an on / off state of the switching element of the liquid crystal panel And a scanning line driving circuit for performing vertical scanning by identifying whether the number of scanning lines of the input image signal is equal to the number of scanning lines n or the number of scanning lines less than n. When the number-of-scanning-lines identification circuit and the number-of-scanning-lines identification circuit identify the input of an image signal having m scanning lines, (nm) in a blanking period of the image signal The scanning line driving circuit is controlled so as to change the scanning speed in the invalid display period between steps in a stepwise or continuous manner, and at the same time, in the invalid display period between (nm) lines, the scanning line driving circuit A liquid crystal display device comprising: a scanning speed variable circuit that controls an output scanning voltage to be fixed to an off level at which the switching element is not turned on, wherein a display capability of the liquid crystal panel is greater than the number of scanning lines. When image signals of a small number m of effective display scanning lines are input, the scanning speed is changed stepwise or continuously to perform black display, and the black display of the effective display area and the black display of the invalid display area are performed. It has the effect of making the luminance difference inconspicuous.

Further, according to the present invention, for example, the effective display area for displaying m effective image signals is the center of the vertical position of the liquid crystal panel, and the (nm) invalid display areas are It is characterized in that the scanning of that part is performed simultaneously in the upper and lower areas, and the scanning of the invalid area is completed in a shorter time by simultaneously scanning and driving the invalid display areas located above and below the screen It has the effect that it can be done.

Thus, instead of the high-speed scanning control circuit provided in the conventional liquid crystal display device, the scanning speed is changed stepwise or continuously during the blanking period to control the scanning line driving circuit, and at the same time, the output scanning voltage is controlled. Is provided with a scanning speed variable circuit that controls so as to fix the switching element to an off level that does not turn on the switching element, so that an image signal of m effective display scanning lines less than the display capability scanning line number n of the liquid crystal panel is obtained. When input, the difference in brightness between the black display in the effective display area and the black display in the invalid display area can be made inconspicuous.

More specifically, the display capability of the liquid crystal panel The number m of effective display scanning lines less than the number n of scanning lines
When a book image signal is input, the scanning line driving circuit is controlled by changing the scanning speed in the invalid display area stepwise or continuously during the blanking period of the image signal, and at the same time, the scanning is performed in the invalid display area. The voltage is fixed at an off level that does not turn on the TFT, and a variable scanning speed circuit is provided to control the liquid crystal panel to display black without applying a signal from the signal line drive circuit, thereby enabling black display and invalid display in the effective display area. An advantageous effect is obtained in that the difference in luminance from the black display in the display area is inconspicuous, and a liquid crystal display device capable of displaying image signals having various aspect ratios with higher quality can be realized.

[0048]

As is apparent from the above description,
The present invention is directed to, for example, a luminance difference between a black display in an effective display area and a black display in an invalid display area when an image signal having an effective display scanning line number smaller than the display capability of the liquid crystal panel is input. Has the advantage of being less noticeable.

[Brief description of the drawings]

FIG. 1 is a block diagram of a liquid crystal display device according to Embodiment 1 of the present invention.

FIG. 2 is a signal waveform diagram for describing an operation of the liquid crystal display device in Embodiment 1 of the present invention.

FIG. 3 is a liquid crystal panel 11 according to Embodiment 1 of the present invention.
Illustration of the display area of

FIG. 4 is a diagram illustrating characteristics of a voltage written to a liquid crystal element 85 with respect to a time change according to Embodiment 1 of the present invention;

FIG. 5 is a diagram illustrating transmittance characteristics of the liquid crystal element 85 with respect to an applied voltage according to the first embodiment of the present invention.

FIG. 6 is a block diagram of a conventional liquid crystal display device.

FIG. 7 is a signal waveform diagram for explaining the operation of a conventional liquid crystal display device.

FIG. 8 is a detailed explanatory diagram of the liquid crystal panel 11 of the liquid crystal display device according to the first embodiment of the present invention.

[Explanation of symbols]

 11, 61 Liquid crystal panel 12, 62 Signal line drive circuit 13, 63 Scan line drive circuit 14, 64 Scan line number discrimination circuit 15 Scanning speed variable circuit 21, 71 Image signal 22, 72 Image valid period 23, 73 Blanking period 24 , 74 scan clock pulse 25, 75 normal scan pulse part 26 scan pulse variable part 31 effective display area 32 invalid display area 65 high-speed scan control circuit 76 high-speed scan pulse part 82 signal line 83 scan line 84 TFT 85 liquid crystal element

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/20 650 G09G 3/20 650B 650E F-term (Reference) 2H093 NA43 NC09 NC11 NC28 NC34 NC50 ND07 5C006 AC22 AF36 AF46 AF72 AF73 BB16 BC03 FA04 FA08 FA22 5C080 AA10 BB05 DD05 FF11 JJ02 JJ04 JJ05

Claims (6)

[Claims] 1. A detecting means for detecting the number of scanning signal lines to be used for displaying an image data signal input from the outside on a liquid crystal panel, wherein the detected number is the total number of the scanning signal lines. If the number is less than (1) displaying the image data signal in an effective display area provided on the liquid crystal panel having a scanning signal line to be used for displaying the image data signal; In order to display predetermined data in an invalid display area provided in the liquid crystal panel having a scanning signal line that is not used for displaying a signal, a period of a scanning clock signal used when sequentially scanning the scanning signal line is set. Control means for controlling the scanning clock signal of the scanning signal line for scanning the invalid display area, the scanning clock signal of the scanning signal line on the effective display area side. Who cycle, the effective display area to be greater than the period of the scan clock signal on the opposite side of the scanning signal line and the control means is a liquid crystal display device which performs continuously the control. 2. A detecting means for detecting the number of scanning signal lines to be used for displaying an image data signal inputted from the outside on a liquid crystal panel, and wherein the detected number is the total number of the scanning signal lines. (1) displaying the image data signal in an effective display area provided at the center of the liquid crystal panel having a scanning signal line to be used for displaying the image data signal;
(2) In order to display predetermined data in two invalid display areas provided above and below the liquid crystal panel having scanning signal lines not used for displaying the image data signal,
Control means for controlling a period of a scan clock signal used when sequentially scanning the scan signal lines, wherein the scan signal lines for performing at least one scan of the two invalid display areas The cycle of the scan clock signal of the above, so that the cycle of the scan clock signal of the scan signal lines above and below the invalid display area is larger than the cycle of the scan clock signal of the scan signal line at the center of the invalid display area,
A liquid crystal display device in which the control means performs the control continuously. 3. The scanning of a scanning signal line performed to display predetermined data in the two invalid display areas is performed simultaneously during a blanking period of the image data signal input from the outside. Liquid crystal display device. 4. A cycle of a scan clock signal of the scan signal line for scanning the effective display area is larger than a cycle of a scan clock signal of the scan signal line for scanning the invalid display area. The liquid crystal display device according to claim 1. 5. A detecting means for detecting the number of scanning signal lines to be used for displaying an image data signal inputted from the outside on a liquid crystal panel of the liquid crystal display device according to claim 1, and said detecting means. When the number of the scanning data lines is smaller than the total number of the scanning signal lines, (1) the image data signals are provided in an effective display area provided in the liquid crystal panel having the scanning signal lines to be used for displaying the image data signals. Is displayed,
(2) Used for sequentially scanning the scanning signal lines to display predetermined data in an invalid display area provided on the liquid crystal panel having a scanning signal line not used for displaying the image data signal. A program for causing a computer to function as all or part of control means for controlling the period of a scan clock signal. 6. A detecting means for detecting the number of scanning signal lines to be used for displaying an image data signal inputted from the outside on a liquid crystal panel of the liquid crystal display device according to claim 2, and said detecting means. When the number of the scanning signal lines is smaller than the total number of the scanning signal lines, (1) the image is displayed in an effective display area provided at the center of the liquid crystal panel having the scanning signal lines to be used for displaying the image data signal. Displaying the data signal, and (2) performing the scanning in order to display predetermined data in two invalid display areas provided above and below the liquid crystal panel having scanning signal lines not used for displaying the image data signal. A program for causing a computer to function as all or part of control means for controlling the period of a scan clock signal used when sequentially scanning signal lines.