JP2005345780A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of preventing superposed display and blinking display of a meter indicator displayed on a liquid crystal panel. <P>SOLUTION: In the liquid crystal panel, an image corresponding to a background is displayed, until the transmittance of a liquid crystal, corresponding to an indicator (disappearing indicator) of an image displayed last time, is made to be lower than 10% at which the image is recognized to be erased. After that, the image to be displayed this time is displayed so that transmittance of the liquid crystal, corresponding to an indicator (displayed indicator) of an image to be displayed this time is made to be higher than 10%. When the image is thus displayed, the image displayed last time and the image to be displayed this time are switched and displayed within a prescribed time (32ms), within which the display will at least not recognized as being a blinking display. Thus, superposition display and blinking display of the indicator are prevented and the indicator is smoothly rotated and displayed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device that displays vehicle information of a vehicle on a liquid crystal panel.

  Conventionally, a liquid crystal display device has been used as a device for causing a driver to recognize vehicle information such as vehicle speed and simple navigation. In such a liquid crystal display device, segment type liquid crystal panels are employed, and vehicle information is displayed as numerical values on each segment type liquid crystal panel.

  However, when the vehicle speed or the like is displayed on the segment type liquid crystal panel as described above, for example, two numbers are superimposed and displayed on a portion displaying one number due to a delay in the response of the liquid crystal used in the liquid crystal panel. So-called ghost characters appear.

Thus, a liquid crystal display device that can prevent the above-described superimposed display in a segment type liquid crystal panel has been proposed (see, for example, Patent Document 1). In this liquid crystal display device, when a different number is displayed with a change in a value such as a vehicle speed in a segment type liquid crystal panel that displays one number, a blank image in which nothing is displayed is displayed after the number is displayed. . After this, different numbers are displayed. This prevents two numbers from appearing to overlap in a segment type liquid crystal panel that displays one number.
JP-A-7-248486

  However, in the above-described conventional technology, when a number is displayed on the segment type liquid crystal panel, for example, a blank image where nothing is displayed is displayed, that is, a time when nothing is displayed is provided. Time interval is opened, and the displayed number is recognized as blinking.

  On the other hand, instead of displaying vehicle information such as vehicle speed on the segment type liquid crystal panel, it is conceivable to display an image on a single TFT type liquid crystal panel. Thereby, it is considered that the meter itself can be displayed as an image, and vehicle information such as the vehicle speed can be displayed with the pointer as in the analog meter.

  However, similarly to the above-described conventional segment type liquid crystal panel, for example, when the value of the vehicle speed is changed and the hands are rotated, there is a problem that a plurality of hands are seen due to the superimposed display due to the delay of the liquid crystal response. In addition, in order to prevent the meter pointer from being superimposed, if a blank image is displayed in the same manner as the conventional segment type liquid crystal panel, the pointer blinks when the pointer moves as in the above case. It will be done.

  An object of the present invention is to provide a liquid crystal display device capable of preventing a meter pointer superimposed display and a blinking display to be displayed on a TFT type liquid crystal panel in view of the above points.

  In order to achieve the above object, the inventors examined the cause of superimposed display and blinking display in which a plurality of pointers appear due to a delay in the response of the liquid crystal when the pointers are displayed on the liquid crystal panel.

  FIG. 5 is a diagram showing the transmittance of the liquid crystal of the TFT liquid crystal panel with respect to the timing for displaying the pointer. In FIG. 5, the horizontal axis represents time, and the vertical axis represents the liquid crystal transmittance (%) of the liquid crystal panel. The waveform shown on the upper side of FIG. 5 shows the transmittance of the liquid crystal corresponding to the pointer that is erased as the vehicle speed changes. Further, in FIG. 5, the waveform shown at the bottom indicates the transmittance of the liquid crystal corresponding to the pointer that is newly displayed as the vehicle speed changes. Here, when the transmittance of the liquid crystal falls below 10%, the image displayed on the liquid crystal panel becomes invisible. The display screen of the liquid crystal panel is black, and the meter pointer and dial are white.

  For example, when the pointer is rotated and displayed when the vehicle speed changes, the white voltage is switched to the black voltage for the liquid crystal at the time T0 shown in FIG. 5 in the pointer that disappears when the pointer rotates. . On the other hand, the pointer displayed by turning the pointer is switched from the black voltage to the white voltage at the time T0, as described above.

  However, as described above, the liquid crystal cannot instantaneously follow the switching of the applied voltage due to the delay in the response of the liquid crystal. For this reason, as the voltage is switched, the transmittance of the liquid crystal gradually decreases or increases. Accordingly, the pointer to be erased is not erased unless the transmittance of the liquid crystal falls below 10% after a predetermined time has elapsed. However, as shown in FIG. 5, before the transmittance of the liquid crystal of the pointer to be erased falls below 10%, the transmittance of the liquid crystal of the newly displayed pointer exceeds 10%. For this reason, since the transmittance of the liquid crystal in both the pointer to be deleted and the pointer to be newly displayed exceeds 10%, the time Tsup for displaying the two pointers on the liquid crystal panel is generated.

  The same switching timing of the applied voltage between the pointer to be erased and the pointer to be displayed causes a problem that a plurality of rotating pointers can be seen. In a state where the value of the vehicle speed constantly changes, due to the delay in the response of the liquid crystal as described above, a plurality of hands are displayed as an afterimage on the liquid crystal panel, which gives the driver a feeling of strangeness.

  On the other hand, the blinking display of the pointer occurs because the human eye generally recognizes the switching of the display of 30 Hz (about 33 ms) or less as the blinking display. Therefore, when the pointer is rotated and displayed as the vehicle speed changes, it is necessary to perform an image switching display so as not to recognize that at least human eyes are blinking.

  Therefore, according to the first aspect of the present invention, the detection means (10) for detecting a signal representing vehicle information and the control for generating the image information of the pointer so as to receive the signal and display the pointer according to the signal. Means (20), image generation means (30, 40, 50) for receiving image information and generating an image based on the image information and outputting image data of the image; and a liquid crystal panel for displaying the image, Display means (60) for receiving image data and displaying an image on the liquid crystal panel, wherein the liquid crystal panel recognizes that the transmittance of the liquid crystal corresponding to the pointer of the previously displayed image has been erased. After that, the transmittance of the liquid crystal corresponding to the pointer of the image displayed this time exceeds the predetermined transmittance, and the transmittance of the liquid crystal corresponding to the pointer of the image displayed last time is 100. Is characterized in that as the transmittance of the liquid crystal corresponding to the pointer of the image to be displayed at least this time within a predetermined time is 100%, an image to be displayed this time are to be displayed from below the.

  In this way, by displaying the image displayed this time after the transmittance of the liquid crystal corresponding to the previously displayed image falls below the predetermined transmittance, the previously displayed pointer is not displayed in the image displayed this time. Thereby, since the superimposed display can be prevented, the pointer display that smoothly rotates can be realized. In addition, at least a predetermined time during which a person does not recognize the blinking display until the image displayed this time is displayed after the previously displayed image is erased on the liquid crystal panel is displayed. Flashing display can be prevented.

  In the invention according to claim 2, the control means has means for creating image information of the background image on which the pointer is not drawn, and the image creation means creates the background image based on the image information of the background image. And a means for outputting the image data of the background image. In the liquid crystal panel, the background image is displayed until the transmittance of the liquid crystal corresponding to the pointer of the previously displayed image is at least lower than the predetermined transmittance. After the image to be displayed this time is displayed so that the transmittance of the liquid crystal corresponding to the pointer of the image to be displayed exceeds the predetermined transmittance, and the transmittance of the liquid crystal corresponding to the pointer of the image displayed previously falls below 100% The image to be displayed this time is displayed so that the transmittance of the liquid crystal corresponding to the pointer of the image to be displayed this time is at least 100% within a predetermined time. .

  In this way, the background image is displayed while the previously displayed image and the currently displayed image are displayed. As a result, the pointer is surely erased once and then displayed again, so that the superimposed display of the pointer can be prevented. Further, by performing image switching between the previously displayed image and the currently displayed image within at least a predetermined time that is not recognized as blinking display, it is possible to prevent the image from blinking.

  According to the third aspect of the present invention, τr is a time until the transmittance of the liquid crystal corresponding to the pointer of the previously displayed image becomes 100%, and the transmittance of the liquid crystal corresponding to the image displayed this time is Assuming that the time from 0% to 90% is τd, the predetermined time is not less than τr + τd [ms] and not more than 32 [ms].

  Thus, the predetermined time is set to τr + τd [ms] or more and 32 [ms] or less. The lower limit of the predetermined time corresponds to the lowest value at which the pointer of the previously displayed image and the pointer of the image displayed this time are not displayed simultaneously. On the other hand, the upper limit of the predetermined time corresponds to a limit value at which a human does not recognize image switching as blinking. Therefore, blinking display of an image can be prevented by setting the predetermined time to τr + τd or more and 32 ms or less.

  The invention according to claim 4 is characterized in that the predetermined transmittance is 10%. In this way, the predetermined transmittance of the liquid crystal is set to 10%. Thereby, when the transmittance of the liquid crystal is less than 10%, the image displayed on the liquid crystal panel becomes invisible. Therefore, as described in claims 1 and 2, when the transmittance of the liquid crystal corresponding to the previously displayed image falls below 10%, the image to be displayed next is displayed, so that the image is displayed on the liquid crystal panel. It is possible to prevent the pointer from being superimposed and displayed.

  The invention according to claim 5 is characterized in that the vehicle information is at least one of a vehicle speed and an engine speed.

  Such vehicle information is displayed on the liquid crystal panel. Therefore, when a variable value such as the vehicle speed or the engine speed is displayed as a pointer, the invention according to any one of claims 1 to 4 can prevent the pointer from being superimposed and blinked on the liquid crystal panel. It can be displayed to rotate smoothly.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of a liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 1, the liquid crystal display device includes a detection unit 10, a control unit 20, a display controller unit 30, a ROM 40, a VRAM 50, and a display unit 60.

  The detection part 10 detects vehicle information, such as a vehicle speed and an engine speed, for example. In this embodiment, the detection unit 10 is provided with a known vehicle speed sensor for detecting the vehicle speed, and a pulse signal detected by the vehicle speed sensor is output. The detection unit 10 corresponds to the detection means of the present invention.

  The control unit 20 executes an image display process for displaying a meter image of the vehicle speed detected by the detection unit 10 on the display unit 60 described later, and includes a CPU. This process is executed according to the meter image display program stored in the control unit 20.

  In order to execute the above processing, the control unit 20 has a function of inputting a pulse signal from the detection unit 10 and converting the pulse signal into a vehicle speed. The control unit 20 also has a function of creating image information of an image to be displayed on the display unit 60.

  In order to create the image information, the control unit 20 selects a meter image (background image) representing a scale. In the present embodiment, since the vehicle speed is displayed as a meter, a meter image in which a scale of the vehicle speed is drawn is selected. Further, the control unit 20 calculates coordinates of the start point and end point of the pointer in the background image in order to display a bar-shaped pointer indicating the value of the vehicle speed on the meter image of the vehicle speed.

  In this manner, the control unit 20 uses the background image that displays the vehicle speed, and creates image information such as the position at which the obtained vehicle speed pointer is displayed. At this time, the control unit 20 creates image information each time the vehicle speed value changes, and outputs the created image information to the display controller unit 30. The control unit 20 corresponds to the control means of the present invention.

  The display controller unit 30 has an image drawing function for displaying an image on the display unit 60. The display controller unit 30 is a well-known device called a graphic display controller (GDC), and includes a dedicated IC for image drawing having a gate array.

  The display controller unit 30 first receives image information from the control unit 20. In order to display this image information on the display unit 60, the VRAM 50 described later creates a one-frame image based on the image information, and inputs the image data of the one-frame image created by the VRAM 50. The image data is output to the display unit 60.

  The display controller unit 30 also has a timing function for causing the display unit 60 to display one frame image created in the VRAM 50. That is, it controls when the plurality of one-frame images created in the VRAM 50 are displayed on the display unit 60. This timing will be described in detail later.

  The ROM 40 is a storage unit that stores data, and is a known memory that stores image data of an image displayed on the display unit 60. The image stored in the ROM 40 is, for example, a meter image (hereinafter referred to as a dial image) on which only a scale for indicating the vehicle speed with a pointer is drawn. The ROM 40 outputs the image data of the dial face image specified in the image information input from the display controller unit 30 to the VRAM 50 via the display controller unit 30.

  The VRAM 50 creates meter image image data for displaying a meter image on the display unit 60, and is a well-known video RAM for storing the created meter image image data. Specifically, the VRAM 50 is a one-frame image in which the pointer is drawn on the dial image based on the dial image input from the ROM 40 via the display controller unit 30 and the coordinates of the pointer input from the display controller unit 30. Create Then, the generated image data of one frame is output to the display controller unit 30.

  The above display controller unit 30, ROM 40, and VRAM 50 correspond to the image creating means of the present invention.

  The display unit 60 displays an image of one frame of image data input from the display controller unit 30, and includes a TFT type liquid crystal panel (hereinafter referred to as a liquid crystal panel). In the liquid crystal panel, a thin film transistor (TFT) is provided in each pixel (dot) of the screen, and a voltage is directly applied to the liquid crystal by turning on or off the TFT switch. Thereby, the arrangement of the liquid crystal of each dot is controlled, and a desired image is displayed by changing the transmittance of light transmitted through the liquid crystal.

  The display unit 60 is installed on, for example, an instrument panel of a vehicle, and an image displayed on the display unit 60 can be visually recognized while the driver is driving. Note that the liquid crystal panel of the display unit 60 is preferably arranged in front of the driver in the instrument panel.

  The liquid crystal panel used in the display unit 60 employs a progressive method, that is, a method in which an image of one frame is displayed by one scanning. In such progressive image display, one frame is rewritten every (1/60) second (about 16 ms). That is, the frequency of the vertical synchronization signal for one frame is 60 Hz, and an image of 30 frames is displayed on the liquid crystal panel per second.

  Thus, in the liquid crystal panel, the vertical synchronization signal of one frame is set to 60 Hz. Therefore, the display unit 60 outputs a vertical synchronization signal to the display controller unit 30 in order to synchronize one frame image input from the display controller unit 30 with the vertical synchronization signal. The display unit 60 corresponds to the display unit of the present invention.

  The above is the configuration of the liquid crystal display device according to the present invention.

  Next, image display processing performed by the liquid crystal display device will be described with reference to a flowchart shown in FIG. This process is executed by the liquid crystal display device and executed by a program recorded in the CPU of the control unit 20, that is, a meter image display program.

  The meter image display program is started when the ignition switch of the vehicle is turned on, and is terminated when the ignition switch is turned off.

  First, at step 110, the vehicle speed is acquired. Specifically, a pulse signal corresponding to the vehicle speed is detected by the vehicle speed sensor of the detection unit 10. This pulse signal is output to the control unit 20 and converted into the vehicle speed by the control unit 20.

  In step 120, it is determined whether or not the vehicle speed value has changed. This is determined based on whether or not the vehicle speed value obtained from the pulse signal input from the detection unit 10 to the control unit 20 is different from the previously acquired vehicle speed value. If it is determined that the vehicle speed has changed, the routine proceeds to step 130. If it is determined in this step that the vehicle speed has not changed, the process proceeds to step 140 described later.

  In step 130, it is determined whether or not no-display information is set. That is, it is determined whether or not a pointer is drawn on the currently displayed dial image. This is because when the vehicle speed changes, the meter image before the vehicle speed changes and the vehicle speed change so that the pointer image cannot be seen in the dial image, in other words, the pointer rotates smoothly. This is to display a dial image on which a pointer is not drawn between subsequent meter images.

  This pointer display non-display information represents a history of creation and display of a dial face image on which a pointer is not drawn, and is created in step 190 described later and set in the control unit 20. In this step, if no display information is set, the process proceeds to step 140. On the other hand, if no display information is set, the process proceeds to step 180.

  In steps 140 to 170, a pointer display image creation process for creating a meter image on which the pointer is drawn is performed. First, the processing of step 130 or step 120 is performed, and when proceeding to step 140, in step 140, no-display information is cleared. This non-display information is information set in step 190 described later.

  In step 150, pointer coordinate calculation and coordinate holding are performed. That is, the coordinates of the position of the pointer in the dial image are obtained so that the vehicle speed value acquired in step 110 is displayed on the dial image with the pointer. In the present embodiment, the meter center position in the dial image is the starting point of the pointer, and the scale position indicating the vehicle speed is the end point. Thus, the coordinates of the pointer for displaying the value of the vehicle speed as a pointer are obtained, and the pointer coordinates are held in the control unit 20 and included in the image information.

  In step 160, a dial image is created. Specifically, first, when image information including pointer coordinates and the like is input to the display controller unit 30, the display controller unit 30 creates a dial image in order to display the vehicle speed on the display unit 60. An instruction is output to the ROM 40 and the VRAM 50. Receiving this, the ROM 40 outputs image data of a dial face image for displaying the vehicle speed as a pointer to the VRAM 50 via the display controller unit 30. Then, the VRAM 50 that has received the image data of the dial image creates this one-frame dial image.

  In step 170, an image in which the vehicle speed is displayed as a pointer is created. Specifically, it is created as follows. Coordinates for drawing the dial image from the ROM 40 and the pointer from the display controller unit 30 are input to the VRAM 50. Receiving these, the VRAM 50 draws a straight line connecting the coordinates of the start point of the pointer (position at the center of the meter) and the coordinates of the end point (position indicating the value of the vehicle speed) in the dial image. A drawn one-frame image is created. One frame of image data created in this way is stored once in the memory of the VRAM 50 and is output to the display controller unit 30.

  As described above, when the pointer display image creation process is performed in steps 140 to 170, the process proceeds to step 200.

  On the other hand, if it is determined in step 130 that no display information is set, a dial face image creation process shown in steps 180 and 190 is performed. In step 180, a dial image is created. In this step, the same processing as in step 160 is performed.

  In step 190, information indicating no pointer display is set. In other words, in order to leave as a history the creation and display of the dial image in which the pointer is not drawn, which has been generated in step 180, information indicating no pointer display is set in the control unit 20. This pointer display non-display information is used when it is determined in step 130 whether or not a dial image on which the pointer is drawn is displayed. The image data of the dial face image thus created is stored once in the memory of the VRAM 50 and is output to the display controller unit 30.

  As described above, when the dial face image creation processing is performed in steps 180 and 190, the process proceeds to step 200.

  When the pointer display image creation process (steps 140 to 170) and the dial face image creation process (steps 180 and 190) are performed as described above, the process proceeds to step 200.

  In step 200, it is determined whether a vertical synchronization signal is input. That is, in order for an image to be correctly displayed on the liquid crystal panel of the display unit 60, it is necessary to output image data matching the vertical synchronization signal of the liquid crystal panel from the display controller unit 30 to the liquid crystal panel of the display unit 60. For this reason, the display controller unit 30 determines whether or not the vertical synchronization signal of the liquid crystal panel is input from the display unit 60. In this step, if it is determined that the vertical synchronization signal is not input to the display controller unit 30, this step is repeated until the vertical synchronization signal is input, and if it is determined that the input is input, the process proceeds to step 210.

  In step 210, a meter image is displayed. Specifically, the display controller unit 30 acquires the image data of the image from the VRAM 50, and outputs the image data of the image in synchronization with the vertical synchronization signal of the liquid crystal panel of the display unit 60. The display unit 60 displays the image data of the input image on the liquid crystal panel. As a result, any image created in the pointer display image creation process (steps 140 to 170) and the dial face image creation process (steps 180 and 190) is displayed.

  As described above, an image to be displayed is created according to the vehicle speed of the vehicle, and is displayed on the liquid crystal panel of the display unit 60 in step 210. Here, the timing at which the display controller unit 30 displays an image on the display unit 60 in step 210 will be described with reference to FIG.

  FIG. 3 is a diagram showing an example of the display timing of the pointer when the pointer is rotated and displayed. In FIG. 3, the waveform shown at the top is the transmittance of the liquid crystal corresponding to the pointer that is erased as the vehicle speed changes. Furthermore, in FIG. 3, the waveform shown at the bottom is the transmittance of the liquid crystal corresponding to the pointer that is newly displayed as the vehicle speed changes.

  Here, the rise or fall time of the transmittance waveform of the liquid crystal is defined. First, in the display unit 60, a voltage applied to the liquid crystal to display white on the liquid crystal panel is a white voltage, and a voltage applied to the liquid crystal to display black on the liquid crystal panel is a black voltage. In this embodiment, it is assumed that the pointer and the dial are drawn in white, and the other areas are drawn in black.

  As shown in FIG. 3, the time until the transmittance of the liquid crystal falls below 10% after the white voltage applied to the liquid crystal to erase the pointer is switched to the black voltage is denoted by τr. Further, the time until the transmittance of the liquid crystal exceeds 90% after the black voltage applied to the liquid crystal to newly display the pointer is switched to the white voltage is represented by τd. These τr and τd vary depending on the physical properties of the liquid crystal used in the liquid crystal panel, but in the present embodiment, both adopt about 10 ms of liquid crystal.

  As described above, the time for which one frame is rewritten on the liquid crystal panel of the display unit 60 is about 16 ms. Here, since the human eye recognizes switching of display at 30 Hz (about 33 ms) or more as blinking display, rewriting of an image of one frame must be performed within 32 ms. Therefore, in this embodiment, the display time of one frame is 16 ms, and the dial image (1 frame) on which the pointer is drawn and the dial image (1 frame) on which the pointer is not drawn are displayed in 32 ms or less. .

  On the other hand, the minimum time required for image rewriting is τr + τd. That is, if the image is rewritten in a time shorter than this time, the pointer of the image displayed last time and the pointer of the image displayed this time are displayed at the same time, so this time is set as the lower limit value.

  Therefore, image rewriting is performed at τr + τd [ms] or more and 32 [ms] or less. Needless to say, the lower limit (τr + τd) depends on the physical property value of the liquid crystal, and thus changes depending on the physical property value of the liquid crystal to be used.

  Further, the switching of one frame image displayed on the liquid crystal panel is performed at each time point T1, T2,... Shown in FIG. The time interval at each time point is 16 ms as described above.

  When the vehicle speed is constant, as shown in FIG. 4A, an image in which the meter M and the pointer I1 are displayed on the dial image B is displayed on the liquid crystal panel of the display unit 60 (steps 110, 120, 140-170, 200, 210). In such a situation, when the vehicle speed changes, as described above, meter images indicating the vehicle speed value with the hands are created (steps 110 to 130, 140 to 170, 200, 210 and steps 110 to 130). , 180, 190, 200, 210).

  Then, as shown in FIG. 3, the white voltage applied to the liquid crystal displaying the pointer I1 is switched to the black voltage. This time is T1. That is, the time point T1 corresponds to the end timing of displaying the pointer I1. Between the time T1 and the time τr, the pointer I1 remains displayed due to the response delay of the liquid crystal. However, since τr is 10 ms as described above, the transmittance of the liquid crystal becomes 0% within 16 ms from the time T1, and the pointer I1 displayed on the liquid crystal panel before the time T1 becomes invisible.

  At time T1, a dial image B on which the pointer I1 is not drawn is displayed from the dial image B on which the pointer I1 is drawn. This is shown in FIG. In this way, an image of only the meter M on which the pointer I1 is not drawn is displayed.

  Then, at the time point T2, a meter image in which the changed vehicle speed value is displayed as a pointer is displayed. That is, the black voltage applied to the liquid crystal corresponding to the pointer is switched to the white voltage. In other words, the time point T2 corresponds to the start timing of displaying the hands. Here, due to the delay in the response of the liquid crystal, it takes time t until the transmittance of the liquid crystal for displaying the pointer exceeds 10%. This time t is a very short time compared to the rise time τd of the transmittance of the liquid crystal. So it can be ignored. Thus, when the transmittance of the liquid crystal exceeds 10%, the changed vehicle speed value is displayed as a pointer. This situation is shown in FIG. As shown in this figure, the changed value of the vehicle speed is displayed on the meter M of the dial face image B by the pointer I2.

  Thus, even if the displayed pointer I1 is erased and the pointer I2 is newly displayed, the meter image is rewritten within 32 ms, so that the pointers I1 and I2 blink to the human eye. Is not recognized. In other words, the transmittance of the liquid crystal corresponding to the pointer I2 of the currently displayed image is 100% within at least 32 ms after the transmittance of the liquid crystal corresponding to the pointer I1 of the previously displayed image falls below 100%. Since the image to be displayed is displayed, it is not recognized as blinking display by human eyes. Note that the dial image B is common regardless of whether or not the hands I1 and I2 are displayed, so that it is recognized that only the hands I1 and I2 are moving.

  Thereafter, if there is no change in the vehicle speed, the same image continues to be displayed. If a change in the vehicle speed occurs, the image is rewritten in the same manner as described above.

  As described above, in the present embodiment, the transmittance of the liquid crystal corresponding to the image displayed last time is 10% before (the image displayed last time) and after (the image displayed this time) before the pointer is rotated. The image to be displayed this time is displayed after falling below. Thereby, the superimposed display of the pointer can be prevented. In addition, at least a predetermined time (32 ms) in which a person does not recognize the blinking display until the image to be displayed this time is displayed after the previously displayed image is deleted is displayed on the liquid crystal panel. The flashing image can be prevented from being displayed. As described above, the pointer can be smoothly rotated and displayed.

  In addition, an image corresponding to the background, that is, a dial face image on which no pointer is drawn is displayed between the previously displayed image and the currently displayed image. Thereby, since the pointer is surely erased once, the superimposed display of the pointer can be prevented.

  In the present embodiment, switching between the previously displayed image and the currently displayed image is made at least 32 ms or less. This numerical value corresponds to a limit value at which a human does not recognize image switching as blinking. By setting the image display switching time within such time, it is possible to prevent the image switching from being recognized as a blinking display.

  As described above, the display timing of the image displayed last time and the image displayed this time is set to the display timing considering the response of the liquid crystal, so that the pointer can be smoothly rotated and displayed.

(Other embodiments)
In the first embodiment, the detection unit 10 includes a vehicle speed sensor for detecting the vehicle speed. However, a sensor other than the vehicle speed sensor may be included. For example, an engine speed sensor for detecting the engine speed is provided in the detection unit 10, a pulse signal detected by the engine speed sensor is output to the control unit 20, and the engine speed is displayed on the display unit 60. A meter image may be displayed.

  The detection unit 10 may include a plurality of sensors. For example, two meters of the vehicle speed and the engine speed can be drawn in one frame. That is, a plurality of meter images can be displayed on one screen by including a plurality of values in the image information.

  In the first embodiment, when the vehicle speed changes, a dial face image in which the pointer is not drawn is displayed between the meter image in which the previous vehicle speed is displayed as a pointer and the meter image in which the current vehicle speed is displayed as a pointer. However, it is not necessary to display a dial face image on which this pointer is not drawn. That is, after the transmittance of the liquid crystal corresponding to the pointer of the image displayed last time is less than 10% recognized as the image erased, the transmittance of the liquid crystal corresponding to the pointer of the image displayed this time exceeds 10%. Displays the image to be displayed this time.

  At this time, the transmittance of the liquid crystal corresponding to the pointer of the image displayed this time at least within a predetermined time (τr + τd and 32 ms or less) after the transmittance of the liquid crystal corresponding to the pointer of the previously displayed image falls below 100%. The image to be displayed this time is displayed so that becomes 100%. Thereby, the superimposed display and blinking display of the pointer can be prevented, and the pointer can be displayed so as to rotate smoothly.

  In the liquid crystal panel of the display unit 60, the frequency of the vertical synchronization signal is 60 Hz, but may be 120 Hz according to the physical property value of the liquid crystal.

  In the first embodiment, the control unit 20 and the display controller unit 30 are separated from each other, but the display controller unit 30 including the control unit 20 may be adopted. In such a case, the signal from the detection unit 10 is directly input to the display controller unit 30.

  In the first embodiment, the flowchart shown in FIG. 2 shows an example of implementation, and the present invention is not limited to this.

  The steps shown in each figure correspond to means for executing various processes.

It is a block block diagram of the liquid crystal display device which concerns on one Embodiment of this invention. It is a flowchart showing the content of the meter image display program which the control part of FIG. 1 performs. It is the figure which showed an example of the display timing of the pointer at the time of rotating and displaying the pointer. It is the figure which showed a mode that a pointer | guide was rotated and displayed at the timing shown by FIG. It is the figure which showed the transmittance | permeability of the liquid crystal of the liquid crystal panel with respect to the timing which displays a pointer | guide.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Detection part, 20 ... Control part, 30 ... Display controller part, 40 ... ROM,
50 ... VRAM, 60 ... display section, B ... face image, I1, I2 ... pointer, M ... meter.

Claims (5)

Detecting means (10) for detecting a signal representing vehicle information;
Control means (20) for receiving the signal and creating image information of the pointer to display the pointer according to the signal;
Image generating means (30, 40, 50) for receiving the image information and generating an image based on the image information and outputting image data of the image;
A liquid crystal panel for displaying the image; and receiving means for receiving the image data and displaying the image on the liquid crystal panel (60),
In the liquid crystal panel, after the transmittance of the liquid crystal corresponding to the pointer of the image displayed last time is lower than the predetermined transmittance recognized as the image erased, the transmittance of the liquid crystal corresponding to the pointer of the image displayed this time is The transmittance of the liquid crystal corresponding to the pointer of the image displayed this time is at least within a predetermined time after the transmittance of the liquid crystal corresponding to the pointer of the previously displayed image falls below 100% so as to exceed the transmittance. The liquid crystal display device characterized in that the image to be displayed this time is displayed so as to be 100%. The control means has means for creating image information of a background image on which no pointer is drawn, and the image creation means creates the background image based on the image information of the background image. Means for outputting image data;
In the liquid crystal panel, the background image is displayed until the transmittance of the liquid crystal corresponding to the pointer of the previously displayed image is at least below the predetermined transmittance, and then the liquid crystal corresponding to the pointer of the image displayed this time is displayed. The image to be displayed this time is displayed such that the transmittance exceeds the predetermined transmittance, and the transmittance of the liquid crystal corresponding to the pointer of the previously displayed image is less than 100%, at least within the predetermined time. 2. The liquid crystal display device according to claim 1, wherein the image to be displayed this time is displayed such that the transmittance of the liquid crystal corresponding to the pointer of the image to be displayed this time is 100%. The time required for the liquid crystal transmittance corresponding to the pointer of the previously displayed image to reach the predetermined transmittance is set to τr, and the liquid crystal transmittance corresponding to the image displayed this time is changed from 0% to 90%. If the time to become τd,
3. The liquid crystal display device according to claim 1, wherein the predetermined time is not less than τr + τd [ms] and not more than 32 [ms]. The liquid crystal display device according to claim 1, wherein the predetermined transmittance is 10%. 5. The liquid crystal display device according to claim 1, wherein the vehicle information is at least one of a vehicle speed and an engine speed.

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