JP5768698B2 - Liquid crystal display device for vehicle - Google Patents

Description

  The present invention relates to a liquid crystal display device for a vehicle.

  The liquid crystal panel has a characteristic that a certain amount of time is required to reach the target transmittance even when an applied voltage corresponding to the target transmittance is applied in order to change the transmittance. For this reason, for example, when the display control of the new image displayed next to the old image is performed at the same time as the erasure control of the currently displayed old image, the information represented by the two images in the process of switching the image As a result, the display quality may be impaired.

  Various countermeasures have been taken against such problems (see Patent Documents 1 to 3). In Patent Document 1, an applied image to a liquid crystal panel is controlled so that a displayed old image is erased, and then a new image is displayed after a non-display period. In Patent Document 2, in the case of performing display control for displaying a new image at the same time as erasing control for erasing an old image that is currently displayed, the display period of the new image is determined from the response time of the liquid crystal. By making the length longer, the user can surely see the new image. In Patent Literature 3, image blurring is suppressed by turning off the light source while the pixel transmittance changes.

Japanese Patent No. 3196480 JP 2010-39387 A JP 2011-75800 A

  However, since the technique of Patent Document 1 provides a non-display period during which the light from the light source provided behind the liquid crystal panel is not transmitted during the period of switching from the old image to the new image, the technique switches to the new image. Takes time.

  Further, unlike the technique of Patent Document 1, the technique of Patent Document 2 does not provide a non-display period, erases the old image, and displays the new image. Therefore, the time until switching to the new image is Shorter than that of Document 1. However, in the technique of Patent Document 2, since switching to a new image is performed while the light source is turned on, it is not possible to prevent display quality from being impaired.

  Here, when the liquid crystal display device is mounted on a vehicle, the liquid crystal panel of the liquid crystal display device has a vehicle abnormality (seat belt not worn, An image representing various information up to contents that are highly urgent in driving the vehicle such as a warning of a decrease in the remaining amount of fuel is displayed. However, the user cannot stare at the liquid crystal display device during operation. Because of these circumstances, when a liquid crystal display device is used in a vehicle, the user can only determine whether the displayed image content is highly urgent or reference level. In addition, the display color is changed according to the information represented by the image. For example, if the image is highly urgent information such as warning the vehicle abnormality for the user, the display color is red or yellow, and if the image is of a reference level such as average fuel consumption, the display color is white.

  In the technique of Patent Document 3, the light source is merely turned off when the transmittance of the pixel is changed, and then turned on. Therefore, the display color cannot be changed according to the image displayed in the display area.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to perform image switching in a short time as much as possible while suppressing deterioration in display quality, and according to an image displayed on a liquid crystal panel. Another object of the present invention is to provide a vehicle liquid crystal display device capable of providing a different display color.

In order to achieve the above object, the invention of claim 1 is a liquid crystal panel having a plurality of pixels whose transmittance is changed by controlling an applied voltage;
Illumination means provided behind the liquid crystal panel and having a plurality of light sources for projecting light of different colors onto the liquid crystal panel,
A display control means for determining an image representing predetermined information to be notified to the user, and controlling the voltage applied to the plurality of pixels according to the image to display the image on the liquid crystal panel;
A light source control unit that turns on any one of the light sources that emits light of a color corresponding to an image displayed on the liquid crystal panel; and
The display control means has a new image as an image displayed next to the old image at the same time as the applied voltage is controlled so that the old image as the image currently displayed on the liquid crystal panel is erased. By controlling the applied voltage to be displayed, the old image is switched to the new image,
Of the multiple light sources, the light source that emits light of the color corresponding to the old image is defined as the old image light source,
When a light source that emits light of a color according to the new image, unlike the old image light source, is defined as the new image light source.
When the image is switched from the old image to the new image, the light source control means turns off the old image light source in the lighting state together with the new image light source, turns on the new image light source after a predetermined time has passed since the turn-off ,
As the predetermined information represented by the new image is more urgent for the user of the vehicle, the predetermined time is set shorter .

  According to the first aspect of the invention, when the image is switched from the old image to the new image, the display control means displays the new image at the same time as controlling the applied voltage so that the old image is erased. Since the applied voltage is controlled as described above, the old image erasing operation and the new image displaying operation are performed almost simultaneously. Thereby, the switching time of the image from the start of erasing the old image to the completion of the display of the new image can be shortened as much as possible.

Furthermore, according to the first aspect of the present invention, when the image is switched to the new image from the old image, until a predetermined time has elapsed, the existing image source is turned off with the new image source by the light source control means. Thus, during the off period of the old image sources and new image light source may be prevented from being visually recognized what two images with each other is made if, suppress a reduction in display quality during image switching it can. In addition, the light source control means, after the existing image source, and the new image light source is turned off a predetermined time, since the light the Shin'e image light source, the new image is to be displayed in the display color corresponding to the information .

  Various types of information are displayed on the liquid crystal display device for a vehicle, from an information image having high urgency to a user to an image having low information. In particular, images of highly urgent information need to be transmitted to the user as soon as possible.

Therefore, according to the first aspect of the invention, the predetermined time is set shorter as the image of information that is more urgent for the user is displayed as a new image. To the person as soon as possible.

In the invention of claim 2 , when there are at least two types of images having different urgency as images displayed as new images, and the image displayed as a new image is an image representing highly urgent information, For pixels that change from the maximum transmittance to the minimum transmittance when switching to a new image, and for pixels that change from the minimum transmittance to the maximum transmittance, the end of the predetermined time after the point where the transmittance of these pixels is reversed If the image that is set as the time point and is displayed as a new image represents information that is less urgent than the information that is more urgent, the time after the completion of erasing the old image is set as the end point of the predetermined time It is characterized by being.

  An image representing predetermined information is displayed on the liquid crystal panel by changing the transmittance of each of the plurality of pixels. Further, the image representing the predetermined information displayed on the liquid crystal panel is erased by making the transmittances of the plurality of pixels all the same. That is, when the image display is switched, the old image is erased and the new image is displayed. Therefore, in a plurality of images, from the minimum transmittance and the pixels that change from the maximum transmittance to the minimum transmittance. There will be pixels that change to maximum transmittance.

  For example, if the liquid crystal panel is negatively displayed, the transmittance of the pixels forming the information is higher than the transmittance of the background pixels. In this display format, when the image is switched, among the pixels that form information in the old image, there are pixels whose transmittance changes from the maximum transmittance to the minimum transmittance in the liquid crystal panel. Among the pixels forming the shape, there are pixels whose transmittance changes from the minimum transmittance to the maximum transmittance. On the other hand, in the case of positive display, the transmittance of the pixels forming the information is lower than the transmittance of the pixels serving as the background. In this display format, when the image is switched, the liquid crystal panel includes pixels whose transmittance changes from the minimum transmittance to the maximum transmittance among the pixels forming information in the old image. Among the pixels forming the shape, there are pixels whose transmittance changes from the maximum transmittance to the minimum transmittance.

  When the image is switched, the transmittance of the pixel changes in this way. Therefore, comparing the pixel that changes from the maximum transmittance to the minimum transmittance and the pixel that changes from the minimum transmittance to the maximum transmittance, The transmittance of the selected pixel is reversed at a certain point. For example, when the light source behind the liquid crystal panel is turned on at this time, a synthesized image of the old and new images is displayed, but the new image is more easily visible to the user.

By setting the end point of the predetermined time as in the invention of claim 2 , when an image representing highly urgent information is displayed as a new image, while ensuring the visibility of the new image, Deterioration of display quality can be suppressed. In addition, when an image representing information that is less urgent than information that is more urgent than the information that is more urgent is displayed as the new image, the old image has been erased when the light source is turned on. This makes it difficult to ensure a reduction in display quality when switching images.

Here, the liquid crystal panel generally has a characteristic that the reaction time of the liquid crystal changes depending on the temperature of the liquid crystal panel. According to the invention of claim 3 , since the predetermined time is changed depending on the temperature of the liquid crystal panel, it is possible to suppress the change in display quality from being suppressed by the temperature change.

In the invention of claim 4 , when the applied voltage is controlled by the display control means so that the old image is erased, and when the applied voltage is controlled so that the new image is displayed, the light source control means The image light source is turned off together with the new image light source.

  According to the invention of claim 1, since the output of the command signal for erasing the old image and displaying the new image is performed at the same time, immediately after the command signal is output from the display control means, the old image and the new image are displayed. There is a possibility that a combination of the two information parts is visually recognized.

According to the invention of claim 4 , it is possible to suppress the process of changing the transmittance of the pixels from being visually recognized immediately after the start of switching from the old image to the new image. As a result, it is possible to further improve the effect of suppressing the deterioration in display quality when switching images.

It is a system diagram for demonstrating the structure of the liquid crystal display device for vehicles by 1st Embodiment of this invention. FIG. 3 is a diagram illustrating an example of an image displayed on a screen of a liquid crystal panel in the first embodiment of the present invention. FIG. 3 is a diagram illustrating an example of an image displayed on a screen of a liquid crystal panel in the first embodiment of the present invention. FIG. 3 is a diagram illustrating an example of an image displayed on a screen of a liquid crystal panel in the first embodiment of the present invention. 4 is a flowchart illustrating a control flow executed by a CPU in the first embodiment of the present invention. 6 is a time chart illustrating a state of a liquid crystal panel and a light source when a CPU executes a control flow illustrated in FIG. 5 in the first embodiment of the present invention.

  Hereinafter, a fuel supply system according to a first embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
As shown in FIGS. 2 to 4, the vehicle liquid crystal display device 1 displays various images 40 a, 40 b, 40 c, and 40 d on the screen 50, so that the vehicle state can be indicated to the user (for example, the driver). It is a device to provide. The liquid crystal display device 1 for vehicles is installed, for example, in a combination meter located in front of the driver's seat. The installation position of the liquid crystal display device 1 for vehicles is not limited to a combination meter, but is set to an instrument panel positioned in front of the driver's seat, as long as the images 40a, 40b, 40c, and 40d can be viewed. May be.

  As shown in FIG. 1, the vehicle liquid crystal display device 1 includes a display unit 2, a control unit 4, and the like. The display unit 2 displays various images 40a, 40b, 40c, and 40d on the screen 50. The control unit 4 controls the display of various images 40a, 40b, 40c, and 40d on the screen 50.

  The display unit 2 includes a case 6, a liquid crystal panel 8, a diffusion plate 10, a first light source 16, a second light source 18, a third light source 20, a fourth light source 22, a circuit board 14, a partition unit 12, a thermistor 24, and the like. ing. The case 6 is supported by the case of the combination meter, and supports the liquid crystal panel 8, the diffusion plate 10, the partition 12, the circuit board 14, and the thermistor 24.

  The liquid crystal panel 8 is a dot matrix type transmissive liquid crystal panel having a plurality of pixels arranged in a matrix, and a liquid crystal element is sealed between two glass substrates provided with transparent electrodes. . As a voltage is applied to the transparent electrode corresponding to each pixel from a drive circuit 28 described later, the light transmittance of each pixel changes and the gradation changes. Note that the gradation of the liquid crystal panel 8 of the present embodiment is two gradations. That is, when a voltage is applied to the transparent electrode corresponding to a predetermined pixel, the orientation of the liquid crystal element changes and the maximum transmittance is obtained. When the application of voltage is released, the orientation of the liquid crystal element changes and the minimum transmittance is obtained. When the transmittance of the pixel is maximized, the pixel transmits most of light incident from behind to the user side. Further, when the transmittance of the pixel is minimized, the pixel blocks most of the light from the back and prevents light from being transmitted to the user side.

  Note that the display format of the liquid crystal panel 8 of the present embodiment is negative display. That is, the average fuel consumption image 40a shown in FIG. 2 includes an information part 42a composed of pixels having a predetermined transmittance, and a background part 44a composed of pixels having a transmittance different from the pixels corresponding to the information part 42a. , Represents average fuel consumption information. The pixel of the part corresponding to the information part 42a has the maximum transmittance, and the pixel of the part corresponding to the background part 44a representing the background other than the information part 42a has the minimum transmittance. Similarly to the average fuel consumption image 40a, the seat belt warning image 40b and the remaining amount warning image 40c shown in FIG. 3 and FIG. 4 are composed of information parts 42b and 42c and background parts 44b and 44c, respectively. , And remaining fuel warning information. The pixels corresponding to the information portions 42b and 42c have the maximum transmittance, and the pixels corresponding to the background portions 44b and 44c have the minimum transmittance. The distance image 40d is also composed of an information part 42d and a background part 44d, and represents distance information. The pixel of the part corresponding to the information part 42d has the maximum transmittance, and the pixel of the part corresponding to the background part 44d has the minimum transmittance.

  Here, the characteristics of the liquid crystal panel 8 will be described. When a voltage is applied to the transparent electrode so as to obtain the maximum transmittance from the minimum transmittance state, the transmittance reaches the target maximum transmittance with a delay from the voltage application. On the contrary, when the application of the voltage to the transparent electrode is canceled so that the minimum transmittance is obtained from the state of the maximum transmittance, the transmittance becomes the target minimum transmittance after the applied voltage is released. It reaches. Further, the response time of the liquid crystal panel 8 when the minimum transmittance becomes the maximum transmittance is different from the response time of the liquid crystal panel 8 when the maximum transmittance becomes the minimum transmittance. Also, these response times vary depending on the temperature of the liquid crystal panel 8. That is, the response time becomes longer as the temperature of the liquid crystal panel 8 decreases.

  The screen 50 of the liquid crystal panel 8 has first and second display areas 50a and 50b as shown in FIGS. The first display area 50a includes, for example, an average fuel consumption image 40a indicating the average fuel consumption of the vehicle, a seat belt warning image 40b indicating non-wearing of the seat belt, and a remaining amount indicating that the remaining amount of fuel has fallen below a predetermined remaining amount. Vehicle information such as a quantity alarm image 40c is displayed, and vehicle information such as a distance image 40d indicating the travel distance of the vehicle is displayed in the second display area 50b. The information of the average fuel consumption image 40a and the information of the distance image 40d are information for reference when the user drives the vehicle, and are more urgent than the information of the seat belt warning image 40b and the information of the remaining amount warning image 40c. The nature is low. The information of the seat belt warning image 40b is very important information when the user drives the vehicle, and is more urgent than the information of the remaining amount warning image 40c.

  The diffusion plate 10 is provided behind the liquid crystal panel 8, diffuses light emitted from first to fourth light sources 16 to 22 described later, and causes the diffused light to enter the liquid crystal panel 8.

  The first to third light sources 16 to 20 are light sources that illuminate the first display area 50a, and the fourth light source 22 is a light source that illuminates the second display area 50b. The first to fourth light sources 16 to 22 are mounted on the circuit board 14 and project light of different colors onto the liquid crystal panel 8 by an applied voltage from a light source control circuit 26 described later. The 1st-4th light sources 16-22 are comprised from the light emitting diode (LED), for example.

  The 1st light source 16 radiates | emits light which a user recognizes as white about the light which passed the diffusion plate 10 and the liquid crystal panel 8. FIG. The second light source 18 emits light that the user perceives as red for the light that has passed through the diffusion plate 10 and the liquid crystal panel 8. The 3rd light source 20 radiates | emits the light which a user recognizes as yellow about the light which passed through the diffusion plate 10 and the liquid crystal panel 8. FIG.

  The partition unit 12 prevents the light from the first to third light sources 16 to 20 from entering the second display area 50b and the light from the fourth light source 22 from entering the first display area 50a. It is installed between the diffusion plate 10 and the circuit board 14.

  The thermistor 24 detects the temperature of the liquid crystal panel 8 and is provided in the vicinity of the liquid crystal panel 8. The thermistor 24 outputs a temperature signal corresponding to the temperature of the liquid crystal panel 8 to the control unit 4. The thermistor 24 is not necessarily attached to the case 6 as long as the temperature of the liquid crystal panel 8 can be detected. For example, the attachment position of the thermistor 24 may be the liquid crystal panel 8.

  The control unit 4 includes a drive circuit 28, a light source control circuit 26, a central processing unit (CPU) 30, and the like. The drive circuit 28 applies a voltage to the transparent electrode corresponding to each pixel in accordance with a command signal related to an image from the CPU 30. By applying this voltage, the transmittance of each pixel is controlled, and the gradation changes. The light source control circuit 26 applies a voltage to the first to fourth light sources 16 to 22 in accordance with a command signal related to an image from the CPU 30. In accordance with the application of this voltage, the lighting of the first to fourth light sources 16 to 22 is controlled. Various sensors for detecting the state of the vehicle, a control device for controlling the vehicle, a thermistor, and the like are electrically connected to the CPU 30, and the CPU 30 can obtain various types of information regarding the state of the vehicle. The CPU 30 displays an image representing predetermined information on the liquid crystal panel 8 by executing a control program stored in advance using information on the state of the obtained vehicle and information such as a temperature signal from the thermistor 24. Command signal is generated and output to the drive circuit 28. Further, the CPU 30 outputs a command signal for controlling turning on / off of the first to fourth light sources 16 to 22 to the light source control circuit 26 based on the information and the control program.

  For example, when displaying the average fuel consumption image 40a and the distance image 40d on the liquid crystal panel 8, the CPU 30 displays the information part 42a / background part 44a representing the average fuel consumption information and the information part 42d / background part 44d representing the distance information on the liquid crystal panel. 8 is output to the drive circuit 28. Based on this command signal, the drive circuit 28 applies a voltage to each pixel to control the transmittance of each pixel. Furthermore, the CPU 30 outputs a command signal for turning on the first and fourth light sources 16 and 22 to the light source control circuit 26 as light sources corresponding to the information of the images 40a and 40d. Based on this command signal, the light source control circuit 26 applies a voltage to the first and fourth light sources 16 and 22. As a result, the average fuel consumption image 40a in which the information part 42a is white is displayed in the first display area 50a, and the distance image 40d in which the information part 42d is white is displayed in the second display area 50b. .

  When displaying the seat belt warning image 40b and the distance image 40d on the liquid crystal panel 8, the CPU 30 includes an information part 42b / background part 44b representing the seat belt warning information and an information part 42d / background part 44d representing the distance information. A command signal to be displayed on the liquid crystal panel 8 is output to the drive circuit 28. Based on this command signal, the drive circuit 28 applies a voltage to each pixel to control the transmittance of each pixel. Further, the CPU 30 outputs a command signal for turning on the second and fourth light sources 18 and 22 to the light source control circuit 26 as light sources corresponding to the information of the images 40b and 40d. Based on this command signal, the light source control circuit 26 applies a voltage to the second and fourth light sources 18 and 22. As a result, the seat belt warning image 40b in which the information part 42b is red is displayed in the first display area 50a, and the distance image 40d in which the information part 42d is white is displayed in the second display area 50b. The

  When displaying the remaining amount alarm image 40c and the distance image 40d on the liquid crystal panel 8, the CPU 30 includes an information unit 42c and a background unit 44c representing the remaining amount alarm information, and an information unit 42d and a background unit 44d representing the distance information. A command signal to be displayed on the liquid crystal panel 8 is output to the drive circuit 28. Based on this command signal, the drive circuit 28 applies a voltage to each pixel to control the transmittance of each pixel. Further, the CPU 30 outputs a command signal for turning on the third and fourth light sources 20 and 22 to the light source control circuit 26 as light sources corresponding to the information of the images 40c and 40d. Based on this command signal, the light source control circuit 26 applies a voltage to the third and fourth light sources 20 and 22. As a result, the remaining amount warning image 40c in which the information part 42c is yellow is displayed in the first display area 50a, and the distance image 40d in which the information part 42d is white is displayed in the second display area 50b. The

  In addition, the CPU 30 determines an image to be displayed on the screen 50 in accordance with various types of information regarding the vehicle state input to the CPU 30, and generates a command signal corresponding to the determined image. For example, the average fuel consumption image 40a shown in FIG. 2 is displayed on the screen 50 when the user selects the display of average fuel consumption with a selection switch or the like. 3 is displayed on the screen 50 when the user is not wearing the seat belt. For example, even when the display of the average fuel consumption image 40a is selected, or even when the remaining fuel amount is in the state where the remaining amount warning image 40c is displayed, it is displayed with priority. Even when the display of the average fuel consumption image 40a is selected, the average fuel consumption image 40a is deleted and the remaining amount warning image 40c is displayed when the remaining amount of fuel falls below a predetermined remaining amount. As described above, various images are switched on the screen 50 according to various information input to the CPU 30 and display selection.

  Next, an image switching operation will be described. Here, the switching operation when switching from the average fuel consumption image 40a shown in FIG. 2 to the seat belt warning image 40b shown in FIG. 3 will be described as an example. In the state shown in FIG. 2, when information indicating that the seat belt is not worn is input to the CPU 30, the CPU 30 outputs a command signal for turning off the first light source 16 to the light source control circuit 26 and the average fuel consumption image. A command signal for erasing 40a is output to the drive circuit 28. The drive circuit 28 to which this command signal is input applies a voltage to each pixel so that the pixel has the minimum transmittance so that the transmittance of the pixel corresponding to the information portion 42a is the transmittance of the background portion 44a. . Thereby, the first light source 16 is turned off, and the transmittance of the pixel to be erased in the information section 42a gradually changes toward the minimum transmittance. At this time, since the first light source 16 is turned off, all the light sources that emit light toward the first display area 50a are turned off. Then, the CPU 30 outputs a command signal for displaying the seat belt warning image 40b to be displayed next at the same time as the output of the command signal (control of the voltage applied to each pixel) such that the average fuel consumption image 40a is deleted. Is output to the drive circuit 28. The drive circuit 28 to which this command signal is input applies a voltage to each pixel so that the transmittance of the pixel corresponding to the information unit 42b is the maximum transmittance. Thereby, the transmittance of the pixel corresponding to the information part 42b gradually changes toward the maximum transmittance. That is, the operation for deleting the average fuel consumption image 40a and the operation for displaying the seat belt warning image 40b are performed almost simultaneously. Even when the average fuel consumption image 40a shown in FIG. 2 is switched to the remaining amount warning image 40c shown in FIG. 4, or when the seat belt warning image 40b shown in FIG. 3 is changed to the images 40a and 40c shown in FIG. Switching is performed by a similar operation. Since the image is switched in this way, the transmittance is the image for the pixels forming the information part in both the old image and the new image, and the pixels forming the background part in both the old image and the new image. Does not change before and after switching.

  Next, the control of the vehicle liquid crystal display device 1 described above will be described using the control flow of FIG. 5 and the time chart of FIG. The control flow shown in FIG. 5 is started when the ignition switch of the vehicle is turned on, and is ended when the ignition switch is turned off.

  In step S110, initialization is performed. In step S120, the drive circuit 28 determines an image to be displayed in the first display area 50a, and displays a command signal corresponding to the determined image and a command signal for displaying the distance image 40d to be displayed in the second display area 50b. Output to. When the display of the average fuel consumption is selected by the user, the seat belt is not worn, and the remaining fuel amount is equal to or greater than the predetermined remaining amount, the CPU 30 instructs to display the average fuel consumption image 40a. Output a signal. Even when the display of the average fuel consumption is selected or the remaining amount of fuel is below a predetermined remaining amount, the CPU 30 outputs a command signal for displaying the seat belt warning image 40b when the seat belt is not worn. . When the remaining amount of fuel is below the predetermined remaining amount, the CPU 30 outputs a command signal for displaying the remaining amount warning image 40c only when the seat belt is worn.

  In step S130, the command signal for lighting any one of the first to third light sources 16 to 20 and the fourth light source 22 are turned on according to the information represented by the image displayed in the first display area 50a. A command signal for causing the light source control circuit 26 to output the command signal. Specifically, when the average fuel consumption image 40a is displayed, the CPU 30 outputs a command signal for turning on the first light source 16. When the seat belt warning image 40b is displayed, the CPU 30 outputs a command signal for turning on the second light source 18. When the remaining amount warning image 40c is displayed, the CPU 30 outputs a command signal for turning on the third light source 20.

  In step S140, it is determined whether or not the image displayed in the first display area 50a is scheduled to be switched. Whether or not this image switching is scheduled can be determined by whether or not the CPU 30 has generated a command signal related to an image different from the image currently displayed in the first display area 50a. In step S140, if a command signal for an image different from the currently displayed image is generated, the process proceeds to step S150. If not, the process is continued until a command signal for a different image is generated. Stay in S140.

  In step S150, which is executed when a command signal for an image different from the currently displayed image is generated, the temperature of the liquid crystal panel 8 is detected based on the temperature signal from the thermistor 24. In subsequent step S160, an update time T is calculated. The update time T is a turn-off time of the first to third light sources 16 to 20 when the display is updated from the currently displayed image to the next image. In other words, the update time T is from when the light source that was turned on is temporarily turned off when the display is switched from the currently displayed image to the next image, until the light source corresponding to the next displayed image is turned on. Is the time.

  Next, a procedure for calculating the update time T will be described. The update time T is calculated based on the next displayed image and the temperature of the liquid crystal panel 8. Hereinafter, the next displayed image is referred to as a new image. On the other hand, the currently displayed image is called an old image.

  When the new image is the average fuel consumption image 40a that is less urgent than the images 40b and 40c, the CPU 30 instructs the command signal to delete the information part of the old image and the information part of the new image to be displayed. The signal is output to the drive circuit 28, and after the drive circuit 28 controls the voltage applied to each pixel according to the command signal, the pixel that is changed from the information portion to the background portion in the old image is displayed in the background portion. The time until the point at which erasing is completed with the corresponding pixel transmittance is calculated as the basic time Tb. Note that the time from the start of controlling the voltage applied to each pixel to the completion of erasing is the time when the liquid crystal panel 8 is at a predetermined temperature, and is the time previously obtained through experiments or the like. Thereafter, in this embodiment, the basic time Tb is corrected by a value related to the temperature of the liquid crystal panel 8, and the update time T is calculated. In this correction, if the temperature of the liquid crystal panel 8 is lower than the temperature assumed by the CPU 30, the update time T becomes longer than the basic time Tb. If the temperature of the liquid crystal panel 8 is higher than the temperature assumed by the CPU 30, The update time T is shorter than the basic time Tb.

  When the new image is a seat belt warning image 40b or a remaining amount warning image 40c that is more urgent than the image 40a, the CPU 30 displays a command signal for deleting the information part of the old image and the information part of the new image. The command signal is output to the drive circuit 28, and the drive circuit 28 controls the voltage applied to each pixel in accordance with the command signal, and then the pixel to be changed to the information portion of the new image. The time until the time when the transmittance exceeds the transmittance of the pixel to be changed to the background portion of the old image (the time when the transmittance is reversed) is calculated as the basic time Tb. Note that the time from the start of control of the voltage applied to each pixel to the point in time when the transmittance is reversed is the time when the liquid crystal panel 8 is at a predetermined temperature, which is obtained in advance through experiments or the like. Thereafter, in this embodiment, the basic time Tb is corrected by a value related to the temperature of the liquid crystal panel 8, and the update time T is calculated. In this correction, if the temperature of the liquid crystal panel 8 is lower than the temperature assumed by the CPU 30, the update time T becomes longer than the basic time Tb. If the temperature of the liquid crystal panel 8 is higher than the temperature assumed by the CPU 30, The update time T is shorter than the basic time Tb.

  In step S170, all of the first to third light sources 16 to 18 are turned off. In step S180, control for switching from the old image to the new image is executed. Specifically, the CPU 30 outputs a command signal for erasing the old image to the drive circuit 28, and at the same time as the drive circuit 28 controls the applied voltage to each pixel in accordance with the command signal. Outputs a command signal for displaying a new image to the drive circuit 28, and the drive circuit 28 controls the voltage applied to each pixel in accordance with the command signal.

  In step S190, it is determined whether or not the time from the start of the process in step S170 has passed the update time T calculated in step S160. If it is determined that the time from the start of the process has passed the update time T or longer, the process proceeds to step S200. If not, the process remains at step S190 until the time has passed the update time T or longer. In step S200, any one of the first to third light sources 16 to 18 corresponding to the new image is turned on. Then, the process returns to step S140.

  The control flow executed by the CPU 30 has been described above. Next, operation | movement of the liquid crystal display device 1 for vehicles when the above-mentioned control flow is performed is demonstrated using FIG. FIG. 6 shows a display state of an image on the liquid crystal panel 8 and lighting / extinguishing states of the light sources 16 to 20. The image switching in the first half shows switching from the seat belt warning image 40b shown in FIG. 3 to the average fuel consumption image 40a shown in FIG. 2, and the image switching in the latter half is changed from the average fuel consumption image 40a shown in FIG. Switching to a seat belt warning image 40b is shown.

  First, the operation when switching from the seat belt warning image 40b (see FIG. 3) to the average fuel consumption image 40a (see FIG. 2) will be described. Until the time t1, information indicating that the seat belt is not worn is input to the CPU 30. Therefore, the CPU 30 outputs a command signal for turning on the second light source 18 to the light source control circuit 26, and outputs a command signal for displaying the seat belt warning image 40 b on the screen 50 to the drive circuit 28. At this time, the first and third light sources 16 and 20 are turned off. Accordingly, as shown in FIG. 6, until the time t1, the seat belt warning image 40b in which the information part 42b is red is displayed in the first display area 50a of the liquid crystal panel 8 (see FIG. 3). .

  When information indicating that the seat belt is worn and information indicating that the display of the average fuel consumption image 40a is selected at time t1, the CPU 30 calculates the current average fuel consumption. Then, a command signal for displaying the calculation result as the average fuel consumption image 40a is generated. Then, the CPU 30 calculates the update time T based on the fact that the new image is the average fuel consumption image 40a and the temperature information of the input liquid crystal panel 8 as described above (at times t1 and t2 shown in FIG. 6). Time between).

  Then, the CPU 30 outputs a command signal for turning off the second light source 18 that has been lit to the light source control circuit 26. Thereby, since the second light source 18 is turned off, the user recognizes that the seat belt warning image 40b of the liquid crystal panel 8 has disappeared. At the same time when the second light source 18 is turned off, the CPU 30 executes an image switching process. By executing this switching process, the transmittance of the pixels to be erased in the information portion 42b of the seat belt warning image 40b is lowered, and the transmittance of the pixels displayed in the information portion 42a of the average fuel consumption image 40a is raised. Thereby, the erasing operation of the old image and the displaying operation of the new image are performed almost simultaneously, so that the image switching time can be shortened as much as possible.

  When the time t2 is reached, that is, when the update time T has elapsed, the CPU 30 outputs a command signal for turning on the first light source 16 to the light source control circuit 26. As a result, the first light source 16 is turned on. When the first light source 16 is turned on, the transmittance of the pixels to be erased in the information part 42b of the seatbelt alarm image 40b is minimum, so that the first display area 50a of the liquid crystal panel 8 has the structure shown in FIG. Only the average fuel consumption image 40a as shown will be displayed. In this way, according to the display of the average fuel consumption image 40a, it is possible to reliably suppress a decrease in display quality at the time of image switching. In this example, all the light sources 16 to 20 including the second light source 18 are turned off based on the applied voltage control for erasing the seat belt warning image 40b and the applied voltage control for displaying the average fuel consumption image 40a. As a result, it is possible to reliably suppress the visual combination of the two information parts 42a and 42b immediately after the start of the image switching, and to enhance the display quality deterioration suppressing effect. In addition, since the update time T is changed according to the temperature of the liquid crystal panel 8, it is possible to suppress the change in display quality from being suppressed due to the temperature change of the liquid crystal panel 8.

  Next, the operation when switching from the average fuel consumption image 40a to the seat belt warning image 40b will be described. Until time t3, information indicating that the display of average fuel consumption is selected is input to the CPU 30. Therefore, CPU30 calculates an average fuel consumption according to it, and produces | generates the command signal for displaying the calculation result as the average fuel consumption image 40a. Then, the CPU 30 outputs the generated command signal to the drive circuit 28 and outputs a command signal for lighting the first light source 16. At this time, the second and third light sources 18 and 20 are turned off. Therefore, as shown in FIG. 6, the average fuel consumption image 40a in which the information part 42a is white is displayed in the first display area 50a of the liquid crystal panel 8 (see FIG. 2).

  When information indicating that the seat belt is not worn is input to the CPU 30 at time t3, the CPU 30 generates a command signal for displaying the seat belt warning image 40b. Then, as described above, the CPU 30 calculates the update time T based on the fact that the new image is the seat belt warning image 40b and the input information regarding the temperature of the liquid crystal panel 8 (time t3 and t4 shown in FIG. 6). Time between). The update time T is shorter than the update time T when the average fuel consumption image 40a is displayed as a new image.

  Then, the CPU 30 outputs a command signal for turning off the first light source 16 that has been lit to the light source control circuit 26. As a result, the first light source 16 is turned off, and the user recognizes that the average fuel consumption image 40a of the liquid crystal panel 8 has disappeared. At the same time when the first light source 16 is turned off, the CPU 30 executes an image switching process. By executing this switching process, the transmittance of the pixels to be erased in the information portion 42a of the average fuel consumption image 40a decreases, and the transmittance of the pixels displayed in the information portion 42b of the seat belt warning image 40b increases. Thereby, the erasing operation of the old image and the displaying operation of the new image are performed almost simultaneously, so that the image switching time can be shortened as much as possible.

  When the time t4 is reached, that is, when the update time T has elapsed, the CPU 30 outputs a command signal for turning on the second light source 18 to the light source control circuit 26. Thereby, the 2nd light source 18 lights. When the second light source 18 is turned on, the transmittance of the pixels in the information portion 42b of the seat belt warning image 40b exceeds the transmittance of the pixels to be deleted in the information portion 42a of the average fuel consumption image 40a. Although the image 40a is visually recognized, the seat belt warning image 40b is more easily visible to the user. According to the display of the seat belt warning image 40b, information that is highly urgent for the user to drive the vehicle, such as the seat belt warning image 40b, while suppressing deterioration in display quality at the time of image switching. It can be transmitted to users as soon as possible. Also in this example, as in the previous example, the first light source 16 is included based on the output of a command signal for deleting the average fuel consumption image 40a and a command signal for displaying the seat belt warning image 40b. Since all the light sources 16 to 20 are turned off, it is possible to surely suppress the combination of the two information parts 42a and 42b from immediately after the start of the image switching, and to suppress the deterioration in display quality. Can be increased. In addition, also in this example, since the update time T is changed according to the temperature of the liquid crystal panel 8, it is possible to suppress the display quality deterioration suppressing effect from changing due to the temperature change of the liquid crystal panel 8.

  In this embodiment, the end point of the basic time Tb is a time point at which the transmittance of the pixel changed to the information portion of the new image exceeds the transmittance of the pixel changed to the background portion of the old image. However, it may be after the time point exceeding the time point and before the time point when the deletion of the old image is completed. Even if the basic time Tb is calculated based on such an idea, the information represented by the new image can be transmitted to the user at an early stage.

  In the present embodiment, the first to third light sources 16 to 20 correspond to the “illuminating means” described in the claims, and the CPU 30 and the drive circuit 28 that execute steps S120 and S180 include the “display” described in the claims. The CPU 30 that executes steps S130, S170, and S200 corresponds to “light source control means” recited in the claims.

(Other embodiments)
The first embodiment according to the present invention has been described above. However, the present invention is not construed as being limited to the above-described embodiments, and various embodiments and combinations can be made without departing from the scope of the present invention. Can be applied to.

  For example, in the previous embodiment, the CPU 30 executes the image switching control (step S180) and then executes the light source extinguishing control (step S170). However, these controls may be reversed.

  In the previous embodiment, one of the first to third light sources is turned on according to the information represented by the image, but a plurality of light sources are used so that the display color of the image becomes the target display color. May be lit. For example, when the information part 42a of the average fuel consumption image 40a emits white light, white display may be realized by turning on all the red, blue, and yellow light sources. By doing so, it is possible to display an image with more display colors than the number of light sources to be prepared.

  In the previous embodiment, the liquid crystal panel 8 whose display format is negative display has been described. The effect of the present invention can be obtained even with the liquid crystal panel 8 having a positive display. When the display format of the liquid crystal panel 8 is positive display, for example, the pixel of the portion corresponding to the information portion 42a of the average fuel consumption image 40a has the minimum transmittance, and the pixel of the portion corresponding to the background portion 44a is Maximum transmittance. Similarly to the average fuel consumption image 40a, the seat belt warning image 40b and the remaining amount warning image 40c have the minimum transmittance in the pixels corresponding to the information portions 42b and 42c of the images 40b and 40c. The pixels corresponding to 44b and 44c have the maximum transmittance.

  In this case, the update time T set when the new image is the seat belt warning image 40b or the remaining amount warning image 40c is set as follows. The CPU 30 outputs a command signal for erasing the information part of the old image and a command signal for displaying the information part of the new image to the drive circuit 28, and the drive circuit 28 responds to these command signals. When the transmittance of the pixel changed to the information portion of the new image is lower than the transmittance of the pixel changed to the background portion of the old image after controlling the applied voltage to each pixel (the transmittance is The time until the reverse) is calculated as the basic time Tb. Thereafter, the basic time Tb is corrected by a value related to the temperature of the liquid crystal panel 8, and the update time T is calculated.

  In the previous embodiment, the gradation of the liquid crystal panel 8 is two gradations, but the effect of the present invention can be obtained even when a liquid crystal panel having three or more gradations is used. In this case, when the new image is the seat belt warning image 40b or the remaining amount warning image 40c, the end point of the basic time Tb is from the maximum transmittance to the minimum transmittance at the time of switching from the old image to the new image. For the pixels that change to the minimum and the pixels that change from the minimum transmittance to the maximum transmittance, the point after the point where the transmittances of these pixels are reversed is the end point of the predetermined time.

  DESCRIPTION OF SYMBOLS 1 Liquid crystal display device for vehicles, 2 Display part, 4 Control part, 6 Case, 8 Liquid crystal panel, 10 Diffusion plate, 12 Partition part, 14 Circuit board, 16 1st light source (illuminating means), 18 2nd light source (illuminating means) ), 20 3rd light source (illuminating means), 22 4th light source, 24 thermistor (detection means), 26 light source control circuit, 28 drive circuit (display control means), 30 central processing unit (CPU) (display control means, light source) Control means), 40a average fuel consumption image, 40b seat belt warning image, 40c remaining amount warning image, 40d distance image, 42a, 42b, 42c, 42d information part, 44a, 44b, 44c, 44d background part, 50 screen, 50a first 1 display area, 50b 2nd display area

Claims (4)

A liquid crystal panel having a plurality of pixels whose transmittance is changed by controlling the applied voltage;
Illuminating means provided behind the liquid crystal panel and having a plurality of light sources that project light of different colors onto the liquid crystal panel;
A display control means for determining an image representing predetermined information to be notified to a user, and controlling the applied voltage to the plurality of pixels according to the image, thereby displaying the image on the liquid crystal panel;
A light source control unit that turns on any one of the plurality of light sources that emits light of a color corresponding to an image displayed on the liquid crystal panel;
The display control means, as an image displayed next to the old image at the same time as controlling the applied voltage so that the old image as the image currently displayed on the liquid crystal panel is erased By controlling the applied voltage so that a new image is displayed, the old image is switched to the new image,
Of the plurality of light sources, a light source that emits light of a color corresponding to the old image is defined as an old image light source,
Of the plurality of light sources, a light source that emits light of a color corresponding to the new image unlike the old image light source is defined as a new image light source.
When the image is switched from the old image to the new image, the light source control means turns off the old image light source in a lighting state together with the new image light source, and after a predetermined time has passed since the turn-off, the new image light source It is lit,
The liquid crystal display device for a vehicle , wherein the predetermined time represented by the new image is set to be shorter as the information that is more urgent for a vehicle user . There are at least two types of images with different urgency as images displayed as the new image,
When the image displayed as the new image is an image representing highly urgent information, from the pixel and the minimum transmittance that change from the maximum transmittance to the minimum transmittance at the time of switching from the old image to the new image For pixels that change to maximum transmittance, the point after the point where the transmittance of these pixels is reversed is set as the end point of the predetermined time,
When the image displayed as the new image is an image representing information that is less urgent than the information that is more urgent, the time after the completion of erasing the old image is set as the end time of the predetermined time. The liquid crystal display device for a vehicle according to claim 1 . A detecting means for detecting the temperature of the liquid crystal panel;
The predetermined time is a vehicle for a liquid crystal display device according to claim 1 or 2, characterized in that changes in accordance with the detected by the detection means temperature. When the applied voltage is controlled by the display control means so that the old image is erased and the applied voltage is controlled so that the new image is displayed, the light source control means vehicle liquid crystal display device according to any one of claims 1 to 3, characterized in that to the off together with the new image light source.

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