JP2010091816A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve visibility of a user by controlling brightness of a screen based on the amount of external light emitted to the front side of a display device and circumstance information indicating circumstances. <P>SOLUTION: The display device is provided with: a first external light sensor 14 detecting the amount of external light emitted to the front side of the display part 11, a second external light sensor 15 detecting the amount of external light emitted to a top surface side or a back side of the display part 11, and a microcomputer 16 receiving the circumstance information indicating circumstances. The microcomputer 16 controls brightness of the screen of the display part 11 based on the external light quantity from the first external light sensor, external light quantity from the second external light sensor, and circumstance information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a display device that performs dimming of an image according to an ambient environment.

  As shown in FIG. 13, it is suggested from the visual sensitivity curve and color matching function of the color blind person that there are three types of photoreceptors (cones) having different spectral sensitivities in the human visual system ( Three-color theory). Further, cone spectral sensitivity is obtained from the color matching function of a healthy person and the confusion color center of a two-color type color blind person. The visual sensitivity of the human visual system varies depending on the wavelength of light, and takes a peak value at 555 nm in photopic vision. If the sensitivity to light of other wavelengths is obtained on the basis of the sensitivity at this time, the relative visibility to the entire visible light is obtained. In dark vision, the sensitivity is the best for 507 nm light. This shift of the sensitivity curve to the short wavelength side in a dark place is called Purkinje shift. A value obtained by multiplying radiance and visibility is called luminance. In the human visual system, color is perceived in photopic vision, but there is no color vision because there is only one type of photoreceptor (rod) in scotopic vision. The rod spectral sensitivity is equal to the dark visual sensitivity.

  FIG. 14 is a diagram showing the number of photoreceptor cells in the rod with respect to the human visual axis. The rod works from a darkness of about 1 lx and reacts only to the brightness. Since the cone works at 10 lx or more, the function of the rod is important for seeing dark objects. However, since the frame hardly exists at the center of the viewpoint, in the dark place, for example, the light from a car navigation system or the like away from the center of the field of view may be dazzled, which may hinder driving.

  As described above, since the visual characteristics of the human visual system are greatly different between the photopic vision and the dark vision, a dimming function of the screen of the display device is required in an environment such as a car interior.

Conventionally, in-vehicle display devices capable of dimming according to the external environment are roughly classified into the following two types.
1. A type that captures external light by placing sensors on the back or top and adjusts light in conjunction with the brightness of the atmosphere (mainly on-dash type)
2. A type that adjusts to the preset brightness when the light is turned on (mainly in-dash dips) in conjunction with the illumination information of the car

  Above 1. In the case of this type, since the external light is taken in to determine the dimming, it can be a dimming function that is relatively linked to the external light, but because the sensor is on the back or top surface, the direction of travel of the car Of outside light. As a result, when the inclination of the sun is low (early morning, evening, white night, etc.), the display unit becomes brighter than the brightness in the traveling direction. In addition, at night, the display section is relatively dark and visibility is poor.

  2. This type is linked with the illumination switch of the car regardless of the brightness of the external light, so when the illumination switch of the car is turned on, the LCD display backlight is forcibly adjusted to a preset brightness. It will shine. As a result, when illumination is turned on during the daytime (eg, bad weather), a reverse phenomenon occurs in which the display portion becomes dark although the outside is bright, which significantly degrades visibility. Also, if you have a function that allows you to set this dimming amount in advance, if you set the dimming amount to increase visibility in bad weather, it will be bright and dazzling when it is dark, which is the original purpose of use. It becomes an obstacle to safe driving.

JP 2003-257893 A

  As described above, the conventional liquid crystal display device mainly controls the light of the backlight, and is not linked to the image quality (brightness / contrast / color / hue / sharpness, etc.) of the screen. Even if the user has a function that works in conjunction, the state is simply set in advance, and there are few cases in which light actually enters the screen that the user sees. As a result, the screen looks black and the contrast deteriorates, resulting in poor image quality. For example, in sufficiently bright conditions such as the daytime (not dimmed), the gradation from black to white can be expressed well, but in bad weather, the backlight is dimmed, The black-side gradation is not sufficiently expressed, and blackout occurs. This weakens the dynamic range and results in degradation of image quality.

  The present invention has been made in view of these problems, and provides a display device that improves the visibility of a user.

  In order to solve the above-described problems, a display device according to the present invention includes a display unit that displays an image, a front external light sensor that detects an external light amount irradiated on the front side of the display unit, and a surrounding that indicates an ambient condition. A dimming information input unit for inputting information, and a control unit for controlling the brightness of the screen of the display unit based on the external light amount and the ambient information.

  The present invention controls the brightness of the screen based on the amount of external light applied to the front side of the display unit and the surrounding information indicating the surrounding situation, so that the light jumps into the display image adjusted according to the surrounding situation. However, it is possible to prevent the visibility of the user from deteriorating.

Hereinafter, specific embodiments of the present invention will be described in the following order with reference to the drawings.
1. Overall configuration Fig. 1
2. Example 1 FIG.
3. Example 2 FIGS. 3 to 5
4). Specific Example 3 FIGS. 6 to 12

[1. overall structure]
The display device shown as a specific example of the present invention improves the visibility of the user according to the ambient conditions and the amount of external light irradiated on the front side. As information indicating ambient conditions, for example, on / off information on indoor lights, illumination switches (hereinafter also referred to as illumination information) indicating on / off of vehicle lights, vehicle width lights, interior lights, and the like can be used. Here, for example, an in-vehicle device capable of inputting illumination information in Car Audio, Car AV Center, Car Navigation, Car TV, and the like will be described as an example.

  FIG. 1 is a block diagram illustrating a configuration of a display device in this embodiment. The display device includes a display unit 11, a video processing unit 12, a timing controller 13, a first external light sensor 14, a second external light sensor 15, a microcomputer 16, and a light control unit 17. ing.

  The display unit 11 is a display device such as an LCD (Liquid Crystal Display), an organic ELD (Electro Luminescence Display), or an FLD (Fluorescent Display). The video processing unit 12 performs processing such as image quality control, scaling, timing control, and format conversion on the input video signal of a predetermined format. Image quality control corrects image brightness, contrast, color depth, hue, and sharpness. The timing controller 13 is a display control signal generating IC (Integrated Circuit) of the display device. For example, the timing controller 13 receives a video signal and rearranges the data into a format in which the display element can correctly represent an image and a color.

  The first outside light sensor 14 detects the amount of outside light irradiated on the front surface of the display unit 11. The amplifier 141 converts a voltage and a method so that the brightness information detected by the first external light sensor 14 is taken into the microcomputer 16. The first external light sensor 14 can detect the brightness in the viewing direction on the user side, and improves visual contrast and visibility as will be described later.

  The second external light sensor 15 detects the amount of external light applied to the top surface (upper surface) or the back surface of the display unit 11. The amplifier 151 converts the voltage and method in order to capture the brightness information detected by the second external light sensor 15 into the microcomputer 16. As will be described later, the second external light sensor 15 improves visual contrast and visibility in conjunction with the external light amount and illumination information in the first external light sensor 14.

  The microcomputer 16 includes an external light amount detected by at least the first external light sensor 14 out of the first external light sensor 14 and the second external light sensor 15, and, for example, a car light, a vehicle width light, an interior light, and the like. The video processing unit 12 and the light control unit 17 are controlled based on the illumination information. In the video processing unit 12, the brightness and contrast of the image are controlled by a control line such as I2C (Inter Integrated Circuit), and in the light control unit 17, the brightness of the entire display screen of the display device is controlled.

  The light control unit 17 adjusts the entire display screen of the display device. For example, when the display unit 11 is an LCD, the backlight disposed on the back surface of the LCD is dimmed to improve visibility.

  In such a configuration, the microcomputer 16 receives an external light amount irradiated on the front side of the display unit 11 detected by the first external light sensor 14 and illumination information indicating the surrounding situation. The microcomputer 16 has a dimming parameter table as will be described later, so that the dimming of the screen can be linearly changed to improve the visual contrast and visibility.

  In addition, the second external light sensor 15 that detects the amount of external light applied to the back side or the top surface side of the display unit 11 is provided, so that it differs from the first external light sensor 14 that matches the viewing direction of the user. For example, brightness information outside the vehicle can be obtained. Thereby, it becomes possible to perform a finer situation setting and to improve a user's visibility.

  Next, specific dimming control in the display device will be described.

[2. Specific Example 1]
The display device shown as the specific example 1 adjusts the backlight based on the external light amount detected by the first external light sensor 14 and the illumination information. The microcomputer 16 is provided with a dimming parameter table as shown in FIG. 2, and multi-level (linear) dimming is possible.

  FIG. 2 is a diagram illustrating an example of parameters of illumination intensity of the backlight with respect to the external light amount. In this example, eight levels of intensity are set according to the amount of front light when the illumination switch is on and when the illumination switch is off. The illumination intensity with respect to the front light quantity is higher when the illumination is on.

  By dimming the backlight using such a table, for example, if the light enters the screen at night when the illumination switch is on, the illumination intensity of the backlight will increase, preventing blackout of the image. Can do.

  Conventionally, the in-dash type (embedded type) that cannot capture outside light can only be linked with the illumination information of the car, but by capturing outside light in front of the display unit 11, Thus, it is possible to realize a dimming function linked with outside light.

[3. Specific Example 2]
The display device shown as the specific example 2 includes an external light amount detected by the first external light sensor 14 (front sensor) provided on the front surface of the display unit 11 and a first light device provided on the back surface or the top surface of the display unit 11. The external light quantity detected by the external light sensor 15 (back sensor) 2 is used. This prevents the display screen from being dimmed in the dark even in situations where the light of the car (illumination switch) is turned on in a relatively bright situation such as poor visibility (fog, morning, hail, rain, etc.) In addition, deterioration of visibility can be prevented.

  FIG. 3 is a diagram illustrating the relationship between the external light amounts of the front sensor and the back sensor when the illumination switch is in the OFF state. In FIG. 3, when the external light intensity of the front sensor is very large compared to the external light intensity of the back sensor (D1: Front sensor >> Back sensor), the lights of the morning sun, the western sun, the rear car, etc. are strongly irradiated. The situation is assumed. In addition, when the external light intensity of the front sensor is larger than the external light intensity of the back sensor (D2: Front sensor >> Back sensor), it is assumed that the light from the sun, the sun, and the back car is weakly illuminated. The Further, when the external light amount of the front sensor is slightly larger than the external light amount of the back sensor (D3: Front sensor> Back sensor), it is assumed that the room light is turned on during the daytime or at night. Further, when the external light quantity of the front sensor is almost the same as the external light quantity of the back sensor (D4: Front sensor≈Back sensor) and slightly small (D5: Front sensor <Back sensor), it is daytime, nighttime, etc. It is assumed that In addition, when the external light quantity of the front sensor is smaller than the external light quantity of the back sensor (D6: Front sensor << Back sensor), it is assumed that the light of the oncoming vehicle, etc. is weakly illuminated. Is done. In addition, when the external light intensity of the front sensor is very small compared to the external light intensity of the back sensor (D7: Front sensor <<< Back sensor), the morning sun, western sun, direct sunlight, nighttime oncoming lights, etc. are strongly irradiated The situation is assumed.

  FIG. 4 is a diagram illustrating the relationship between the external light amounts of the front sensor and the back sensor when the illumination switch is on. In FIG. 4, when the external light quantity of the front sensor is much larger than the external light quantity of the back sensor (N1: Front sensor >> Back sensor), it is assumed that the light from the rear vehicle is strongly irradiated. Is done. In addition, when the external light amount of the front sensor is larger than the external light amount of the back sensor (N2: Front sensor >> Back sensor), a situation is assumed in which the light of the rear vehicle is weakly irradiated. Further, when the external light amount of the front sensor is slightly larger than the external light amount of the back sensor (N3: Front sensor> Back sensor), a situation where the room light is ON at night is assumed. In addition, when the external light amount of the front sensor is substantially the same as the external light amount of the back sensor (N4: Front sensor≈Back sensor), it is assumed that it is nighttime. Further, when the external light amount of the front sensor is slightly smaller than the external light amount of the back sensor (N5: Front sensor <Back sensor), it is assumed that the night light, the vicinity of the street light, the morning, bad weather, and the like. In addition, when the external light intensity of the front sensor is smaller than the external light intensity of the back sensor (N6: Front sensor << Back sensor), the situation is such that the light of the oncoming vehicle at night is weakly illuminated, urban area, morning, bad weather It is assumed that In addition, when the external light amount of the front sensor is very small compared to the external light amount of the back sensor (N7: Front sensor <<<< Back sensor), it is assumed that the light of the oncoming vehicle at night is strongly illuminated. .

  In this way, by obtaining the difference information between the external light amount irradiated on the front side of the display unit 11 and the external light amount irradiated on the back side or the top surface side of the display unit 11, a more specific detailed situation setting can be performed. It is possible to improve the visibility of the user.

  FIG. 5 is a diagram illustrating an example of a dimming parameter of the backlight based on the difference information of the external light amount. As shown in FIG. 3, when the illumination is off (D1 to D7), the microcomputer 16 controls the illumination intensity of the backlight to 1 to 7. Further, as shown in FIG. 4, when the illumination is on (N1 to N7), the microcomputer 16 controls the illumination intensity of the backlight to 4 to 10.

  As a result, the brightness of the light control amount of the backlight can be controlled by turning on and off the illumination switch, and the light control amount of the backlight can also be controlled based on the difference in the external light amount between the front sensor and the back sensor. Therefore, when turning on the vehicle illumination, as in the conventional interlocking type with only an illumination switch, it is relatively bright because of the darkness in the evening and poor visibility (fog, morning, hail, rain, etc.) In this situation, it is possible to prevent the same dimming.

[Specific Example 3]
The display device shown as the specific example 3 is similar to the specific example 2 in that the external light amount detected by the first external light sensor 14 (front sensor) provided in front of the display unit 11 and the back surface of the display unit 11 or The external light amount detected by the second external light sensor 15 (back sensor) provided on the top surface is used. Further, in the third specific example, the video processing unit 12 corrects the brightness, contrast, color density, hue, and sharpness of the image to further improve user visibility.

  FIG. 6 is a diagram illustrating an image quality definition table based on the front light amount and the back light amount when the illumination switch is in the off state, and FIG. 7 is an image quality based on the front light amount and the back light amount when the illumination switch is on. It is a figure which shows a definition table. In this example, an image quality definition table having 64 gradations is provided for each of the eight steps (a to h) of the front light amount and the eight steps (A to H) of the back light amount when the illumination switch is turned on and off.

  FIG. 8 is a diagram showing image quality parameters when the illumination switch is on and when the illumination switch is off. In this example, backlight dimming (DIM), image brightness (BRT), contrast (CON), hue (COL, HUE), corresponding to the numbers of the image quality definition tables shown in FIGS. Each image quality parameter of sharpness (SHP) is defined.

  FIG. 9 is a diagram showing the degree of backlight with respect to the image quality parameter. 10 is a diagram showing the degree of brightness and contrast with respect to the image quality parameter, FIG. 11 is a diagram showing the degree of hue with respect to the image quality parameter, and FIG. 12 is a diagram showing the degree of sharpness with respect to the image quality parameter. . Here, the table shown in FIG. 9 is provided, for example, in the light control unit 17 and controls the backlight of the display unit 11 in accordance with the image parameter from the microcomputer 16. 10 to 12 are provided, for example, in the microcomputer 16 and control processing in the video processing unit 12 via signal lines.

  As described above, in specific example 3, not only the dimming of the backlight according to the on / off of the illumination switch, the external light amount of the front sensor, and the external light amount of the back sensor, but also the brightness, contrast, color density, hue of the image, Control at least one of the sharpnesses. In other words, by performing linear image quality control such as color depth and sharpness with respect to the brightness perceived by humans, it is possible to improve the visual image quality and improve the visibility.

  In addition, as a result of preventing gaze on a screen that is difficult to see in the bright and reducing glare in the dark, the burden on the eyes can be reduced and a safety drive can be provided. Furthermore, by improving the visibility in the on state of the illumination switch, it is possible to improve the entertainment properties linked with the in-vehicle illumination.

  In the above-described embodiment, the liquid crystal display device including the back panel has been described. However, the present invention is not limited to this, and is applicable to display devices such as organic ELD (Electro Luminescence Display) and FLD (Fluorescent Display). It is.

It is a block diagram which shows the structure of the display apparatus in this Embodiment. It is a figure which shows the example of the parameter of the illumination intensity of the backlight with respect to external light quantity. It is a figure which shows the relationship of the external light quantity of a front sensor and a back sensor in case an illumination switch is an OFF state. It is a figure which shows the relationship of the external light quantity of a front sensor and a back sensor in case an illumination switch is an ON state. It is a figure which shows an example of the light control parameter of the backlight based on the difference information of external light quantity. It is a figure which shows the image quality definition table based on the front light quantity and back light quantity when an illumination switch is an OFF state. It is a figure which shows the image quality definition table based on the front light quantity and back light quantity in case an illumination switch is in an ON state. It is a figure which shows the image quality parameter in the case where an illumination switch is an ON state, and the case where an illumination switch is an OFF state. It is a figure which shows the degree of the backlight with respect to an image quality parameter. It is a figure which shows the degree which shows the brightness and contrast with respect to an image quality parameter. It is a figure which shows the degree of the hue with respect to an image quality parameter. It is a figure which shows the degree which shows the sharpness with respect to an image quality parameter. It is a figure which shows the spectral sensitivity of a human photoreceptor (cone). It is a figure which shows the number of photoreceptor cells of a rod with respect to a human visual axis.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Display part, 12 Image processing part, 13 Timing controller, 14 1st external light sensor, 15 2nd external light sensor, 16 Microcomputer, 17 Dimming part

Claims (6)

A display for displaying an image;
A front external light sensor for detecting an external light amount irradiated on the front side of the display unit;
A dimming information input unit for inputting ambient information indicating the surrounding situation;
A display device comprising: a control unit that controls the screen brightness of the display unit based on the external light amount and the ambient information. An external light sensor for detecting the amount of external light applied to the back side or the top side of the display unit;
The control unit adjusts the brightness of the screen based on the external light amount irradiated on the front side of the display unit, the external light amount irradiated on the back side or the top surface side of the display unit, and the ambient information. The display device according to claim 1 to be controlled.   The control unit obtains difference information between the external light amount irradiated on the front side of the display unit and the external light amount irradiated on the back side or the top surface side of the display unit, and the difference information and the surrounding information are obtained. The display device according to claim 2, wherein the brightness of the screen is controlled based on the display. A video processing unit for correcting the brightness, contrast, color density, hue, and sharpness of the image is provided.
The display device according to claim 3, wherein the control unit controls at least one of brightness, contrast, color density, hue, and sharpness of the image. The display unit is an LCD (Liquid Crystal Display) having a backlight,
The display device according to claim 4, wherein the control unit dims the backlight.   The display device according to claim 5, wherein the surrounding information is on / off of an illumination switch of a vehicle.

Images