JP2011059334A - Image display control device and control method - Google Patents

Abstract

An object of the present invention is to efficiently drive a backlight and reduce power consumption.
An image display control apparatus capable of dividing a display surface for displaying an image into a plurality of light source element regions and controlling brightness for each region, wherein the plurality of light source element regions are irradiated with each of the plurality of light source element regions. Based on the information on the light source element 143a and the displayed image, the brightness of the image displayed in each light source element area is determined, and the display data monitor unit 147 that controls the power supplied to the light source element 143a based on the determined brightness. And a backlight driving unit 144 that individually supplies power to the light source element 143a to emit light according to the control.
[Selection] Figure 3

Description

  The present invention relates to an image display control device and a control method, and more particularly to power saving of a display device.

  In recent years, computerization of information has been promoted, and for example, an LCD (Liquid Crystal Display) is used as a display device for displaying computerized information. As LCDs, there are transmissive, transflective, reflective, etc. depending on the light emission method, but in transmissive and transflective LCDs, a backlight is provided on the back of the liquid crystal panel, The backlight functions as a display device by illuminating the liquid crystal panel from the back.

  In such an LCD, power is consumed in driving the liquid crystal panel and the backlight, and in order to reduce the power consumption of the entire LCD, it is necessary to save power for each of the liquid crystal panel and the backlight. is there. Here, in the control of the backlight of the LCD mounted on the camera with a liquid crystal finder, in order to reduce power consumption, only the area of the display screen that is necessary for display is turned on, and the area that is not necessary for display Has been proposed (see, for example, Patent Document 1).

  However, in the technique disclosed in Patent Document 1, it is assumed that the type of image displayed for each range on the display screen is determined in advance. For example, in the case of an LCD mounted on a camera with a viewfinder disclosed in Patent Document 1, an LCD display screen such as an area where an image equivalent to a silver halide image is displayed, an area where character information is displayed, etc. The type of image displayed in each of the upper ranges is determined in advance.

  Therefore, when using the method disclosed in Patent Document 1 to reduce the power consumption of the backlight, the type of image displayed in each range on the display screen is determined for each device on which the LCD is mounted. It is necessary to configure a range for controlling the backlight according to the determination result, and to configure a driver corresponding to the backlight, which increases the design load during mounting. In addition, it is necessary to design a backlight for each device on which an LCD is mounted, which leads to a deterioration in productivity.

  Furthermore, when the image displayed for each range on the display screen cannot be determined in advance, for example, in the case of a PC (Personal Computer), a liquid crystal television, or the like, the method disclosed in Patent Document 1 may be applied. Can not. In the case of the method disclosed in Patent Document 1, an area where an image equivalent to a silver halide image is displayed is determined as one area, and the same backlight is controlled. Since there are necessary parts and unnecessary parts, the driving of the backlight is not completely efficient.

  The above-mentioned problem is not limited to the backlight of the LCD, but the entire area of the display surface, such as an organic EL (Electro-Luminescence) display device or an FED (Field Emission Display), is divided into a plurality of parts, respectively. If the display device can control the brightness for each area, it can be a problem as well. That is, the above problem can be a problem in the drive control of the light emitting means in the display device including the above-described LCD.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the efficiency of driving the light emitting means of the display device and reduce the power consumption.

  In order to solve the above problems, one embodiment of the present invention is an image display control device that can divide a display surface for displaying an image into a plurality of regions and control the luminance for each region. A luminance determination for determining a luminance of an image displayed in each of the plurality of areas based on information of a light source unit including a plurality of light source elements that irradiate each of the plurality of areas and an image displayed on the display surface; A drive control unit that controls power supplied to the light source element based on the determined luminance, and a light source drive unit that individually supplies power to the plurality of light source elements according to the control to emit light. It is characterized by that.

  Here, it is preferable that the drive control unit performs control so that the light source element corresponding to the area determined to be black is turned off.

  In addition, the luminance determination unit can determine the luminance by comparing the color difference of the image displayed for each of the plurality of regions with a predetermined threshold value.

  In addition, the brightness determination unit can determine the brightness by comparing a brightness difference between images displayed for each of the plurality of regions with a predetermined threshold value.

  The luminance determination unit can determine the luminance by comparing a contrast ratio of an image displayed for each of the plurality of regions with a predetermined threshold value.

  Moreover, it is preferable to further include a threshold value storage unit that stores the threshold value, and a threshold value changing unit that changes the threshold value according to a user operation.

  In addition, it is preferable that the luminance determination unit further includes a function of determining the luminance of at least one of the plurality of areas based on information regarding the luminance of an image displayed in the surrounding area.

  Moreover, it is preferable that the said brightness | luminance judgment part uses the brightness | luminance of each of these several area | region determined based on the information of the image displayed on the said display surface as information regarding the brightness | luminance of the image displayed on a surrounding area | region. .

  In addition, the luminance determination unit can determine the luminance of at least one of the plurality of areas based on an average value of weight values corresponding to the luminance of images displayed in the surrounding area.

  The display surface may be a liquid crystal panel surface of a liquid crystal display device, and the light source unit may be a backlight unit of the liquid crystal display device.

  On the other hand, according to another aspect of the present invention, a display surface for displaying an image is divided into a plurality of regions, and a plurality of light source elements that irradiate each region, and a light source drive that supplies power to the light source elements to emit light. And a drive control unit for controlling the power supplied to the light source element, wherein the brightness determination unit is configured to control the plurality of images based on information on an image displayed on the display surface. The brightness of the image displayed in each of the regions is determined, the drive control unit controls the power supplied to the light source element based on the determined brightness, and the light source driving unit controls the plurality of light sources according to the control. The device is characterized in that power is individually supplied to the element to emit light.

  According to the present invention, it is possible to efficiently drive the backlight and reduce power consumption.

1 is a block diagram illustrating a hardware configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a functional configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the function structure of the display panel which concerns on embodiment of this invention. It is a figure which shows typically arrangement | positioning of the light source element contained in the backlight unit which concerns on embodiment of this invention. It is a figure which shows the circuit structure of the light source element which concerns on embodiment of this invention. It is a figure which shows the display data monitor part which concerns on embodiment of this invention, and the function structure of its periphery. It is a figure which shows the aspect of the display image and brightness | luminance judgment which concern on other embodiment of this invention. It is a figure which shows the aspect of the adjacent area | region judgment which concerns on other embodiment of this invention. It is a flowchart which shows the brightness | luminance judgment operation | movement which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, an example in which a backlight control apparatus capable of reducing power consumption is mounted on an image forming apparatus as a multifunction peripheral (MFP) including functions of a printer, a scanner, a copier, and the like. explain.

  FIG. 1 is a block diagram illustrating a hardware configuration of an image forming apparatus 1 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment includes an engine that executes image formation in addition to the same configuration as an information processing terminal such as a general server or a PC (Personal Computer). That is, the image forming apparatus 1 according to the present embodiment includes a CPU (Central Processing Unit) 10, a RAM (Random Access Memory) 20, a ROM (Read Only Memory) 30, an engine 40, a HDD (Hard Disk Drive) 50, and an I / O. F60 is connected via the bus 90. Further, an LCD (Liquid Crystal Display) 70 and an operation unit 80 are connected to the I / F 60.

  The CPU 10 is a calculation unit and controls the operation of the entire image forming apparatus 1. The RAM 20 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 10 processes information. The ROM 30 is a read-only nonvolatile storage medium and stores a program such as firmware. The engine 40 is a mechanism that actually executes image formation in the image forming apparatus 1.

  The HDD 50 is a non-volatile storage medium that can read and write information, and stores an OS (Operating System), various control programs, application programs, and the like. The I / F 60 connects and controls the bus 90 and various hardware and networks. The LCD 70 is a visual user interface for the user to check the state of the image forming apparatus 1. The operation unit 80 is a user interface for a user to input information to the image forming apparatus 1 such as a keyboard and a mouse.

  In such a hardware configuration, a program stored in a recording medium such as the ROM 30 or the HDD 50 or an optical disk (not shown) is read out to the RAM 20 and operates according to the control of the CPU 10 to constitute a software control unit. A functional block that realizes the functions of the image forming apparatus 1 according to the present embodiment is configured by a combination of the software control unit configured as described above and hardware.

  Next, the functional configuration of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating a functional configuration of the image forming apparatus 1 according to the present embodiment. As shown in FIG. 2, the image forming apparatus 1 according to the present embodiment includes a controller 100, an ADF (Auto Document Feeder) 110, a scanner unit 120, a paper discharge tray 130, a display panel 140, and a paper feed table. 150, a print engine 160, a paper discharge tray 170, and a network I / F 180.

  The controller 100 includes a main control unit 101, an engine control unit 102, an input / output control unit 103, an image processing unit 104, and an operation display control unit 105. As shown in FIG. 2, the image forming apparatus 1 according to the present embodiment is configured as a multifunction machine having a scanner unit 120 and a print engine 160. In FIG. 2, the electrical connection is indicated by solid arrows, and the flow of paper is indicated by broken arrows.

  The display panel 140 is an output interface that visually displays the state of the image forming apparatus 1 and is an input when the user directly operates the image forming apparatus 1 or inputs information to the image forming apparatus 1 as a touch panel. It is also an interface (operation unit). The display panel 140 according to the present embodiment has a configuration for reducing the power consumption of the backlight drive mechanism, and this is the gist of the present embodiment. Detailed functions of the display panel 140 will be described later. The network I / F 180 is an interface for the image forming apparatus 1 to communicate with other devices via the network, and uses an Ethernet (registered trademark) or a USB (Universal Serial Bus) interface.

  The controller 100 is configured by a combination of software and hardware. Specifically, a control program such as firmware stored in a ROM 30, a nonvolatile memory, and a nonvolatile recording medium such as the HDD 50 or an optical disk is loaded into a volatile memory (hereinafter referred to as a memory) such as the RAM 20, and is controlled by the CPU 10. The controller 100 is configured by a software control unit configured according to the above and hardware such as an integrated circuit. The controller 100 functions as a control unit that controls the entire image forming apparatus 1.

  The main control unit 101 plays a role of controlling each unit included in the controller 100, and gives a command to each unit of the controller 100. The engine control unit 102 serves as a drive unit that controls or drives the print engine 160, the scanner unit 120, and the like. The input / output control unit 103 inputs a signal or a command input via the network I / F 180 to the main control unit 101. The main control unit 101 also controls the input / output control unit 103 to access other devices via the network I / F 180.

  The image processing unit 104 generates drawing information based on the print information included in the input print job, under the control of the main control unit 101. The drawing information is information for drawing an image to be formed in the image forming operation by the print engine 160 as an image forming unit. Also, the print information included in the print job is information converted into a format that can be recognized by the image forming apparatus 1 by a printer driver installed in an information processing apparatus such as a PC, and is described by PDL (Page Description Language). Information. The operation display control unit 105 displays information on the display panel 140 or notifies the main control unit 101 of information input via the display panel 140.

  When the image forming apparatus 1 operates as a printer, first, the input / output control unit 103 receives a print job via the network I / F 180. The input / output control unit 103 transfers the received print job to the main control unit 101. When receiving the print job, the main control unit 101 controls the image processing unit 104 to generate drawing information based on the print information included in the print job.

  When drawing information is generated by the image processing unit 104, the engine control unit 102 executes image formation on a sheet conveyed from the paper feed table 150 based on the generated drawing information. That is, the print engine 160 functions as an image forming unit. As a specific mode of the print engine 160, an image forming mechanism using an ink jet method, an image forming mechanism using an electrophotographic method, or the like can be used. The document on which the image has been formed by the print engine 160 is discharged to the discharge tray 170.

  When the image forming apparatus 1 operates as a scanner, the operation display control is performed according to a user operation on the display panel 140 or a scan execution instruction input from an information processing terminal for an external client via the network I / F 180. The unit 105 or the input / output control unit 103 transfers a scan execution signal to the main control unit 101. The main control unit 101 controls the engine control unit 102 based on the received scan execution signal.

  The engine control unit 102 drives the ADF 110 and conveys the document to be imaged set on the ADF 110 to the scanner unit 120. Further, the engine control unit 102 drives the scanner unit 120 and images a document conveyed from the ADF 110. If no original is set on the ADF 110 and the original is set directly on the scanner unit 120, the scanner unit 120 images the set original according to the control of the engine control unit 102. That is, the scanner unit 120 operates as an imaging unit.

  In the imaging operation, an imaging element such as a CCD included in the scanner unit 120 optically scans the document, and imaging information generated based on the optical information is generated. The engine control unit 102 transfers the imaging information generated by the scanner unit 120 to the image processing unit 104. The image processing unit 104 generates image information based on the imaging information received from the engine control unit 102 according to the control of the main control unit 101. Image information generated by the image processing unit 104 is stored in a storage medium attached to the image forming apparatus 1 such as the HDD 40. That is, the scanner unit 120, the engine control unit 102, and the image processing unit 104 work together to function as a document reading unit.

  The image information generated by the image processing unit 104 is stored in the HDD 40 or the like as it is according to a user instruction or transmitted to an external device via the input / output control unit 103 and the network I / F 180. That is, the scanner unit 120 and the engine control unit 102 function as an image input unit.

  Further, when the image forming apparatus 1 operates as a copying machine, the image processing unit 104 generates drawing information based on imaging information received by the engine control unit 102 from the scanner unit 120 or image information generated by the image processing unit 104. To do. Based on the drawing information, the engine control unit 102 drives the print engine 160 as in the case of the printer operation.

  Next, the display panel 140, which is the gist of the present embodiment, will be described in more detail. FIG. 3 is a diagram showing a functional configuration of the display panel 140 according to the present embodiment. As shown in FIG. 3, the display panel 140 according to the present embodiment includes a touch panel 141, a liquid crystal panel 142, a backlight unit 143, a backlight driving unit 144, a liquid crystal panel driving unit 145, a touch panel driving unit 146, and a display data monitoring unit. 147.

  The touch panel 141 and the touch panel drive unit 146 are configured for the display panel 140 to function as an operation unit, and are configured by a capacitance sensor in the present embodiment. That is, an electric field is formed on the surface of the touch panel 141 by the touch panel drive unit 146. When the user touches the surface of the touch panel 141, the electric charge of the touched portion is discharged and the potential changes. The touch panel drive unit 146 recognizes the position touched by the user on the surface of the touch panel 141 by detecting the change in the potential.

  The liquid crystal panel 142 is configured by sealing a liquid crystal material whose transmittance is changed by applying a voltage in a space between transparent electrodes. The liquid crystal panel driving unit 145 applies a voltage to the electrode corresponding to each pixel on the panel surface of the liquid crystal panel 142 to control the transmittance, and the backlight unit 143 illuminates the liquid crystal panel 142 from the back side. An image is displayed on the panel surface 142.

  The backlight unit 143 is a light source unit that irradiates the liquid crystal panel 142 and displays an image as described above. As shown in FIG. 4, in the backlight unit 143 according to the present embodiment, a plurality of light source elements 143a are arranged on a matrix, and each light source element 143a is obtained by dividing the entire liquid crystal panel 142 on the matrix. Irradiate the area. Thereby, the backlight unit 143 can irradiate the entire display range of the liquid crystal panel 142. The plurality of light source elements 143a are configured to be individually turned on / off and the brightness can be adjusted by the backlight driving unit 144. By individually controlling the plurality of light source elements 143a, the light source elements 143a of the present embodiment can be controlled. The power saving that is the gist is realized.

  As shown in FIG. 5, an LED (Light Emitting Diode) can be used as the light source element 143 a. A drive terminal is connected to each of the LEDs arranged on the matrix, and by individually controlling a voltage applied to each terminal, it is possible to turn on / off each LED and adjust the luminance. .

  When an LED is used as the light source element 143a, a light source element 143a is configured by using a white LED or R (red), G (green), and B (blue) LEDs as one set to mix three colors of light. Some produce white light. Also, a method of obtaining white by combining phosphors with short wavelength LEDs, a method of obtaining white by combining phosphors with blue LEDs, or a method of obtaining white by combining yellow phosphors with blue LEDs, etc. There is. In addition, as the light source element 143a, a fluorescent tube such as a CCFL (Cold Cathode Fluorescent Lamp) can be used.

  The backlight drive unit 144 is a light source drive unit that individually drives each light source element 143a by applying a voltage to each drive terminal of each light source element 143a as described in FIG. The backlight driving unit 144 controls lighting / extinguishing or luminance of each light source element 143a based on a control signal input from the display data monitoring unit 147.

  As described above, the liquid crystal panel drive unit 145 controls the transmittance of each pixel on the display surface of the liquid crystal panel 142 by controlling the voltage applied to the transparent electrode of the liquid crystal panel 142. The liquid crystal panel drive unit 145 controls the liquid crystal panel 142 based on the image signal input from the operation display control unit 105.

  The display data monitor unit 147 is a configuration according to the gist of the present embodiment. Specifically, the display data monitor unit 147 determines a voltage to be applied to each drive terminal of each light source element 143a based on the image signal input from the operation display control unit 105. The voltage applied to the drive terminal is a voltage applied by the backlight drive unit 144 to each drive terminal of each light source element 143a. In other words, in the present embodiment, the backlight drive unit 144 and the display data monitor unit 147 function together as an image display control device. A detailed configuration of the display data monitor unit 147 will be described with reference to FIG.

  FIG. 6 is a block diagram showing a configuration of the display data monitor unit 147 according to the present embodiment and peripheral connection relationships. As shown in FIG. 6, the display data monitor unit 147 includes a backlight control unit 147a, a display data filter unit 147b, and a display data filter setting unit 147c. The configuration of the display data monitor unit 147 as shown in FIG. 6 may be realized by hardware as an integrated circuit, or may be realized by software using the configuration of the CPU 10, RAM 20, etc. described in FIG. good.

  The backlight control unit 147 a is configured to output a control signal to the backlight drive unit 144 in the display data monitor unit 147. As described above, the control signal is a signal for controlling the voltage applied to each drive terminal of each light source element 143a by the backlight drive unit 144. That is, the backlight control unit 147a functions as a drive control unit that controls the power supplied to the light source element. The backlight control unit 147a outputs the control signal according to the result of filtering by the display data filter unit 147b.

  The display data filter unit 147b divides the entire display surface of the liquid crystal panel 142 in accordance with the light source element 143a as described in FIG. 4 based on the display data input from the operation display control unit 105 to the liquid crystal panel drive unit 145. It is a luminance determination unit that recognizes display data for each area (hereinafter referred to as a light source element area) and determines the luminance for each light source element area according to the recognition result. The display data filter unit 147b inputs the luminance for each light source element region determined in this way to the backlight control unit 147a as a result of the filtering described above.

  The backlight control unit 147a determines the drive voltage of each light source element 143 based on the luminance determination result input in this manner, and outputs the above-described control signal. The determination of luminance for each light source element region by the display data filter unit 147b will be described in detail later.

  The display data filter setting unit 147c holds parameter values when the display data filter unit 147b determines the luminance for each light source element region based on the display data. The display data filter unit 147b executes the determination of the luminance for each light source element region described above based on the parameter value held by the display data filter setting unit 147c. Examples of the parameter value include a filtering method, a threshold value for determining luminance, and the like. That is, the display data filter setting unit 147c functions as a threshold value storage unit.

  The display data filter setting unit 147c acquires the parameter value from the operation display control unit 105, and holds the parameter value. For example, when the image forming apparatus 1 is turned on, the operation display control unit 105 inputs the parameter value to the display data filter unit 147c according to the control of the main control unit 101. The initial values of the parameter values are stored in, for example, the ROM 30 and the HDD 40 shown in FIG. In addition, the user can arbitrarily set the parameter value by operating the display panel 140. That is, the display data filter setting unit 147c also functions as a threshold value changing unit.

  Next, a mode of filtering by the display data filter unit 147b according to the present embodiment will be described. FIGS. 7A, 7B, and 7C are diagrams illustrating aspects of filtering by the display data filter unit 147b. 7A shows an image (hereinafter referred to as a display image) that is input from the operation display control unit 105 to the liquid crystal panel drive unit 145 and displayed on the liquid crystal panel 142, that is, a display acquired by the display data filter unit 147b. It is a figure which shows the image of data.

  As shown in FIG. 7A, the display image according to the present embodiment includes a photographic area A and a black outer frame area B. Further, the outer frame area B has a portion where characters are displayed. When the data filter unit 147b performs filtering on such a display image and determines the luminance, for example, FIG. 7B is obtained. FIG. 7B is a diagram illustrating an example of luminance for each light source element region determined by the display data filter unit 147b based on the image illustrated in FIG. As shown in FIG. 7B, as a result of filtering by the display data filter unit 147b, it is determined that the photo area A is “normal”, that is, the luminance is normal, and the outer frame area B is “low”, that is, the luminance is high. It is judged to be low.

  FIG. 7C is a diagram illustrating another example of luminance for each light source element region determined based on the image illustrated in FIG. As shown in FIG. 7C, as a result of filtering by the display data filter unit 147b, it is determined that the photo area A is “normal”, that is, the brightness is normal, as in the case of FIG. 7B. Further, since the outer frame area B is black, as a general rule, the light source element is turned off as indicated as “off”, and only the portion where characters are displayed is determined to be “low”, that is, the luminance is low. Has been.

  The difference between the determination results in FIGS. 7B and 7C is due to the difference in the parameters of the display data filter setting unit 147c. Hereinafter, an aspect of luminance determination by the display data filter unit 147b will be described. As modes of brightness determination by the display data filter unit 147b, modes of color number determination, color difference determination, brightness difference determination, contrast determination, and the like are conceivable. In the case of determining the number of colors, the display data filter unit 147b determines the luminance based on the number of colors of the pixels included in each light source element region based on the acquired display data.

  For example, general display data is 8 bits each of RGB (Red, Green, Blue) and about 16 million colors. The table data filter unit 147b counts the number of colors represented by the RGB data for each light source element region, and compares the threshold value provided for the count result with the count result. Thus, it is determined whether the number of colors is “large”, “normal”, or “small”. Then, the display data filter unit 147b converts the determination results such as “large”, “normal”, and “low”, and the luminance “high”, “normal” as shown in FIGS. The judgment result such as “,” “low” is obtained.

  7C is a control mode of the light source element 143a applied when the color of the pixel included in the light source element region is black, and does not supply power to the light source element 143a. Indicates to turn off. When determining “OFF” shown in FIG. 7C, the display data filter unit 147b refers to the RGB value of the display data, and determines that it is “OFF” if the color of the light source element region is black. To do. The display data filter unit 147b determines whether or not to determine “off” based on the parameter value held by the display data filter setting unit 147c.

  Note that the RGB value of one pixel is indicated by a 6-digit hexadecimal number such as “000000” or “FFFFFF”. The 1st and 2nd digits indicate R, the 4th digit indicates G, the 5th and 6th digits indicate B, respectively. Therefore, if the 6-digit hexadecimal number is the same, it can be determined that the colors are the same. In addition to the case where the 6-digit hexadecimal numbers completely match, a predetermined width may be provided in the range determined to be the same.

  In the case of the color difference determination, the display data filter unit 147b determines the luminance by obtaining the color difference of the pixels included in the light source element region and comparing the obtained color difference with a predetermined threshold value. Specifically, the display data filter unit 147b first calculates the difference between the maximum value and the minimum value of each color of R, G, and B of the pixels included in the light source element region in the above-described RGB data.

  For example, the color difference between the color represented by “FFFF00” in hexadecimal (yellow) and the color (blue) represented by “0000FF” is R: FF-00 = FF (decimal 255), G: FF-00 = FF (decimal number 255), B: FF-00 = FF (decimal number 255), and the total is “765”. In this way, the display data filter unit 147 obtains the color difference for each light source element region and compares it with the threshold value set in the display data filter setting unit 147c, so that the color difference is “large” with respect to the obtained color difference. It is judged whether it is “normal” or “small”. The determination result is converted to obtain determination results such as “high”, “normal”, and “low” in luminance.

In the case of the brightness difference determination, the display data filter unit 147b determines the brightness by calculating the brightness difference of the pixels included in the light source element region and comparing the determined brightness difference with a predetermined threshold value. Specifically, the display data filter unit 147b obtains the brightness of each color by applying the above-described RGB data to the following equation (1).

Here, in the above formula (1), R, G, and B are values that represent each value of the RGB data described above in decimal. Further, “lightness coefficient _R ”, “lightness coefficient _G ”, and “lightness coefficient _B ” are coefficients for converting the values of R, G, and B into lightness values, respectively. In this way, the brightness of the pixels included in each light source element region is obtained, and the difference between the maximum value and the minimum value is obtained, whereby the brightness difference in each light source element region can be obtained.

  In this way, the display data filter unit 147b obtains the brightness difference for each light source element region, and compares it with the threshold value set in the display data filter setting unit 147c. It is determined whether it is “large”, “normal”, or “small”. The determination result is converted to obtain determination results such as “high”, “normal”, and “low” in luminance.

  In the case of contrast determination, the display data filter unit 147b determines the brightness by determining the contrast ratio of the image displayed for each light source element region and comparing the determined contrast ratio with a predetermined threshold value. Specifically, the display data filter unit 147b obtains the brightness of each color by applying the above-described RGB data to the above-described equation (1).

  In this way, by obtaining the brightness of the pixels included in each light source element region and obtaining the ratio between the maximum value and the minimum value, the contrast ratio in each light source element region can be obtained. The display data filter unit 147b obtains the contrast ratio for each light source element region in this way and compares it with the threshold value set in the display data filter setting unit 147c. It is determined whether it is “large”, “normal”, or “small”. The determination result is converted to obtain determination results such as “high”, “normal”, and “low” in luminance.

  As the determination based on the display image, in addition to the above-described aspect, for example, an aspect in which RGB data is converted into YCbCr data and the determination is made based on Y of the YCbCr data, that is, the luminance value. In this case, the display data filter unit 147b compares the threshold value set for the Y value with the Y value, and determines whether the luminance is “high”, “normal”, or “low”. The threshold value for Y is held in the display data filter setting unit 147c, as in the other embodiments described above.

  As described above, in the determination based on the display image according to the present embodiment, the luminance of the light source element 143a by the normal driving voltage is set to “normal”, and there is a problem in the visibility of the image even if the luminance is decreased according to the display image. The portion where there is no brightness is lowered, and the portion where the luminance should be raised is raised in order to improve the visibility of the image. Thereby, the power consumption of the entire backlight unit 143 can be reduced while improving the visibility without impairing the visibility.

  Further, the display data filter unit 147b according to the present embodiment, in addition to the determination based on the display image as shown in FIGS. A determination based on the luminance of the adjacent light source element region (hereinafter referred to as adjacent region determination) is performed on the luminance determined for each region. Details of this adjacent area determination will be described below.

  By performing the filtering as described with reference to FIGS. 7A to 7C, only one luminance is determined to be “high” in a region where “normal” or “low” luminance or “extinction” continues. May exist. For example, when the number of colors and the color difference of the display image are in the vicinity of a set threshold value, a case where only one region exceeds the threshold value may be considered. For such a region, the luminance can be lowered to “normal”, and such control is preferable from the viewpoint of power saving.

  For this reason, the display data filter unit 147b according to the present embodiment performs adjacent region determination in addition to the above-described display image determination. FIGS. 8A and 8B are diagrams illustrating an aspect of determining an adjacent region. In the case of FIG. 8A, in the state before the determination, the central light source element region having the luminance “high” is the light source element region having the luminance “normal”, “low”, and “off” in the vertical and horizontal directions. The light source element regions of “normal”, “low”, and “off” are adjacent to the same luminance region, while the central region is not adjacent to the same luminance region. . In such a case, the display data filter unit 147b determines to decrease the luminance of the central region by one step. In the case of FIG. 8A, since the original luminance is “high”, it is changed to “normal”.

  In the case of FIG. 8B, in the state before the determination, the central light source element region having the luminance “high” has the same luminance as the region adjacent to the upper side. Further, the region adjacent to the upper side is further adjacent to another region having a luminance of “high”. In such a case, the display data filter unit 147b does not change the luminance for the central region.

  As a specific method for performing the determination as shown in FIGS. 8A and 8B, for example, three points, two points, and one for luminance “high”, “normal”, “low”, and “off”, respectively. A method of performing weighting using weight values such as points and 0 points, obtaining an average value to which the above-mentioned weight values are applied with respect to the luminance of eight regions around the target region, and determining based on the average value Can be considered. In this case, the display data filter unit 147b sets a threshold for the calculated average value, and applies any one of “increase the central luminance by one”, “the central luminance as it is”, or “decrease the central luminance by one”. You can decide what to do.

  For example, two values such as “1.4” and “2.5” may be used as the threshold value. That is, the display data filter unit 147b determines that the calculated average value is “less than 1.4 points”, “1.4 points or more and less than 2.5 points”, “2.5 points or more. ”And determine whether to apply“ decrease the central luminance by one ”,“ the central luminance as it is ”, or“ increase the central luminance by one ”.

  When such a method is applied to the examples of FIGS. 8A and 8B, in the case of FIG. 8A, the average value of the surrounding eight regions is “1.125”. If it is less than ", the process of" decrease the central brightness by 1 "is applied. On the other hand, in the case of FIG. 8B, since the average value of the surrounding eight regions is “1.625”, “1.4 points or more and less than 2.5 points” is obtained. It becomes.

  Here, even when the process of “decrease the central luminance by 1” is applied as a result of the determination, if the central luminance is “low”, it is not set to “off”. Keep “low”. Thereby, it can prevent that the image which should be displayed is no longer displayed. Even if the process of “increasing the central luminance by 1” is applied, if the central luminance is “high”, the luminance is not further increased and “high” is maintained. To do.

  In determining the adjacent region, not only the luminance information after the above-described display image determination but also each aspect of display image determination, that is, in each determination process such as color number determination, color difference determination, brightness difference determination, and contrast determination, etc. Further, the number of colors, the color difference, the brightness difference, and the contrast ratio can be weighted by the weight values as described above, and the processing by calculating the average value as described above can be executed.

  Further, with respect to the luminance “high”, “normal”, “low”, and “off”, the weight values such as 3 points, 2 points, 1 point, and 0 point are examples, and the display data filter setting unit 147c. It is possible to change the weight value by changing the parameter value held by.

  In the above description, the determination is made based on the average value of the luminance weight values of the eight surrounding areas. However, the determination may be made based on the difference between the calculated average value and the luminance of the central area. Is possible. For example, in the case of FIG. 8A, the average value of the surroundings is “1.125”, whereas the luminance in the center region is “high”, so that it is “3”. The average value is “−1.875” with respect to the luminance of the central region. For example, “± 1.25” is set as the threshold value for the calculated value. Then, if the calculated value is “+1.25” or more, the display data filter unit 147b performs a process of “increasing the central luminance by 1”, and if it is “−1.25” or less, The process of “decrease brightness by 1” can be performed.

  In the examples of FIGS. 8A and 8B, eight regions around the target optical element region are determined. For example, in addition to the eight surrounding regions, two regions, upper, lower, left, and right are used. Twelve areas including the adjacent area may be set as the determination target, or the determination target may be further expanded.

  Note that such adjacent region determination processing is further executed in addition to the above-described display image determination, and even if only display image determination is executed, the problem according to the present embodiment can be solved. It is.

  FIG. 9 is a flowchart showing a filtering operation by the display data filter unit 147b according to the present embodiment. FIG. 9 shows a determination operation for one light source element region. That is, in practice, the operation shown in FIG. 9 is executed for all light source element regions.

  As illustrated in FIG. 9, when the display data filter unit 147b acquires image data (S901), the display data filter unit 147b determines whether or not the pixels included in the light source element region are black (S902). When the pixel included in the light source element region is black (S902 / YES), the display data filter unit 147b sets the light source element region to “off” (S903).

  When the pixel included in the light source element region is not black (S902 / NO), the display data filter unit 147b performs the above-described display image determination (S904). In the process of S904, the display data filter unit 147b may execute any one of the above-described color number determination, color difference determination, brightness difference determination, and contrast determination, or a combination of a plurality of processes. Also good.

  When the display image determination in S904 is completed, determination results such as “high”, “normal”, and “low” in luminance are obtained as described above. Based on the determination result thus obtained, the display data filter unit 147b executes the adjacent region determination as described above (S905). By the processing of S905, a determination result is obtained in which only one point protrudes and a high luminance area or the like is corrected. The display data filter unit 147b outputs the determination result obtained through S903, S904, and S905 to the backlight control unit 147a (S906), and ends the process. By such processing, the filtering processing by the display data unit 147b is completed.

  As described above, in the backlight control device of the display panel 140 according to the present embodiment, it is possible to control the illuminance of the light source element of the backlight for each area obtained by dividing the display surface into a plurality of areas. The luminance is determined based on the image information of the displayed image, and the illuminance of each light source element is controlled according to the determination result. Accordingly, it is possible to reduce the driving power of the light source element in an area where the illuminance is unnecessary or low without impairing the visibility of the image displayed on the display surface, thereby saving power of the display device. It becomes possible.

  In the above embodiment, the backlight control of the liquid crystal display device has been described as an example. However, the gist of the present embodiment is that, in the luminance control of the image display device, the necessary luminance is determined based on the displayed image, and the luminance is adjusted based on the determination result, thereby reducing the driving power of the light emitting means. There is to save. Therefore, the present invention can also be applied to an organic EL (Electro-Luminescence) display device, an FED (Electro-Luminescence) display device, an FED (Field Emission Display), and the like.

  For example, when the control method according to the above embodiment is applied to an organic EL display device, the display data filter unit 147b and the display data filter setting unit 147c can be the same as those in the above embodiment, and the backlight Instead of the control unit 147a, a light emission amount control unit that controls a voltage applied to the organic material is used. Then, based on the determination result of the display data filter unit 147b, the light emission amount control unit inputs a control signal to the drive unit that drives the organic material that is the light source element. Thereby, the effect similar to the said embodiment can be acquired.

  In addition, when the control method according to the above embodiment is applied to the FED, the display data filter unit 147b and the display data filter setting unit 147c can be the same as those in the above embodiment, and the backlight control unit Instead of 147a, a light emission amount control unit for controlling the voltage applied to the cathode terminal is used. In the same manner as described above, the light emission amount control unit inputs a control signal to the drive unit that drives the cathode terminal, which is a light source element, based on the determination result of the display data filter unit 147b. Thereby, the effect similar to the said embodiment can be acquired.

  In the above-described embodiment, the display panel 140 mounted on the image forming apparatus 1 has been described as an example. However, the present invention is not limited to this, and the present invention can be applied to general image display apparatuses such as a television receiver and a PC display monitor. It is possible to obtain the same effect as described above.

1 image forming apparatus,
10 CPU,
20 RAM,
30 ROM,
40 engines,
50 HDD,
60 I / F,
70 LCD,
80 operation unit,
90 bus,
100 controller,
101 Main control unit,
102 engine control unit,
103 I / O control unit,
104 image processing unit,
105 operation display control unit,
110 ADF,
120 scanner unit,
130 paper output tray,
140 display panel,
141 touch panel,
142 LCD panel,
143 backlight unit,
143 light source element,
144 Backlight drive unit,
145 LCD panel driver,
146 touch panel drive unit,
147 display data monitor unit,
147a backlight control unit,
147b Display data filter section,
147c display data filter setting section,
150 paper feed table,
160 print engine,
170 paper output tray,
180 Network I / F

JP-A-10-319491

Claims (11)

An image display control apparatus capable of dividing a display surface for displaying an image into a plurality of areas and controlling the luminance for each area,
A light source unit comprising a plurality of light source elements for irradiating each of the plurality of regions;
A luminance determining unit that determines the luminance of the image displayed in each of the plurality of regions based on information of the image displayed on the display surface;
A drive control unit for controlling power supplied to the light source element based on the determined luminance;
An image display control device comprising: a light source drive unit that individually supplies power to the plurality of light source elements to emit light according to the control.   The image display control apparatus according to claim 1, wherein the drive control unit performs control so that the light source element corresponding to the area determined to be black is turned off.   3. The image display control according to claim 1, wherein the luminance determination unit determines the luminance by comparing a color difference of an image displayed for each of the plurality of regions with a predetermined threshold value. apparatus.   4. The image according to claim 1, wherein the brightness determination unit determines the brightness by comparing a brightness difference of an image displayed for each of the plurality of regions with a predetermined threshold value. 5. Display control device.   5. The brightness determination unit according to claim 1, wherein the brightness determination unit determines the brightness by comparing a contrast ratio of an image displayed for each of the plurality of regions with a predetermined threshold. Image display control device. A threshold storage unit storing the threshold;
The image display control apparatus according to claim 3, further comprising a threshold value changing unit that changes the threshold value according to a user operation.   The brightness determination unit further includes a function of determining brightness of at least one of the plurality of areas based on information related to brightness of an image displayed in a surrounding area. The image display control device according to any one of the above.   The luminance determination unit uses the luminance of each of the plurality of areas determined based on information of an image displayed on the display surface as information on the luminance of an image displayed in a surrounding area. The image display control device according to claim 7.   The brightness determination unit determines the brightness of at least one of the plurality of areas based on an average value of weight values according to the brightness of an image displayed in the surrounding area. An image display control device according to claim 1. The display surface is a liquid crystal panel surface of a liquid crystal display device,
The image display control device according to claim 1, wherein the light source unit is a backlight unit of a liquid crystal display device. A plurality of light source elements that divide a display surface for displaying an image into a plurality of areas and irradiate each area, a light source driving unit that supplies power to the light source elements to emit light, and power that is supplied to the light source elements A control method of an image display control device including a drive control unit for controlling
A luminance determination unit that determines the luminance of the image displayed in each of the plurality of regions based on information of the image displayed on the display surface;
A drive control unit that controls power supplied to the light source element based on the determined luminance;
The light source driving unit supplies power to the plurality of light source elements individually according to the control to cause light emission.

Images