JP5291555B2 - MONITOR DEVICE AND SCREEN BRIGHTNESS CONTROL METHOD - Google Patents

Description

  The present invention relates to a monitor device installed at a train station platform or the like, and a screen brightness control method of the monitor device.

  In a conventional monitor device, a liquid crystal display unit with a narrow viewing angle is fixedly mounted in the housing, so that the incident state of direct sunlight and the illumination device such as a fluorescent lamp installed in the surrounding area are illuminated. Depending on the situation and the reflection situation of the vehicle, surrounding buildings, etc., the visibility of various information displayed on the liquid crystal display unit is poor, and there is a problem that accurate monitoring by the monitor device is hindered. In order to solve such a problem, a monitor device capable of adjusting the angle between the liquid crystal display unit and the hood is known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2006-154592

  In the monitor device shown in Patent Document 1, since the angle between the hood and the liquid crystal display unit can be adjusted, a certain degree of visibility can be secured, but light from the outside such as sunlight is reflected on the screen. There is a problem that it is not possible to completely solve the problem. In order to solve such a problem that external light is reflected on the screen surface of the display unit, a transparent plate that suppresses the reflection of the surface is attached to the front surface of the screen. If is attached, reflection can be suppressed to some extent. However, since the fluorescent tube used for the backlight of the monitor device using liquid crystal has low luminance, there is a problem that sufficient brightness of the display screen cannot be secured if a transparent plate that suppresses reflection is attached.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a monitor device and a screen brightness control method capable of ensuring sufficient display screen brightness.

  The present invention is a monitor device including a backlight using a high-intensity white LED and a liquid crystal display device that displays an image captured by a camera, and an optical sensor that detects brightness around the monitor device; And control means for adjusting the light emission luminance of the backlight in accordance with the output value of the photosensor.

  The present invention includes a plurality of the optical sensors, wherein at least one optical sensor detects light applied to the display screen side of the liquid crystal display device, and the other optical sensors irradiate a surface different from the display screen. It is characterized by detecting light to be transmitted.

  In the present invention, when the output value of one photosensor of the plurality of photosensors exceeds a first threshold, the control means sets the emission luminance of the backlight to the first emission luminance. When the output values of all of the plurality of photosensors are equal to or lower than the second threshold value while the first light emission luminance is set, the light emission luminance of the backlight is changed to the first light emission luminance. The light emission luminance is set to 2.

  The present invention provides a backlight using a high-intensity white LED, a liquid crystal display device that displays an image captured by a camera, an optical sensor that detects the brightness around the monitor device, and a screen brightness of the liquid crystal display A screen brightness control method in a monitor device comprising a control means for controlling the control device, wherein the control means adjusts the light emission brightness of the backlight according to the output value of the photosensor.

  According to the present invention, a monitor device including a backlight using a high-intensity white LED and a liquid crystal display device that displays an image captured by a camera, a light sensor that detects brightness around the monitor device, Control means that adjusts the light emission luminance of the backlight according to the output value of the light sensor, so that the effect of ensuring sufficient display screen brightness even when the ambient brightness changes is obtained. It is done.

It is a block diagram which shows the structure of one Embodiment of this invention. 3 is a flowchart showing an operation for controlling the luminance of backlights 31 and 32 shown in FIG. 1. It is the front view and back view of a monitor apparatus which show the attachment position of the optical sensors 21-24 shown in FIG. It is explanatory drawing which shows the relationship between ambient brightness (illuminance) and screen brightness | luminance.

  Hereinafter, a monitor device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment. In this figure, reference numeral 1 denotes a control unit that controls the screen brightness of the monitor device. Reference numerals 21 to 24 are optical sensors that output electrical signals corresponding to the intensity of received light. Reference numerals 31 and 32 denote backlights in which white LEDs (Light Emitting Diodes) with high luminance are two-dimensionally arranged. The white LEDs constituting the backlights 31 and 32 can adjust the light emission luminance by changing the supplied current value.

  Reference numerals 41 and 42 denote liquid crystal displays that display color images, and a bright image can be displayed by illuminating the backlights 31 and 32 from the back side. Reference numerals 51 and 52 denote cameras that capture images for checking the state of passengers on the train conductor at the station platform. Images captured by the cameras 51 and 52 are displayed on the liquid crystal displays 41 and 42. Although FIG. 1 shows a configuration including two cameras 51 and 52 and two liquid crystal displays, a configuration including three or more cameras and three or more liquid crystal displays may be used as necessary. Good.

  Reference numeral 11 denotes a CPU (Central Processing Unit) that controls the light emission luminance of the backlights 31 and 32. Reference numeral 12 denotes an input port that inputs sensor signals output from the four optical sensors 21 to 24 and passes them to the CPU 11. Reference numeral 13 denotes an LED driving unit that controls the current supplied to the LEDs constituting the backlights 31 and 32 to cause the backlights 31 and 32 to emit light. Reference numeral 14 denotes an output port that receives a control signal output from the CPU 11 and transfers it to the LED drive unit 13.

  Here, with reference to FIG. 3, the attachment position of the optical sensors 21-24 shown in FIG. 1 is demonstrated. FIG. 3 is a front view and a rear view showing the external appearance of the monitor device. As shown in FIG. 3, of the four optical sensors 21 to 24, the two optical sensors 21 and 22 receive the light emitted to the screens of the liquid crystal displays 31 and 32, so that the liquid crystal displays 31 and 32 can receive light. 32 is attached to the screen display side (front side). Further, the remaining two photosensors 23 and 24 are attached one by one on the left and right sides of the back side of the monitor device so that the light irradiated on the back side of the monitor device can be received.

  The attachment positions of the optical sensors 21 and 22 shown in FIG. 3 are merely examples, and the attachment positions may be anywhere as long as the light irradiated on the screen display side of the liquid crystal displays 31 and 32 can be received efficiently. Further, the attachment positions of the optical sensors 23 and 24 shown in FIG. 3 are also an example, and any attachment positions may be used as long as the light irradiated on the back side of the monitor device can be received efficiently.

Next, an operation in which the CPU 11 shown in FIG. 1 controls the light emission luminance of the backlights 31 and 32 according to the ambient brightness will be described with reference to FIG. FIG. 2 is a flowchart showing an operation in which the CPU 11 shown in FIG. 1 controls the light emission luminance of the backlights 31 and 32 according to the ambient brightness. First, when the power of the monitor device is turned on, the CPU 11 outputs a control signal to the LED drive unit 13 via the output port 14. This control signal is a signal indicating that the backlights 31 and 32 are caused to emit light so that the screen luminance of the liquid crystal displays 41 and 42 is 1000 cd / m ² . The LED drive unit 13 receiving this control signal supplies a current value to be supplied to the LEDs constituting the backlights 31 and 32.

A current value to be supplied to the LED is stored in the LED driving unit 13 so that the screen luminance is 1000 cd / m ² . Here, when a predetermined current value (the maximum value of the current value that can be supplied to the LED) is set so that the light emission luminance of the LEDs constituting the backlights 31 and 32 becomes the maximum value, the screen luminance of the liquid crystal displays 41 and 42 becomes 1000 cd. / M ² . When a current value to be supplied to the LED is supplied from the LED drive unit 13, images captured by the cameras 51 and 52 are displayed on the liquid crystal displays 41 and 42, respectively, in a state where the screen luminance is 1000 cd / m ^2. (Step S1). Note that the value of the screen brightness immediately after the power is turned on does not have to be 1000 cd / m ² , and may be a predetermined screen brightness.

Next, the CPU 11 reads the output values of the four photosensors 21 to 24 via the input port 12 (step S2), and any one of the output values of the four photosensors exceeds 900 lx. It is determined whether there is an optical sensor (step S3). This determination is based on whether or not the relationship between the output value of the optical sensor and the illuminance is measured in advance, and whether the illuminance exceeds a sensor output value corresponding to 900 lx. As a result of this determination, if at least one optical sensor exceeds 900 lx, the CPU 11 causes the backlights 31 and 32 to emit light so that the screen luminance of the liquid crystal displays 41 and 42 becomes 1000 cd / m ^2. The control signal shown is output to the LED drive unit 13 via the output port 14 (step S4).

In response to this, when the current value to be supplied to the LED is supplied from the LED driving unit 13, images captured by the cameras 51 and 52 with the screen luminance of 1000 cd / m ² are respectively displayed on the liquid crystal displays 41 and 42. Will be displayed. That is, if the illuminance detected by at least one of the four optical sensors 21 to 24 exceeds 900 lx, the screen brightness is 1000 cd / m ² . This state is maintained until a new control signal is output from the CPU 11.

On the other hand, if none of the output values of the four photosensors 21 to 24 exceeds 900 lx in step S3, the CPU 11 determines that all the output values of the four photosensors read in step S2 are 550 lx or less. Is determined (step S5). This determination is based on whether or not the relationship between the output value of the optical sensor and the illuminance is measured in advance and whether the illuminance is equal to or less than the sensor output value corresponding to 550 lx. If all the four optical sensors 21 to 24 are 550 lx or less as a result of this determination, the CPU 11 emits the backlights 31 and 32 so that the screen brightness of the liquid crystal displays 41 and 42 is 600 cd / m ^2. A control signal indicating that the operation is to be performed is output to the LED drive unit 13 via the output port 14 (step S6).

In response to this, when the current value to be supplied to the LED is supplied from the LED driving unit 13, images captured by the cameras 51 and 52 with the screen luminance of 600 cd / m ² are respectively displayed on the liquid crystal displays 41 and 42. Will be displayed. That is, if the illuminance detected by all the four optical sensors 21 to 24 is 550 lx or less, the screen luminance is 600 cd / m ² . Here, it is assumed that the screen brightness of the liquid crystal displays 41 and 42 is 600 cd / m ² when the predetermined current value is set so that the light emission brightness of the LEDs constituting the backlights 31 and 32 is 60% of the maximum value. This state is maintained until a new control signal is output from the CPU 11.

Next, in step S5, when all the output values of the four photosensors are not less than 550 lx, the CPU 11 maintains the current state (step S7). That is, the CPU 11 does nothing. Thereby, the current value of the current supplied from the LED drive unit 13 is maintained at the value set in step S4 or S6. That is, if the screen luminance of 600 cd / ^{m 2} current state of the screen luminance is kept 600 cd / ^{m 2,} if the screen luminance is 1000 cd / ^{m 2} current state of the screen luminance is 1000 cd / ^{m 2} Maintained. The CPU 11 repeatedly executes this processing operation until the power of the monitor device is turned off.

Next, how the ambient brightness (illuminance) and screen luminance change by the processing operation shown in FIG. 2 will be described with reference to FIG. FIG. 4 is a diagram illustrating the relationship between ambient brightness (illuminance) and screen brightness. When the brightness (illuminance) around the monitor device gradually increases and even one of the four optical sensors 21 to 24 exceeds 900 lx, the screen brightness is switched to 1000 cd / m ² . Even when the brightness is further increased, the screen brightness is maintained at 1000 cd / m ² .

On the other hand, when the screen brightness is maintained at 1000 cd / m ² , the ambient brightness gradually decreases, and when all the four photosensors 21 to 24 become 550 lx or less, the screen brightness becomes 600 cd / m ² . Switch. And even when it gets darker, the screen brightness is maintained at 600 cd / m ² . When the surroundings become bright again and even one of the four optical sensors 21 to 24 exceeds 900 lx, the operation of switching the screen luminance to 1000 cd / m ² is repeated.

  In the above description, as shown in FIG. 4, an example in which the screen brightness is switched to two levels has been described. However, it is not always necessary to have two levels, and the screen brightness is switched to three or more levels according to the ambient brightness. You may do it. Further, the four photosensors shown in FIG. 1 are not necessarily provided, and if at least one can detect the light irradiated on the screen of the liquid crystal display, the other photosensors are: One may be sufficient. In this case, other optical sensors (photosensors that are not sensors that detect the light applied to the screen of the liquid crystal display) do not necessarily need to detect the light applied to the back side of the monitor device. It can be installed anywhere as long as it can detect the brightness. Moreover, the structure which attached 5 or more of optical sensors may be sufficient. Further, the threshold value for performing the determination to switch the screen brightness may not be the illuminance, but may simply be the output value of the optical sensor. Further, instead of setting the control target to be the screen brightness, the current value supplied to the LED may be simply set to, for example, 100% or 50% of the current value that can be supplied, and the screen brightness may be switched in two steps as a result. .

  As described above, in the monitor device including the backlight using the high-intensity white LED and the liquid crystal display device that displays the image captured by the camera, the optical sensor that detects the brightness around the monitor device, Control means to adjust the light emission brightness of the backlight according to the output value of the light sensor, it can be adjusted to the optimal screen brightness corresponding to the ambient illuminance change, improving the visibility of the display screen Can be made.

  In addition, a plurality of photosensors are provided, at least one photosensor detects light applied to the display screen side of the liquid crystal display device, and other photosensors detect light applied to a surface different from the display screen. Thus, even when the morning sun or sunset directly hits the monitor device, the screen brightness can be adjusted to the optimum, and the visibility of the display screen can be improved.

  In addition, when the output value of one of the plurality of optical sensors exceeds the first threshold, the backlight emission luminance is set to the first emission luminance, and the first emission luminance is set. When the output value of all of the plurality of photosensors is equal to or lower than the second threshold while the light emission brightness is set to the second light emission brightness, When the light is dark, the light emission luminance can be suppressed and energy saving can be realized.

  Furthermore, since the high brightness white LED is used, the absolute screen brightness can be improved, and even when a transparent plate that reduces reflection on the screen surface is attached to the screen, sufficient visibility can be secured.

  Note that a screen brightness control process is performed by recording a program for realizing the functions of the CPU 11 shown in FIG. 1 on a computer-readable recording medium, causing the computer system to read and execute the program recorded on the recording medium. May be performed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  The present invention can be applied to a monitor device that needs to display an image in a place where an illuminance change is large such that it receives direct sunlight.

  DESCRIPTION OF SYMBOLS 1 ... Control part, 11 ... CPU, 12 ... Input port, 13 ... LED drive part, 14 ... Output port, 21, 22, 23, 24 ... Optical sensor 31, 32 ... Backlight, 41, 42 ... Liquid crystal display, 51, 52 ... Camera

Claims (2)

A monitor device including a backlight using a high-intensity white LED and a liquid crystal display device that displays an image captured by a camera,
A plurality of optical sensors for detecting brightness around the monitor device;
Control means for adjusting the light emission luminance of the backlight according to the output value of the light sensor,
At least one of the optical sensors detects light applied to the display screen side of the liquid crystal display device, and the other optical sensor detects light applied to a surface different from the display screen;
The control means sets the light emission luminance of the backlight to the first light emission luminance when the output value of one of the plurality of light sensors exceeds a first threshold value, When the output values of all of the plurality of photosensors are equal to or lower than the second threshold value while the first emission luminance is set, the backlight emission luminance is set to the second emission luminance. A monitor device characterized by being set to . A backlight using a high-intensity white LED, a liquid crystal display device that displays an image captured by a camera, a plurality of light sensors that detect the brightness around the monitor device, and a screen brightness of the liquid crystal display Control means for
At least one said light sensors, in said detecting light to be irradiated on the display screen side of the liquid crystal display device, the other of the optical sensors, the display screen monitor device you detect the light irradiated to the surface different from the A screen brightness control method,
When the control means adjusts the light emission luminance of the backlight according to the output value of the light sensor, the output value of one of the plurality of light sensors is a first threshold value. Is exceeded, the light emission luminance of the backlight is set to the first light emission luminance, and while the first light emission luminance is set, the output values of all the plurality of photosensors are set to the second light emission luminance. A screen luminance control method, characterized in that, when the threshold value is below a threshold value, the light emission luminance of the backlight is set to a second light emission luminance .

Images