JP6679203B2 - Display unit, display device, and display method - Google Patents

Description

  The present invention relates to a display unit capable of controlling a current flowing through each of LEDs (Light Emitting Diodes) arranged in a matrix on a plane, a display device using the display unit, and a display method of the display unit.

  Large image display devices installed on public facilities, stadiums, walls of buildings, etc. that display information such as guides, competitions, and advertisements use LEDs as display devices and LCDs (Liquid Crystal Display). There is. Large-scale image display devices installed outdoors require high-intensity image display in order to display images with good visibility in a bright environment illuminated by sunlight, and LEDs are used to achieve this. To be done.

  The LED-type large image display device forms a screen by arranging a large number of LEDs on a plane, and displays an image by changing the brightness of each LED. In addition, color display of an image is realized by using LEDs of three colors of red, green and blue.

  The brightness of the LED is controlled by changing the magnitude of the current flowing through the LED. When the current value is 0, the LED is black in the off state, and the larger the current flowing, the brighter the LED shines. A drive circuit is used for current control. A drive circuit is required for each LED. Although it is possible to form a drive circuit by combining electronic components, an IC (Integrated Circuit) equipped with a drive circuit is generally used because current control of a large number of LEDs is required.

  Large-scale image display devices installed outdoors are often installed in high places or in places that are difficult to approach, so it is often difficult for workers to perform maintenance, making it possible to implement maintenance functions from remote locations. It has been demanded.

  Further, the large-sized image display device operates all day depending on the installation location, and it may be difficult to perform maintenance by turning off the power. In places where maintenance is difficult, it is required to detect abnormalities and restore automatically while operating.

  When a failure occurs in the display unit, it is necessary to replace the failed display unit, but there is also a case where the large image display device is restored by turning off the power once and then turning it on again.

  The cause of the phenomenon that can be recovered by once turning off the power is the latch-up phenomenon of the LED drive circuit. Latch-up is a state in which the semiconductor element is uncontrollable in the ON state and current continues to flow, and occurs when a voltage higher than the rated voltage is input to the semiconductor element due to noise, static electricity, or the like. In order to recover from the latch-up state, it is necessary to temporarily stop the power supply to the semiconductor element in the latch-up state and supply it again.

  If the device is a large-scale image display device that has not been operated for 24 hours, it is restored when the device is turned off and restarted. However, it is not preferable to turn off the power of a large-scale image device that operates for 24 hours because it is disadvantageous to the user. Therefore, when a display abnormality occurs due to latch-up or the like, it is preferable to temporarily turn off the power of the display unit in which the display abnormality has occurred and turn it on again while keeping the display of the large-sized image display device continued.

  As a prior art, there is disclosed a technique of shutting off the power supply to the drive circuit when an abnormality occurs in the drive circuit that drives the display panel. (Patent Document 1)

  Further, there is disclosed a technique of comparing a brightness calculation value calculated from video data displayed on a large-sized display panel with a measured brightness value to determine a failure state of a light emitting device. (Patent Document 2)

JP, 11-305721, A JP, 2011-209637, A

  In the drive device described in Patent Document 1, when an abnormality occurs in the drive circuit, the power supply to the drive circuit is cut off by using the cutoff unit (fuse), so the power supply to the drive circuit is restarted. Cannot be recovered.

  In the control method of the image display device described in Patent Document 2, the brightness of all the light emitting devices is measured, and an abnormality is detected by comparing the brightness calculated value calculated from the video data with the measured brightness value. Therefore, the brightness is measured. In order to do so, a brightness measuring device is required.

A display unit according to the present invention includes a video receiving unit that receives video data, a light emitting element unit configured to display a video based on the video data by light emission, the light emitting element unit including a plurality of light emitting elements arranged in a matrix on a plane. Display control means for generating a brightness control signal for controlling the brightness of each of the light emitting elements based on the video data; driving means for driving each of the light emitting elements based on the brightness control signal; A black image determination means for determining a black image, a current detection means for detecting a current value I of a current flowing from a power source to the light emitting element portion, and the black image determination means determine that the video data is a black image. In this case, the display abnormality of the light emitting element unit is detected based on the current value I _B of the current flowing during the period in which the black image is displayed , which is detected by the current detection unit. If the display abnormality detecting means and the display abnormality detecting means do not detect the display abnormality, the power supply to the driving means is continued, and if the display abnormality is detected, the power supply to the driving means is kept constant. And a power control means for restarting after stopping for a time.

  A display device according to the present invention includes a display panel in which a plurality of display units are arranged in a matrix, a power supply unit for supplying power to each of the display units, and a power supply from the power supply unit to each of the display units. And a display unit control means for controlling.

A display method according to the present invention includes a step of receiving video data, and based on the video data, a brightness of each of the light emitting elements is adjusted with respect to a plurality of light emitting elements arranged in a matrix on a plane of the light emitting element section. A step of generating a brightness control signal for controlling, a step of driving each of the light emitting elements by a driving means based on the brightness control signal, a step of detecting a current value flowing to the light emitting element part, and the image A black image determination of data; a step of comparing a current value I _B of a current flowing to the light emitting element portion with the abnormality determination threshold current I _TH1 when the video data is determined to be a black image; When the current value I _B is equal to or more than the abnormality determination threshold current I _TH1, a step of stopping the power supply to the driving means by the power supply control means for a certain time, and the passage of the certain time. Restarting the power supply to the drive means by the power supply control means after a lapse of time.

  According to the display unit of the present invention, it is possible to detect the display abnormality by the display abnormality detection unit, and when the display abnormality is detected, the power supply control circuit controls the power supply to the drive circuit to display. It is possible to recover from an abnormality.

  According to the display device of the present invention, when a display abnormality occurs in the display unit, the power of only the display unit in which the display abnormality has occurred is stopped and turned on again. It is not necessary to stop the entire power supply of the display unit, and the display unit in which no display abnormality has occurred can continue the display operation.

  According to the display method of the present invention, it is possible to detect the display abnormality by the display abnormality detection unit, and when the display abnormality is further detected, the power supply control circuit controls the power supply to the drive circuit to display. It is possible to recover from an abnormality.

It is a block diagram which shows the structure of the display unit which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of LED in the display unit which concerns on Embodiment 1 of this invention. It is a figure which shows the external appearance of the display unit which concerns on Embodiment 1 of this invention. FIG. 6 is an explanatory diagram of PWM, which is one type of modulation method in the display unit according to the first embodiment of the present invention. It is a block diagram which shows the structure of the electric current detection part in the display unit which concerns on Embodiment 1 of this invention. It is a figure explaining the process of the electric current detection part in the display unit which concerns on Embodiment 1 of this invention. FIG. 5 is a diagram for explaining LED abnormality detection by current detection in the display unit according to the first embodiment of the present invention. It is a block diagram which shows the structure of the display abnormality detection part in the display unit which concerns on Embodiment 1 of this invention. FIG. 6 is a timing chart of power supply OFF control to the drive circuit when a display abnormality is detected in the display unit according to the first embodiment of the present invention. FIG. 6 is a control flow diagram of display abnormality detection in the display unit according to the first embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of the display device according to the first embodiment of the present invention. It is a block diagram which shows the structure of the display unit which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the electric current detection part in the display unit which concerns on Embodiment 2 of this invention. It is a figure explaining the averaging process of the electric current detection part in the display unit which concerns on Embodiment 2 of this invention. FIG. 9 is a diagram showing noise-like current fluctuations in the drive circuit in the display unit according to the second embodiment of the present invention. It is a block diagram which shows the structure of the display unit which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the display unit which concerns on Embodiment 4 of this invention. It is a block diagram which shows the structure of the display apparatus which concerns on Embodiment 5 of this invention.

Embodiment 1.
FIG. 1 is a block configuration diagram schematically showing the configuration of the display unit 100 according to the first embodiment. The display unit 100 is, for example, a device that displays images such as various guides, live broadcast images of competitions, and advertisement images on public facilities, stadiums, walls of buildings, and the like, and is a basic unit that constitutes a screen for displaying images. Is a unit. The display unit 100 is a unit in which about 2000 LEDs are arranged on a plane, and a large number of display units 100 are spread in a two-dimensional matrix to form one screen. The display unit 100 displays an image by controlling the brightness of each LED on the display unit 100 according to the image data.

  As shown in FIG. 1, the display unit 100 includes a video reception circuit 101, a display control circuit 102, a drive circuit 103, and a plurality of LEDs 114 (light emitting elements) arranged in a matrix on a plane. An element unit 104, a current detection unit 105, a black image determination circuit 106, a display abnormality detection unit 107, and a power supply control circuit 108 are provided.

  The video receiving circuit 101 receives video data to be displayed by the display unit 100 from the outside, and outputs the video data to the display control circuit 102 and the black image determination circuit 106.

  The display control circuit 102 generates a brightness control signal for individually controlling the brightness of each LED 114 forming the light emitting element section 104 based on the video data output by the video receiving circuit 101, and performs display control.

  The drive circuit 103 drives each LED 114 that constitutes the light emitting element section 104 based on the brightness control signal generated by the display control circuit 102.

  The LED 114 emits an image based on the image data to display the image.

  FIG. 2 is a diagram showing the configuration of the LED 114 described above. FIG. 2 shows a configuration in which one LED 114 includes three LED light emission sources 114a, 114b, 114c. In the LED light emission sources 114a, 114b, 114c included in one LED 114, the LED light emission source 114a emits red light, the LED light emission source 114b emits green light, and the LED light emission source 114c emits blue light. By changing the brightness of each of the three LED light emission sources 114a, 114b, 114c, various colors can be produced and a color image can be displayed. Although FIG. 2 shows a configuration in which a plurality of LEDs 114 including the three LED light emission sources 114a, 114b, 114c are arranged, the number of LED light emission sources included in the LED 114 is not limited to three. Further, instead of the LEDs 114 capable of emitting three colors, the display unit 100 may have LEDs emitting red, green and blue individually arranged in a matrix on a plane.

  FIG. 3 is a diagram showing an appearance of the display unit 100 according to the first embodiment. The display unit 100 has LEDs 114 for displaying an image arranged in a matrix on a plane. For example, 30 LEDs 114 are arranged in the horizontal direction and 20 LEDs 114 are arranged in the vertical direction on the display unit 100.

  The current detection unit 105 detects the current of the power supplied to each LED 114.

  The black image determination circuit 106 determines whether the video data output by the video reception circuit 101 is a black image.

  The display abnormality detection unit 107 detects a display abnormality of the image based on the current value detected by the current detection unit 105 when the black image determination circuit 106 determines that the image data is a black image.

  The power supply control circuit 108 supplies power to the drive circuit 103 in response to the display abnormality detected by the display abnormality detection unit 107.

  Hereinafter, detailed operations of the display unit 100 will be described.

  The video receiving circuit 101 receives video data to be displayed on the display unit 100 from the terminal 112 and outputs it to the display control circuit 102. When the display unit 100 has, for example, 30 horizontal and 20 vertical LEDs 114 arranged, it receives video data to be displayed on the 600 LEDs 114. When each LED 114 includes three LED light emission sources, video data to be displayed on 1800 LED light emission sources is received. In this case, the video data includes information on the respective brightness when the 1800 LED light emitting sources emit light. The video data receives, for example, what has been sent as an electrical signal of CMOS (Complementary Metal Oxide Semiconductor) or LVDS (Low Voltage Differential Signaling), and outputs it as an electrical signal of CMOS. Hereinafter, the control target will be described by taking the LED 114 as a unit, but here, the control of the LED 114 means individually controlling the LED light emission sources forming the LED 114.

  The display control circuit 102 performs display control according to the video data output from the video receiving circuit 101. The display control circuit 102 displays the image by controlling the brightness of each LED 114 according to the information regarding the light emission included in the image data. The display control circuit 102 generates a brightness control signal corresponding to each LED 114 in order to control the brightness of each LED 114. The brightness is controlled by, for example, PWM (Pulse Width Modulation). FIG. 4 is an explanatory diagram of PWM, which is one type of modulation method in the display unit 100 according to the first embodiment. As shown in FIG. 4, the PWM is a method of controlling the output by the ON / OFF width of a signal, and is always ON when the brightest light is emitted and is always OFF when the light is not emitted. As the ON period is increased from the normally OFF state, brighter light is emitted.

  The drive circuit 103 drives each LED 114 based on the brightness control signal generated by the display control circuit 102. The drive circuit 103 receives the brightness control signal output from the display control circuit 102, and controls the light emission by passing a current through the LED 114 based on the brightness control signal.

  When the display control circuit 102 controls the brightness by PWM, the drive circuit 103 is, for example, a current drive circuit capable of turning on and off a fixed current value. When the brightness control signal indicates the ON state, the drive circuit 103 sends a current having a predetermined current value to the LED 114, and when the brightness control signal indicates the OFF state, the drive circuit 103. The driving circuit 103 controls the light emission of the LED 114 by setting the magnitude of the current flowing to the LED 114 to 0. The current value of the current passed when the brightness control signal indicates the ON state is the current value at which the LED 114 emits the brightest light.

  The light emitting element section 104 emits light and displays an image in accordance with the light emission control by the drive circuit 103. The light emitting element section 104 is composed of a plurality of LEDs 114 arranged in a matrix on a plane. When the display control circuit 102 controls the brightness by PWM, the light emitting element portion 104 is turned on when the drive circuit 103 is supplying a current of a predetermined current value to the light emitting element portion 104. It will be in a state of being. Further, the light emitting element portion 104 is in the off state when the magnitude of the current passed by the drive circuit 103 to the light emitting element portion 104 is zero. The brightness of the light emitting element section 104 is determined by the temporal ratio of the lit state and the extinguished state.

  The current detection unit 105 detects the current of the power supplied to each LED 114. FIG. 5 is a block diagram showing an example of the configuration of the current detection unit 105 in the display unit 100. As shown in FIG. 5, the current detector 105 includes a current-voltage converter 501, a first amplifier 502, a voltage limiter 503, a second amplifier 504, and an analog-digital converter 505. .

  The current-voltage converter 501 converts the current value of the current flowing from the power supply into a voltage value. The current-voltage converter 501 is realized by a resistor having a small value of about 10 milliohms. The resistance for detecting the magnitude of the current is called a shunt resistor. In FIG. 5, the electric power supplied from the terminal 506 passes through the current-voltage conversion unit 501, is output from the terminal 507, and is supplied to each unit of the display unit 100. Further, the obtained voltage value is output from the current / voltage conversion unit 501 to the first amplification unit 502. Assuming that the resistance value of the shunt resistor is R and the magnitude of the current is I, the current-voltage converter 501 outputs a voltage value (I × R).

The first amplification unit 502 amplifies the voltage output from the current-voltage conversion unit 501 to calculate an amplified voltage value V _A , and outputs the amplified voltage value V _A to the voltage limiting unit 503. The first amplification unit 502 is realized by, for example, an operational amplifier.

The voltage limiting unit 503 cuts a voltage equal to or higher than a predetermined threshold voltage V _TH with respect to the amplified voltage value V _A output from the first amplifying unit 502, calculates the limiting voltage V _R, and calculates the second limiting voltage V _R. The signal is output to the amplification unit 504. The reason for calculating the limiting voltage V _R by cutting the voltage equal to or higher than the threshold voltage V _TH is to cut the voltage in a range unnecessary for the determination of the display abnormality at the time of the black image and improve the accuracy of the display abnormality determination. is there. The voltage limiting unit 503 is realized by, for example, a diode and an operational amplifier. The predetermined threshold voltage V _TH is a voltage value corresponding to 20 (mA) which is a current value that flows when one LED 114 emits the brightest light, for example.

The second amplifying unit 504, calculates the amplification limit voltage value V _RA amplifies the limit voltage V _R the voltage limiting section 503 is calculated, and output to an analog-digital converter 505. The second amplification unit 504 is realized by, for example, an operational amplifier.

The analog-digital converter 505 converts the amplification limit voltage value V _RA output by the second amplifier 504 from an analog value to a digital value, and also converts the voltage value into a current value to calculate a current value I. Output to the terminal 508. The analog-digital conversion unit 505 is realized by, for example, an A / D converter (Analog-to-Digital converter).

  The current detection unit 105 outputs the current value I output from the analog-digital conversion unit 505 from the terminal 508 as a current detection result.

FIG. 6 shows the relationship between the voltage values in the current detection unit 105, where P1 is the amplified voltage value V _A , P2 is the amplified voltage value V _R , P3 is the limited voltage VR, and P4 is the amplified limited voltage value V _RA . The relationship between the voltage values indicated by circles is a case where the voltage P2 output from the first amplification unit 502 exceeds the threshold voltage V _TH , and the relationship between the voltage values indicated by triangles is the first relationship. This is a case where the voltage P2 output from the amplification unit 502 does not exceed the threshold voltage V _TH . For example, assuming that the threshold voltage V _TH is 20 (mA) × resistance value R, 0 to 20 (can be obtained by obtaining the fourth voltage value in either case of the relationship between the voltage values indicated by circles and triangles. It is possible to detect the magnitude of the current in the range of about mA). Note that in the current detection unit 105, when the accuracy of the analog-digital conversion unit 505 is high, the voltage limiting unit 503 and the second amplification unit 504 may be omitted. In this case, since the number of parts can be reduced, it is possible to further reduce the cost.

  In the case where 1800 LED light emitting sources are arranged in the display unit 100, assuming that the current value flowing when one LED light emitting source emits the brightest light is 20 (mA), all the LED light emitting sources of the display unit 100. When is turned on, a current of about 20 (mA) × 1800 = 36000 (mA) = 36 (A) flows from the power supply. On the other hand, the current when only one LED light source is turned on is 20 (mA).

FIG. 7 is an explanatory diagram of the display abnormality detection of the LED 114 in the display unit 100 of the first embodiment. As shown in FIG. 7A, when all the LEDs 114 are turned on and a maximum current of about 36 A is flowing, an abnormality occurs in one LED light emission source of one LED 114 at time t. When only one LED is constantly turned off, it is necessary to detect a fluctuation of 20 (mA) for a current value of about 36 A, and it is difficult to detect a display abnormality.
On the other hand, when all the LEDs 114 of the display unit 100 are turned off and almost no current is flowing, an abnormality occurs in one LED light emission source of one LED 114 at time t, and only one LED light emission source is always on. In the case of lighting, it is only necessary to be able to measure the current in the range of 0 to 20 (mA) as shown in FIG. 7B, so that the display abnormality detection becomes easy.
According to the present invention, when all the LEDs 114 of the display unit 100 are extinguished and no current is flowing, an abnormality occurs in one LED light emission source of one LED 114 at the time t and one LED light emission source is generated. Only when it is always on, it is possible to detect display abnormalities. The details of the display abnormality detection method are shown below.

  The black image determination circuit 106 determines whether the video data received and output by the video reception circuit 101 is a black image and outputs a black image determination result. Here, the black image is a state in which all the LEDs 114 of the display unit 100 are turned off or a state close thereto. The black image determination circuit 106 determines a black image when the values of the brightness control signals for all the LEDs 114 in the received video data are equal to or less than a predetermined threshold value. For example, the black image determination circuit 106 determines as a black image when the values of the brightness control signals for all the LEDs 114 in the received video data are all in the OFF state.

When the video data is determined as the black image by a black image determining circuit 106, when the value of the current flowing from the power source to each LED114 and I _B, the display abnormality detector 107, the display abnormality in the signal using the current value I _B Detect. FIG. 8 shows an example of the configuration of the display abnormality detection unit 107. In the configuration of FIG. 8, the display abnormality detection unit 107 includes an average value calculation unit 801, a standard deviation calculation unit 802, a threshold current calculation unit 803, a threshold current storage unit 804, and a display abnormality determination unit 805. The display abnormality detection unit 107 can be realized using, for example, a CPU, a microcomputer, or the like.

In the average value calculation unit 801, when the determination of the black image determination circuit 106 input from the terminal 808 indicates a black image, the determination of the black image determination circuit 106 input from the terminal 806 indicates a black image. The current average value of the current value I _B that is the current flowing during the period is calculated, and the average of the current values I _B is output to the threshold current calculation unit 803. The current average value of the current values I _B is I _MN1 .

The standard deviation calculation unit 802 calculates the standard deviation of the current value I _B input from the terminal 806 when the black image determination circuit 106 input from the terminal 808 indicates a black image, and calculates the current value I _B. The standard deviation of _B is output to the threshold current calculation unit 803. The standard deviation of the current value I _B is I _SD1 .

The threshold current calculation unit 803 obtains an abnormality determination threshold current from the average current value I _MN1 output by the average value calculation unit 801 and the standard deviation I _SD1 output by the standard deviation calculation unit 802, and transfers it to the threshold current storage unit 804. Output. If the abnormality determination threshold current I _TH1 is set, the abnormality determination threshold current I _TH1 is _calculated by the following equation (1).
I _TH1 = I _MN1 + (I _SD1 × 3) (1)
According to the equation (1), the current value I _B when the determination of the black image determination circuit 106 input from the terminal 808 indicates a black image falls within the range of the normal current value distribution during the black image. It is possible to obtain the threshold current for determining whether or not there is.

The threshold current storage unit 804 stores the abnormality determination threshold current I _TH1 output by the threshold current calculation unit 803. The abnormality determination threshold current I _TH1 is calculated when a threshold current update instruction is issued from the terminal 807. As an instruction to update the threshold current from the terminal 807, for example, a test image is displayed when a large-sized image display device is installed, and an instruction is issued only once when the test is completed, so that no abnormality occurs. It is possible to obtain and store the abnormality determination threshold current I _TH1 from the current value when the black image is displayed in the state. Further, it is preferable that the threshold current update instruction from the terminal 807 is issued in accordance with environmental changes such as changes in temperature. The initial value of the threshold current storage unit 804 before the installation of the large-sized image display device is set to, for example, -1 (A) so that it can be seen that the initial value is the initial value.

The display abnormality determination unit 805 outputs the abnormality determination threshold current I _TH1 stored in the threshold current storage unit 804 and the terminal 806 when the determination of the black image determination circuit 106 input from the terminal 808 indicates a black image. The input current value I _B is compared. When the current value I _B is equal to or higher than the abnormality determination threshold current I _TH1 , it is detected that the display abnormality has occurred, and therefore the display abnormality is output to the terminal 809. When the current value I _B is less than the abnormality determination threshold current I _TH1 , the occurrence of the display abnormality is not detected, so that the display abnormality is output to the terminal 809. However, when the abnormality determination threshold current I _TH1 stored in the threshold current storage unit 804 is the initial value, no comparison is performed and the display abnormality detection result is output as no display abnormality. By comparing the abnormality determination threshold current I _TH1 stored in the threshold current storage unit 804 with the current value I _B input from the terminal 806, the display abnormality detection unit 107 can detect the display abnormality. Further, since the display abnormality is determined only by simple comparison, it can be easily realized.

  The power supply control circuit 108 supplies power to the drive circuit 103 in response to the display abnormality detected by the display abnormality detection unit 107. When the display abnormality detection unit 107 does not detect a display abnormality, the power supply control circuit 108 continues to supply power to the drive circuit 103 of the display unit 100. When the display abnormality detection unit 107 detects a display abnormality, the power supply control circuit 108 stops the power supply to the drive circuit 103 of the display unit 100 for a certain period of time. The time for stopping the power supply varies depending on the light emitting element used, but is, for example, about 1 second, which is the length at which the power supply to the LED 114 is completely stopped. After the elapse of a certain time, the power supply control circuit 108 restarts the power supply to the drive circuit 103 of the display unit 100. Therefore, when a display abnormality occurs due to the latch-up phenomenon, the power supply to the drive circuit 103 of the display unit 100 is stopped, and after a certain time has elapsed, the power supply to the drive circuit 103 of the display unit 100 is restarted. As a result, it is possible to recover from the display abnormality caused by the latch-up phenomenon.

FIG. 9 shows a timing chart of the display abnormality detection when the black image is displayed and the control for stopping the power supply to the drive circuit 103 when the display abnormality is detected in the display unit 100 according to the first embodiment. Section determination of the black image determination circuit 106 which is input from the terminal 808 indicates a black image, B1 and B2, a B3～B4, when abnormality determination threshold current is _{I TH1,} in a section B1 and B2 are Since the current value is less than the abnormality determination threshold current I _TH1 , no display abnormality is detected. On the other hand, in the section of B3 to B4, since the current value is equal to or higher than the abnormality determination threshold current I _TH1 , the display abnormality is detected.

  A display abnormality detection method for the display unit 100 according to the first embodiment will be described with reference to the control flow chart shown in FIG.

  When the power of the display device 1 is turned on, in step S1, the current detection unit 105 detects the current value of the current flowing through the light emitting element unit 104.

  In step S2, the black image determination circuit 106 determines whether the video data when the current is detected in step S1 is a black image. When it is determined that the video data is a black image, the process proceeds to step S3, and when it is determined that the video data is not the black image, the process proceeds to step S1.

In step S3, when the display abnormality detection unit 107 determines that the image data is a black image by the black image determination circuit 106, the current value I _B of the current flowing to the light emitting element unit detected by the current detection unit 105 is It is compared whether or not the abnormality determination threshold current I _TH1 or more. If the current value I _B is greater than or equal to the abnormality determination threshold current I _TH1 , the process proceeds to step S4, and if the current value I _B is less than the abnormality determination threshold current I _TH1 , the process proceeds to step S1.

  In step S4, the power supply control circuit 108 stops the power supply to the drive circuit 103.

  In step S5, the power supply control circuit 108 continues to stop the power supply to the drive circuit 103 until a certain period of time elapses.

  In step S6, the power supply control circuit 108 stops the power supply to the drive circuit 103, and after a lapse of a certain time, the power supply control circuit 108 restarts the power supply to the drive circuit 103.

  After the process of step S6, the process proceeds to step S1.

  FIG. 11 is a block diagram showing the configuration of the display device 1 according to the first embodiment. As shown in FIG. 11, a plurality of display units 100 are arranged in a two-dimensional matrix to form a display panel 11. The display device 1 is connected to a power supply unit 12 for supplying power to each display unit 100, and the power supply to each display unit 100 is controlled by a display unit control circuit 13.

  In the display unit 100 according to the first embodiment, the display abnormality detection unit 107 can detect the display abnormality, and when the display abnormality is detected, the display unit 100 in which the display abnormality has occurred is powered off. Without it, it is possible to recover by only turning off the power supply of the drive circuit 103 and turning it on again.

  In the display device 1 shown in FIG. 11, when a display abnormality occurs in the display unit 100, the power of only the display unit 100 in which the display abnormality has occurred is stopped and turned on again. It is not necessary to stop the power supply of the entire display device 1, and the display unit 100 in which no display abnormality has occurred can continue the display operation.

  Further, since the display abnormality is detected by using the current detection unit 105, there is an effect that a luminance measuring device for measuring the luminance of the light emitting device becomes unnecessary. Further, in order to detect the display abnormality by detecting the current of the entire display unit 100, when detecting the current value of the current flowing through each LED 114, that is, the current value of the current flowing through each drive circuit 103 is individually detected. As compared with the case of performing the above, it is possible to reduce the number of current detection units 105, and it is possible to realize cost reduction of the device.

  According to the display unit 100 according to the first embodiment, it is possible to detect the display abnormality by the display abnormality detection unit 107, and when the display abnormality is detected, the power supply control circuit 108 supplies power to the drive circuit 103. It is possible to control the supply and recover from the display abnormality.

Embodiment 2.
The display unit 200 according to the second embodiment has a configuration in which the black image determination result output by the black image determination circuit 106 is input not only to the display abnormality detection unit 107 but also to the current detection unit 201. The configuration of the display unit 200 according to the second embodiment is shown in FIG. It should be noted that description of configurations and operations that are the same as or corresponding to those of the first embodiment will be omitted, and only portions that are different in configuration and operations from the first embodiment will be described.

  FIG. 13 is a block diagram showing the configuration of the current detection unit 201 in the display unit 200 according to the second embodiment. As shown in FIG. 13, the current detection unit 201 has a configuration in which an averaging unit 509 and a terminal 510 are added to the current detection unit 105 shown in FIG. The black image determination result output from the black image determination circuit 106 is input from the terminal 510.

When the black image determination result input from the terminal 510 indicates that the black image is a black image, the averaging unit 509 calculates the current average value of the current values I _B output by the analog-digital conversion unit 505 to obtain the current. The current average value I _BMN of the detection result is output to the terminal 508.

The current detection unit 201 outputs the current average value I _BMN of the current detection result output by the averaging unit 509 from the terminal 508.

The display abnormality detection unit 107 in the display unit 200 according to the second embodiment _compares the current average value I _BMN with the abnormality determination threshold current I _TH1 calculated by the method described in the first embodiment to display an abnormality in the display. To detect.

The operation of the averaging unit 509 will be described with reference to the timing chart of FIG. FIG. 14 is a diagram showing an example of the timing. As shown in FIG. 14, the current average value of the current value I _B is calculated for the range of the section a, the section b, and the section c that are black images during the average value calculation cycle T1, and the averaging process is performed. The current average value I _BMN of the result of the detected current is output to the terminal 508. After that, during the next average value calculation cycle T1, the current average value of the current value I _B is obtained for the range of the section d and the section e forming a black image, and the current detection result of the averaging process is calculated. The current average value I _BMN is output to the terminal 508. That is, the averaging unit 509 obtains the current average value of the current value I _B for the section which is the black image during the average value calculation cycle T1 and performs the averaging process on the current average of the current detection results. The value I _BMN is output on terminal 508. Therefore, even if the black image does not continue, it is possible to accurately detect the display abnormality. The average value calculation period T1 can be set at any time. By setting the average value calculation period T1 longer, it is possible to further reduce the influence of noise, but if it is too long, the display abnormality continues, so it is set between several tens of seconds and several tens of minutes. Is desirable.

In the display unit 200 according to the second embodiment, about 1800 drive circuits are mounted, so that noise-like current fluctuations may accumulate. Therefore, in the drive circuit 103, a noise-like current variation may occur. FIG. 15 is a diagram showing a noise-like current variation in the drive circuit 103 in the display unit 200 according to the second embodiment, which shows a black image during the average value calculation cycle T1 in FIG. The current fluctuation is shown. Q in FIG. 15 shows a noise-like current variation in the drive circuit 103. In order to suppress the influence on the current detection result due to the noise-like current fluctuation of the drive circuit 103 in the black image state, the averaging unit 509 of the current detection unit 201 sets the current value for the section that is the black image. executing an averaging process of I _B. The averaging process makes it possible to reduce the influence of current fluctuations. The averaging unit 509 can be realized by using, for example, a CPU or a microcomputer.

  In the display unit 200 according to the second embodiment, when the black image determination result input from the terminal 510 indicates that the image is a black image, the current detection result obtained by performing the averaging process by the current detection unit 201 is displayed on the terminal. Since it can be output from 508, the influence on the current detection due to the noise-like current fluctuation can be suppressed, and the accurate abnormal state detection can be performed.

Embodiment 3.
The display unit 300 according to the third embodiment has a configuration in which a black image switching circuit 301 is added to the display unit 100 according to the first embodiment. The structure of the display unit 300 is shown in FIG. It should be noted that description of configurations and operations that are the same as or corresponding to those of the first and second embodiments will be omitted, and only portions that are different from the configurations and operations of the first and second embodiments will be described.

  The black image switching circuit 301 displays black image data corresponding to black image display in place of the video data output by the video receiving circuit 101 during the black image instructed period by the black image switching instruction input from the terminal 302. It is output to the control circuit 102 and the black image determination circuit 106. When the black image switching instruction is not input, the video data output from the video receiving circuit 101 is output to the display control circuit 102 and the black image determination circuit 106.

  The black image switching instruction input from the terminal 302 is issued when the entire surface of the image displayed on the display panel 11 is displayed as a black image due to display switching or the like.

  In the display unit 300 according to the third embodiment, a black image is explicitly displayed when the entire surface of the image displayed on the display device 1 is displayed as a black image due to display switching or the like, so that the display image does not feel uncomfortable. The current value flowing due to the display abnormality of the display unit 300 can be detected more accurately, and the processing for obtaining the abnormality determination threshold current in the display abnormality detection unit 107 can be efficiently performed. Therefore, it is possible to more accurately and efficiently perform the abnormality determination for the display abnormality detection of each display unit 300 of the display device 1.

Fourth Embodiment
The display unit 400 according to the fourth embodiment is configured such that a black image switching instruction to the black image switching circuit 301 of the display unit 300 according to the third embodiment is input from the black image determination circuit 106. The configuration of the display unit 400 according to the fourth embodiment is shown in FIG. It should be noted that description of configurations and operations that are the same as or corresponding to those of the first, second, and third embodiments will be omitted, and only portions that are different in configurations and operations from the first, second, and third embodiments will be described.

  FIG. 17 is a diagram showing the configuration of the display unit 400 according to the fourth embodiment. When the determination result of the black image determination circuit 106 indicates a black image, the black image surface switching circuit 401 displays the black image data corresponding to the black image display instead of the video data output by the video reception circuit 101. Output to 102.

  In the third embodiment, when the entire image displayed on the display device 1 becomes a black image display due to display switching or the like, the black image is explicitly displayed to detect the display abnormality. In the display unit 400 according to the above, when the black image determination circuit 106 determines a black image, the black image is explicitly displayed to detect a display abnormality. In addition, the black image plane switching circuit 401 may be operated by a timer or the like, for example, only for several hours in a day.

  In the display unit 400 according to the fourth embodiment, the black image is explicitly displayed based on the black image determination for each display unit. Therefore, even when the entire display of the display device 1 is not the black image, the third embodiment is described. Has the same effect as.

Embodiment 5.
The display device 2 according to the fifth embodiment has a configuration in which the display units 300 described in the third embodiment are arranged in a matrix on a plane. The configuration of the display device 2 according to the fifth embodiment is shown in FIG. As shown in FIG. 18, in the display device 2 according to the fifth embodiment, the display units 21 are arranged in a matrix on a plane to form the display panel 21. It should be noted that description of configurations and operations that are the same as or corresponding to those of the first, second, third, and fourth embodiments will be omitted, and only portions of the configurations and operations that differ from those of the first, second, third, and fourth embodiments will be described. .

  In the display device 2 according to the fifth embodiment, the display unit control circuit 13 sequentially outputs a black image switching instruction to each display unit 300 at regular intervals, and the video data output by the video receiving circuit 101 is output. Instead of, the black image data corresponding to the black image display is displayed. The certain period of time for inputting the black image switching instruction can be determined according to the installation location of the display device 5 or the like.

  The timing of sequentially outputting the black image switching instruction to each display unit 300 can be determined according to the installation location of the display device 5 and the like.

  In the display device 2 according to the fifth embodiment, a black image switching instruction is sequentially output to each display unit 300 at regular intervals, so that black image display is performed instead of the video data output by the video receiving circuit 101. It is possible to display the black image data corresponding to, and it is possible to detect the abnormal display even when the black image display does not occur for a long time. Moreover, since the output timing of the black image switching instruction to each display unit 300 can be determined according to the installation state of the display device 2, it is possible to minimize the discomfort given to the display image.

As described above, in the first to fifth embodiments, the light emitting element forming the light emitting element section 104 has been described by taking the LED as an example, but other light emitting elements such as an organic EL element may be used.
It should be noted that the present invention is not limited to the shapes described in the first to fifth embodiments, and within the scope of the invention, the respective embodiments can be freely combined, or the respective embodiments can be appropriately modified, It can be omitted.

DESCRIPTION OF SYMBOLS 1 and 2 Display device 11, 21 Display panel 12 Power supply unit, 13 Display unit control circuit 100, 200, 300, 400 Display unit 101 Video receiving circuit, 102 Display control circuit, 103 Driving circuit, 104 Light emitting element part 105 Current detection part , 106 black image determination circuit 107 display abnormality detection unit 108 power supply control circuit, 110 to 112 terminals, 114 LED
114a, 114b, 114c LED light source 201 Current detection unit 301 Black image plane switching circuit 401 Black image plane switching circuit 501 Current-voltage conversion unit, 502 First amplification unit, 503 Voltage limiting unit 504 Second amplification unit, 505 Analog Digital conversion unit, 506 to 508 terminals 509 averaging unit, 510 terminals 801, average value calculation unit, 802 standard deviation calculation unit, 803 threshold current calculation unit 804 threshold current storage unit, 805 display abnormality determination unit, 806 to 809 terminals

Claims (10)

Video receiving means for receiving video data,
A light emitting element section configured by a plurality of light emitting elements arranged in a matrix on a plane for displaying an image based on the image data by light emission;
Display control means for generating a brightness control signal for controlling the brightness of each of the light emitting elements based on the video data;
Drive means for driving each of the light emitting elements based on the brightness control signal;
A black image determining means for determining a black image of the video data,
Current detecting means for detecting a current value I of a current flowing from a power source to the light emitting element section;
When the black image determination unit determines that the video data is a black image, the light emission is performed based on the current value I _B of the current flowing during the period in which the black image is displayed , which is detected by the current detection unit. Display abnormality detecting means for detecting display abnormality of the element part,
When the display abnormality detection unit does not detect the display abnormality, the power supply to the drive unit is continued, and when the display abnormality is detected, the power supply to the drive unit is stopped for a certain time and then restarted. Power control means,
A display unit including. The display abnormality detection means,
Threshold current storage means for storing an abnormality determination threshold current I _TH1 which is a criterion for the display abnormality;
Comparing the current value I _B and the abnormality judgment threshold current I _TH1, when the current value I _B is the abnormality judgment threshold current I _TH1 above, and determines the display abnormality determination unit and the display abnormality occurs ,
The display unit according to claim 1, further comprising: The display abnormality detection means,
When an instruction to change the abnormality determination threshold current I _TH1 is input from the outside,
An average value calculation means for calculating the current value I _B as a current average value I _MN1 averaged over the period displaying the black image,
Standard deviation calculating means for calculating a standard deviation I _SD1 of the current value I _B within the period in which the black image is displayed;
I _TH1 = I _MN1 + (I _SD1 × 3)
A threshold current calculation unit that calculates the abnormality determination threshold current I _TH1 and outputs the abnormality determination threshold current I _TH1 to the threshold current storage unit;
The display unit according to claim 2, further comprising: The current detection means,
Current-voltage conversion means for converting a current flowing to the light emitting element portion into a voltage,
First amplifying means for amplifying the voltage to calculate an amplified voltage V _A ;
Based on the predetermined threshold voltage V _TH, and cut the threshold voltage V _TH over voltage in the amplified voltage V _A, the voltage limiting means for calculating a limit voltage V _R,
Second amplifying means for amplifying the limiting voltage V _R to calculate an amplification limiting voltage V _RA ;
Analog-to-digital conversion means for converting the amplification limit voltage V _RA from an analog value to a digital value and for converting the amplification limit voltage V _RA into a current value to calculate the current value I;
The display unit according to any one of claims 1 to 3, further comprising: Said current detecting means, for every averaging period T1, and calculates the current average value I _BMN by averaging processing the current flowing during the period displaying the black image in the inside averaging period T1 Further equipped with averaging means,
The display abnormality detection means,
Threshold current storage means for storing an abnormality determination threshold current I _TH1 which is a criterion for the display abnormality;
Using the current average value I _BMN as the current value I _B , the current average value I _BMN and the abnormality determination threshold current I _TH1 are compared, and the current average value I _BMN is equal to or higher than the abnormality determination threshold current I _TH1. The display unit according to claim 1, wherein it is determined that a display abnormality has occurred.   The black image data corresponding to the black image is output to the black image determination means and the display control means instead of outputting the video data based on a black image switching instruction from the outside, which receives the video data from the video receiving means. The display unit according to any one of claims 1 to 5, further comprising a black image switching unit for outputting   When the video data is received from the video receiving means and the video data is determined by the black image determining means to be a black image, black image data corresponding to the black image is output instead of outputting the video data. The display unit according to claim 1, further comprising a black image switching unit that outputs the black image determination unit and the display control unit. A display panel in which a plurality of display units according to any one of claims 1 to 7 are arranged in a matrix.
A power supply unit for supplying power to each of the display units,
Display unit control means for controlling power supply from the power supply unit to each of the display units;
Display device. A display panel having a plurality of display units according to claim 6 arranged in a matrix;
A power supply unit for supplying power to each of the display units,
Display unit control means for controlling power supply from the power supply unit to each of the display units, and for sequentially outputting a black image switching instruction to each of the display units at regular intervals,
Display device. Receiving video data,
A step of generating a brightness control signal for controlling the brightness of each of the light emitting elements with respect to the plurality of light emitting elements arranged in a matrix on the plane of the light emitting element based on the video data;
Driving each of the light emitting elements by driving means based on the brightness control signal;
A step of detecting a current value flowing to the light emitting element section;
Performing a black image determination of the video data,
Comparing the current value I _B of the current flowing to the light emitting element unit with the abnormality determination threshold current I _TH1 when the video data is determined to be a black image;
Stopping the power supply to the drive unit by the power supply control unit for a certain period of time when the current value I _B is equal to or more than the abnormality determination threshold current I _TH1 ;
Restarting the power supply to the drive means by the power supply control means after the elapse of the certain time,
A display method including.

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