JP2006119274A - Led display device and display control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED display device of which the electric power consumption can be reduced. <P>SOLUTION: Each of DC/DC-R2R, DC/DC-G2G and DC/DC-B2B supplies a driving voltage to LEDs of the color corresponding to themselves. Thus, it is possible to supply the LEDs of each color with driving voltage which is different from that of the LEDs of other colors. The difference voltage which is obtained by subtracting the VF of the LEDs from the driving voltage, can be therefore independently set for each color of the LEDs. The difference voltage affects the power consumption at current controllers 104d. As a result, by separately controlling the driving voltage of the LEDs of each color, the power consumption at the current controllers 104d corresponding to the LEDs of each color can be reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an LED display device and a display control method, and more particularly to an LED display device using a plurality of LEDs that emit different colors and a display control method thereof.

  Conventionally, an LED display device in which pixels having LEDs (Light Emitting Diodes) of three primary colors of red (R), green (G), and blue (B) are arranged in a matrix is known (Patent Document 1). (See JP-A-7-226536).

  FIG. 3 is a circuit diagram showing an example of a conventional LED display device.

  In FIG. 3, a conventional LED display device includes three primary color LED devices 101, column switches 102a to 102c, a column decoder 103, current limiting circuits 104a to 104c, a DA converter circuit 105, a microcomputer 106, and the like. And a DC / DC converter 107.

  The three primary color LED device 101 includes a plurality of pixels 101amn. The plurality of pixels 101amn are arranged in a matrix. Note that m of the pixel 101amn represents the column number of the pixel, and n of the pixel 101amn represents the row number of the pixel.

  Each pixel 101amn includes a red LED 101R, a green LED 101G, and a blue LED 101B.

  Each of the column switches 102 a to 102 c connects the LED included in the pixel 101 amn of each column to the DC / DC converter 107. The DC / DC converter 107 is used as a power source that outputs a constant voltage (drive voltage) for lighting each LED.

  The column decoder 103 turns on / off the column switches 102 a to 102 c based on a control signal output from the microcomputer 106. Specifically, the column decoder 103 alternatively turns on the column switches 102a to 102c, and further switches the on-state column switches 102 in order.

  Each of the current limiting circuits 104a to 104c controls a current flowing through each color LED in each row.

  Each of the current limit circuits 104a to 104c includes a current limiter 104dR, a current limiter 104dG, and a current limiter 104dB. The current limiter 104dR controls the current flowing through the LEDs 101R in each row. The current limiter 104dG controls the current flowing through the LEDs 101G in each row. The current limiter 104dB controls the current flowing through the LEDs 101B in each row.

  The DA conversion circuit 105 supplies the comparison voltage to each of the current limiting circuits 104a to 104c. This comparison voltage is used to set the current flowing through each of the current limiting circuits 104a to 104c.

  The microcomputer 106 controls the DA converter circuit 105 and the column decoder 103 to display characters or images on the three primary color LED devices 101.

  The DC / DC converter 107 is a constant voltage power source that outputs a constant voltage (drive voltage) for lighting each LED. The DC / DC converter 107 converts the voltage of the battery 108 into a predetermined voltage (driving voltage) and outputs the predetermined voltage to the column switches 102a to 102c.

  The LED display device shown in FIG. 3 is driven by a dynamic LED lighting method. Note that the LED dynamic lighting method is a widely known method.

  Here, the dynamic lighting method of the LED will be briefly described.

  When the column switch 102 alternatively selected by the column decoder 103 is turned on, the output of the DC / DC converter 107 is supplied to the anode of the LED connected to the column switch 102. Note that the output of the DC / DC converter 107 is a constant voltage.

  A current that is limited by the current limiting circuit 104 flows through the LED to which the output of the constant voltage is supplied, and the LED is lit with a luminance corresponding to the current value.

  For example, in a state where the column switch 102a is on, LEDs included in the pixel 101a11, the pixel 101a12, and the pixel 101a13 are turned on, and the other LEDs are turned off.

  Since the column recorder 103 sequentially switches the column switch 102 in the ON state at regular intervals, each LED is lit intermittently in units of columns. If the period of intermittent lighting is earlier than human visual responsiveness, it seems to the user that each LED is continuously lit. In addition, the brightness | luminance of each LED is fluctuate | varied according to the magnitude | size of the electric current which flows into LED.

  Next, a loss generated in the current limit circuit 104, specifically, a loss generated in the current limiter 104d will be described.

  FIG. 4 is a circuit diagram showing an example of the current limiter 104d. In FIG. 4, the same components as those shown in FIG.

  In FIG. 4, the current limiter 104d includes a detection resistor 104d1, a transistor 104d2, and an OP amplifier 104d3.

  The detection resistor 104d1 converts the current flowing through the LED into a voltage.

  The OP amplifier 104d3 controls the base current of the transistor 104d2 based on the voltage generated by the detection resistor 104d1. Specifically, the OP amplifier 104d3 controls the base current of the transistor 104d2 so that the voltage generated by the detection resistor 104d1 matches the comparison voltage supplied from the DA conversion circuit 105. For this reason, a current corresponding to the comparison voltage flows stably through the LED connected to the current controller 104d.

When a current flows through the LED, the following power loss occurs in the current limiter 104d.
Power loss = LED current x (detection resistor voltage drop + transistor Vce)
= LED current x (output voltage of DC / DC converter 107-LED forward drop
Voltage)
The LED current is a current that flows through the LED connected to the current limiter 104d.

  The power loss of the current limiter 104d is affected by the output voltage of the DC / DC converter 107. Furthermore, if the output voltage of the DC / DC converter 107 is reduced, the power loss of the current limiter 104d is reduced.

  In order to reduce the size of the device, reduce heat generation, or save power, it is necessary to reduce the power loss of the current limiter 104d. Therefore, the output voltage of the DC / DC converter 107 is set as follows.

Output voltage of DC / DC converter 107 = resistance value of detection resistor × maximum LED current + Vce that requires a minimum number of transistors
+ A margin considering the variation of the LED VF + LED VF at the maximum LED current VF means a forward voltage drop.

  The VF of the LED differs depending on the material of the LED. For example, the blue LED is about 4V, the green LED is about 3.3V, and the red LED is about 2.5V. Therefore, for the calculation of the output voltage setting of the DC / DC converter 107, 4V of the blue LED is used as the VF of the LED at the maximum LED current.

  Note that the VF of the LED is affected by the magnitude of the LED current, and variations of individual LEDs also occur about ± 0.5V. For this reason, the margin considering the variation of the LED VF and the like is usually about 0.5V to 1.0V.

  In addition, in order for the transistor to operate in the active region, a Vce voltage of about 0.5 V is required at the minimum, and at a Vce voltage lower than that, the operation in the saturation region becomes impossible and the target current limit control is impossible. Become. Further, when Vce becomes larger than necessary, the transistor loss is the collector current × Vce, so that the power loss increases and the heat generation increases, which hinders downsizing or low power consumption of the device. In the example shown in FIG. 4, (the output voltage of the DC / DC converter 107−the VF of the LED−the voltage drop of the detection resistor) is the Vce of the transistor.

  Patent Document 2 (Japanese Patent Laid-Open No. 8-47251) describes a DC / DC converter that can reduce an output voltage used as a drive voltage.

The DC / DC converter described in Patent Document 2 outputs a drive voltage to a plurality of drive units including an LCD panel. The DC / DC converter uses the lowest voltage among the drive voltages supplied to each drive unit as the feedback voltage, and controls the output voltage based on the difference between the feedback voltage and the reference voltage.
JP-A-7-226536 JP-A-8-47251

  The output voltage of the DC / DC converter 107 is set with a large margin in advance in consideration of the variation of the LEDs. For this reason, Vce actually applied to the transistor as Vcs is larger than necessary, and unnecessary power loss occurs.

  Further, there is a difference of nearly 2V between the VF of the blue LED and the VF of the red LED, and the output voltage of the DC / DC converter is set based on the VF of the blue LED having a large VF. For this reason, the Vce of the transistor that drives the red LED is nearly 2 V higher than the Vce of the transistor that drives the blue LED, and the loss is large. This loss is caused by using a common power supply voltage as a power supply for a plurality of types of LEDs having different VFs.

  Further, the output control technique of the DC / DC converter described in Patent Document 2 also supplies the output voltage of the DC / DC converter to a plurality of drive units as in the conventional example shown in FIG. For this reason, even if the output voltage of the DC / DC converter described in Patent Document 2 is used as a power source for a plurality of types of LEDs having different VFs, useless power consumption occurs.

  An object of the present invention is to provide an LED display device and an LED display control method capable of reducing power consumption.

  In order to achieve the above object, an LED display device according to the present invention includes a plurality of LEDs that emit different colors, a driving voltage supply unit that supplies a driving voltage to each of the plurality of LEDs, and each of the LEDs has the color. In the LED display device that corresponds to any one of the LED display devices including a plurality of current limiters that are connected in series with the LED of the color corresponding to the self and that limit the current flowing through the connected LED, the drive voltage supply unit includes: A plurality of drive voltage supply units corresponding to each color are included, and each of the plurality of drive voltage supply units supplies a drive voltage to the LED of the color corresponding to itself.

  Further, the display control method of the present invention corresponds to one of the colors, a plurality of LEDs that emit different colors, a driving voltage supply unit that supplies a driving voltage to each of the plurality of LEDs, A display control method performed by an LED display device, including a plurality of current limiters that are connected in series with LEDs of a color corresponding to the self and limit a current flowing through the connected LEDs, wherein the drive voltage supply unit includes: , Including a plurality of drive voltage supply units corresponding to the respective colors, and each of the plurality of drive voltage supply units supplying a drive voltage to the LED of the color corresponding to itself.

  According to the above invention, each of the plurality of drive voltage supply units supplies the drive voltage to the LED of the color corresponding to itself. For this reason, it becomes possible to supply the drive voltage different from LED of another color to LED of each color. Therefore, a difference voltage obtained by subtracting the LED forward voltage from the drive voltage can be set independently for each LED color. This differential voltage affects the power consumption of the current limiter. For this reason, it becomes possible to reduce the power consumption of the current limiter corresponding to LED of each color by controlling the drive voltage of LED of each color separately.

  Each of the plurality of driving voltage supply units receives a voltage at a connection point between the LED of the color corresponding to itself and a current limiter to which the LED is connected, and the received voltage becomes a predetermined value. It is desirable to control the drive voltage.

  According to the above invention, if the predetermined value is set so that the current limiter operates stably and the power consumption of the current limiter is reduced, the state where the power consumption in the current limiter is low is continued. The Therefore, it is possible to reduce power consumption in the current limiter.

  Further, the plurality of LEDs include a plurality of LEDs of the same color, the plurality of current limiters include a plurality of current limiters corresponding to the same color, and each of the current limiters corresponding to the same color is self The plurality of driving voltage supply units are connected to different LEDs among the LEDs corresponding to the color, and each of the plurality of drive voltage supply units includes a plurality of current limiting LEDs connected to each of the plurality of LEDs It is desirable to receive the minimum voltage from the voltages at each connection point with the device, and to control the drive voltage so that the received voltage becomes a predetermined value.

  According to the above invention, if the current limiter operates stably and the power consumption of the current limiter is reduced as the predetermined value, the current limiter is operated while stably operating all the current limiters. It is possible to reduce the power consumption of the device.

  Each of the plurality of drive voltage supply units may be a DC / DC converter that converts a battery voltage into the drive voltage. In this case, the power consumption of the current limiter can be reduced in an LED matrix display device that can use a battery as a power source.

  Each color is preferably red, green and blue. In this case, the power consumption of the current limiter can be reduced in the LED display device capable of full color display.

  The red, green, and blue LEDs constitute a pixel, and the pixel is preferably arranged in a matrix. In this case, the power consumption of the current limiter can be reduced in the LED matrix display device capable of full color display.

  According to the present invention, it is possible to control the driving voltage of each color LED separately. For this reason, it becomes possible to reduce the power consumption of the current limiter corresponding to each color LED.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram illustrating an LED display device according to an embodiment of the present invention. In FIG. 1, the same components as those shown in FIG.

  In FIG. 1, the LED display device includes three primary color LED devices 101, column switches 1a to 1c, a column decoder 103, current limiting circuits 104a to 104c, a DA converter circuit 105, a microcomputer 106, and a drive. A voltage supply unit 2 and a diode 3 are included.

  The three-primary-color LED device 101 includes a plurality of pixels 101amn arranged in a matrix. Note that m of the pixel 101amn represents the column number of the pixel, and n of the pixel 101amn represents the row number of the pixel.

  Each pixel 101amn includes a red LED 101R, a green LED 101G, and a blue LED 101B. Note that each pixel 101amn may include the LED 101R, the LED 101G, and the LED 101B built in one package. Further, the forward voltage drop (hereinafter referred to as VF) of the LEDs of the respective colors are different from each other.

  The microcomputer 106 controls the current flowing through the LEDs of the respective colors (RGB) in the three primary color LED devices 101 to display characters or images on the three primary color LED devices 101 or uses the three primary color LED devices 101 as illumination. Or

  The drive voltage supply unit 2 includes a plurality of drive voltage supply units corresponding to each color (RGB), specifically, a red DC / DC converter (hereinafter referred to as “DC / DC-R”) 2R and a green color. A DC / DC converter (hereinafter referred to as “DC / DC-G”) 2G and a blue DC / DC converter (hereinafter referred to as “DC / DC-B”) 2B are included.

  Each of DC / DC-R2R, DC / DC-G2G, and DC / DC-B2B converts the voltage of battery 108 into a drive voltage and outputs the drive voltage to column switches 1a to 1c. In this embodiment, a chopper type step-down DC / DC converter is used as each DC / DC converter.

  The DC / DC-R2R supplies a drive voltage to the LED 101R via the column switch 1. The DC / DC-R 2G supplies a drive voltage to the LED 101G via the column switch 1. The DC / DC-R 2B supplies a driving voltage to the LED 101B via the column switch 1.

  The DC / DC-R2R receives a voltage at a connection point between the LED 101R and the current limiter 104dR, and drives so that the received voltage (hereinafter referred to as “output voltage of the current limiter 104dR”) becomes a predetermined value. Control the voltage.

  Specifically, DC / DC-R2R accepts the output voltage of current limiter 104dR as a feedback voltage. The DC / DC-R2R controls the drive voltage so that the output voltage of the current limiter 104dR becomes (resistance value of the detection resistor 104d1 × maximum LED current + minimum necessary Vce of the transistor 104d2).

  In this embodiment, the DC / DC-R2R accepts the smallest output voltage among the output voltages of the plurality of current limiters 104dR. The minimum voltage of the current limiter 104dR is such that the anode of the diode 3 whose anode side is pulled up (not shown) is connected to the output terminal of each current limiter 104dR, and the anode side of these diodes 3 is connected in common. By doing so, it can be easily detected.

  The DC / DC-R2G receives the voltage at the connection point between the LED 101G and the current limiter 104dG, and drives so that the received voltage (hereinafter referred to as “the output voltage of the current limiter 104dG”) becomes a predetermined value. Control the voltage.

  Specifically, DC / DC-R2G accepts the output voltage of current limiter 104dG as a feedback voltage. The DC / DC-R2G controls the drive voltage so that the output voltage of the current limiter 104dG becomes (resistance value of the detection resistor 104d1 × maximum LED current + minimum necessary Vce of the transistor 104d2).

  In the present embodiment, the DC / DC-R 2G receives the smallest output voltage among the output voltages of the plurality of current limiters 104dG. The minimum voltage of the current limiter 104dG is such that the anode of the diode 3 whose anode side is pulled up (not shown) is connected to the output terminal of each current limiter 104dG, and the anode side of these diodes 3 is connected in common. By doing so, it can be easily detected.

  The DC / DC-R2B receives a voltage at a connection point between the LED 101B and the current limiter 104dB, and is driven so that the received voltage (hereinafter referred to as “output voltage of the current limiter 104dB”) becomes a predetermined value. Control the voltage.

  Specifically, DC / DC-R2B accepts the output voltage of current limiter 104dB as a feedback voltage. The DC / DC-R2B controls the drive voltage so that the output voltage of the current limiter 104dB is (resistance value of the detection resistor 104d1 × maximum LED current + minimum necessary Vce of the transistor 104d2).

  In the present embodiment, the DC / DC-R 2B accepts the smallest output voltage among the output voltages of the plurality of current limiters 104dB. The minimum voltage of the current limiter 104 dB is such that the anode of the diode 3 whose anode side is pulled up (not shown) is connected to the output terminal of each current limiter 104 dB, and the anode side of these diodes 3 is connected in common. By doing so, it can be easily detected.

  According to this embodiment, the minimum Vce necessary for the active region operation of the transistor 104d2 is supplied to the transistor 104d2, regardless of the magnitude of the LED current, the magnitude of the LED VF, and the variation in the LED VF. For this reason, low loss can be realized with stable operation of the LED display device.

  Next, the operation will be described.

  FIG. 2 is a timing chart for explaining the operation of the LED display device. Hereinafter, the operation of the LED display device will be described with reference to FIG.

  2A shows the on / off state of the column switch 1a, FIG. 2B shows the on / off state of the column switch 1b, and FIG. 2C shows the on / off state of the column switch 1c. Indicates. 2D shows the current limit state of the current limiter 104aR, FIG. 2E shows the current limit state of the current limiter 104aG, and FIG. 2F shows the power limit state of the current limiter 104aB. Indicates.

  The LED display device is driven by the LED dynamic lighting method.

  The column switches 1a to 1c are turned on one by one in order by the column decoder 103 (see FIGS. 2A to 2C).

  The drive voltage of DC / DC-R2R is supplied to the plurality of LEDs 101R through the on-state column switch 1. The DC / DC-R2G drive voltage is supplied to the plurality of LEDs 101G via the on-state column switch 1. Also, the DC / DC-R2B drive voltage is supplied to the plurality of LEDs 101B via the on-state column switch 1.

  The LED 101 supplied with the driving voltage flows a current limited by the current limiting circuit 104, and the LED is lit with a luminance corresponding to the current value.

  According to this embodiment, each of DC / DC-R2R, DC / DC-G2G, and DC / DC-B2B supplies a driving voltage to the LED of the color corresponding to itself. For this reason, it becomes possible to supply the drive voltage different from LED of another color to LED of each color.

  Therefore, a difference voltage obtained by subtracting the LED VF from the drive voltage can be set independently for each LED color. This difference voltage affects the power consumption of the current limiter 104d. For this reason, the power consumption of the current limiter 104d corresponding to the LED of each color can be reduced by separately controlling the drive voltage of the LED of each color.

  In this embodiment, each of DC / DC-R2R, DC / DC-G2G, and DC / DC-B2B is a connection point between the LED corresponding to the self and the current limiter 104d to which the LED is connected. A voltage is received, and the drive voltage is controlled so that the received voltage becomes a predetermined value. For this reason, if the predetermined value is set so that the current limiter 104d operates stably and the power consumption of the current limiter 104d is reduced, the current limiter 104d operates stably and the power consumption is reduced. Less state continues.

  In this embodiment, each of DC / DC-R2R, DC / DC-G2G, and DC / DC-B2B includes a plurality of LEDs corresponding to the self and a plurality of currents connected to the plurality of LEDs. A drive voltage is controlled so that the minimum voltage is received from the voltage at the connection point with the limiter 104d, and the received voltage becomes a predetermined value. For this reason, if a value that allows the current limiter 104d to operate stably and reduces the power consumption of the current limiter 104d is used as the predetermined value, the current limiter 104d can be operated stably while the current limiter 104d is operated stably. The power consumption of 104d can be reduced.

  Further, according to this embodiment, by efficiently driving the LED matrix display device, it is possible to suppress heat generation of the device and to reduce power consumption.

  In this embodiment, a DC / DC converter that converts battery voltage into drive voltage is used as a plurality of drive voltage supply units. For this reason, it is possible to reduce power consumption in an LED matrix display device that can use a battery as a power source.

  In this embodiment, red, green and blue LEDs are used. For this reason, it is possible to reduce power consumption in an LED display device capable of full-color display.

  In this embodiment, red, green and blue LEDs constitute pixels, and the pixels are arranged in a matrix. For this reason, it is possible to reduce power consumption in an LED matrix display device capable of full color display.

  In the above-described embodiment, the three primary color LED device 101 in which the three primary color LEDs are incorporated in one pixel (package) and its driving circuit are shown. However, the three-primary-color LED device 101 may be an LED display device using LEDs in which three-color LEDs are enclosed in separate packages. Further, instead of the three primary color LED devices 101, an LED display device using two color LEDs may be used.

  In the embodiment described above, the illustrated configuration is merely an example, and the present invention is not limited to the configuration.

It is the block diagram which showed the LED display apparatus of one Example of this invention. It is a timing chart for demonstrating operation | movement of this LED display apparatus. It is the block diagram which showed the conventional LED display apparatus. It is a circuit diagram showing an example of a current limiter.

Explanation of symbols

1a to 1c column switch 2 drive voltage supply unit 2R DC / DC-R
2G DC / DC-G
2B DC / DC-B
3 diode 101 3 primary color LED device 101a pixel 101R red LED
101G green LED
101B Blue LED
DESCRIPTION OF SYMBOLS 103 Column decoder 104a-104c Current limit circuit 104d Current limiter 104d1 Detection resistance 104d2 Transistor 104d3 OP amplifier 105 DA converter circuit 106 Microcomputer

Claims (12)

A plurality of LEDs that emit different colors, a driving voltage supply unit that supplies a driving voltage to each of the plurality of LEDs, each corresponding to one of the colors, and in series with an LED of a color corresponding to itself In an LED display device comprising: a plurality of current limiters that connect and limit the current flowing through the connected LEDs;
The drive voltage supply unit includes a plurality of drive voltage supply units corresponding to each color,
Each of the plurality of driving voltage supply units supplies a driving voltage to an LED of a color corresponding to itself. The LED display device according to claim 1,
Each of the plurality of drive voltage supply units receives the voltage at the connection point between the LED of the color corresponding to itself and the current limiter to which the LED is connected, and the drive is performed so that the received voltage becomes a predetermined value. LED display device that controls voltage. The LED display device according to claim 2,
The plurality of LEDs includes a plurality of LEDs of the same color,
The plurality of current limiters include a plurality of current limiters corresponding to the same color,
Each of the current limiters corresponding to the same color is connected to different LEDs among the LEDs corresponding to the same color,
Each of the plurality of driving voltage supply units receives a minimum voltage from among voltages at connection points between a plurality of LEDs of a color corresponding to the plurality of driving voltage supply units and a plurality of current limiters connected to the plurality of LEDs. The LED display device controls the drive voltage so that the received voltage becomes a predetermined value. The LED display device according to any one of claims 1 to 3,
Each of the plurality of drive voltage supply units is an LED display device that is a DC / DC converter that converts a battery voltage into the drive voltage. The LED display device according to any one of claims 1 to 4,
Each said color is a red, green, and blue LED display device. The LED display device according to claim 5,
An LED display device in which red, green, and blue LEDs constitute pixels, and the pixels are arranged in a matrix. A plurality of LEDs that emit different colors, a driving voltage supply unit that supplies a driving voltage to each of the plurality of LEDs, each corresponding to one of the colors, and in series with an LED of a color corresponding to itself A plurality of current limiters that connect and limit the current flowing through the connected LEDs, and a display control method performed by an LED display device,
The drive voltage supply unit includes a plurality of drive voltage supply units corresponding to each color,
A display control method including a supply step in which each of the plurality of drive voltage supply units supplies a drive voltage to an LED of a color corresponding to itself. The display control method according to claim 7,
The supplying step includes
Each of the plurality of driving voltage supply units receives a voltage at a connection point between the LED of the color corresponding to the driving voltage supply unit and the current limiter to which the LED is connected; and
And a control step of controlling the drive voltage so that each of the plurality of drive voltage supply units has a predetermined voltage. The display control method according to claim 8,
The plurality of LEDs includes a plurality of LEDs of the same color, the plurality of current limiters include a plurality of current limiters corresponding to the same color, and each of the current limiters corresponding to the same color corresponds to the self. Connected to different LEDs among the color LEDs
In the receiving step, each of the plurality of drive voltage supply units is a minimum of voltages at a connection point between a plurality of LEDs having a corresponding color and a plurality of current limiters connected to the plurality of LEDs. Display control method including receiving a voltage of. The display control method according to any one of claims 7 to 9,
The display control method, wherein each of the plurality of drive voltage supply units is a DC / DC converter that converts a battery voltage into the drive voltage. The display control method according to any one of claims 7 to 10,
The display control method, wherein each of the colors is red, green, and blue. The display control method according to claim 11,
A display control method in which red, green, and blue LEDs constitute pixels, and the pixels are arranged in a matrix.

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