JP2006023585A - Method for driving display device and display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply voltages of different values to light emitting elements of different colors arranged in units of scanning lines. <P>SOLUTION: The organic EL elements 30 emit light in red, green, and blue, respectively. A scan line driving circuit 14 generates a scanning signal. An R power source 18, a G power source 20, and a B power source 22 are the power sources having different voltages. A selection circuit 16 selects any one from among the R power source 18, the G power source 20, the B power source 22, and a GND 24 on the basis of a timing signal 210. The selection circuit 16 applies the voltage of the selected power source to at least the organic EL element 30 of the driving object. A PWM circuit 26 performs pulse width modulation of the voltage of the power source selected by the selection circuit 16 on the basis of the pixel value inputted as the pulse signal 212. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display device drive technique, and more particularly to a display device drive method for driving light emitting elements arranged in a matrix and a display device using the drive method.

  In a display device using an organic EL (electroluminescence) element or an LED (Light Emitting Diode) as a light emitting element, a plurality of light emitting elements are generally arranged in a matrix. In such a display device, generally, a signal for causing a light emitting element to emit light is input in the column direction of the matrix, and a scanning signal is input in the row direction of the matrix. In addition, in the matrix, light emitting elements that emit red, green, and blue light are arranged as one combination, so that the display device displays a color image (see, for example, Patent Document 1).

JP 2002-333863 A

  When the light emitting element is an organic EL element, a predetermined voltage is applied to emit light. At this time, in order to adjust the luminance between red light emission, green light emission, and blue light emission, even if the luminances are the same, an organic EL element that should emit light in red and an organic that should emit light in green The value of the voltage applied to the EL element and the organic EL element that should emit blue light is set to a different value. At that time, if a power source for applying a voltage to the organic EL elements corresponding to each color is separately provided, the control of the apparatus becomes easy. On the other hand, in a display device with a horizontally long display area, if the scroll display in the left and right directions is made smooth, the change in display content on the display device can be made smooth. In order to realize this, organic EL elements that emit light of the same color are arranged in the matrix column direction. In that case, a voltage is applied from the power supply corresponding to each color from the direction of the column of the matrix.

  Under such circumstances, the present inventor has come to recognize the following problems. In a display device having a vertically long display area, it is desirable to smoothly scroll in the vertical direction. For this purpose, organic EL elements emitting light of the same color should be arranged in the row direction. At this time, since the voltage to be applied to the organic EL element is different in color units, an applied voltage line for applying a voltage to the organic EL element should also be arranged in the row direction. However, since the scanning lines are provided in the row direction, it is difficult to route the signal lines, and it is difficult to provide a voltage application line for applying a voltage to the organic EL element.

  The present invention has been made in view of such circumstances, and an object thereof is to apply a signal to a light emitting element even when light emitting elements that emit light of the same color are arranged in the direction of a scanning line. A driving method of a display device and a display device using the same.

  In order to solve the above-described problems, a driving method of a display device according to an embodiment of the present invention is determined according to the color of a pixel to be driven from a plurality of power supply voltages when driving the pixels constituting the display device. The selected power supply voltage is selected and the pixel is driven by applying the power supply voltage to the pixel.

  “Pixel” is generally the smallest unit that constitutes an image. However, if the color components are the three primary colors of RGB, each of RGB contained in the smallest unit that constitutes an image, for example, an RGB display Each light emitting element may be referred to as a pixel.

  According to this aspect, since one is selected from a plurality of power supply voltages corresponding to the color of the pixel to be driven and the selected power supply voltage is applied to the pixel, the power supply voltage corresponding to the color of the pixel can be applied.

  The power supply voltage may be set according to the characteristics of elements that realize different pixel colors. According to this aspect, the power supply voltage suitable for the element characteristics can be set.

  Another embodiment of the present invention is a display device. This device is a matrix type display device in which the scanning line direction and the voltage application line direction are orthogonal to each other, and pixels of the same color are arranged on the same scanning line, and pixels of different colors are arranged on adjacent scanning lines. As described above, a plurality of pixels respectively arranged on the scanning line, a plurality of power sources corresponding to the colors of the pixels, and one of the plurality of power sources are selected, and the selected power source is selected via the voltage application line. A selection circuit that applies at least the voltage of the power source to the pixel to be driven. The selection circuit selects a power supply corresponding to the color of the pixel arranged on the predetermined scanning line when the pixel is driven with respect to the predetermined scanning line, and at least the voltage of the selected power supply is set to the predetermined scanning line. Applied to the pixels arranged on the line.

  According to this aspect, since one of a plurality of power supplies corresponding to the color of the pixel to be driven is selected and the voltage of the selected power supply is applied to the pixel, pixels that emit light of the same color in the direction of the scanning line Even when they are arranged, a power supply voltage corresponding to the color of the pixel can be applied to the pixel while preventing the circuit from becoming complicated.

  A plurality of pulse width modulation circuits that write desired pixel values to the respective pixels arranged on the same scanning line may be further provided. The pulse width modulation circuit may control the application period of the power supply voltage selected by the selection circuit. According to this aspect, since the application period of the power supply voltage is controlled according to the desired pixel value and then applied to the pixel, the pixel can emit light with the desired brightness while adjusting the brightness of the pixels of different colors. .

  Yet another embodiment of the present invention is also a display device. This device is a matrix type display device in which the scanning line direction and the voltage application line direction are orthogonal to each other, and pixels of the same color are arranged on the same scanning line, and pixels of different colors are arranged on adjacent scanning lines. As described above, a plurality of pixels arranged on the scanning line and a width of the scanning pulse for driving the pixel arranged on each scanning line are set according to the color of the pixel arranged on the scanning line. In order to write a desired pixel value for each pixel arranged on one scanning line with a setting circuit, the voltage application line controls the period during which the power supply voltage should be applied to each pixel and is arranged on the scanning line. And a pulse width modulation circuit provided by the number of pixels. In the pulse width modulation circuit, the period during which the power supply voltage is applied to each pixel through the voltage application line is proportional to the width of the scanning pulse corresponding to the color in units of pixel color.

  According to this aspect, the maximum value of the period during which the voltage is applied to the pixel is adjusted according to the color of the pixel while the period during which the voltage is applied to the pixel is adjusted according to the luminance when displaying the pixel. Even with one, the luminance can be adjusted according to the color of the pixel.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, and the like are also effective as an aspect of the present invention.

  According to the present invention, a signal can be applied to a light emitting element even when light emitting elements that emit light of the same color are arranged in the direction of the scanning line.

Example 1
Before describing the present invention in detail, an outline will be described. Example 1 of the present invention relates to a display device in which organic EL elements as light emitting elements are arranged in a matrix. Further, the display device according to the present embodiment is passive matrix driving, and the scanning lines are arranged in the row direction of the matrix and the voltage application lines are arranged in the column direction of the matrix. Each organic EL element emits light according to the voltage. Further, a voltage to be applied to the organic EL element via the voltage application line is supplied from a power source, and a plurality of power sources are provided according to the number of colors emitted from the organic EL element. That is, since the organic EL element emits red, green, and blue light, the power source for red (hereinafter referred to as “R power source”), the power source for green (hereinafter referred to as “G power source”), and blue Power supply (hereinafter referred to as “B power supply”). These power supplies provide different values of voltage.

  Here, organic EL elements that emit light of the same color are arranged on one scanning line. Since the organic EL elements arranged on one scanning line are to be driven, the display device according to the present embodiment selects a power source corresponding to the color of the organic EL element on the corresponding scanning line, and selects the selected power source. Is applied to the organic EL element. Since the scanning line to be driven is sequentially changed, the selected power source is also changed in synchronization therewith. Further, the voltage applied to the organic EL element is PWM (Pulse Width Modulation) based on the pixel value to be displayed on the corresponding organic EL element, and then applied to the organic EL element. In this embodiment, since the voltage application line for applying a voltage to the organic EL element is arranged so as to be orthogonal to the scanning line, the voltage application line can be provided in the display device.

  FIG. 1 illustrates a configuration of a display device 100 according to the first embodiment. The display device 100 includes a control circuit 10, a voltage application line driving circuit 12, a scanning line driving circuit 14, a selection circuit 16, an R power source 18, a G power source 20, a B power source 22, a GND 24, and a first PWM circuit collectively referred to as a PWM circuit 26. 26a, a second PWM circuit 26b, a third PWM circuit 26c, an NPWM circuit 26n, and a display panel 28. The display panel 28 includes an eleventh organic EL element 30aa, a twelfth organic EL element 30ab, a thirteenth organic EL element 30ac, a first N organic EL element 30an, a twenty-first organic EL element 30ba, 22nd organic EL element 30bb, 23rd organic EL element 30bc, 2nd N organic EL element 30bn, 31st organic EL element 30ca, 32nd organic EL element 30cb, 33rd organic EL element 30cc, 3rd N organic EL element 30cn, An M1 organic EL element 30ma, an M2 organic EL element 30mb, an M3 organic EL element 30mc, and an MN organic EL element 30mn are provided.

  As signals and signal lines, a first pulse signal collectively referred to as display data 200, synchronization data 202, display data 204, voltage application line synchronization data 206, scanning line synchronization data 208, timing signal 210, and pulse signal 212. 212a, second pulse signal 212b, third pulse signal 212c, Nth pulse signal 212n, first voltage application line 214a, voltage application line 214b, second voltage application line 214b, third voltage application line 214c, It includes an N voltage application line 214n, a first scanning line 216a, a second scanning line 216b, a third scanning line 216c, and an Mth scanning line 216m, which are collectively referred to as a scanning line 216.

  The control circuit 10 inputs display data 200 and synchronization data 202 from the outside. The display data 200 is image data to be displayed on the display panel 28 described later. Here, since the display panel 28 has a matrix display of M rows × N columns, the display panel 28 includes M × N organic EL elements 30. Since each of the organic EL elements 30 emits light in red, green, and blue, the display data 200 is data corresponding to each gradation. The synchronization data 202 includes row and column information that should correspond to the display data 200. The control circuit 10 outputs information equivalent to the display data 200 as display data 204, and outputs timing information corresponding to the display data 204 as voltage application line synchronization data 206. In addition, the control circuit 10 outputs row switching, that is, scanning information as scanning line synchronization data 208.

  The organic EL element 30 emits light in red, green, and blue, respectively. In the drawing, the organic EL element 30 that emits red light is indicated by “R”, the organic EL element 30 that emits green light is indicated by “G”, and the organic EL element 30 that emits blue light is indicated by “B”. That is, in the plurality of organic EL elements 30, the organic EL elements 30 of the same color are arranged on the same scanning line 216, and the organic EL elements 30 of different colors are arranged on the adjacent scanning lines 216. Further, the organic EL element 30 is disposed at the intersection of a matrix in which M scanning lines 216 and N voltage application lines 214 are orthogonal to each other. Furthermore, since the organic EL element 30 is driven in a passive matrix, light is emitted according to the voltage values of the voltage application line 214 and the scanning line 216.

  The scanning line driving circuit 14 generates a scanning signal based on the scanning line synchronization data 208 input from the control circuit 10. Here, one of the plurality of scanning lines 216 is selected in the order of the first scanning line 216a and the second scanning line 216b so that the scanning signal is output from only one of the M scanning lines 216. A scanning signal is output.

  The R power source 18, the G power source 20, and the B power source 22 are power sources having different voltage values. Reference numeral 24 denotes a ground. Here, the R power supply 18 outputs a voltage to be applied to the organic EL element 30 displayed in red, for example, the eleventh organic EL element 30aa and the twelfth organic EL element 30ab. The G power supply 20 outputs a voltage to be applied to the organic EL element 30 displayed in green, for example, the 21st organic EL element 30ba and the 22nd organic EL element 30bb. Further, the B power supply 22 outputs a voltage to be applied to the organic EL element 30 displayed in blue, for example, the 31st organic EL element 30ca and the 32nd organic EL element 30cb.

  The selection circuit 16 selects any one of the R power source 18, the G power source 20, the B power source 22, and the GND 24 based on the timing signal 210. That is, a power supply corresponding to the color of the organic EL element 30 driven by the scanning signal is selected in synchronization with the scanning signal generated by the scanning line driving circuit 14. This is because when the organic EL element 30 is driven with respect to the predetermined voltage application line 214, a power supply corresponding to the color of the organic EL element 30 arranged on the predetermined voltage application line 214 is selected. It corresponds to. For example, when the scanning line driving circuit 14 outputs a scanning signal from the first scanning line 216a, the selection circuit 16 selects the R power source 18, and the scanning line driving circuit 14 receives the scanning signal from the second scanning line 216b. When outputting, the selection circuit 16 selects the G power supply 20. FIG. 2 shows an outline of the operation of the selection circuit 16. The left side of the figure shows the row number, that is, the number of the scanning line 216, and the left side of the figure shows the power source to be selected according to the number of the row. Returning to FIG. The selection circuit 16 applies at least the voltage of the selected power source to the organic EL element 30 to be driven via the voltage application line 214.

  The voltage application line drive circuit 12 receives display data 204 and voltage application line synchronization data 206. The voltage application line synchronization data 206 is synchronized with the timing of the scanning signal generated by the scanning line driving circuit 14, and the display data 204 also includes information on the color to be displayed. The application line driving circuit 12 generates information on the power source to be selected according to the timing of the scanning signal as the timing signal 210 and outputs the information to the selection circuit 16. In addition, pixel value information to be displayed is generated as a pulse signal 212 in accordance with the timing of the scanning signal and output to the PWM circuit 26.

  The PWM circuit 26 performs pulse width modulation on the voltage of the power source selected by the selection circuit 16 based on the pixel value input as the pulse signal 212. This is equivalent to writing a desired pixel value to each organic EL element 30 arranged on the same scanning line 216. As a result, the period during which the voltage of the power source selected by the selection circuit 16 is to be applied to the organic EL element 30 is controlled by the PWM circuit 26. For example, in order to increase the luminance of a predetermined color, a signal that increases the period to be applied to the organic EL element 30 is generated.

  FIGS. 3A to 3D show signals output from the PWM circuit 26 and the scanning line driving circuit 14. FIG. 3A shows the voltage of the power supply selected by the selection circuit 16. Here, since the organic EL element 30 emits light in the order of red, green, and blue, the selection circuit 16 selects the R power source 18, the G power source 20, and the B power source 22 in order. As a result, among the peaks shown in FIG. 3A, “P1” corresponds to the voltage output from the R power supply 18, “P2” corresponds to the voltage output from the G power supply 20, and “P3 "Corresponds to the voltage output from the B power source 22. As illustrated, the voltage increases in the order of the R power source 18, the B power source 22, and the G power source 20. In the figure, portions indicated by a low level other than “P1”, “P2”, and “P3” correspond to the ground voltage, and the selection circuit 16 selects the GND 24 at that time.

  FIG. 3B shows the first pulse signal 212 a output from the voltage application line drive circuit 12. The first pulse signal 212a corresponds to the selected scanning line 216, and “P1 ′”, “P2 ′”, and “P3 ′” are the eleventh organic EL element 30aa, the twenty-first organic EL element 30ba, and the 31 is luminance information corresponding to the organic EL element 30ca. Here, since the luminance increases in the order of the 31st organic EL element 30ca, the 11th organic EL element 30aa, and the 21st organic EL element 30ba, the width of the pulse also increases in that order.

  FIG. 3C shows a signal that is subjected to pulse amplitude modulation by the first PWM circuit 26a and output via the first voltage application line 214a. “P1 ″” corresponds to “P1” and “P1 ′”, “P2 ″” corresponds to “P2” and “P2 ′”, and “P3 ″” corresponds to “P3” and “P3”. Corresponds to '". As a result, the signal “P1 ″” has the pulse width indicated by “P1 ′” in FIG. 3B while having the voltage indicated by “P1” in FIG. The same applies to the signals indicated by “P2 ″” and “P3 ″”. FIG. 3D shows a scanning signal output from the scanning line driving circuit 14 via the first scanning line 216a. In the case of the low level in the drawing, the eleventh organic EL element 30aa and the twelfth organic EL element 30ab. Etc. are selected. With the above signal, the eleventh organic EL element 30aa emits light with a luminance corresponding to the signal “P1 ″”.

  FIG. 4 is a flowchart showing a display procedure in the display device 100. The selection circuit 16 counts the number L of the scanning lines 216 based on the timing signal 210 (S10). Note that L is set to 1 when a new image is displayed. The selection circuit 16 divides L by 3 (S12). If the remainder is 1 (Y in S14), the R power source 18 is selected (S16). If the remainder is not 1 (N in S14) and the remainder is 2 (Y in S18), the G power source 20 is selected (S20). If the remainder is not 2 (N in S18), the B power source 22 is selected (S22). The selection circuit 16 outputs the voltage of the selected power supply to the PWM circuit 26 (S24). The signal subjected to pulse amplitude modulation by the PWM circuit 26 is applied to the organic EL element 30 through the voltage application line 214 (S26).

  According to the embodiment of the present invention, one of a plurality of power supply voltages corresponding to the emission color of the organic EL element to be driven is selected, and the selected power supply voltage is applied to the organic EL element. It is possible to apply a power supply voltage in accordance with. In addition, since one of a plurality of power sources corresponding to the emission color of the organic EL element to be driven is selected and the voltage of the selected power source is applied to the organic EL element, the same color is emitted in the direction of the scanning line. Even in the case where the organic EL elements are arranged, it is possible to apply a power supply voltage corresponding to the color of the organic EL element to the organic EL element while suppressing the complexity of the configuration of the display device. In addition, since the application period of the power supply voltage is controlled according to the desired pixel value and then applied to the organic EL element, the organic EL element is adjusted to the desired brightness while adjusting the brightness of the organic EL elements of different colors. Can emit light. In addition, since organic EL elements that emit light of the same color in the direction of the scanning line can be arranged, the movement of an image displayed on a display device having a vertically long display area can be made smooth. In addition, control is facilitated because only power supplies of different voltages are switched.

(Example 2)
Example 2 of the present invention relates to a display device in which organic EL elements as light emitting elements are arranged in a matrix as in Example 1. The arrangement of the organic EL elements, the scanning lines, and the voltage application lines in the matrix is the same as that in the first embodiment. However, unlike the first embodiment, the display device according to the second embodiment includes a single power source despite a plurality of colors to be emitted by the organic EL element. Instead, the period during which a voltage is applied to the organic EL element is changed according to the color to be emitted by the organic EL element. That is, the signal period on the scanning line is changed according to the color of the organic EL elements arranged on the scanning line. Further, the voltage applied to the organic EL element via the voltage application line is PWM, but the period of the PWM signal is also changed according to the color of the organic EL element that should emit light. That is, when red, green, and blue light are emitted with high luminance, the voltage application period from the voltage application line should be lengthened, but the voltage required to achieve the same luminance is “red: green: blue. If “5: 1: 2”, the voltage application period is adjusted accordingly.

  FIG. 5 illustrates a configuration of the display device 100 according to the second embodiment. Similar to the display device 100 of FIG. 1, the display device 100 includes a control circuit 10, a voltage application line drive circuit 12, a scanning line drive circuit 14, and a PWM circuit 26, which are collectively referred to as a first PWM circuit 26a, a second PWM circuit 26b, and a third PWM. A circuit 26c, an N-th PWM circuit 26n, and a display panel 28 are provided. The configuration of the organic EL element 30 included in the display panel 28 is the same as that in FIG. Further, the display device 100 includes a power supply 40 and a setting circuit 42. Further, as the signals and signal lines, display data 200, synchronization data 202, display data 204, voltage application line synchronization data 206, scanning line synchronization data 208, pulse signal 212, voltage application, as in the display device 100 of FIG. A line 214, a scanning line 216, setting circuit synchronization data 220, a PWM setting signal 222, and a scanning line drive circuit setting signal 224.

  The control circuit 10 operates in the same manner as the control circuit 10 of FIG. 1, but outputs the setting circuit synchronization data 220 corresponding to the voltage application line synchronization data 206 and the scanning line synchronization data 208. The arrangement of the organic EL elements 30 is the same as that shown in FIG.

  The setting circuit 42 sets the width of the scanning signal for driving the organic EL elements 30 arranged on each scanning line 216 based on the setting circuit synchronization data 220 to the organic EL arranged on the scanning line 216. It is set according to the color of the element 30. In Example 2, since the value of the voltage to be applied to the organic EL element 30 is the same, the period during which the voltage is applied is changed according to the color emitted by the organic EL element 30. For example, in order to cause the organic EL element 30 to emit light with the same luminance, the period during which the voltage is applied to the red organic EL element 30 is lengthened, while the period during which the voltage is applied to the green organic EL element 30 is shortened. . If the description is made according to the configuration of the display device 100 of FIG. 5, when scanning signals are output in the order of the first scanning line 216 a, the second scanning line 216 b, and the third scanning line 216 c, the corresponding organic EL elements 30. Since the colors emitted by are in the order of red, green, and blue, the setting circuit 42 uses the PWM setting signal 222 and the scanning line drive circuit setting signal 224 as signals for changing the width of the scanning signal in accordance with those colors. Output as.

  The scanning line driving circuit 14 generates a scanning signal based on the scanning line driving circuit setting signal 224. The width of the scanning signal is changed according to the color that the organic EL element 30 should emit. FIGS. 6A to 6D show signals output from the scanning line driving circuit 14. FIG. 6A shows the scanning line drive circuit setting signal 224 generated by the setting circuit 42. The peak portion indicated by “P1” in FIG. 6A and the subsequent valley portion correspond to the period during which the organic EL element 30 should emit light in red, and the peak portion indicated by “P2” The subsequent valley portion corresponds to a period in which the organic EL element 30 should emit light in green. A peak portion indicated by “P3” and a valley portion subsequent thereto correspond to a period during which the organic EL element 30 should emit blue light. As shown in the figure, the signal period becomes longer in the order of red, blue, and green. Since “P4” is the same as “P1”, “P1” to “P3” are periodically repeated.

  FIG. 6B shows a scanning signal output to the first scanning line 216a, which is at a low level during a signal period related to “P1” in FIG. In order to generate such a signal, the scanning line driving circuit 14 includes a counter and the like, and counts a period from the start to the end of the signal related to “P1” to generate the signal. 6C and 6D are scanning signals output to the second scanning line 216b and the third scanning line 216c, respectively. Like FIG. 6B, FIG. 6A and FIG. It goes low during the period of the signal related to “P2” and “P3”. That is, the scanning line driving circuit 14 outputs a scanning signal in which the signal period is changed according to the color emitted by the organic EL element 30.

  Returning to FIG. The power source 40 is a power source for applying a voltage to the organic EL element 30. Unlike the first embodiment, the power source 40 has a single voltage value. The voltage application line drive circuit 12 receives the display data 204 and the voltage application line synchronization data 206 and outputs a pulse signal 212.

  The PWM circuit 26 performs pulse width modulation on the voltage of the power supply 40 based on the pixel value input as the pulse signal 212. This is to control the period during which the power supply voltage is applied to each organic EL element 30 by the voltage application line 214 in order to write a desired pixel value to each organic EL element 30 arranged on one scanning line 216. It corresponds to doing. The PWM circuit 26 makes the period during which the power supply voltage should be applied to each organic EL element 30 through the voltage application line 214 in proportion to the width of the scanning signal corresponding to the color in units of color of the organic EL element 30.

  This will be specifically described as follows. As described above, the period of the scanning signal is changed according to the color to be emitted by the organic EL element 30. On the other hand, when the organic EL element 30 emits light with a predetermined color and the highest luminance, the period during which a voltage is to be applied to the organic EL element 30 is lengthened. Here, in order to adjust both, the period during which the voltage is applied when light is emitted with the maximum luminance is changed according to the period of the scanning signal. For example, the scanning signal period corresponding to red, green, and blue is “50 μs: 10 μs: 20 μs”, and the period in which the voltage is applied in order to emit light with the maximum luminance is for red, green, and blue. “50 μs: 10 μs: 20 μs”. On the other hand, the period in which the voltage is applied in order to emit light with an intermediate luminance is set to “25 μs: 5 μs: 10 μs” for red, green, and blue. Thus, the period during which the voltage is applied is normalized by the period of the scanning signal corresponding to each color.

  7A to 7C show signals output from the PWM circuit 26. FIG. FIG. 7A shows the PWM setting signal 222 generated by the setting circuit 42. The peak portion indicated by “P1” in FIG. 7A and the subsequent valley portion correspond to a period during which the organic EL element 30 should emit light in red, and the peak portion indicated by “P2” The subsequent valley portion corresponds to a period in which the organic EL element 30 should emit light in green. A peak portion indicated by “P3” and a valley portion subsequent thereto correspond to a period during which the organic EL element 30 should emit blue light. As shown in the figure, the signal period becomes longer in the order of red, blue, and green. Since “P4” is the same as “P1”, “P1” to “P3” are periodically repeated. As described above, the content of the PWM setting signal 222 is the same as the content of the scanning line driving circuit setting signal 224.

  FIG. 7B shows the first pulse signal 212a. The pulse signal 212 indicates luminance in a period of Hi level. That is, the longer the Hi level period, the higher the luminance. It is assumed that the periods of “P1 ′”, “P2 ′”, and “P3 ′” shown in FIG. 7B have the same length and each corresponds to the maximum luminance. “P1 ′” corresponds to “P1”, “P2 ′” corresponds to “P2”, and “P3 ′” corresponds to “P3”. Here, the reason why the corresponding timings are shifted will be described later.

  FIG. 7C shows a signal subjected to pulse width modulation by the first PWM circuit 26a. The period corresponding to the maximum luminance as shown in FIG. 7B is normalized based on the period of the scanning signal corresponding to each color as shown in FIG. That is, in FIG. 7B, the same “P1 ′”, “P2 ′”, and “P3 ′” Hi level periods are adjusted according to the period of the scanning signal in FIG. Yes. Here, “P1 ″”, “P2 ″”, and “P3 ″” correspond to “P1 ′”, “P2 ′”, and “P3 ′”, respectively. As described above, since the PWM circuit 26 needs to recognize the width of the scanning signal in advance in order to adjust the period of the pulse width modulated signal according to the width of the scanning signal, FIG. “P1 ′”, “P2 ′”, and “P3 ′” in FIG. 7A are input at a timing that precedes “P1”, “P2”, and “P3” in FIG.

  FIG. 8 is a flowchart showing a display procedure in the display device 100. The PWM circuit 26 inputs information regarding the width of the scanning signal by the PWM setting signal 222 (S40). The PWM circuit 26 performs pulse width modulation on the voltage of the power supply 40 based on the information on luminance (S42), and adjusts the width of the pulse width modulated signal according to the width of the scanning signal (S44). Further, the signal pulse-width modulated by the PWM circuit 26 is applied to the organic EL element 30 via the voltage application line 214.

  According to the embodiment of the present invention, the maximum value of the period during which the voltage is applied to the organic EL element is adjusted while the period during which the voltage is applied to the organic EL element is adjusted according to the luminance when displaying the organic EL element. Since it adjusts according to the color of an element, even if there is one power supply, a brightness | luminance can be adjusted according to the color of an organic EL element.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In Embodiments 1 and 2 of the present invention, the display device 100 includes an organic EL element 30 as a light emitting element. However, the present invention is not limited to this. For example, an LED, a VFD, or an inorganic EL element corresponding to each color may be used. At that time, the power supply voltage and the voltage application period may be set in accordance with the characteristics of the light-emitting elements that realize different colors. According to this modification, various light emitting elements can be applied. In addition, a power supply voltage and an application period suitable for the element characteristics can be set. That is, the luminance of the light emitting element may be adjusted.

  In the first and second embodiments of the present invention, the display device 100 has the scanning lines 216 arranged in the row direction of the matrix and the voltage application lines 214 arranged in the column direction. However, the present invention is not limited to this. For example, the scanning lines 216 may be arranged in the matrix column direction, and the voltage application lines 214 may be arranged in the row direction. According to this modification, the present invention can be applied to various arrangements on the matrix. That is, light emitting elements that emit light of the same color may be arranged in the direction of one scanning line.

1 is a diagram illustrating a configuration of a display device according to Example 1. FIG. It is a figure which shows the operation | movement outline | summary of the selection circuit of FIG. 3A to 3D are diagrams showing signals output from the PWM circuit and the scanning line driving circuit of FIG. 2 is a flowchart showing a display procedure in the display device of FIG. 1. 6 is a diagram illustrating a configuration of a display device according to Example 2. FIG. 6A to 6D are diagrams illustrating signals output from the scanning line driving circuit of FIG. 7A to 7C are diagrams showing signals output from the PWM circuit of FIG. It is a flowchart which shows the procedure of the display in the display apparatus of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Control circuit, 12 Voltage application line drive circuit, 14 Scan line drive circuit, 16 Selection circuit, 18 R power supply, 20 G power supply, 22 B power supply, 24 GND, 26 PWM circuit, 28 Display panel, 30 Organic EL element, 40 Power supply, 42 setting circuit, 100 display device, 200 display data, 202 synchronization data, 204 display data, 206 voltage application line synchronization data, 208 scan line synchronization data, 210 timing signal, 212 pulse signal, 214 voltage application line, 216 scanning line, 220 setting circuit synchronization data, 222 PWM setting signal, 224 scanning line drive circuit setting signal.

Claims (5)

  When driving a pixel constituting a display device, a power supply voltage determined corresponding to the color of the pixel to be driven is selected from a plurality of power supply voltages, and the power supply voltage is applied to the pixel. A method for driving a display device, characterized by comprising:   The method of driving a display device according to claim 1, wherein the power supply voltage is set in accordance with characteristics of elements that realize different pixel colors. A matrix type display device in which a scanning line direction and a voltage application line direction are orthogonal to each other,
A plurality of pixels arranged on the scanning line so that pixels of the same color are arranged on the same scanning line and pixels of different colors are arranged on the adjacent scanning lines;
A plurality of power supplies corresponding to the pixel colors,
A selection circuit that selects any one power supply from a plurality of power supplies and applies a voltage of the selected power supply to at least a pixel to be driven via a voltage application line;
The selection circuit selects a power source corresponding to the color of the pixel arranged on the predetermined scanning line when driving the pixel with respect to the predetermined scanning line, and sets the voltage of the selected power source to at least the predetermined scanning line. A display device characterized by being applied to pixels arranged on a scanning line. A plurality of pulse width modulation circuits for writing a desired pixel value to each pixel arranged on the same scanning line;
The display device according to claim 3, wherein the pulse width modulation circuit controls a voltage application period of a power source selected by the selection circuit. A matrix type display device in which a scanning line direction and a voltage application line direction are orthogonal to each other,
A plurality of pixels arranged on the scanning line so that pixels of the same color are arranged on the same scanning line and pixels of different colors are arranged on the adjacent scanning lines;
A setting circuit that sets the width of the scanning pulse for driving the pixels arranged on each scanning line in accordance with the color of the pixel arranged on the scanning line;
In order to write a desired pixel value for each pixel arranged on one scanning line, the period during which the power supply voltage should be applied to each pixel is controlled by the voltage application line, and the number of pixels arranged on the scanning line And a pulse width modulation circuit provided only
The display apparatus according to claim 1, wherein the pulse width modulation circuit makes a period in which a power supply voltage is applied to each pixel through a voltage application line proportional to the width of a scanning pulse corresponding to the color in a pixel unit.

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