JP2006011058A - Electro-optical device, its driving method and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electro-optical device capable of uniforming luminance of a plurality of sub-areas, and to provide its driving method and an electronic apparatus. <P>SOLUTION: A display area Z of the electro-optical device 10 is composed of a plurality of display panels Z1 to Z4. A plurality of pixel circuits 400 are formed in each of the display panels Z1 to Z4 and an OLED element is formed in each pixel circuit 400. A power supply circuit 18 generates offset voltages Vofs1 to Vofs4 so that the luminance of respective display panels Z1 to Z4 is uniformed. An X driver 16 generates a gradation voltage signal on the basis of image data D, adds the gradation voltage signal to the offset voltage and generates an output gradation voltage signal. Then the X driver 16 supplies a data signal obtained by time division multiples of a triangular wave voltage signal SS and the output gradation voltage signal to a data line 103. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electro-optical device that drives a current-driven element such as an organic light-emitting diode element, a driving method thereof, and an electronic apparatus.

In recent years, organic light emitting diodes (hereinafter referred to as “OLED elements”) elements called organic electroluminescence elements and light emitting polymer elements have attracted attention as next-generation light-emitting devices that replace liquid crystal elements. Since this OLED element is a self-luminous type, it has less viewing angle dependence, and since it does not require a backlight or reflected light, it is suitable for low power consumption and thinning. It has characteristics.
Here, the OLED element is a current-type driven element that does not have voltage holdability like a liquid crystal element and cannot maintain a light emitting state when current is interrupted. Therefore, when an OLED element is driven by an active matrix method, a voltage corresponding to the gradation of the pixel is written to the gate of the driving transistor in the writing period (selection period), and the voltage is held by a gate capacitance or the like. In general, the drive transistor keeps a current corresponding to the gate voltage flowing through the OLED element.

In this configuration, it has been pointed out that the threshold voltage characteristics of the driving transistor vary, and therefore the brightness of the OLED element is different for each pixel and the display quality is lowered. Therefore, in recent years, during the writing period, the drive transistor is diode-connected, and a constant current is passed from the drive transistor to the data line, so that the current corresponding to the current to be passed to the OLED element is passed to the gate of the drive transistor. There has been proposed a technique that compensates for variations in threshold voltage characteristics of drive transistors by programming to write a voltage (see, for example, Patent Documents 1 and 2).
US Pat. No. 6,229,506 (see FIG. 2) Japanese Patent Laying-Open No. 2003-177709 (see FIG. 3)

  By the way, when the display area of the electro-optical device is divided into a plurality of sub-areas, and there are variations in the characteristics of the OLED elements and transistors for each sub-area, when each sub-area is driven by an individual drive module, In some cases, different types of elements are used as the OLED elements in each region. In such an electro-optical device, the conventional technique has a problem that the display brightness cannot be made uniform among a plurality of sub-regions, and the brightness in the screen is different.

  SUMMARY An advantage of some aspects of the invention is that it provides an electro-optical device, a driving method thereof, and an electronic apparatus that can make the luminance of a plurality of regions uniform. is there.

  In order to solve the above problems, an electro-optical device according to the present invention supports a plurality of scanning lines, a plurality of data lines, and an intersection of the scanning lines and the data lines in a display region having a plurality of sub-regions. And each of the plurality of pixel circuits provided, and individually generating an offset voltage corresponding to each of the plurality of sub-regions so that the luminance of the plurality of sub-regions approaches a target value. Power supply means, and drive means for generating a data signal using the offset voltage corresponding to a sub-region to which a pixel circuit to be driven belongs from among the plurality of offset voltages and supplying the data signal to the data line, Each of the plurality of pixel circuits includes an electro-optical element and a supply unit that compares the data signal with a reference voltage and supplies a drive current to the electro-optical element for a period according to the comparison result.

  According to the present invention, the light emission period of the electro-optic element is determined by the comparison result between the data signal and the reference voltage, but the data signal is generated using the offset voltage. Here, the offset voltage is selected according to the sub-region to which the pixel circuit to be driven belongs. Accordingly, it is possible to adjust the luminance between the plurality of sub-regions. The electro-optical element means an element whose optical characteristics can be controlled by an electric action, and includes, for example, an organic light emitting diode.

  In the electro-optical device described above, the driving unit selects an output gradation voltage in a writing period, selects an output setting voltage in a light emission period, and generates the data signal. The supply unit of the pixel circuit includes: Holding means for holding the differential voltage between the output gradation voltage and the reference voltage supplied in the writing period, and a voltage obtained by combining the output setting voltage and the differential voltage supplied in the light emission period; It is preferable that the apparatus further includes a current supply unit that compares the reference voltage and supplies the drive current to the electro-optical element for a period according to the comparison result.

  In this case, at least one of the output setting voltage (for example, triangular wave voltage) and the output gradation voltage of the data signal is generated using the offset voltage. In other words, the relative relationship between the output setting voltage and the output gradation voltage can be determined by the offset voltage. Further, combining the output triangular wave voltage and the differential voltage in the light emission period means, for example, that if the output set voltage is the output triangular wave voltage, a voltage that is a voltage drop from the output triangular wave voltage by the differential voltage is generated. Here, if the output triangular wave voltage is Vx, the output gradation voltage is Vy, the reference voltage is Vref, and the differential voltage is ΔV, the holding means holds ΔV = Vy−Vref, and the synthesized voltage is Vx−ΔV. = Vx-Vy + Vref. Since this is compared with the reference voltage Vref, Vx and Vy are equivalently compared. Since the relative relationship between Vx and Vy is determined by the offset voltage selected according to the sub-region, the luminance between the plurality of sub-regions can be adjusted.

  Here, the supply means of the pixel circuit is specifically a capacitor provided between a control means whose output terminal is connected to the electro-optical element, and between the data line and an input terminal of the control means. A first switching element which is provided between an element and an input terminal of the control means and an output terminal thereof, and is turned on in the writing period and turned off in the light emission period; and a power supply to which a power supply voltage is supplied Preferably, a second switching element is provided between the line and the power supply terminal of the control means, and is turned on during the writing period and the light emitting period. Here, the capacitive element corresponds to the holding means, and the control means, the first switching element, and the second switching element correspond to the current supply means. The control means may be a transistor element or an inverter circuit.

  The driving unit generates a set voltage and a gradation voltage corresponding to a gradation to be displayed, and based on the offset voltage selected from the plurality of offset voltages corresponding to the plurality of sub-regions. An output gradation voltage and an output setting voltage are generated by setting a potential difference between the gradation voltage and the set voltage, the output gradation voltage is selected in a writing period, and the output triangular wave voltage is selected in a light emission period The data signal is preferably generated. In this case, the potential difference between the output gradation voltage and the output set voltage is set according to the offset voltage.

  As a specific mode of the driving means, an offset voltage selecting means for selecting and outputting from among the plurality of offset voltages according to the sub-region to which the electro-optical element to which luminance should be displayed belongs, and a floor to be displayed. A gradation voltage generating means for generating the output gradation voltage by adding the offset voltage selected by the offset voltage selecting means to a gradation voltage corresponding to a tone; and generating the set voltage as the output set voltage A setting voltage generation unit that selects the output gradation voltage in the writing period, selects the output setting voltage in the light emission period, and outputs the data signal to the data line. It is preferable to provide. In this case, the relative potential difference between the output gradation voltage and the output setting voltage is adjusted by adding the offset voltage to the gradation voltage.

  Further, as another specific aspect of the drive means, an offset voltage selection means for selecting and outputting from among the plurality of offset voltages according to the sub-region to which the electro-optic element to display brightness belongs, A gradation voltage generating means for generating the gradation voltage as the output gradation voltage, and a setting voltage for generating the output setting voltage by adding the offset voltage selected by the offset voltage selecting means to the triangular wave voltage Generating means; and output selection means for selecting the output gradation voltage in the writing period, selecting the output setting voltage in the light emission period, and outputting the data signal to the data line. preferable. In this case, the relative potential difference between the output gradation voltage and the output set voltage is adjusted by adding the offset voltage to the set voltage.

  In the electro-optical device described above, the sub-region is configured by a display panel, and the power supply unit has the same target value as the voltage generation unit that individually generates the offset voltage for each sub-region, It is preferable to include a voltage adjusting unit that adjusts the offset voltage so that the luminances of the sub-regions approach each other. According to the present invention, when the display area is composed of a plurality of display panels, the luminance between the panels can be made uniform. As a result, the boundary between the panels can be made inconspicuous, and a plurality of display panels can be used as if they were one large display panel.

  The electro-optical device described above includes a plurality of drive modules that drive the plurality of data lines, and the plurality of sub-regions correspond to the data lines that each of the plurality of drive modules drives, Voltage generating means for individually generating the offset voltage for each region, and voltage adjusting means for adjusting the offset voltage so that the target values are the same and the luminance values of a plurality of sub-regions approach each other. It is preferable. According to the present invention, when driving using a plurality of drive modules, the brightness of the plurality of sub-regions can be made uniform by adjusting the offset voltage even if there are variations in characteristics between the drive modules. Thereby, the boundary of a sub-region can be made inconspicuous. When one display area is constituted by a plurality of display panels and each display panel is driven by a plurality of drive modules, the range of data lines corresponding to each drive module corresponds to each sub-area. Of course.

  In the electro-optical device described above, each of the plurality of sub-regions is provided with a plurality of types of electro-optical elements having different emission colors, and the power supply unit individually sets the offset voltage for each sub-region. It is preferable to include a voltage generating unit for generating, and a voltage adjusting unit for individually setting the target value and adjusting the offset voltage so as to achieve white balance. In electro-optical elements having different emission colors, different materials are selected depending on the emission color, and therefore the emission efficiency is usually different. According to the present invention, the electro-optic elements having different emission colors are arranged for each sub-region, and the offset voltage is individually generated for each sub-region. Therefore, it is possible to adjust the white balance by individually setting the offset voltage.

In the electro-optical device described above, it is preferable that the voltage adjusting unit measures a current consumed by the pixel circuits in the plurality of sub-regions for each sub-region, and adjusts the offset voltage based on the measurement result. According to the present invention, since the offset voltage is adjusted according to the current consumption for each sub-region, not only the offset voltage is set at the factory, but also the offset voltage is always adjusted to maintain the optimum state. Is possible.
In the electro-optical device described above, the output setting voltage may be a triangular wave voltage. Alternatively, the output setting voltage may be a sawtooth voltage. Alternatively, the output setting voltage may be a sine wave voltage.
Next, an electronic apparatus according to the present invention includes the above-described electro-optical device, and corresponds to, for example, a large display in which a plurality of panels are connected, a personal computer, a mobile phone, and a portable information terminal.

  Next, the driving method of the electro-optical device according to the present invention corresponds to the intersection of the plurality of scanning lines, the plurality of data lines, and the scanning lines and the data lines in the display region having the plurality of sub-regions. Each of the plurality of pixel circuits, and each of the plurality of pixel circuits compares the electro-optic element, a data signal supplied via the data line, and a reference voltage to obtain a comparison result. A method of driving an electro-optical device having a current supply means for supplying a driving current to the electro-optical element for a corresponding period, wherein the first step of measuring the luminance of each of the plurality of sub-regions is measured. A second step of individually generating an offset voltage corresponding to each of the plurality of sub-regions so that the luminance approaches a target value determined for each sub-region, and a level corresponding to the set voltage and the gradation to be displayed; Generates regulated voltage and An output gradation voltage and an output by setting a potential difference between the gradation voltage and the set voltage based on the offset voltage selected from among the plurality of offset voltages corresponding to the plurality of sub-regions; A fourth step of generating a set voltage; and a fifth step of selecting the output gradation voltage in a writing period and selecting the output set voltage in a light emission period and outputting the data signal to the data line; Is provided. According to the present invention, since the offset voltage is adjusted based on the measurement result of the luminance of each sub-region, the actually measured luminance can be reflected in the luminance to be displayed. As a result, the luminance of the sub area can be adjusted accurately.

  In this driving method, it is preferable that the target value is set so that the luminance values of the plurality of sub-regions are equal. In this case, the luminance between the sub-regions can be made uniform. In addition, when a plurality of types of electro-optical elements having different emission colors are provided in each of the plurality of sub-regions, it is preferable that the target value is set so as to achieve white balance.

<First Embodiment>
FIG. 1 is a block diagram showing the configuration of the electro-optical device according to the first embodiment of the invention. As shown in FIG. 1, the electro-optical device 10 is configured by connecting four display panels Z1, Z2, Z3, and Z4. In each of the plurality of display panels Z1 to Z4, a plurality of scanning lines 101 are extended in the horizontal direction (X direction), while a plurality of data lines (signal lines) 103 are arranged in the vertical direction (Y direction) in the figure. ). A pixel circuit (electronic circuit) 400 is provided so as to correspond to each intersection of the scanning line 101 and the data line 103.

  Here, for convenience of explanation, in the present embodiment, the number of scanning lines 101 (number of rows) of each display panel Z1 to Z4 is “360”, the number of data lines (number of columns) is “480”, and the pixel circuit 400 However, a configuration is assumed in which the pixels are arranged in a matrix of 360 rows × 480 columns. A display area Z of 720 rows × 960 columns is formed by the four display panels Z1 to Z4. In other words, the display area Z is divided into a plurality of sub areas (corresponding to the display panels Z1 to Z4). However, the present invention is not intended to be limited to this arrangement.

A power supply voltage Vdd and a lower voltage GND are commonly supplied from the power supply circuit 18 to the display panels Z1 to Z4. Further, the power supply circuit 18 generates offset voltages Vofs1, Vofs2, Vofs3, and Vofs4 corresponding to each of the display panels Z1 to Z4 and supplies the generated voltages to the X driver 16. The technical significance of the offset voltages Vofs1 to Vofs4 will be described later. In addition, when not distinguishing the offset voltage for every display panel Z1-Z4, it only describes with the offset voltage Vofs.
The pixel circuit 400 includes an OLED element 420 to be described later, and a predetermined image is displayed in gradation by controlling the period for supplying current to the OLED element 420 for each pixel circuit 400. In FIG. 1, a control line 102 is extended in parallel with the scanning line 101.

The Y driver 14 selects the scanning line 101 row by row and supplies an H level scanning signal to the selected scanning line 101. Further, a control signal synchronized with this selection is supplied to the control line 102. That is, the Y driver 14 supplies a scanning signal and a control signal to the scanning line 101 and the control line 102 for each row.
Here, for convenience of explanation, a scanning signal supplied to the scanning line 101 of the i-th row (i is an integer satisfying 1 ≦ i ≦ 720 and is used for generalizing the row) is represented by GWRT-i. Is written. Similarly, a control signal supplied to the i-th control line 102 is denoted as GEL-i.

On the other hand, the X driver 16 is connected to each of the pixel circuits for one row corresponding to the scanning line 101 selected by the Y driver 14, that is, to each of the pixel circuits 400 of 1 to 960 columns located in the selected row. Data signals are supplied through the data line 103 in the 960th column.
The control circuit 12 supplies a clock signal (not shown) to each of the Y driver 14 and the X driver 16 to control both drivers, and the image data D defining the gradation for each pixel to the X driver 16. Supply. Furthermore, the control circuit 12 includes a triangular wave generation circuit 12A that generates a triangular wave voltage signal SS.

  FIG. 2 shows a block diagram of the X driver 16. As shown in the figure, the X driver 16 includes a serial / parallel conversion unit 16A and a signal supply unit 16B. The serial / parallel converter 16A converts the serial image data D into parallel image data d1, d2,... D960 and outputs the converted data. The signal supply unit 16B includes 960 signal supply circuits 160A, to which a triangular wave voltage signal SS is supplied. Each signal supply circuit 160 A generates data signals X 1, X 2,... X 960 and outputs them to the data line 103. Of the 960 signal supply circuits 160A, 480 signal supply circuits 160A from the left end correspond to the display panels Z1 and Z4, and are supplied with offset voltages Vofs1 and Vofs4. The 480 signal supply circuits 160A from the right end correspond to the display panel Z2 and the display panel Z3, and are supplied with offset voltages Vofs2 and Vofs3.

  FIG. 3 shows the configuration of the signal supply circuit 160A in the j-th column, and FIG. 4 shows its timing chart. The other signal supply circuits are configured similarly. For convenience of explanation, j is an integer that satisfies 1 ≦ j ≦ 480. The signal supply circuit 160A in this example supplies the data signal Xj to the display panels Z1 and Z4 via the jth data line 103. The signal supply circuit 160A includes a DA converter 161 to which image data dj is supplied. The DA converter 161 outputs a gradation voltage signal Vdata obtained by performing DA conversion on the image data dj to one input terminal of the adder 162. The offset voltage selection circuit 163 selects one of the offset voltages Vofs1 or Vofs4 based on the first selection signal SEL1 and outputs it to the other input terminal of the adder 162.

  As shown in FIG. 4, one frame period (1F) is divided into an address period Ta and a light emission period Tb. In the address period Ta, the plurality of scanning lines 101 are sequentially selected, and the data signal Xj is sequentially supplied to the pixel circuit 400 connected to the selected scanning line 101. In the present embodiment, the display area Z is composed of four display panels Z1 to Z4. The signal supply circuit 160A in the j-th column corresponds to the display panels Z1 and Z4. Accordingly, the scanning line 101 (360 lines) of the display panel Z1 is selected in the first half period Ta1 of the address period Ta, while the scanning line 101 (360 lines) of the display panel Z4 is selected in the second half period Ta2.

  The first selection signal SEL1 becomes H level in the first half period Ta1, and becomes L level in the second half period Ta2. When the first selection signal SEL1 is at the H level, the offset voltage selection circuit 163 selects the offset voltage Vofs1, and when the first selection signal SEL1 is at the L level, the offset voltage selection circuit 163 selects the offset voltage Vofs4. That is, the offset voltage Vofs is selected according to the display panel to which the pixel circuit 400 to be driven belongs.

  The adder 162 adds the offset voltage (Vofs1 or Vofs4 in this example) selected by the offset voltage selection circuit 163 and the gradation voltage signal Vdata to generate an output gradation voltage signal Vdata ′, and outputs the output voltage. The signal is supplied to one input terminal of the selection circuit 164. The addition referred to here includes both the meanings of when the value of Vdata is large and when it is small. A triangular wave voltage signal SS is supplied to the other input terminal of the output voltage selection circuit 164 as an output triangular wave voltage signal SS ′. As shown in FIG. 4, the second selection signal SEL2 is a signal that becomes H level in the address period Ta and becomes L level in the light emission period Tb. The output voltage selection circuit 164 selects the output gradation voltage signal Vdata ′ when the second selection signal SEL2 is at the H level, while selecting the output triangular wave voltage signal SS ′ when the second selection signal SEL2 is at the L level, the data signal Xj is selected. Generate. Therefore, the data signal Xj is a signal obtained by time-division multiplexing the output gradation voltage signal Vdata 'and the output triangular wave signal SS'.

  FIG. 5 shows the configuration of the pixel circuit 400 in the i-th row and j-th column belonging to the display panel Z1. As shown in the figure, a capacitive element 430 is provided between the data line 103 and the input terminal of the inverter INV. A switch element SW1 is provided between the input terminal and the output terminal of the inverter INV. The switch element SW2 is provided between the power supply terminal of the inverter INV and the power supply line L1, and supplies the power supply voltage Vdd to the inverter INV in the on state, and stops the power supply in the off state. The cathode of the OLED element 420 is grounded (GND), and its anode is connected to the output terminal of the inverter INV.

  FIG. 6 shows a timing chart of the pixel circuit 400 in the i-th row and the j-th column. First, in the address period Ta, the output gradation voltage signal Vdata 'is supplied from the signal supply circuit 160A via the data line 103, and then in the light emission period Tb, the output triangular wave voltage signal SS' is supplied. The writing period Tw in the address period Ta corresponds to each pixel circuit 400. In the writing period Tw, since the scanning signal GWRT-i and the control signal GEL-i are at the H level, the switch elements SW1 and SW2 are turned on. At this time, since the output voltage of the inverter INV is fed back to its input terminal, the input voltage Vin of the inverter INV becomes the inversion threshold voltage Vres of the inverter INV. The inversion threshold voltage Vres is a substantially intermediate voltage between the negative power supply voltage and the positive power supply voltage of the inverter INV.

  In the writing period Tw, a voltage (Vdata′−Vres) is applied to both ends of the capacitor 430. Since the scanning signal GWRT-i is at the H level only in the writing period Tw, the switch element SW1 is turned off until the writing period Tw of the next frame when the writing period Tw ends. Accordingly, the terminal of the capacitor 430 connected to the inverter INV is in a floating state. Therefore, the applied voltage (Vdata′−Vres) of the capacitor 430 is maintained until the next writing period Tw. The switch element SW2 is turned on during the light emission period Tb. During the period Tb, the triangular wave voltage signal SS ′ is supplied to the data line 103.

At this time, since the applied voltage (Vdata′−Vres) of the capacitor 430 does not change, the input voltage Vin of the inverter INV in the light emission period Tb is Vin = SS ′ − (Vdata′−Vres). When the input voltage Vin falls below the inversion threshold voltage Vres, the output voltage of the inverter INV becomes H level, the OLED element 420 emits light with a constant luminance, and when the input voltage Vin exceeds the inversion threshold voltage Vres, the inverter The output voltage of INV becomes L level, and the OLED element 420 is turned off. Here, the OLED element 420 emits light during a period Tc in which the following conditions are satisfied.
Vin <Vres
SS '-(Vdata'-Vres) <Vres
SS '<Vdata'
That is, when the output triangular wave voltage signal SS ′ falls below the output gradation voltage signal Vdata ′, the OLED element 420 emits light with a constant luminance.

  Here, since the output gradation voltage signal Vdata ′ is obtained by adding the gradation voltage signal Vdata and the offset voltage Vofs, the period Tc can be controlled by adjusting the offset voltage Vofs, and thus the luminance can be increased. Can be adjusted. When the electro-optical device 10 is configured by a plurality of display panels Z1 to Z4 as in the present embodiment, the display panels Z1 to Z4 are manufactured individually, and thus the characteristics of the OLED element 420 are the characteristics of the plurality of display panels Z1 to Z4. Usually, they are not the same and vary.

The power supply circuit 18 of this embodiment includes a voltage source 18A and an adjustment unit 18B. The voltage source 18A generates offset voltages Vofs1, Vofs2, Vofs3, and Vofs4, and the adjusting unit 18B controls the voltage source 18A so that the luminance of the display panels Z1 to Z4 is uniform, so that the offset voltages Vofs1, Vofs2, Vofs3, And adjust Vofs4. Specifically, the processing of the adjustment unit 18B has the following modes.
In the first mode, each of the display panels Z1 to Z4 is driven with image data indicating the same gradation, and the current consumed by each of the plurality of display panels Z1 to Z4 is measured in the power supply circuit 18, and the current consumption is The offset voltages Vofs1, Vofs2, Vofs3, and Vofs4 are adjusted to be equal. According to this adjustment method, for example, by performing the above-described adjustment process immediately after the electro-optical device 10 is turned on, even if the characteristics of the OLED element 420 and the like change with time, the display panels Z1 to Z1. The brightness of Z4 can be made uniform. In addition, each display panel Z1 to Z4 is provided with a dummy pixel circuit that does not contribute to display, the current flowing through the dummy pixel circuit is measured, and the offset voltages Vofs1, Vofs2, Vofs3, and Vofs4 are adjusted so that the current consumption becomes equal. May be. In this case, it is possible to always correct the brightness by measuring the current consumption.

In the second mode, offset voltages Vofs1, Vofs2, Vofs3, and Vofs4 are set when the electro-optical device 10 is shipped. In this aspect, first, the display panels Z1 to Z4 are driven with image data showing the same gradation. Secondly, the luminance of each of the display panels Z1 to Z4 is measured using a measuring device (for example, a CCD camera). Third, offset voltages Vofs1, Vofs2, Vofs3, and Vofs4 are set so that the measured luminances are close to each other. It should be noted that a volume may be provided so that the user can subsequently change the offset voltages Vofs1, Vofs2, Vofs3, and Vofs4 set at the time of shipment.
As described above, in the present embodiment, the offset voltages Vofs1, Vofs2, Vofs3, and Vofs4 are individually set for the display panels Z1 to Z4 as a plurality of sub-regions constituting the display region Z. Can be uniform. A plurality of panels can be used as a single panel.

Second Embodiment
In the electro-optical device 10 according to the first embodiment described above, one display region Z is configured by combining a plurality of display panels Z1 to Z4. On the other hand, in the electro-optical device 10 according to the second embodiment, the display area Z is configured by a single display panel.
FIG. 7 is a block diagram illustrating a configuration of the electro-optical device 10 according to the second embodiment. As shown in the figure, the X driver 16 includes a plurality of drive modules M1, M2, and M3. Each of the drive modules M1 to M3 drives the sub areas S1, S2, and S3 obtained by dividing the display area. Here, the offset voltage Vofs is independent in each of the sub-regions S1, S2, and S3, and is supplied to the drive modules M1, M2, and M3 as the offset voltages Vofs1, Vofs2, and Vofs3.

  Each of the drive modules M1 to M3 includes the above-described signal supply circuit 160A. However, since the offset voltage Vofs is individually supplied, it is not necessary to select the offset voltage Vofs. For this reason, the signal supply circuit 160A of the second embodiment deletes the offset voltage selection circuit 163 from the signal supply circuit 160A of the first embodiment shown in FIG. 3 and directly supplies the offset voltage Vofs to the adder 162. It is configured as follows.

  The characteristics of the transistors constituting the drive modules M1 to M3 are not necessarily the same and have certain variations. Due to the variation in the characteristics of the transistors, even if the same image data D is supplied to the drive modules M1 to M3, the voltage value of the data signal varies between the drive modules M1 to M3. As a result, the luminance may be non-uniform between the sub-regions S1, S2, and S3.

Similar to the electro-optical device 10 of the first embodiment, the electro-optical device 10 of the second embodiment has offset voltages Vofs1, Vofs2, and Vofs3 so that the luminance of the sub-regions S1 to S3 is uniform in the power supply circuit 18. Generated. Specifically, there are the following modes.
In the first mode, the sub-regions S1 to S3 are driven with image data indicating the same gradation, and the current consumed in the plurality of sub-regions S1 to S3 is measured in the power supply circuit 18, respectively. The offset voltages Vofs1, Vofs2, and Vofs3 are adjusted so that According to this adjustment method, even if the transistor characteristics of the drive modules M1 to M are changed with time by performing the above-described adjustment process immediately after the electro-optical device 10 is turned on, each subregion The brightness of S1 to S3 can be made uniform. In addition, dummy pixel circuits that do not contribute to display are provided in each of the sub-regions S1 to S3, currents flowing through the dummy pixel circuits are measured, and offset voltages Vofs1, Vofs2, and Vofs3 are adjusted so that current consumption becomes equal. Also good. In this case, it is possible to always correct the brightness by measuring the current consumption.

In the second mode, the offset voltages Vofs1, Vofs2, and Vofs3 are set when the electro-optical device 10 is shipped. In this aspect, first, each of the sub-regions S1 to S3 is driven with image data indicating the same gradation. Second, the luminance of each of the sub-regions S1 to S3 is measured using a measuring device (for example, a CCD camera). Third, the offset voltages Vofs1, Vofs2, and Vofs3 are set so that the measured luminances are close to each other. A volume may be provided so that the user can change the offset voltages Vofs1, Vofs2, and Vofs3 set at the time of shipment.
As described above, in the present embodiment, the offset voltages Vofs1, Vofs2, and Vofs3 are individually set for the plurality of sub-regions S1 to S3 constituting the display region Z. Therefore, the characteristics of the drive modules M1 to M3 are different. Also, the brightness of the entire screen can be made uniform. As a result, the boundary of the sub-region can be made inconspicuous.

<Third Embodiment>
The electro-optical device 10 according to the first and second embodiments described above is configured to perform gradation display for single-color pixels, but the electro-optical device 10 according to the third embodiment corresponds to color display. Is.
FIG. 8 is a block diagram illustrating a configuration of the electro-optical device 10 according to the third embodiment. The display area Z of the electro-optical device 10 is configured by a single display panel. The display area Z is constituted by sub-areas Zr, Zg, and Zb corresponding to R (red), G (green), and B (blue). An R pixel circuit 400R is arranged in the sub-region Zr, a G pixel circuit 400G is arranged in the sub-region Zg, and a B pixel circuit 400B is arranged in the sub-region Zb.

The OLED elements 420 used in the pixel circuits 400R, 400G, and 400B are OLED elements 420R, 420G, and 420B. For the OLED elements 420R, 420G, and 420B, the light emitting layers are selected so as to emit light in red, green, and blue, respectively. That is, different types of light emitting materials are used corresponding to each color. For this reason, the luminous efficiencies of the OLED elements 420R, 420G, and 420B are often different. In order to achieve white balance, it is necessary to adjust the light emission amount of each color.
Therefore, in the present embodiment, the power supply circuit 18 supplies a set of the offset voltage Vofsr corresponding to the sub region Zr, the offset voltage Vofsg corresponding to the sub region Zg, and the offset voltage Vofsb corresponding to the sub region Zb. Since these determine the gradation of each color of RGB, they are adjusted at the factory so as to achieve white balance. A volume may be provided so that the user can change the offset voltages Vofsr, Vofsg, and Vofsb set at the time of shipment.

<Application example>
In each of the embodiments described above, the signal supply circuit 160A adds the offset voltage Vofs to the gradation voltage signal Vdata to generate the output gradation voltage Vdata ′, while outputting the triangular wave voltage signal SS supplied from the control circuit 12 The output voltage selection circuit 164 was supplied as a triangular wave voltage signal SS ′. That is, the relative level of the gradation voltage and the triangular wave voltage is adjusted by adding the offset voltage Vofs to the gradation voltage signal Vdata. However, the present invention is not limited to this, and the gradation voltage is not limited to this. As long as the relative potential difference between the triangular wave voltage and the triangular wave voltage can be set according to the offset voltage, any configuration may be used. For example, the output triangular wave voltage signal SS ′ may be generated by adding the offset voltage Vofs to the triangular wave voltage signal SS.

  FIG. 9 shows a signal supply circuit 160B. The signal supply circuit 160B adds the offset voltage Vofs to the triangular wave voltage signal SS to generate the data signal Xj. As shown in this figure, the output signal of the offset voltage signal selection circuit 163 is supplied to one input terminal of the adder 162. A triangular wave voltage signal SS is supplied to the other input terminal, and a signal obtained by adding the offset voltage Vofs to the triangular wave voltage signal SS is supplied to the output voltage selection circuit 164 as an output triangular wave signal SS ′. The output voltage selection circuit 164 selects the gradation voltage signal Vdata supplied as the output gradation voltage signal Vdata 'and the output triangular wave voltage signal SS' to generate the data signal Xj. In the first to third embodiments described above, the luminance can be adjusted by using the signal supply circuit 160B instead of the signal supply circuit 160A.

<Electronic equipment>
Next, an electronic apparatus to which the electro-optical device 10 according to the above-described first to third embodiments and application examples is applied will be described. FIG. 10 shows a configuration of a mobile personal computer to which the electro-optical device 10 is applied. The personal computer 2000 includes an electro-optical device 10 as a display unit and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002. Since the electro-optical device 10 uses the OLED element 420, it is possible to display an easy-to-see screen with a wide viewing angle.
FIG. 11 shows a configuration of a mobile phone to which the electro-optical device 10 is applied. A cellular phone 3000, a plurality of operation buttons 3001, scroll buttons 3002, and the electro-optical device 10 as a display unit are provided. By operating the scroll button 3002, the screen displayed on the electro-optical device 10 is scrolled.
FIG. 12 shows the configuration of a portable information terminal (PDA: Personal Digital Assistants) to which the electro-optical device 10 is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and the electro-optical device 10 as a display unit. When the power switch 4002 is operated, various types of information such as an address book and a schedule book are displayed on the electro-optical device 10.
The electronic apparatus to which the electro-optical device 10 is applied includes, in addition to those shown in FIGS. 11 to 12, a digital still camera, a liquid crystal television, a viewfinder type, a monitor direct-view type video tape recorder, a car navigation device, a pager, Examples include electronic notebooks, calculators, word processors, workstations, videophones, POS terminals, and devices equipped with touch panels. The electro-optical device 10 described above can be applied as a display unit of these various electronic devices. In addition, it is not limited to a display unit of an electronic device that directly displays an image or a character, but is applied as a light source of a printing device that is used to indirectly form an image or a character by irradiating light to the photosensitive member. Also good.

1 is a block diagram illustrating a configuration of an electro-optical device according to a first embodiment of the invention. FIG. 3 is a block diagram showing an X driver of the same electro-optical device. FIG. It is a block diagram which shows the signal supply circuit of the X driver. It is a timing chart which shows operation | movement of the signal supply circuit. It is a figure which shows the pixel circuit of the same electro-optical apparatus. 6 is a timing chart showing the operation of the electro-optical device. FIG. 6 is a block diagram illustrating a configuration of an electro-optical device according to a second embodiment of the invention. FIG. 10 is a block diagram illustrating a configuration of an electro-optical device according to a third embodiment of the invention. It is a block diagram which shows the signal supply circuit which concerns on an application example. It is a figure which shows the personal computer using the same electro-optical apparatus. It is a figure which shows the mobile telephone using the same electro-optical apparatus. It is a figure which shows the portable information terminal using the same electro-optical apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Electro-optical apparatus, 12 ... Control circuit, 12A ... Triangular wave generation circuit, 14 ... Y driver, 16 ... X driver, 18 ... Power supply circuit, 18A ... Voltage source, 18B ... Adjustment part, 101 ... Scanning line, 102 ... Control Line 102, data line, 160A, 160B, signal supply circuit, 161, DA converter, 162, adder, 163, offset voltage selection circuit, 164, output voltage selection circuit, 400, 400R, 400G, 400B, pixel circuit , INV: inverter, SW1, SW2 ... switch element, 420 ... OLED element, 430 ... capacitive element, Vofs1 to Vofs4, Vofsr, Vofsg, Vofsb ... offset voltage.

Claims (19)

An electro-optic including a plurality of scanning lines, a plurality of data lines, and a plurality of pixel circuits provided corresponding to intersections of the scanning lines and the data lines in a display region having a plurality of sub-regions. A device,
Power supply means for individually generating an offset voltage corresponding to each of the plurality of sub-regions so that the luminance of the plurality of sub-regions approaches a target value;
Drive means for generating a data signal using the offset voltage corresponding to a sub-region to which a pixel circuit to be driven belongs from among the plurality of offset voltages and supplying the data signal to the data line;
Each of the plurality of pixel circuits includes an electro-optical element, and a supply unit that compares the data signal with a reference voltage and supplies a driving current to the electro-optical element for a period according to the comparison result. apparatus. The driving unit selects an output gradation voltage in a writing period, selects an output setting voltage in a light emission period, and generates the data signal.
The supply means of the pixel circuit includes:
Holding means for holding the differential voltage between the output gradation voltage and the reference voltage supplied in the writing period;
A current supply for comparing the reference voltage with a voltage obtained by combining the output setting voltage and the differential voltage supplied during the light emission period, and supplying the drive current to the electro-optic element only during a period according to the comparison result Means,
The electro-optical device according to claim 1. The supply means of the pixel circuit includes:
Control means for connecting an output terminal to the electro-optic element;
A capacitive element provided between the data line and the input terminal of the control means;
A first switching element which is provided between an input terminal of the control means and an output terminal thereof and is turned on in the writing period and turned off in the light emitting period;
A second switching element provided between a power supply line to which a power supply voltage is supplied and a power supply terminal of the control means, and being turned on in the writing period and the light emitting period;
The electro-optical device according to claim 1, further comprising: The electro-optical device according to claim 3, wherein the control unit is a transistor element. The electro-optical device according to claim 3, wherein the control unit is an inverter circuit. The driving means includes
Generate a set voltage and a gradation voltage according to the gradation to be displayed,
An output gradation voltage and an output setting voltage are generated by setting a potential difference between the gradation voltage and the set voltage based on the offset voltage selected from the plurality of offset voltages corresponding to the plurality of sub-regions. And
Selecting the output gradation voltage in a writing period and generating the data signal by selecting the output setting voltage in a light emission period;
The electro-optical device according to claim 1, wherein the electro-optical device is any one of the above. The driving means includes
An offset voltage selection means for selecting and outputting from among the plurality of offset voltages according to the sub-region to which the electro-optic element to display luminance belongs;
A gradation voltage generation means for generating the output gradation voltage by adding the offset voltage selected by the offset voltage selection means to a gradation voltage corresponding to a gradation to be displayed;
Set voltage generating means for generating the set voltage as the output set voltage;
Output selection means for selecting the output gradation voltage in the writing period, selecting the output setting voltage in the light emission period, and outputting the data signal to the data line;
The electro-optical device according to claim 6. The driving means includes
An offset voltage selection means for selecting and outputting from among the plurality of offset voltages according to the sub-region to which the electro-optic element to display luminance belongs;
Gradation voltage generating means for generating the gradation voltage as the output gradation voltage;
A setting voltage generating means for generating the output setting voltage by adding the offset voltage selected by the offset voltage selecting means to the setting voltage;
Output selection means for selecting the output gradation voltage in the writing period, selecting the output setting voltage in the light emission period, and outputting the data signal to the data line;
The electro-optical device according to claim 6. The sub-region is composed of a display panel,
The power source means
Voltage generating means for individually generating the offset voltage for each of the sub-regions;
The target value is the same, and the voltage adjustment means for adjusting the offset voltage so that the luminance of a plurality of sub-regions approach each other;
The electro-optical device according to claim 1, wherein the electro-optical device is provided. A plurality of drive modules for driving the plurality of data lines;
The plurality of sub-regions correspond to the data lines driven by the plurality of drive modules,
Voltage generating means for individually generating the offset voltage for each of the sub-regions;
The target value is the same, and the voltage adjustment means for adjusting the offset voltage so that the luminance of a plurality of sub-regions approach each other;
The electro-optical device according to claim 1, wherein the electro-optical device is provided. Each of the plurality of sub-regions is provided with a plurality of types of electro-optical elements having different emission colors,
The power source means
Voltage generating means for individually generating the offset voltage for each of the sub-regions;
The target values are individually set, and voltage adjusting means for adjusting the offset voltage so as to achieve white balance;
The electro-optical device according to claim 1, further comprising: 12. The voltage adjusting unit according to claim 9, further comprising: measuring a current consumed by the pixel circuits in the plurality of sub-regions for each of the sub-regions, and adjusting the offset voltage based on a measurement result. The electro-optical device according to any one of the above. The electro-optical device according to claim 1, wherein the output setting voltage is a triangular wave voltage. The electro-optical device according to claim 1, wherein the output setting voltage is a sawtooth voltage. The electro-optical device according to claim 1, wherein the output setting voltage is a sine wave voltage. An electronic apparatus comprising the electro-optical device according to claim 1. The display area having a plurality of sub-regions includes a plurality of scanning lines, a plurality of data lines, and a plurality of pixel circuits respectively provided corresponding to intersections of the scanning lines and the data lines. Each of the pixel circuits compares the electro-optic element, a data signal supplied via the data line, and a reference voltage, and supplies a drive current to the electro-optic element for a period according to the comparison result. A driving method of an electro-optical device having a supply means,
A first step of measuring the luminance of each of the plurality of sub-regions;
A second step of individually generating an offset voltage corresponding to each of the plurality of sub-regions so that the measured luminance approaches a target value determined for each sub-region;
A third step of generating a set voltage and a gradation voltage corresponding to the gradation to be displayed;
Based on the offset voltage selected from the plurality of offset voltages corresponding to the plurality of sub-regions, an output gradation voltage and an output setting voltage are set by setting a potential difference between the gradation voltage and the set voltage. A fourth step of generating,
A fifth step of selecting the output gradation voltage in a writing period, selecting the output setting voltage in a light emission period, and outputting the data signal to the data line;
A method for driving an electro-optical device comprising: 18. The electro-optical device driving method according to claim 17, wherein the target value is set so that the luminance values of the plurality of sub-regions are equal. Each of the plurality of sub-regions is provided with a plurality of types of electro-optical elements having different emission colors,
The method of driving an electro-optical device according to claim 17, wherein the target value is set so as to achieve white balance.

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