WO2018003204A1 - Display device, temperature compensation circuit, and display device control method - Google Patents

Abstract

A display device in which a transistor drives a light-emitting element, wherein fluctuation in the luminance of the light-emitting element due to a temperature change is suppressed. A low temperature region dependent current generation unit generates, as a low temperature region dependent current, a current having a value that gets smaller as a measured temperature increases in a temperature range where the measured temperature is lower than a prescribed temperature. A general temperature region dependent current generation unit generates, as a total temperature region dependent current, a current having a value that gets larger as the measured temperature increased. A current-voltage conversion unit converts a current from a connection point of the low temperature region dependent current generation unit and the general temperature region dependent current generation unit into voltage and supplies the converted voltage as a gradient voltage. A drive transistor supplies a drive current that corresponds to the gradient voltage to the light-emitting element, causing the light-emitting element to emit light.

Description

Display device, temperature compensation circuit, and display device control method

The present technology relates to a display device, a temperature compensation circuit, and a display device control method. Specifically, the present invention relates to a display device in which a transistor drives a light emitting element, a temperature compensation circuit, and a display device control method.

In recent years, it has advantages such as thin and light weight, low power consumption, high-speed response, and high contrast compared with liquid crystal, and therefore, development and research of display devices using organic light-emitting diodes (OLEDs) are progressing. It has been. A pixel circuit in this display device is provided with an OLED and a MOS (Metal-Oxide-Semiconductor) transistor that drives the OLED. A driver applies a gradation voltage corresponding to the gradation to the MOS transistor, so that a driving current can be supplied to the OLED to emit light. Here, it is known that the threshold voltage of the MOS transistor decreases as the temperature increases. It is known that the drive current output from the MOS transistor changes when a certain gradation voltage is applied due to the fluctuation of the threshold voltage. In view of this, a display device has been proposed that corrects the gradation voltage with reference to a table that describes the correction amount for each temperature in order to keep the drive current constant and suppress fluctuations in luminance even when the temperature changes (see FIG. For example, see Patent Document 1.)

JP 2012-141456 A

In the above-described prior art, the gradation voltage is corrected based on the temperature characteristic of the threshold voltage. However, strictly speaking, the driving current of the MOS transistor depends not only on the threshold voltage but also on the carrier mobility. When the temperature is T, the threshold voltage is proportional to T ⁻¹ , while the carrier mobility is proportional to T ^(−1.5) . For this reason, when the temperature is relatively high, the influence of the carrier mobility becomes larger. Therefore, in the above-described display device that performs correction considering only the temperature characteristics of the threshold voltage, the luminance variation due to the change in carrier mobility cannot be corrected, and the light emitting element cannot emit light with appropriate luminance. There is.

The present technology has been developed in view of such a situation, and an object of the present technology is to suppress a change in luminance of a light emitting element accompanying a temperature change in a display device in which a transistor drives the light emitting element.

The present technology has been made to solve the above-described problems, and a first aspect of the present technology is that a current having a smaller value as the measured temperature is higher in a temperature range where the measured temperature is lower than a predetermined temperature. A low temperature region dependent current generating unit that generates a current as a low temperature region dependent current, a full temperature region dependent current generating unit that generates a current having a larger value as the entire temperature region dependent current as the measurement temperature is higher, and the low temperature region dependent current generating unit. A current-voltage conversion unit that converts a current from a connection point of the temperature-dependent current generation unit to a voltage and supplies it as a gradation voltage, and supplies a drive current corresponding to the gradation voltage to the light emitting element. A display device including a driving transistor that emits light, and a control method thereof. This brings about the effect that the light emitting element emits light by the drive current corresponding to the voltage converted from the current from the connection point of the low temperature region dependent current generator and the all temperature region dependent current generator.

Further, in the first aspect, a constant current generation unit that generates a constant constant current and supplies the constant constant current to the connection point may be further provided. This brings about the effect that the light emitting element emits light by the drive current corresponding to the voltage obtained by converting the current from the connection point of the constant current generating unit, the low temperature region dependent current generating unit, and the all temperature region dependent current generating unit.

The first aspect may further include a holding unit that holds the constant current adjustment value as a constant current adjustment value, and the constant current generation unit generates the constant current adjusted according to the constant current adjustment value. May be. This brings about the effect that a constant current adjusted by the adjustment value is generated.

In the first aspect, the holding unit further holds an adjustment value of the low temperature region dependent current as a low temperature region dependent current adjustment value, and the low temperature region dependent current generation unit includes the low temperature region dependent current adjustment value. The low temperature region dependent current adjusted in accordance with the method may be generated. As a result, the low temperature region dependent current adjusted by the adjustment value is generated.

In the first aspect, the holding unit further holds the adjustment value of the total temperature region dependent current as a low temperature region dependent current adjustment value, and the total temperature region dependent current generation unit is dependent on the total temperature region. The entire temperature region dependent current adjusted according to the current adjustment value may be generated. This brings about the effect | action that the whole temperature range dependence electric current adjusted with the adjustment value is produced | generated.

The first aspect may further include a temperature sensor that supplies a measurement voltage corresponding to the measurement temperature, and the low-temperature region dependent current generation unit is configured to calculate a difference between the voltage corresponding to the measurement voltage and a predetermined voltage. A corresponding current may be supplied as the low temperature region dependent current, and the all temperature region dependent current generator may supply a current corresponding to the measurement voltage as the all temperature region dependent current. Thereby, a low temperature region-dependent current corresponding to the difference between the voltage corresponding to the measured voltage and the predetermined voltage is generated, and the entire temperature region dependent current corresponding to the measured voltage is generated.

Further, in the first aspect, a band gap reference circuit that generates a measurement voltage according to the measurement temperature and a constant reference voltage, and a difference according to a difference between the voltage according to the measurement voltage and the reference voltage A voltage-current converter that outputs a dynamic signal, wherein the low temperature region dependent current generation unit generates the low temperature region dependent current from the differential signal, and the all temperature region dependent current generation unit includes the difference The entire temperature region dependent current may be generated from a dynamic signal. This brings about the effect that the measurement voltage and the constant reference voltage are generated by the band gap reference circuit.

In this first aspect, the drive transistor may be a MOS transistor. Thereby, the light emitting element emits light by the drive current from the MOS transistor.

In addition, a second aspect of the present technology is a low temperature region dependent current generation unit that generates a current having a smaller value as a low temperature region dependent current as the measured temperature is higher in a temperature range where the measured temperature is lower than a predetermined temperature. The temperature compensation circuit includes an entire temperature region dependent current generation unit that generates a current having a larger value as the entire temperature region dependent current as the measurement temperature is higher. This brings about the effect that a low temperature region dependent current and a whole temperature region dependent current are generated.

According to the present technology, in a display device in which a transistor drives a light-emitting element, it is possible to achieve an excellent effect that a change in luminance of the light-emitting element accompanying a temperature change can be suppressed. Note that the effects described here are not necessarily limited, and may be any of the effects described in the present disclosure.

It is a block diagram showing an example of 1 composition of a display in a 1st embodiment of this art. It is a block diagram showing an example of 1 composition of a data input interface in a 1st embodiment of this art. It is a block diagram showing an example of 1 composition of a timing controller in a 1st embodiment of this art. It is a block diagram showing an example of 1 composition of a display controller in a 1st embodiment of this art. It is a circuit diagram showing an example of 1 composition of a gamma correction circuit in a 1st embodiment of this art. It is an example of the graph which shows the relationship between the gradation voltage and gradation in 1st Embodiment of this technique. It is a circuit diagram showing an example of 1 composition of a horizontal driver in a 1st embodiment of this art. It is a block diagram showing an example of 1 composition of an organic EL panel in a 1st embodiment of this art. It is a circuit diagram showing an example of 1 composition of a sub pixel circuit in a 1st embodiment of this art. It is a graph which shows an example of the relation between drive voltage and temperature corresponding to fixed brightness in a 1st embodiment of this art. It is a circuit diagram showing an example of 1 composition of a temperature compensation part in a 1st embodiment of this art. It is a graph which shows an example of relation between current and temperature in a 1st embodiment of this art. It is a figure showing an example of relation between output current and temperature in a 1st embodiment of this art. It is a figure for demonstrating the method of the temperature compensation in 1st Embodiment of this technique. It is a circuit diagram showing an example of 1 composition of a bias voltage supply circuit in a 1st embodiment of this art. It is a circuit diagram showing an example of 1 composition of a constant current generation part in a 1st embodiment of this art. It is a circuit diagram showing an example of 1 composition of a whole temperature range dependence current generating part in a 1st embodiment of this art. It is a circuit diagram showing an example of 1 composition of a low temperature range dependence current generation part in a 1st embodiment of this art. It is a graph which shows an example of the relation between gradation voltage and temperature for every set value in a 1st embodiment of this art. It is a graph which shows an example of the relation between cathode current and temperature for every set value in a 1st embodiment of this art. 7 is a flowchart illustrating an example of the operation of the display device according to the first embodiment of the present technology. It is a circuit diagram showing an example of 1 composition of a temperature compensation part in a modification of a 1st embodiment of this art. It is a circuit diagram showing an example of 1 composition of a temperature compensation part in a 2nd embodiment of this art. It is a circuit diagram showing an example of 1 composition of a BGR (Band Gap Reference) circuit in a 2nd embodiment of this art. It is a circuit diagram showing an example of 1 composition of a voltage current conversion part in a 2nd embodiment of this art, and a whole temperature range dependence current generating part. It is a circuit diagram showing an example of 1 composition of a low temperature range dependence current generation part in a 2nd embodiment of this art.

Hereinafter, modes for carrying out the present technology (hereinafter referred to as embodiments) will be described. The description will be made in the following order.
1. First Embodiment (Example of generating constant current, low temperature region dependent current and full temperature region dependent current)
2. Second embodiment (example of generating low temperature region dependent current and full temperature region dependent current)
3. Third Embodiment (Example in which temperature is measured by a BGR circuit and a low temperature region dependent current and a whole temperature region dependent current are generated)

<1. First Embodiment>
[Configuration example of display device]
FIG. 1 is a block diagram illustrating a configuration example of the display device 100 according to the first embodiment. The display device 100 is a device for displaying an image, and includes a data input interface 110, a timing controller 120, and a display controller 130. The display device 100 includes a register 140, a drive circuit 150, and an organic EL (Electro Luminescence) panel 180. The drive circuit 150 includes a vertical driver 160, a horizontal driver 170, and a gamma correction circuit 200.

In the organic EL panel 180, a plurality of pixel circuits are arranged in a two-dimensional lattice pattern. Hereinafter, a set of pixel circuits arranged in the horizontal direction is referred to as “row”, and a set of pixel circuits arranged in the direction perpendicular to the row is referred to as “column”.

The data input interface 110 receives serially transferred display data from an external device (such as a source device) of the display device 100. The display data is data to be displayed on the display device 100. For example, moving image data including a plurality of pieces of image data in time series and still image data are input as display data. The data input interface 110 converts serial display data into parallel data. Further, the data input interface 110 generates a vertical synchronization signal and a horizontal synchronization signal and supplies them to the timing controller 120 via the signal line 119 together with parallel data. Here, the vertical synchronization signal is a signal indicating timing for displaying image data, and the horizontal synchronization signal is a signal indicating timing for displaying a row.

The timing controller 120 controls the timing at which the display controller 130 operates. The timing controller 120 generates pixel data from the parallel data and supplies the pixel data together with the timing signal to the display controller 130 via the signal line 129.

The display controller 130 controls the drive circuit 150. The display controller 130 supplies pixel data to the horizontal driver 170 via the signal line 138 in synchronization with the timing signal. This pixel data includes gradation information indicating the gradation for each color such as R (Red), G (Green), B (Blue), and W (White). The display controller 130 controls the vertical driver 160 in synchronization with the timing signal.

The vertical driver 160 drives the rows of the organic EL panels 180 in order under the control of the display controller 130.

The register 140 holds a setting value for adjusting the luminance level. The gamma correction circuit 200 performs gamma correction. The gamma correction circuit 200 reads the setting value of the register 140 and generates a gradation voltage indicating a gradation based on the setting value. When the gradation is controlled in 256 steps, for example, 256 different gradation voltages are generated. Then, the gamma correction circuit 200 supplies these gradation voltages to the horizontal driver 170 via the signal line 209. The register 140 is an example of a holding unit described in the claims.

The horizontal driver 170 selects a gradation voltage corresponding to the gradation information in the pixel data for each pixel in the selected row and supplies it to the organic EL panel 180.

[Data input interface configuration example]
FIG. 2 is a block diagram illustrating a configuration example of the data input interface 110 according to the first embodiment. The data input interface 110 includes a clock control unit 111, a high-speed interface 112, a synchronization signal generation unit 113, and a serial / parallel conversion unit 114.

The high speed interface 112 receives serially transferred display data. The clock control unit 111 controls the timing controller 120 to generate a clock signal over a period for displaying display data. The synchronization signal generator 113 generates a horizontal synchronization signal and a vertical synchronization signal based on the display data. The serial / parallel converter 114 converts serial display data into parallel data.

[Timing controller configuration example]
FIG. 3 is a block diagram illustrating a configuration example of the timing controller 120 according to the first embodiment. The timing controller 120 includes a clock generator 121, a timing generator 122, and an image processing unit 123.

The clock generator 121 generates a clock signal having a predetermined frequency under the control of the clock control unit 111. The frequency of this clock signal is higher than that of the horizontal synchronizing signal. The clock generator 121 supplies a clock signal to the display controller 130.

The timing generator 122 generates a timing signal based on the vertical synchronization signal and the horizontal synchronization signal and supplies the timing signal to the display controller 130.

The image processing unit 123 performs various image processing on the parallel data. For example, a process for converting the resolution and a process for interpolating color information (such as W) for each pixel are performed. The image processing unit 123 generates pixel data for each pixel by image processing and supplies the pixel data to the display controller 130.

[Configuration example of display controller]
FIG. 4 is a block diagram illustrating a configuration example of the display controller 130 according to the first embodiment. The display controller 130 includes a vertical logic circuit 131 and a horizontal logic circuit 132.

The vertical logic circuit 131 controls the vertical driver 160 in synchronization with the timing signal. The horizontal logic circuit 132 supplies pixel data to the horizontal driver 170 in synchronization with the timing signal.

[Configuration example of gamma correction circuit]
FIG. 5 is a circuit diagram showing a configuration example of the gamma correction circuit 200 in the first embodiment. The gamma correction circuit 200 includes a maximum voltage generation unit 210, a minimum voltage generation unit 230, and a resistor 220.

The maximum voltage generator 210 generates a gradation voltage VG0 for causing light emission with the minimum luminance. The maximum voltage generator 210 includes an operational amplifier 211, switches 212, 213 and 214, a resistor 215, and a constant current source 216.

The resistor 215 is inserted between the power source and the constant current source 216. The switches 212, 213, and 214 are connected to the resistor 215 at connection points different from each other. The output terminal of the operational amplifier 211 is connected to the inverting input terminal (−) of the operational amplifier 211 itself and the resistor 220.

The switch 212 opens and closes a path between the non-inverting input terminal (+) of the operational amplifier 211 and a corresponding connection point of the resistor 215. The switch 213 opens and closes a path between the non-inverting input terminal (+) of the operational amplifier 211 and a corresponding connection point of the resistor 215. The switch 214 opens and closes a path between the non-inverting input terminal (+) of the operational amplifier 211 and a corresponding connection point of the resistor 215.

Here, the register 140 includes a maximum voltage adjustment value for adjusting the voltage generated by the maximum voltage generation unit 210, a minimum voltage adjustment value for adjusting the voltage generated by the minimum voltage generation unit 230, and a current adjustment. Value. The current adjustment value is a value for adjusting the current generated in the minimum voltage generation unit 230. The maximum voltage adjustment value is input to the maximum voltage generation unit 210, and the minimum voltage adjustment value and the current adjustment value are input to the minimum voltage generation unit 230.

Each of the switches 212, 213 and 214 opens and closes according to the maximum voltage adjustment value in the register 140. The maximum voltage adjustment value is set so that only one of these switches is closed.

With the above-described configuration, any of the switches 212, 213, and 214 supplies a voltage corresponding to the connection point to the operational amplifier 211 as the DC voltage VDCb. The operational amplifier 211 generates a voltage corresponding to the DC voltage VDCb as the gradation voltage VG0 and applies it to one end of the resistor 220.

The minimum voltage generator 230 generates a gradation voltage VG255 for causing light emission with the maximum luminance minimum voltage. The minimum voltage generation unit 230 includes a current-voltage conversion unit 240, an operational amplifier 236, a temperature compensation unit 300, switches 231, 232, and 233, a resistor 234, and a constant current source 235. In addition, the current-voltage conversion unit 240 includes a resistor 241 and an operational amplifier 242.

The resistor 234 is inserted between the power source and the constant current source 235. The switches 231, 232 and 233 are connected to the resistor 234 at connection points different from each other.

The switch 231 opens and closes a path between the non-inverting input terminal (+) of the operational amplifier 242 and a corresponding connection point of the resistor 234. The switch 232 opens and closes a path between the non-inverting input terminal (+) of the operational amplifier 242 and a corresponding connection point of the resistor 234. The switch 233 opens and closes a path between the non-inverting input terminal (+) of the operational amplifier 242 and a corresponding connection point of the resistor 234.

The temperature compensation unit 300 generates an output current I _OUT depending on temperature. The temperature compensation unit 300 outputs the output current I _OUT to the inverting input terminal (−) of the operational amplifier 242.

The resistor 241 is inserted between the inverting input terminal (−) and the output terminal of the operational amplifier 242. The output terminal of the operational amplifier 242 is connected to the non-inverting input terminal (+) of the operational amplifier 236. The output terminal of the operational amplifier 236 is connected to the inverting input terminal (−) of the operational amplifier 236 itself and to the end of the resistor 220 to which the maximum voltage generator 210 is not connected. The operational amplifier 236 is used for impedance conversion.

With the above-described configuration, any of the switches 231, 232, and 233 supplies a voltage corresponding to the connection point to the operational amplifier 242 as the DC voltage VDCw. The resistor 241 converts the output current I _OUT into a voltage. The operational amplifier 242 generates a voltage obtained by adding the DC voltage VDCw to the voltage of the resistor 241, and the operational amplifier 236 supplies the voltage to one end of the resistor 220 as the gradation voltage VG225.

Also, the resistor 220 is inserted between the maximum voltage generation unit 210 and the minimum voltage generation unit 230. The resistor 220 is connected to the horizontal driver 170 at the number of connection points corresponding to the number of gradations. For example, when the gradation is in 256 levels, the horizontal driver 170 is connected at 256 connection points. The voltage at the n-th connection point (n is an integer from 0 to 255) from the side closer to the maximum voltage generation unit 210 is supplied to the horizontal driver 170 as the gradation voltage VGn indicating the n-th gradation.

Although the temperature compensation unit 300 is provided in the gamma correction circuit 200 in the display device 100, the temperature compensation unit 300 may be provided in a device other than the display device 100 as long as the device requires temperature compensation.

FIG. 6 is an example of a graph showing the relationship between the gradation voltage and the gradation in the first embodiment. The vertical axis in the figure indicates the gradation voltages VG0 to VG255. In addition, the horizontal axis in the figure shows the gradation of the pixel when the gradation voltage is applied. As illustrated in the figure, the white gradation voltage VG0 is the lowest and the black gradation voltage VG255 is the highest. Further, the locus of the gradation voltage VGn is a curve, and the luminance can be linearly changed with the change of gradation by applying this nonlinear gradation voltage. In this manner, the process of adjusting the gradation voltage nonlinearly in accordance with the panel characteristics is called a gamma correction process.

FIG. 7 is a circuit diagram showing a configuration example of the horizontal driver 170 in the first embodiment. The horizontal driver 170 is provided with a horizontal analog cell 171 for each column. The horizontal analog cell 171 includes a DA converter 172 and a gradation voltage generator 174. The DA conversion unit 172 includes the same number (for example, 256) of switches 173 as the number of gradations. The gradation voltage generation unit 174 includes an operational amplifier 175 and a number (for example, twelve) of switches 176 equal to the number of subpixels in the pixel.

Here, the pixel data includes sub-pixel enable indicating any of the sub-pixels and gradation information indicating the gradation. When there are 12 subpixels in a pixel and the gradation is 256 levels, for example, a 4-bit subpixel enable and 8-bit gradation information are generated by the display controller 130.

The DA converter 172 converts digital gradation information into an analog gradation voltage. In the DA converter 172, the nth switch 173 opens and closes a path between the power supply line to which the gradation voltage VGn is supplied and the non-inverting input terminal (+) of the operational amplifier 175. When the gradation information indicating the nth gradation is input, only the nth switch 173 shifts to the closed state. As a result, the gradation voltage VGn is supplied to the gradation voltage generation unit 174.

The gradation voltage generation unit 174 supplies the gradation voltage VGn to the subpixel indicated by the subpixel enable. The operational amplifier 175 amplifies the gradation voltage VGn and supplies it to each of the switches 176. When the subpixel enable indicates the mth subpixel (m is an integer from 0 to 11), the mth switch 176 supplies the pixel signal OTm of the gradation voltage VGn to the subpixel.

[Configuration example of organic EL panel]
FIG. 8 is a block diagram illustrating a configuration example of the organic EL panel 180 according to the first embodiment. In the organic EL panel 180, a plurality of pixel circuits 181 are arranged in a two-dimensional lattice pattern. In each of the pixel circuits 181, a predetermined number (for example, 12) of sub-pixel circuits 182 that emit light in different colors are arranged. Each of the sub-pixel circuits 182 is connected to a vertical signal line wired in the vertical direction, a horizontal signal line wired in the horizontal direction, and a power supply line.

Each of the vertical signal lines is connected to the horizontal driver 170, and each of the horizontal signal lines is connected to the vertical driver 160. Further, the pixel signal OTm is supplied through the vertical signal line, and the selection signal SELp (p is an integer) is supplied through the horizontal signal line. This selection signal SELp is a signal for driving the p-th row.

FIG. 9 is a circuit diagram illustrating a configuration example of the sub-pixel circuit 182 according to the first embodiment. The subpixel circuit 182 includes a selection transistor 183, a capacitor 184, a driving transistor 185, and a light emitting element 186. As the selection transistor 183 and the driving transistor 185, for example, an N-type MOS transistor is used. An OLED is used as the light emitting element 186.

The gate of the selection transistor 183 is connected to the horizontal signal line, the source is connected to the vertical signal line, and the drain is connected to the capacitor 184 and the drive transistor 185. Both ends of the capacitor 184 are connected to the gate and source of the driving transistor 185. The source of the driving transistor 185 is connected to the power supply line, and the drain is connected to the light emitting element 186.

With the above configuration, when the high level selection signal SELp is supplied to the horizontal signal line, the selection transistor 183 outputs a current corresponding to the pixel signal OTm to the capacitor 184. Here, the higher the voltage of the pixel signal OTm (gradation voltage VGn), the lower the gate-source voltage of the selection transistor 183 and the smaller the current to the capacitor 184. As a result, the charging voltage of the capacitor 184 becomes lower. Lower. The lower the charging voltage of the capacitor 184, the smaller the drive current (drain current) output from the drive transistor 185 to the light emitting element 186, and the luminance of the light emitting element 186 decreases. In other words, the higher the gradation voltage VGn, the lower the drive voltage (gate-source voltage) of the drive transistor 185 and the lower the luminance. On the other hand, the lower the gradation voltage VGn, the higher the luminance.

FIG. 10 is a graph showing an example of the relationship between the driving voltage and the temperature corresponding to the constant luminance in the first embodiment. In the figure, the vertical axis represents voltage, and the horizontal axis represents temperature T.

Here, the drain current of the MOS transistor can be expressed by the following equation.
I _ds = (1/2) × μC _ox × (W / L) × (V _gs −V _th ) ² Equation 1
In the above formula, I _ds is the drain current, and the unit is, for example, ampere (A). μ is the carrier mobility, and the unit is, for example, square centimeter per volt second (cm ² / V · s). C _ox is the oxide film capacity per unit area, and the unit is, for example, farad per square centimeter (F / cm ² ). W is the gate width, and the unit is, for example, centimeter (cm). L is the gate length, and the unit is, for example, centimeter (cm). V _gs is a gate-source voltage, and its unit is, for example, volts (V). _Vth is a threshold voltage, and its unit is, for example, volts (V).

The gate-source voltage V _gs is expressed by the following expression by _modifying Expression 1.
V _gs = {2I _ds / (μ · C _ox · W / L)} ^0.5 + V _th.

The temperature characteristic of the gate-source voltage V _gs in Equation 2 is expressed by the following equation obtained by differentiating both sides of Equation 2 with respect to temperature.

In the above formula, T is the measurement temperature, and the unit is, for example, degree (° C.).

In Equation 3, the threshold voltage V _{th on the} right side is proportional to T ⁻¹ , while the carrier mobility μ on the right side is proportional to T ^(−1.5) . The solid line in FIG. 10 indicates the temperature characteristic of the drive voltage (that is, V _gs ) corresponding to the constant luminance obtained from Equation 3, and the alternate long and short dash line indicates the characteristic of the threshold voltage _Vth . As illustrated in the figure, the gate - temperature characteristics of the source voltage V _gs between the low temperature side temperature characteristic of the threshold voltage V _th becomes dominant at the right side of the threshold voltage V _th term (Equation 3 at the high temperature side The second term) is canceled by the carrier mobility μ term (the first term on the right side of Equation 3).

As described above, the gradation voltage VGn and the gate-source voltage _{Vgs of} the selection transistor 183 (MOS transistor) are in an inversely proportional relationship. For this reason, by applying the gradation voltage VGn having a temperature characteristic obtained by inverting the solid curve in FIG. 10 up and down, fluctuations in luminance due to temperature changes can be suppressed.

[Configuration example of temperature compensation unit]
FIG. 11 is a circuit diagram illustrating a configuration example of the temperature compensation unit 300 according to the first embodiment. The temperature compensation unit 300 includes a bias voltage supply circuit 310, a temperature sensor 320, and a temperature compensation circuit 330. The temperature compensation circuit 330 includes a low temperature region dependent current generation unit 340, a constant current generation unit 350, and an entire temperature region dependency current generation unit 360.

The bias voltage supply circuit 310 generates a constant bias voltage Vb and supplies it to the constant current generator 350.

The temperature sensor 320 measures temperature. The temperature sensor 320 generates a voltage having a higher level as the measurement temperature is higher as the measurement voltage V _TEMP and supplies the generated voltage to the low temperature region dependent current generation unit 340 and the entire temperature region dependency current generation unit 360.

Constant current generation unit 350, and generates a not dependent on the measured temperature constant current I _A. Low temperature range dependent current generator 340, the measured temperature is a temperature range lower than the predetermined temperature, a current of about the measured temperature is higher small value and generates the low temperature range dependent current I _C. Also, the entire temperature range dependent current generator 360, a current of greater value as the measured temperature is higher and generates the entire temperature range dependent current I _B.

Here, constant current generator 350 and full temperature region dependent current generator 360 are connected in series between the power supply and the ground terminal. The low temperature region dependent current generation unit 340 is inserted between the connection point of the constant current generation unit 350 and the entire temperature region dependency current generation unit 360 and the power source. These connection points are connected to the current-voltage conversion unit 240. With this connection relationship, an output current I _OUT represented by the following equation is output from the connection point to the current-voltage conversion unit 240.
I _OUT = I _B −I _A −I _C Expression 4

Further, the values of the currents I _A , I _B, and I _C in Equation 4 can be individually adjusted by the set value of the register 140.

FIG. 12 is a graph showing an example of the relationship between current and temperature in the first embodiment. In the figure, the vertical axis represents current, and the horizontal axis represents temperature. A in the figure is a graph showing an example of the relationship between the constant current I _A and the temperature T. As illustrated in a in the figure, the constant current I _A does not depend on the temperature and is a constant value.

B in FIG. 12 is a graph showing an example of the relationship between the total temperature range dependent current I _B and the temperature T. As illustrated in b in the figure, the entire temperature range dependent current I _B is, as the temperature T is high, a large value. Incidentally, one-dot chain line b in the figure shows a constant current I _A. Temperature constant current I _A and the entire temperature range dependent current I _B match, for example, is 40 degrees (° C.).

C in FIG. 12 is a graph showing an example of the relationship between the low temperature range dependent current I _C and the temperature T. As illustrated in c in the figure, the low temperature region dependent current I _C becomes smaller as the measurement temperature is higher in a temperature range lower than a predetermined temperature (for example, 40 degrees).

FIG. 13 is a diagram illustrating an example of the relationship between the output current and the temperature in the first embodiment. In the figure, the vertical axis represents the output current I _OUT , and the horizontal axis represents the temperature T. From Equation 4, in the high temperature range of 40 ° C. (° C.) or higher where the low temperature region dependent current I _C is not generated, the output current I _OUT has a value of I _B −I _A , and its locus is a straight line. This output current I _OUT is converted into a gradation voltage VG255 expressed by the following equation by the current-voltage conversion unit 240.
VG255 = VDCw + R (I _B −I _A ) Equation 5
In the above formula, R is the resistance value of the resistor 241, and the unit is, for example, ohm (Ω).

If the equation 5, a constant current _{I A} is larger than the entire temperature range dependent current _{I B,} the current flows into the current-voltage conversion unit 240, the gradation voltage VG255 is reduced to a value lower than the DC voltage VDCw. Further, if the constant current _{I A} and the entire temperature range dependent current _{I B} are equal, gradation voltage VG255 is a value equal to the DC voltage VDCw. Further, if the constant current _{I A} is smaller than the entire temperature range dependent current _{I B,} a current flows from the current-to-voltage converter 240, the gradation voltage VG255 rises to a higher value than the DC voltage VDCw. By setting the temperature (such as 40 degrees) when a constant current I _A and the entire temperature range dependent current I _B is equal to the temperature of the boundary of the high temperature region and low temperature region, flowing a current having a temperature characteristic as a boundary the temperature Alternatively, the gradation voltage VG255 can have a desired temperature characteristic.

The temperature characteristic of the gradation voltage VG255 is expressed by the following expression obtained by differentiating both sides of Expression 5 with respect to temperature.
_{ΔVG255 / ΔT = R (ΔI B} / ΔT) ··· Equation 6

On the other hand, in the low temperature range lower than 40 degrees (° C.) where the low temperature region dependent current I _C is generated, the output current I _OUT becomes the value of I _B −I _A −Ic according to Equation 4, and the locus is a curve and Become. This output current I _OUT is converted into a gradation voltage VG255 expressed by the following equation by the current-voltage conversion unit 240.
_{VG255 = VDCw + R (I B} -I A -Ic) ··· formula 7
In the above formula, R is the resistance value of the resistor 241, and the unit is, for example, ohm (Ω).

Then, the temperature characteristic of the gradation voltage VG255 is expressed by the following expression obtained by differentiating both sides of Expression 7 with respect to temperature.
ΔVG255 / ΔT = R {(ΔI _B / ΔT) − (ΔI _C / T)} Expression 8

From Equation 6 and Equation 8, the temperature characteristics of the gradation voltage VG255 are different between a high temperature range above a predetermined temperature (such as 40 degrees) and a low temperature range below the predetermined temperature. The curve indicating the relationship between the gradation voltage VG255 and the temperature is set so that the shape thereof substantially coincides with that obtained by vertically inverting the drive voltage curve illustrated in FIG. As a result, it is possible to compensate for fluctuations in the drive current associated with temperature changes, make the drive current constant regardless of temperature changes, and suppress fluctuations in luminance associated with temperature changes.

Incidentally, by changing the value of I _B and I _C by the set value of the register 140, it is possible to adjust the temperature gradient of the right side of Equation 6 and Equation 8.

FIG. 14 is a diagram for explaining a temperature compensation method according to the first embodiment. Temperature compensation circuit 330 generates a constant of the constant current I _A and the entire temperature range dependent current I _B and the low temperature range dependent current I _C, supplying an output current I _OUT of the formula 4 to the current-to-voltage conversion unit 240 To do. Then, the current-voltage conversion unit 240 converts the output current I _OUT into a gradation voltage VG255 expressed by Equation 5 or Equation 7.

Then, the horizontal driver 170 generates the pixel signal OTm having the gradation voltage VGn and supplies it to the sub-pixel circuit 182. A drive voltage inversely proportional to the gradation voltage VGn is applied between the gate and source of the drive transistor 185 in the sub-pixel circuit 182. Since this drive voltage substantially coincides with the temperature characteristics illustrated in FIG. 10, fluctuations in the drive current due to temperature changes are compensated. Thereby, the fluctuation | variation of the brightness accompanying a temperature change can be suppressed.

Here, assume a comparative example without generating low temperature range dependent current I _C, produces only constant current I _A and the total temperature range dependent current I _B. As illustrated in FIG. 10, the temperature characteristics of the gate-source voltage corresponding to a constant luminance differ from a predetermined temperature (such as 40 ° C.), whereas in the configuration of the comparative example, the temperature characteristics are in the entire temperature range. Does not change. For this reason, for example, temperature compensation cannot be performed in a low-temperature region, and the luminance varies with a temperature change.

In contrast, if generating a low temperature range dependent current I _C, the gate in the high temperature region and low temperature region - it is possible to change the temperature characteristic of the source voltage, the entire temperature range, to suppress the variation in luminance Can do.

Generally, in the organic EL panel, unlike the liquid crystal panel, the response speed of the image is not limited by the response speed of the panel itself at a low temperature. For this reason, in particular, by providing the temperature compensation unit 300 in a display device using an organic EL panel, the response speed of the image can be increased.

In addition, there is a method of describing correction values for each temperature in a table, but the temperature compensation unit 300 does not require a memory or the like for holding the table, and therefore is lower in cost and smaller in area than such a method. Temperature compensation.

Furthermore, since the operation amplitude of the amplifier in the horizontal driver 170 is widened by temperature compensation, heat generation in the chip is likely to occur. In particular, since the circuit generates heat in a low temperature region as compared with the high temperature region, the generated heat amount is offset with the cooling amount by the outside air, and the panel temperature is stabilized.

[Bias voltage supply circuit]
FIG. 15 is a circuit diagram illustrating a configuration example of the bias voltage supply circuit according to the first embodiment. The bias voltage supply circuit 310 includes a BGR circuit 311, an operational amplifier 312, P- type transistors 313 and 316, an N-type transistor 314, and a resistor 315. As the P-type transistor 313, the N-type transistor 314, and the P-type transistor 316, for example, MOS transistors are used.

The P-type transistor 313, the N-type transistor 314, and the resistor 315 are connected in series between the power supply and the ground terminal. The non-inverting input terminal (+) of the operational amplifier 312 is connected to the connection point of the N-type transistor 314 and the resistor 315, and the output terminal of the operational amplifier 312 is connected to the gate of the N-type transistor 314.

The gate of the P-type transistor 313 is connected in common to the drain of the P-type transistor 313, the gate of the P-type transistor 316, and the constant current generator 350. The source of the P-type transistor 316 is connected to the power source.

The BGR circuit 311 generates a constant voltage independent of temperature and supplies it to the inverting input terminal (−) of the operational amplifier.

With the above configuration, a constant bias voltage Vb independent of temperature is generated and supplied to the constant current generator 350.

[Constant current generator]
FIG. 16 is a circuit diagram showing a configuration example of the constant current generation unit 350 in the first embodiment. The constant current generator 350 includes a P-type transistor 351, a plurality of P-type transistors 352, and a plurality of switches 353.

The P-type transistor 351 is inserted between the power supply and the output terminal of the constant current generator 350. The switch 353 is provided for each P-type transistor 352, and the P-type transistor 352 and the switch 353 corresponding to the transistor are connected in series between the power supply and the output terminal.

Also, a bias voltage Vb is applied to the gates of the P-type transistor 351 and the plurality of P-type transistors 352. Each of the switches 353 opens and closes the path between the corresponding P-type transistor 352 and the output terminal according to the set value of the register 140.

The construction described above, the constant current I _A is generated. Set value in register 140 includes an adjustment value of the constant current I _A, it is possible to adjust the value of I _A by changing the current mirror ratio by the adjustment value.

[All temperature range dependent current generator]
FIG. 17 is a circuit diagram showing a configuration example of the entire temperature region dependent current generation unit 360 in the first embodiment. The entire temperature region dependent current generation unit 360 includes an operational amplifier 361, P- type transistors 362 and 365, an N-type transistor 363, and a resistor 364. The total temperature region dependent current generation unit 360 includes N- type transistors 366 and 367, a plurality of switches 368, and a plurality of N-type transistors 369. As the P-type transistor 362, the N-type transistor 363, the P-type transistor 365, the N-type transistor 366, the N-type transistor 367, and the N-type transistor 369, for example, MOS transistors are used.

P-type transistor 362, N-type transistor 363 and resistor 364 are connected in series between the power supply and the ground terminal. The non-inverting input terminal (+) of the operational amplifier 361 is connected to the connection point of the N-type transistor 363 and the resistor 364, and the output terminal of the operational amplifier 361 is connected to the gate of the N-type transistor 363. The measurement voltage V _TEMP is input to the inverting input terminal (−) of the operational amplifier 361.

The gate of the P-type transistor 362 is connected in common to the drain of the P-type transistor 362 itself and the gate of the P-type transistor 365.

The P-type transistor 365 and the N-type transistor 366 are connected in series between the power supply and the ground terminal. The gate of the N-type transistor 366 is connected to the drain of the N-type transistor 366 itself, the gate of the N-type transistor 367, and the gate of the N-type transistor 369. The drain of the N-type transistor 367 is connected to a connection point with the low temperature region dependent current generation unit 340.

Further, the switch 368 is provided for each N-type transistor 369. The N-type transistor 369 corresponding to the switch 368 is connected in series between the drain of the N-type transistor 367 and the ground terminal. The switch 368 opens and closes a path between the drain of the N-type transistor 367 and the corresponding N-type transistor 369 according to the set value of the register 140.

With the above-described configuration, a current corresponding to the measurement voltage V _TEMP is generated by the N-type transistor 363, and the current is duplicated by the P- type transistors 362 and 365 and the N- type transistors 366 and 367, so that the entire temperature region dependent current I Output as _B. Set value in register 140 includes an adjustment value of the entire temperature range dependent current I _B, it is possible to adjust the value of I _B by changing the current mirror ratio by the adjustment value.

[Low temperature region dependent current generator]
FIG. 18 is a circuit diagram illustrating a configuration example of the low-temperature region dependent current generation unit 340 in the first embodiment. The low temperature region dependent current generation unit 340 includes a constant voltage source 341, operational amplifiers 342 and 343, P- type transistors 344 and 347, an N-type transistor 345, and a resistor 346. The low temperature region dependent current generation unit 340 includes a plurality of P-type transistors 348 and a plurality of switches 349. As the P-type transistor 344, the N-type transistor 345, the P-type transistor 347, and the P-type transistor 348, for example, MOS transistors are used.

The constant voltage source 341 generates a constant DC voltage VB _END and inputs it to the inverting input terminal (−) of the operational amplifier 342. The DC voltage VB _END, the temperature at which a constant current I _A and the entire temperature range dependent current I _B match (e.g., 40 degrees), the output of the operational amplifier 342 is set to such a value as to invert.

Further, the measurement voltage V _TEMP is input to the inverting input terminal (−) of the operational amplifier 343. The non-inverting input terminal (+) of the operational amplifier 343 is connected to the output terminal of the operational amplifier 343 itself.

The P-type transistor 344, the N-type transistor 345, and the resistor 346 are connected in series between the power supply and the output terminal of the operational amplifier 343. The non-inverting input terminal (+) of the operational amplifier 342 is connected to the connection point of the N-type transistor 345 and the resistor 346, and the output terminal of the operational amplifier 342 is connected to the gate of the N-type transistor.

The drain of the P-type transistor 344 is connected to the gates of the P- type transistors 344 and 347 and the respective gates of the P-type transistor 348. The P-type transistor 347 is inserted between the power supply and the output terminal of the low temperature region dependent current generation unit 340.

Further, the switch 349 is provided for each P-type transistor 348. The P-type transistor 348 and the corresponding switch 349 are connected in series between the power supply and the output terminal. Each of the switches 349 opens and closes a path between the corresponding P-type transistor 348 and the output terminal according to the set value of the register 140.

With the above configuration, the operational amplifier 343 outputs the voltage VB corresponding to the measurement voltage V _TEMP . The voltage VB is above the value corresponding to a predetermined temperature (such as 40 degrees) (i.e., high temperature range) operational amplifier 342 in the case of, it outputs a low level, the low temperature region dependent current I _C is not outputted. On the other hand, when the voltage VB is lower than a value corresponding to a predetermined temperature (such as 40 degrees) (that is, a low temperature region), the operational amplifier 342 outputs a high level corresponding to the voltage VB, and a current corresponding to the level is It is generated by the N-type transistor 345. Its current is replicated in such P-type transistors 344,347, it is outputted as a low-temperature range dependent current _{I C.}

The set value in the register 140 includes an adjustment value of the low temperature region dependent current I _C , and the value of I _C can be adjusted by changing the current mirror ratio by the adjustment value.

FIG. 19 is a graph showing an example of the relationship between the gradation voltage and the temperature for each set value in the first embodiment. In the drawing, the vertical axis indicates the gradation voltage VG255, and the horizontal axis indicates the temperature T. The white circle is a plot of the gradation voltage VG255 when the register 140 holds the setting value 1 for emitting light with relatively high luminance. The x mark plots the gradation voltage VG255 when the register 140 holds the setting value 3 for emitting light with a relatively low luminance. The black circle is a plot of the gradation voltage VG255 when the register 140 holds the setting value 2 for emitting light at a luminance between the setting value 1 and the setting value 3.

As illustrated in FIG. 19, the luminance can be increased as the gradation voltage VG255 is decreased. Further, the locus of the gradation voltage VG255 is not a straight line, but the slope changes at a predetermined temperature (such as 40 degrees). If the gradation voltage VG255 having a constant slope is supplied as shown by the alternate long and short dash line, the voltage becomes insufficient in the low temperature range, and the luminance becomes lower than the value indicated by the gradation information.

On the other hand, in the display device 100, as illustrated in FIG. 10, since the output current I _OUT having different temperature characteristics in the low temperature region and the high temperature region is converted into the gradation voltage VG255, the luminance accompanying the temperature change. Fluctuations can be suppressed.

FIG. 20 is a graph showing an example of the relationship between the cathode current and temperature for each set value in the first embodiment. In the drawing, the vertical axis represents the cathode current of the light emitting element 186, and the horizontal axis represents the temperature T. The white circle is a plot of the cathode current when the register 140 holds the set value 1 for emitting light with relatively high luminance. The x mark is a plot of the cathode current when the register 140 holds the set value 3 for emitting light at a relatively low luminance. The black circle is a plot of the cathode current when the register 140 holds the setting value 2 for emitting light at a luminance between the setting value 1 and the setting value 3.

As illustrated in FIG. 20, the cathode current of the light-emitting element 186 has a constant value regardless of the temperature. That is, a change in luminance accompanying a change in temperature is suppressed. This is because the output current I _OUT is generated in accordance with the temperature characteristics of the drive transistor 185 that drives the light emitting element 186 as illustrated in FIG.

[Operation example of display device]
FIG. 21 is a flowchart illustrating an example of the operation of the display device 100 according to the first embodiment. This operation is started, for example, when the display device 100 receives display data.

Temperature compensation unit 300 generates a constant current _{I A} (step S901), it generates the entire temperature range dependent current _{I B} (step S902). The temperature compensation unit 300, the low temperature region dependent current _{I C} be generated, generates an output current I _OUT represented by the formula 4 (step S903). Then, the current-voltage conversion unit 240 converts the output current I _OUT into the gradation voltage VG255 (Step S904). The horizontal driver 170 at the subsequent stage selects the gradation voltage VGn corresponding to the pixel data and supplies it to the pixel circuit (step S905).

The display device 100 determines whether the display is finished (step S906). When the display is not completed (step S906: No), the display device 100 repeatedly executes step S905 and subsequent steps. On the other hand, when the display ends (step S906: Yes), the display device 100 ends the operation for display.

Thus, in the first embodiment of the present technology, to produce a different voltage temperature characteristics at a low temperature region and high temperature region by using the difference between the total temperature range dependent current I _B and the low temperature range dependent current I _C Therefore, a constant current can be output to a transistor having different temperature characteristics in a low temperature region and a high temperature region. Accordingly, the light emitting element 186 can emit light with a certain luminance.

[Modification]
In the first embodiment described above, the temperature compensation unit 300 together with the entire temperature range dependent current I _B and the low temperature region dependent current I _C and generates a constant current I _A, the output current I _OUT by the constant current I _A The level was adjusted. However, only entire temperature range dependent current I _B and the low temperature region dependent current I _C, when the output current I _OUT of the appropriate level is obtained, it is not necessary to generate a constant current I _A. Temperature compensating unit 300 of a modification of the first embodiment is different from the first embodiment in that only generate the entire temperature range dependent current I _B and the low temperature region dependent current I _C.

FIG. 22 is a circuit diagram showing a configuration example of the temperature compensation unit 300 in the modification of the first embodiment. The temperature compensation unit 300 according to the second embodiment is different from the first embodiment in that the bias voltage supply circuit 310 and the constant current generation unit 350 are not provided.

Thus, according to a modification of the first embodiment of the present technology, for generating an output current I _OUT from only entire temperature range dependent current I _B and the low temperature region dependent current I _C, the bias voltage supply circuit 310 And it is not necessary to provide the constant current generator 350. Thereby, the circuit scale can be reduced as compared with the first embodiment.

<2. Second Embodiment>
In the first embodiment described above, the temperature sensor 320 is provided outside the BGR circuit 311. However, since the resistance value of the resistor in the BGR circuit 311 changes according to the temperature, this resistance is used instead of the temperature sensor. Can be used. The temperature compensation unit 300 of the second embodiment is different from the first embodiment in that the measurement voltage V _TEMP corresponding to the temperature is generated by the resistance in the BGR circuit.

FIG. 23 is a circuit diagram showing a configuration example of the temperature compensation unit 300 according to the second embodiment. The temperature compensation unit 300 of the second embodiment includes a BGR circuit 410 and a temperature compensation circuit 420. The temperature compensation circuit 420 includes a voltage / current converter 430, a low temperature region dependent current generator 440, and an entire temperature region dependent current generator 450.

The BGR circuit 410 generates a constant reference voltage BGR _OUT and a measurement voltage V _TEMP corresponding to the temperature and supplies it to the voltage / current converter 430.

The voltage-current converter 430 converts the difference between the reference voltage BGR _OUT and the measurement voltage V _TEMP into a differential signal composed of a pair of currents. The voltage / current converter 430 supplies the differential signal to the low temperature region dependent current generator 440 and the entire temperature region dependent current generator 450.

Low temperature range dependent current generator 440 is for generating a low temperature range dependent current I _C from the differential signals. Entire temperature range dependent current generator 450 is for generating the entire temperature range dependent current I _B from the differential signals. These difference currents are output to the current-voltage converter 240 as the output current I _OUT .

In this second embodiment the temperature compensation unit 300, and can not be adjusted and the total temperature range dependent current I _B and the low temperature range dependent current I _C individually, there is no hindrance to emit light at an appropriate luminance In this case, the above-described circuit that is simpler than that of the first embodiment can be used.

[Configuration example of BGR circuit]
FIG. 24 is a circuit diagram showing a configuration example of the BGR circuit 410 according to the second embodiment. The BGR circuit 410 includes a P-type transistor 411, resistors 412, 413, 418 and 415, bipolar transistors 414 and 416, and an operational amplifier 417. For example, a MOS transistor is used as the P-type transistor 411. As the bipolar transistors 414 and 416, for example, an npn type is used.

The P-type transistor 411, the resistor 412, the resistor 413, the bipolar transistor 414, and the resistor 418 are connected in series between the power supply and the ground terminal. In each of bipolar transistors 414 and 416, the base is connected to the collector (so-called diode connection). In addition, a circuit including a resistor 415 and a bipolar transistor 416 is connected in parallel with a circuit including a resistor 412, a resistor 413, and a bipolar transistor 414.

The inverting input terminal (−) of the operational amplifier 417 is connected to the connection point between the resistors 412 and 413, and the non-inverting input terminal (+) is connected to the connection point between the resistor 415 and the bipolar transistor 416. The output terminal of the operational amplifier 417 is connected to the gate of the P-type transistor 411.

The resistance value of the resistor 418 changes as the temperature changes. For this reason, the voltage at the connection point between the bipolar transistor 414 and the resistor 418 changes with a temperature change. For example, a voltage increase of 1.6 millivolts (mV) with a temperature increase of 1 degree (° C.). This voltage is supplied to the voltage / current converter 430 as the measurement voltage V _TEMP .

In addition, although the base-emitter voltages of the bipolar transistors 414 and 416 change depending on the temperature, the voltage at the connection point of the resistor 415 and the bipolar transistor 416 is a constant voltage independent of the temperature due to the above-described connection configuration. Become. This voltage is supplied to the voltage / current converter 430 as the reference voltage BGR _OUT .

FIG. 25 is a circuit diagram showing a configuration example of the voltage / current converter 430 and the entire temperature region dependent current generator 450 in the second embodiment. The voltage / current converter 430 includes operational amplifiers 431 and 432, N-type transistors 433 and 434, and resistors 435, 436, and 437. The entire temperature region dependent current generation unit 450 includes N-type transistors 451 and 452. As the N- type transistors 433, 434, 451, and 452, for example, MOS transistors are used.

N-type transistors 433 and 434 are connected in series between the power supply and the ground terminal.

The reference voltage BGR _OUT is input to the inverting input terminal (−) of the operational amplifier 431. A non-inverting input terminal (+) of the operational amplifier 431 is connected to a connection point between the N-type transistors 433 and 434. The inverting output terminal of the operational amplifier 431 is connected to the gate of the N-type transistor 433, the low temperature region dependent current generator 440, and the entire temperature region dependent current generator 450. The non-inverting output terminal of the operational amplifier 431 is connected to the gate of the N-type transistor 434, the low temperature region dependent current generator 440, and the entire temperature region dependent current generator 450.

Resistor 437, resistor 435, and resistor 436 are connected in series between the connection point of N-type transistors 433 and 434 and the ground terminal.

The measurement voltage V _TEMP is input to the inverting input terminal (−) of the operational amplifier 432. A non-inverting input terminal (+) of the operational amplifier 432 is connected to a connection point between the resistors 435 and 436. The output terminal of the operational amplifier 432 is connected to a connection point between the resistors 435 and 437.

In the entire temperature region dependent current generation unit 450, the N-type transistors 451 and 452 are connected in series between the power supply and the ground terminal. A differential signal from the voltage / current converter 430 is input to the gates of the N-type transistors 451 and 452. The connection point of N-type transistors 451 and 452 is connected to current-voltage conversion unit 240.

With the above configuration, the operational amplifier 431 compares the voltage according to the measurement voltage V _TEMP with the reference voltage BGR _OUT and generates a differential signal according to the difference between them. The operational amplifier 431 outputs the differential signal to the low temperature region dependent current generation unit 440 and the entire temperature region dependency current generation unit 450. The entire temperature range dependent current generator 450 generates and outputs the entire temperature range dependent current I _B from the differential signals.

FIG. 26 is a circuit diagram showing a configuration example of the low-temperature region dependent current generation unit 440 in the second embodiment. The low temperature region dependent current generation unit 440 includes N- type transistors 441, 442, 443, 444, 445 and 446. As these transistors, for example, MOS transistors are used.

N- type transistors 441 and 442 are connected in series between the power supply and the ground terminal. The drain of the N-type transistor 443 is connected to the connection point of the N- type transistors 441 and 442, and the source is grounded. The gate of the N-type transistor 443 is connected to the drain of the N-type transistor 443 itself and the gate of the N-type transistor 445.

N- type transistors 444 and 445 are connected in series between the power supply and the ground terminal. The gate of the N-type transistor 444 is connected to the drain of the N-type transistor 444 itself and the gate of the N-type transistor 446. The source of the N-type transistor 446 is connected to the power supply, and the drain is connected to the current-voltage conversion unit 240.

With the above-described configuration, a current corresponding to the differential signal from the voltage / current conversion unit 430 is generated, and the current is duplicated by the N- type transistors 443 and 445. Then, the source current component among the replicated current is taken out by the N-type transistors 444 and 446 is output as a low-temperature range dependent current I _C.

As described above, according to the second embodiment of the present technology, since the BGR circuit 410 generates the measurement voltage V _TEMP corresponding to the temperature, it is not necessary to provide the temperature sensor 320 outside the BGR circuit 410. Thereby, the circuit scale of the temperature compensation unit 300 can be reduced.

The above-described embodiment shows an example for embodying the present technology, and the matters in the embodiment and the invention-specific matters in the claims have a corresponding relationship. Similarly, the invention specific matter in the claims and the matter in the embodiment of the present technology having the same name as this have a corresponding relationship. However, the present technology is not limited to the embodiment, and can be embodied by making various modifications to the embodiment without departing from the gist thereof.

It should be noted that the effects described here are not necessarily limited, and may be any of the effects described in the present disclosure.

In addition, this technique can also take the following structures.
(1) a low temperature region dependent current generating unit that generates a current having a smaller value as a low temperature region dependent current as the measured temperature is higher in a temperature range where the measured temperature is lower than a predetermined temperature;
A temperature-dependent current generation unit that generates a current having a larger value as the temperature-dependent current as the measurement temperature is higher;
A current-voltage conversion unit that converts a current from a connection point of the low-temperature region-dependent current generation unit and the all-temperature region-dependent current generation unit into a voltage and supplies it as a gradation voltage; and
A display device comprising: a drive transistor that supplies a light-emitting element with a drive current corresponding to the gradation voltage to emit light.
(2) The display device according to (1), further including a constant current generation unit that generates a constant constant current and supplies the constant constant current to the connection point.
(3) It further comprises a holding unit that holds the adjustment value of the constant current as a constant current adjustment value,
The display device according to (2), wherein the constant current generation unit generates the constant current adjusted according to the constant current adjustment value.
(4) The holding unit further holds the adjustment value of the low temperature region dependent current as a low temperature region dependent current adjustment value,
The display device according to (3), wherein the low temperature region dependent current generation unit generates the low temperature region dependent current adjusted according to the low temperature region dependent current adjustment value.
(5) The holding unit further holds the adjustment value of the entire temperature region dependent current as a low temperature region dependent current adjustment value,
The display device according to (3), wherein the entire temperature region dependent current generation unit generates the entire temperature region dependent current adjusted according to the entire temperature region dependent current adjustment value.
(6) a temperature sensor that supplies a measurement voltage corresponding to the measurement temperature;
The low temperature region dependent current generation unit supplies, as the low temperature region dependent current, a current corresponding to a difference between a voltage corresponding to the measurement voltage and a predetermined voltage,
The display device according to any one of (1) to (5), wherein the entire temperature region dependent current generation unit supplies a current corresponding to the measurement voltage as the entire temperature region dependent current.
(7) a band gap reference circuit that generates a measurement voltage and a constant reference voltage according to the measurement temperature;
A voltage-current converter that outputs a differential signal according to the difference between the voltage according to the measurement voltage and the reference voltage;
The low temperature region dependent current generation unit generates the low temperature region dependent current from the differential signal,
The display device according to any one of (1) to (5), wherein the entire temperature region dependent current generation unit generates the entire temperature region dependent current from the differential signal.
(8) The display device according to any one of (1) to (7), wherein the driving transistor is a MOS transistor.
(9) a low temperature region dependent current generating unit that generates a current having a smaller value as a low temperature region dependent current as the measured temperature is higher in a temperature range where the measured temperature is lower than a predetermined temperature;
A temperature compensation circuit comprising: an entire temperature region dependent current generation unit that generates a current having a larger value as the entire temperature region dependent current as the measurement temperature is higher.
(10) A low temperature region dependent current generation procedure for generating a current having a smaller value as a low temperature region dependent current as the measured temperature is higher in a temperature range where the measured temperature is lower than a predetermined temperature;
A temperature-dependent current generation procedure for generating a current having a larger value as the temperature-dependent current as the measurement temperature is higher,
A current-voltage conversion procedure for converting a current from a connection point of the low-temperature region-dependent current generation unit and the all-temperature region-dependent current generation unit into a voltage and supplying it as a gradation voltage;
A control method for a display device, comprising: a driving procedure for supplying a light-emitting element with a driving current corresponding to the gradation voltage to emit light.

DESCRIPTION OF SYMBOLS 100 Display apparatus 110 Data input interface 111 Clock control part 112 High-speed interface 113 Synchronization signal generation part 114 Serial parallel conversion part 120 Timing controller 121 Clock generator 122 Timing generator 123 Image processing part 130 Display controller 131 Vertical logic circuit 132 Horizontal logic circuit 140 Register 150 Driving Circuit 160 Vertical Driver 170 Horizontal Driver 171 Horizontal Analog Cell 172 DA Converter 173, 176, 212, 213, 214, 231, 232, 233, 349, 353, 368 Switch 174 Grayscale Voltage Generator 175, 211, 236 242, 312, 342, 343, 361, 417, 431, 432 operational amplifier 180 organic E Panel 181 Pixel circuit 182 Sub-pixel circuit 183 Selection transistor 184 Capacitor 185 Drive transistor 186 Light-emitting element 200 Gamma correction circuit 210 Maximum voltage generator 215, 220, 234, 241, 315, 346, 364, 412, 413, 415, 418, 435, 436, 437 Resistance 216, 235 Constant current source 230 Minimum voltage generation unit 240 Current voltage conversion unit 300 Temperature compensation unit 310 Bias voltage supply circuit 311, 410 BGR circuit 313, 316, 344, 347, 348, 351, 352, 362, 365, 411 P-type transistor 314, 345, 363, 366, 367, 369, 433, 434, 441, 442, 443, 444, 445, 446, 451, 452 N-type transistor 320 Temperature sensor Sa 330 and 420 the temperature compensation circuit 340 and 440 low temperature range dependent current generator 341 the constant voltage source 350 constant current generation unit 360,450 entire temperature range dependent current generator 414, 416 bipolar transistors 430 voltage current conversion section

Claims (10)

1. A low temperature region-dependent current generation unit that generates a current having a smaller value as a low temperature region-dependent current as the measured temperature is higher in a temperature range where the measured temperature is lower than a predetermined temperature;
   A temperature-dependent current generation unit that generates a current having a larger value as the temperature-dependent current as the measurement temperature is higher;
   A current-voltage conversion unit that converts a current from a connection point of the low-temperature region-dependent current generation unit and the all-temperature region-dependent current generation unit into a voltage and supplies it as a gradation voltage; and
   A display device comprising: a drive transistor that supplies a light-emitting element with a drive current corresponding to the gradation voltage to emit light.
2. The display device according to claim 1, further comprising a constant current generation unit that generates a constant current and supplies the constant current to the connection point.
3. A holding unit that holds the adjustment value of the constant current as a constant current adjustment value;
   The display device according to claim 2, wherein the constant current generation unit generates the constant current adjusted according to the constant current adjustment value.
4. The holding unit further holds the adjustment value of the low temperature region dependent current as a low temperature region dependent current adjustment value,
   The display device according to claim 3, wherein the low temperature region dependent current generation unit generates the low temperature region dependent current adjusted according to the low temperature region dependent current adjustment value.
5. The holding unit further holds the adjustment value of the total temperature region dependent current as a low temperature region dependent current adjustment value,
   The display device according to claim 3, wherein the entire temperature region dependent current generation unit generates the entire temperature region dependent current adjusted according to the entire temperature region dependent current adjustment value.
6. A temperature sensor for supplying a measurement voltage corresponding to the measurement temperature;
   The low temperature region dependent current generation unit supplies, as the low temperature region dependent current, a current corresponding to a difference between a voltage corresponding to the measurement voltage and a predetermined voltage,
   The display device according to claim 1, wherein the entire temperature region dependent current generation unit supplies a current corresponding to the measurement voltage as the entire temperature region dependent current.
7. A band gap reference circuit that generates a measurement voltage and a constant reference voltage according to the measurement temperature;
   A voltage-current converter that outputs a differential signal according to the difference between the voltage according to the measurement voltage and the reference voltage;
   The low temperature region dependent current generation unit generates the low temperature region dependent current from the differential signal,
   The display device according to claim 1, wherein the entire temperature region dependent current generation unit generates the entire temperature region dependent current from the differential signal.
8. The display device according to claim 1, wherein the driving transistor is a MOS transistor.
9. A low temperature region-dependent current generation unit that generates a current having a smaller value as a low temperature region-dependent current as the measured temperature is higher in a temperature range where the measured temperature is lower than a predetermined temperature;
   A temperature compensation circuit comprising: an entire temperature region dependent current generation unit that generates a current having a larger value as the entire temperature region dependent current as the measurement temperature is higher.
10. A low temperature region dependent current generation procedure for generating a current having a smaller value as a low temperature region dependent current as the measured temperature is higher in a temperature range where the measured temperature is lower than a predetermined temperature;
    A temperature-dependent current generation procedure for generating a current having a larger value as the temperature-dependent current as the measurement temperature is higher,
    A current-voltage conversion procedure for converting a current from a connection point of the low-temperature region-dependent current generation unit and the all-temperature region-dependent current generation unit into a voltage and supplying it as a gradation voltage;
    A control method for a display device, comprising: a driving procedure for supplying a light-emitting element with a driving current corresponding to the gradation voltage to emit light.

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