JP3786126B2 - Driver IC, electro-optical device and electronic apparatus - Google Patents

Description

  The present invention relates to a driver IC, an electro-optical device, and an electronic apparatus for driving an electro-optical element such as a liquid crystal, and more particularly to improvement of temperature compensation necessary for driving the electro-optical element.

  For example, when the liquid crystal is taken as an example of the electro-optic element, the liquid crystal has temperature dependency. When the environmental temperature is different, the transmittance of the liquid crystal is different when the same voltage is applied. Therefore, various temperature compensation measures have been implemented conventionally. One is temperature compensation of the voltage applied to the liquid crystal by linear interpolation. Some of them perform linear interpolation by selecting or synthesizing one of two or more temperature gradients.

  However, in the linear interpolation, since the temperature gradient is constant from the low temperature region to the high temperature region, the temperature dependence characteristics of the actual liquid crystal do not always coincide with each other, and accurate temperature compensation is impossible.

  In addition, the temperature-dependent characteristics of the liquid crystal depend not only on the applied voltage-transmittance characteristics but also on other parameters, but no temperature compensation has been made for this.

  Furthermore, in order to implement this type of temperature compensation, a temperature sensor that detects the environmental temperature is indispensable. Since this temperature sensor is temperature detection for compensating the temperature of the liquid crystal, it is inherent to detect the temperature of the liquid crystal, but in reality it is impossible to detect the temperature of the liquid crystal.

For this reason, conventionally, it must be provided outside the display panel, so that a physical distance is generated between the liquid crystal and the temperature sensor, and this distance increases as the liquid crystal panel increases in size. The temperature of a place with a temperature difference will be detected.
JP-A-9-265080 JP 56-89791 A Japanese Patent Laid-Open No. 11-218731

  An object of the present invention is to provide a driver IC, an electro-optical device, and an electronic apparatus that can perform more accurate temperature compensation in accordance with the temperature dependence of an electro-optical element.

  According to one aspect of the present invention, a driver IC that drives an electro-optical element includes a power supply circuit that outputs a voltage according to temperature-voltage characteristics, an electronic volume that varies an output voltage from the power supply circuit, and an environmental temperature. And a correction table for storing an electronic volume control value corresponding to the temperature detected by the temperature detection unit. The power supply circuit is based on a first power supply circuit having a first temperature-voltage characteristic, a second power supply circuit having a second temperature-voltage characteristic, and output voltages from the first and second power supply circuits. And a temperature gradient selection circuit that outputs a voltage according to a voltage characteristic having a desired temperature gradient. The temperature detection circuit detects the actual temperature based on the first and second temperature-voltage characteristics. Based on the electronic volume switch control value in the correction table corresponding to the actual temperature detected by the temperature detector, the output voltage from the power supply circuit is adjusted by the electronic volume and output. Thereby, for example, it is possible to realize applied voltage correction that matches the temperature dependence of the electro-optic element, such as having different temperature gradients in low temperature, normal temperature, and high temperature regions, or curve interpolation other than linear interpolation.

  According to another aspect of the present invention, a driver IC that drives an electro-optical element includes an oscillator whose oscillation frequency is variable by an electronic volume, a temperature detection unit that detects an environmental temperature, and a temperature detection unit that detects the temperature. And a correction table for storing the electronic volume correction value corresponding to the temperature. The oscillation frequency of the oscillator is variable by adjusting the electronic volume based on the electronic volume correction value in the correction table corresponding to the actual temperature detected by the temperature detection unit. Thereby, since the frame frequency can be varied according to the temperature, it is possible to set the frame frequency following the characteristics of the electro-optic element having a different reaction speed depending on the temperature.

  According to still another aspect of the present invention, a driver IC that drives an electro-optic element includes an oscillator, a gradation clock generation unit that generates a gradation clock based on an oscillation frequency from the oscillator, and the gradation clock generation unit A gradation pulse generator for generating a plurality of gradation pulses having different pulse widths according to gradation values, a temperature detector for detecting an environmental temperature, and a temperature detector And a correction table for storing a gradation pulse width correction value corresponding to the detected temperature. The gradation pulse generation unit varies the pulse width of the plurality of gradation pulses based on the gradation pulse width correction value in the correction table corresponding to the actual temperature detected by the temperature detection unit. This makes it possible to vary the pulse width of the gradation pulse according to the temperature even if the gradation value when the same voltage is applied to the electro-optic element at normal temperature and low temperature has different temperature dependence. The gradation deterioration due to the temperature can be eliminated.

  An electro-optical device according to still another aspect of the invention includes a panel having an electro-optical element between a first substrate and a second substrate, and a driver mounted on the first substrate and driving the electro-optical element. IC. The driver IC includes a temperature detection unit that detects the environmental temperature and a temperature compensation circuit that performs temperature compensation necessary for driving the electro-optic element based on the actual temperature detected by the temperature detection unit. First and second electrodes are formed on the first and second substrates so as to face the electro-optic element. At least one of the first and second electrodes has a redundant portion that is connected to a terminal of the driver IC mounted on the first substrate and extends to the back surface of the driver IC beyond the terminal position. . In this way, the temperature of the electro-optical element is transmitted to the back surface of the driver IC via the electrode and its redundant portion, so that the temperature detection unit in the driver IC can detect a temperature having a small temperature difference with respect to the liquid crystal temperature. . As a result, the accuracy of temperature compensation is improved.

  Hereinafter, embodiments in which the present invention is applied to a liquid crystal device which is an example of an electro-optical device will be described with reference to the drawings.

(Description of liquid crystal device)
FIG. 1 is a schematic explanatory diagram of a simple matrix type liquid crystal device. The liquid crystal panel 10 is, for example, a simple matrix type liquid crystal device, and includes a first substrate (not shown) on which a first electrode (segment electrode) 12 is formed and a second electrode (common electrode) 14. The liquid crystal is sealed between the second substrates (not shown).

  The MPU 20 is responsible for controlling an electronic device in which the liquid crystal device is mounted, such as a mobile phone. For example, two X driver ICs 22 and 24 are provided as driver ICs to which command data, display data, address data, and the like are supplied from the MPU 20. The X driver IC 22 functions as a master, and the X driver IC 24 functions as a slave. The X driver ICs 22 and 24 supply data signals (gradation signals) to the second electrode 14 formed on the liquid crystal panel 10 and are formed by the same IC. However, only the master X driver IC 22 generates a display control signal such as a latch pulse (LP) or a gradation control pulse (GCP) based on a signal from the MPU 20, and the slave X driver IC 24 has a master control signal. These display control signals are input from the X driver IC 22.

  The Y driver IC 26 drives the first electrode 12 of the liquid crystal panel 10. A part of the display control signal is also input to the Y driver IC 26 from the master X driver IC 22.

  The X driver ICs 22 and 24 and the Y driver IC 26 drive the liquid crystal panel 10 by, for example, the MLS (multi-line selection) method. For example, the X driver ICs 22 and 24 and the Y driver IC 26 select the four second electrodes 14 simultaneously during one horizontal scanning period. The data signal is supplied to the two electrodes 14 and the same twelfth electrode 12 is selected a plurality of times within one vertical period.

  Note that the liquid crystal panel 10 to which the present invention is applied is not necessarily limited to a simple matrix type liquid crystal panel driven by MLS, and a MIS (metal-insulator--in addition to one that selects and drives one first electrode 12 as usual). The present invention can also be applied to an active matrix liquid crystal panel using a two-terminal element such as silicon) or MIM (metal-insulating-metal) or a three-terminal element such as TFT (thin film transistor).

(Overview of driver IC)
FIG. 2 is a block diagram of the main part of the X driver IC 22 shown in FIG. In FIG. 2, the following functional blocks are provided as main functional blocks built in the X driver IC 22. The power supply circuit 30 generates a reference voltage necessary for driving the liquid crystal. The voltage generation circuit 40 generates voltages V _LCD and V1 to V4 necessary for driving the liquid crystal based on the output from the power supply circuit 30. The storage unit, for example, the RAM 50 stores display data (gradation data) supplied from the MPU 20. The oscillation circuit 60 is provided with a PWM clock generation circuit 70 that oscillates and outputs a reference frequency and generates a PWM (pulse width modulation) clock (GCP) based on the oscillation frequency from the oscillation circuit 60. The gradation pulse generation circuit 80 generates gradation pulses for a plurality of types, for example, 32 gradations corresponding to each gradation value based on the PWM clock. The PWM decoder 90 selects a corresponding gradation pulse based on the gradation data from the RAM 50 and outputs it for each line. The liquid crystal drive circuit 100 shifts the pulse height of the gradation pulse from the PWM decoder 90 to various voltage values V _LCD , V1 to V4 or the ground voltage V _GND from the voltage generation circuit 40 based on a polarity inversion signal or the like (not shown). The corresponding second electrode 14 shown in FIG.

FIG. 3 shows a signal potential supplied from the liquid crystal driving circuit 100 to one second electrode 14. FIG. 3 shows a waveform when the polarity of the voltage applied to the liquid crystal is inverted for each frame. “1H” shown in FIG. 3 is one horizontal scanning period. In the first frame, the gradation value is determined by the ratio (duty ratio) of the pulse width W at which the voltage becomes V _LCD with respect to 1H. Similarly, in the second frame, the gradation value is determined by the ratio (duty ratio) of the pulse width W in which the voltage is V _{GND in} the period of 1H.

In the present embodiment, according to the characteristics of the liquid crystal panel 10, (1) correction of the voltage values of the voltages V _LCD and V1 to V4 shown in FIG. 3, and (2) the length of the period of 1H shown in FIG. Correction (frame frequency correction), (3) Correction of pulse width W (duty ratio) within 1H for each gradation value is possible.

(Voltage correction circuit)
A power supply circuit 30 shown in FIG. 2 includes a first power supply circuit 30A having a first temperature-voltage characteristic, a first power supply circuit 30B having a second temperature-voltage characteristic, and first and second power supplies. A temperature gradient selection circuit 36 that outputs a voltage according to a voltage characteristic having a desired temperature gradient based on the output voltage from the circuits 30A and 30B.

  The first power supply circuit 30A outputs a voltage A that changes according to a temperature-voltage characteristic of a first temperature gradient (for example, -0.2% / ° C.) shown in FIG. On the other hand, the second power supply circuit 30B outputs a voltage B that changes according to the temperature-voltage characteristic of the second temperature gradient (for example, −0.5% / ° C.) shown in FIG. The temperature gradient selection circuit 36 selects and outputs a voltage C having a desired temperature gradient between the voltages A and B having the first and second temperature gradients shown in FIG.

  The first power supply circuit 30A amplifies the voltage from the constant voltage source 32A having the first temperature gradient characteristic with a predetermined gain by the amplifier 34A and outputs the amplified voltage. A resistor R1 is connected between the output line of the amplifier 34A and the ground. By connecting the middle position of the resistor R1 to the negative terminal of the amplifier 34A, a feedback resistor R1A is formed in the feedback path of the amplifier 34A.

  The second power supply circuit 30B amplifies the voltage from the constant voltage source 32B having the second temperature gradient characteristic with a predetermined gain by the amplifier 34B and outputs the amplified voltage. A resistor R2 is connected between the output line of the amplifier 34B and the ground. By connecting the middle position of the resistor R2 to the negative terminal of the amplifier 34B, a feedback resistor R2A is formed in the feedback path of the amplifier 34B.

  The first and second temperature gradients described above are determined depending on the process characteristics of the MOS transistors constituting the first constant voltage source 32A and the second constant voltage source 32B.

  The temperature gradient selection circuit 36 includes a resistor R3 inserted and connected in the middle of the connection line connecting the output lines of the first and second amplifiers 34A and 34B, and a switch SW1 connected to an arbitrary position in the middle of the resistor R3. And a temperature gradient selection register 38 for storing connection position information of the switch SW1.

  The temperature gradient selection register 38 is a programmable register, and the user can freely select the temperature gradient. However, if the liquid crystal panel 10 to be used is specified, a temperature gradient unique to the liquid crystal panel 10 is selected, and thereafter, the liquid crystal panel 10 is not changed. Here, it is assumed that the temperature gradient selection register 38 has already been initialized and the output voltage from the power supply circuit 30 has the voltage characteristic C in FIG.

  An amplifier 110 is provided following the temperature gradient selection circuit 36. A resistor R4 is connected between the output line of the amplifier 110 and the ground. By connecting the middle position of the resistor R4 to the negative terminal of the amplifier 110, a feedback resistor RA4 is formed in the feedback path of the amplifier 110.

  The first electronic volume switch SW2 is a switch connected to an arbitrary position in the middle of the feedback resistor R4A of the amplifier 110. Here, the resistor selected by the first electronic volume switch SW2 is represented as a resistor R4B as shown in FIG. The voltage characteristic C shown in FIG. 4 can be further corrected by changing the value of the resistor R4B selected by the first electronic volume switch SW2.

The voltage generation circuit 40 provided at the subsequent stage of the first electronic volume switch SW2 includes a fourth amplifier 42 to which a voltage is input via the first electronic volume switch SW2, and between the output line and the ground. And a resistor R5 connected to. Then, the output of the fourth amplifier 42 is set to the voltage V _CLD, and the voltage is divided by resistance using the resistor R5 to generate the voltages V1 to V4.

  In the present embodiment, the voltage characteristic C shown in FIG. 4 is further corrected according to the environmental temperature by controlling the first electronic volume switch SW2 according to the environmental temperature.

  For this purpose, the present embodiment includes a temperature detection unit 120 that detects the environmental temperature using two types of temperature gradient characteristics shown in FIG. As shown in FIG. 2, the temperature detection unit 120 divides the oscillation output of the oscillation circuit 60, and counts the clock from the frequency division circuit 122 and is reset every predetermined count value. 124, the first temperature detection switch SW3 connected to the feedback resistor R1A connected to the first amplifier 34A in the first power supply circuit 30A, and the second amplifier 34B in the second power supply circuit 30B. A temperature detection switch SW4 connected to the feedback resistor R2A connected to the comparator 126, a comparator 126 for comparing voltages input through the first and second temperature detection switches SW3 and SW4, and a comparator 126 And a temperature setting register 128 for outputting data corresponding to the actual temperature based on the output of the counter 124 when changed.

  Here, one of the temperature detection switches SW3 and SW4 sequentially switches the connection point from one end of the feedback resistors R2A and R3A to the other end each time the output from the counter 122 changes. For example, when the switch SW3 is fixed at the position shown in FIG. 2 and the switch SW4 is switched, the voltage input to the comparator 124 via the temperature detection switch SW4 is swept in the direction indicated by the arrow a in FIG. That is, in detecting the arbitrary temperature t1 in FIG. 4, the voltage input to the comparator 124 via the temperature detection switch SW4 is swept from the voltage V1 on the voltage characteristic B. The swept voltage falls below the voltage V2 (voltage input to the comparator 124 via the temperature detection switch SW3) on the voltage characteristic A at a certain point in time, and the output of the comparator 126 is “L” rather than “H”. To change. At this time, when the voltage change amount is ΔV, the change amount ΔV is a value inherent to the temperature t1. Therefore, the temperature setting register 128 can output the actual temperature t1 based on the count value of the counter 122 when the output changes in the comparator 126 (this corresponds to the voltage change amount ΔV). .

  To detect the actual temperature t2, as shown in FIG. 4, by fixing the switch SW4 and switching the switch SW3, the voltage input to the comparator 124 via the temperature detection switch SW3 is changed to that shown in FIG. What is necessary is just to sweep toward the arrow direction b. Thus, the voltage swept from V3 falls below the voltage V4 at a certain time, and the output of the comparator 126 changes from “L” to “H”, for example. As a result, the actual temperature t2 can be detected in the same manner as described above. The output line of the counter 124 shown in FIG. 2 is also connected to the temperature detection switch SW3, but is omitted in FIG.

  The input line to the negative terminal of the comparator 126 is fixedly connected to the middle point of the resistor R1 without going through the switch SW3, and the connection point of the switch SW4 is connected from the ground side of the resistor R2 to the output line side of the amplifier 34B. It is also possible to detect the actual temperature t1 or t2.

  In this way, the temperature detection unit 120 can detect the actual temperature using the temperature gradient characteristic of the power supply circuit 30 itself. As described above, the power supply circuit 30 is provided with the constant voltage sources 30A and 30B having two kinds of temperature gradients, and the liquid crystal applied voltage is corrected based on the actual temperature detected using the two kinds of temperature gradients. Therefore, more accurate correction is possible.

  Next, a configuration for controlling the first electronic volume switch SW2 based on the detected actual temperature will be described. For this purpose, as shown in FIG. 2, the first electronic volume switch control unit 130 has a first correction table 132 formed by, for example, a ROM, PROM or the like in which correction values are set as desired by the liquid crystal panel manufacturer. Similarly, the first register 134 storing the control reference value of the first electronic volume switch SW2 set at the request of the liquid crystal panel manufacturer, and the first addition for adding and outputting the digital values of the two registers Instrument 136.

FIG. 5 shows the temperature dependence characteristics of the liquid crystal applied voltage V _CLD obtained based on the output from the first electronic volume switch SW2 controlled by the first electronic volume switch control unit 130. FIG. 5 shows a temperature dependence characteristic in which the liquid crystal voltage V _CLD has different temperature gradients in the low temperature region Ta, the intermediate temperature region Tb, and the high temperature region Tc. For this purpose, the intermediate temperature region Tb is determined by the temperature gradient selection switch SW1 based on the output from the temperature gradient selection register 38 and the first electronic volume switch SW2 based on the output from the first register 134 in principle. . The low temperature region Ta and the high temperature region Tc are further set by the first electronic volume switch SW2 controlled by the output from the first correction table 132. In the low temperature region Ta, the resistance value of the resistor R4B selected by the first electronic volume switch SW2 is set to be smaller as the temperature is lower (the contact of the switch SW2 is closer to the output side of the third amplifier 110). On the other hand, in the high temperature region Tc, the resistance value of the resistor R4B is set larger as the temperature becomes higher (the contact of the switch SW2 is closer to the ground GND side).

As a result, liquid crystal application voltages V _LCD and V1 to V4 having temperature dependence specific to the liquid crystal panel 10 can be generated from the output voltages of the power supply circuit 30 having two types of temperature gradient characteristics.

  The temperature dependence characteristic shown in FIG. 5 is linear interpolation having a different slope in the three-divided region, but various other modifications can be implemented for the number of divisions and the interpolation format, for example, curve interpolation may be used.

(Frame frequency correction circuit)
The CR oscillation circuit 60 having the capacitor C and the resistor R6 has a variable oscillation frequency (frame frequency) by changing the resistance value of the resistor R6 connected to the oscillation circuit 60 by the second electronic volume switch SW5. . Note that a variable capacitance type can also be used as the oscillation circuit 60.

  As shown in FIG. 2, a second electronic volume switch control unit 140 that controls the second electronic volume switch SW <b> 5 based on the actual temperature detected by the temperature detection unit 120 is provided. The second electronic volume switch SW5 includes a second correction table 142 formed by, for example, a ROM in which a correction value is set according to the desire of the liquid crystal panel manufacturer, and a second electronic volume set according to the request of the liquid crystal panel manufacturer. It has a second register 144 in which the control reference value of the volume switch SW5 is stored, and a second adder 146 that adds and outputs the digital values of both.

  Thus, the reason why the oscillation frequency is varied depending on the temperature is as follows. As shown in FIG. 6, the natural oscillation frequency of the oscillation circuit 60 has a temperature dependency characteristic that decreases as the temperature increases. This is because the resistance value of the resistor (diffusion resistor) R6 in the oscillation circuit 60 increases as the temperature increases as shown in FIG. 6, and the natural oscillation frequency is in an inversely proportional relationship with the resistance value. On the other hand, the liquid crystal molecules move faster as the temperature rises, and the liquid crystal molecules respond until the next writing is performed, thereby degrading the image quality. For this reason, it is preferable that the frame frequency is high in the high temperature region, but the natural oscillation frequency from the oscillation circuit 60 is low on the contrary.

  Therefore, in this embodiment, the natural oscillation frequency shown in FIG. 6 is improved, and a higher frame frequency is obtained as the temperature becomes higher as shown in FIG. For this purpose, the second electronic volume switch SW5 is controlled so that the resistance value of the resistor R6 connected to the oscillation circuit 60 is high in the low temperature region and low in the high temperature region.

  By such a control, the frame frequency can be set to a high frame frequency according to the liquid crystal having a fast reaction speed as the temperature becomes high, and the frame frequency can be set to be low because the reaction speed of the liquid crystal becomes slow as the temperature becomes low.

(About gradation pulse width correction circuit)
The gradation pulse width correction circuit 150 shown in FIG. 2 includes a third correction table 152 formed by a ROM, for example, in which a gradation pulse width correction value is set as desired by the liquid crystal panel manufacturer, and a request from the liquid crystal panel manufacturer. A third register 154 that stores gradation pulse width information for setting the halftone contrast in accordance with the liquid crystal panel 10, and a third addition for adding and outputting the digital values of both of them. Instrument 156.

FIG. 8 has a configuration for generating a gradation pulse corresponding to a certain gradation value. In FIG. 8, a correction table 152A, a register 154A, an adder 156A, and a counter 80A are a part of the third correction table 152, the third register 154, the third adder 156, and the gradation pulse generator 80, respectively. It is a configuration. When 2 ² = 4 gradations, four sets other than the PWM clock generation circuit 70 shown in FIG. 8 are provided. The operation of the circuit of FIG. 8 is shown in the timing chart of FIG.

  In FIG. 8, an adder 156A adds the 5-bit digital values from the correction table 152A and the register 154A. In the counter 80A, data is loaded from the adder 156A, and the carry CA is changed from “L” to “H” by counting up the clock CL by the data value.

  Here, as shown in FIG. 9, the PWM clock generation circuit 70 divides the frame frequency from the oscillation circuit 60 by 32 to generate 32 clocks CL within 1H, and this clock CL is supplied to the counter 80A. Entered. The PWM clock generation circuit 70 further generates a signal XL for resetting the counter 80A every horizontal scanning period 1H.

Therefore, until the counter 80A counts up the value loaded from the adder 156A, the output of the inverter 82 connected to the carry terminal CA of the counter 80A becomes “H” as shown in FIG. L "and this is used as a gradation pulse with a pulse width W. In this way, the gradation value is generated in consideration of the correction value in the third correction table 152. In the case of the present embodiment, this gradation pulse can be selected from 2 ⁵ = 32 stages by using 5-bit data.

  Next, the correction content of the gradation pulse width will be described. FIG. 10 shows the difference in applied voltage-transmittance characteristics of liquid crystal at normal temperature and low temperature. In FIG. 10, a characteristic V-T1 is a characteristic at normal temperature, and a characteristic V-T2 is a characteristic at low temperature.

  Here, voltages Va to Vd shown on the horizontal axis in FIG. 10 are applied voltages to the liquid crystal that can obtain transmittances Ta to Td at room temperature, respectively. However, at low temperatures, for example, even if the voltage Vb is applied to the liquid crystal, the transmittance is lower than the transmittance Tb at room temperature. Further, when the voltage Vc is applied to the liquid crystal at a low temperature, the transmittance is higher than the transmittance Tc at the normal temperature. Therefore, in order to obtain the transmittance Tb at a low temperature, a voltage Va lower than that is applied to the liquid crystal instead of the voltage Vb. To obtain the transmittance Tc at a low temperature, a higher voltage Vd is used instead of the voltage Vc. It can be seen from FIG.

  From the above, in the case of PWM (pulse width modulation) driving, in order to obtain the transmittance Tb at room temperature, a gradation pulse with a pulse width W1 may be used as shown in FIG. In order to obtain the same transmittance Tb, it is necessary to use a gradation pulse having a pulse width W2 (W2 <W1) shown in FIG. Similarly, in order to obtain the transmittance Tc at the normal temperature, a gradation pulse with a pulse width W3 may be used as shown in FIG. 11C. On the other hand, to obtain the same transmittance Tc at the low temperature, FIG. It is necessary to use a gradation pulse having a pulse width W4 (W4> W3) shown in FIG.

  Thus, in order to compensate for the applied voltage-transmittance characteristics of different liquid crystals depending on the temperature, the gradation correction value corresponding to the temperature is stored in the third table 152 and detected by the temperature detection unit 120. The temperature compensation described above can be realized by reading out the corresponding actual temperature. In order to correct the pulse width W2 to be narrower than the wide pulse width W1, a negative digital value may be stored in the third correction table 152 and subtracted by the third adder 156.

(Structure for temperature detection)
Each of the three types of temperature compensation described above compensates for temperature dependence on the liquid crystal, and the most accurate temperature compensation measure is to detect the temperature of the liquid crystal itself.

  Here, the temperature detection unit 120 of the present embodiment performs temperature detection using two types of temperature gradients of the power supply circuit 30 mounted in the X driver IC 22 shown in FIG. Accordingly, there is a physical distance between the X driver IC 22 in which the temperature detection unit 120 is built and the liquid crystal panel 10 in which the liquid crystal exists.

  Therefore, it is preferable to adopt the structure shown in FIGS. FIG. 12 is a plan view of a liquid crystal unit 200 in which a driver IC 220 is mounted on one first glass substrate 210 constituting the liquid crystal panel 10 by COG (chip on glass). The liquid crystal unit 200 is configured, for example, by sealing liquid crystal between a first glass substrate 210 on which the first electrode 12 is formed and a second glass substrate 212 on which the second electrode 14 is formed. . The driver IC 220 shown in FIG. 12 has the functions of the two X driver ICs 22 and 24 and the Y driver IC 26 shown in FIG. Accordingly, the driver IC 220 includes the power supply circuit 30 and the temperature detection unit 120 shown in FIG. 2 and temperature compensation circuits such as the blocks 130, 140, and 150 shown in FIG.

  FIG. 13 is an enlarged view of a part of the first glass substrate 210 where the driver IC 220 is disposed. In the region where the driver IC 220 is disposed (square region indicated by a broken line), the first and second electrodes 12 and 14 (usually transparent electrodes) formed on the first and second glass substrates 210 and 212 are provided. Is extended. Note that the second electrode 14 formed on the second glass substrate 212 is electrically connected to the second electrode 14 formed on the first glass substrate 210 through a conductive portion.

  Here, the first and second electrodes 12 and 14 and the driver IC 220 are connected via bumps 230 shown in FIG. At this time, conventionally, as shown in FIG. 14, the first and second electrodes 12 and 14 are usually formed to extend to a position where the bump 230 is located.

  In the present embodiment, as shown in FIG. 13, the first and second electrodes 12 and 14 extend beyond the position of the bump 230 and extend deeply into the mounting area of the driver IC 220. It has portions 12A and 14A. More preferably, at least one of the redundant portions 12A and 14A of the first and second electrodes 12 and 14 extends to a position facing the position of the power supply circuit 30 mounted on the driver IC 220.

  Thus, the temperature of the liquid crystal sealed in the first and second glass substrates 210 and 212 is transmitted to the driver IC 220 through the first and second electrodes 12 and 14 and the redundant portions 12A and 14A. The For this reason, the temperature detector 120 built in the driver IC 220 can detect a temperature substantially equal to the liquid crystal temperature. Therefore, if this structure is adopted, the above-described three types of temperature compensation can be performed with higher accuracy.

  In forming the redundant portion of the electrode shown in FIG. 13, if the driver IC is divided into X and Y driver ICs as shown in FIG. 1, the redundant portion should be formed only for the driver IC having the temperature sensor. Good. Therefore, in the example of FIG. 1, it is sufficient to form the redundant portion 14A of the second electrode 14 on the back surface of the X driver IC 22 in which the temperature detection unit 120 is built.

  Further, the structure shown in FIG. 13 can be applied to other than the simple matrix liquid crystal device. For example, in the case of an active matrix liquid crystal device using TFT, MIM, etc. as an active element, a signal electrode (formed on the active matrix substrate side) connected to the pixel electrode facing the liquid crystal via the TFT or MIM, The above-described redundant portion may be formed on at least one of the common electrodes (formed on the counter substrate side) facing the pixel electrode.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention. For example, an electronic device to which the present invention is applied may be any electronic device in which a display unit using an electro-optical element such as a liquid crystal element is mounted in addition to the above-described form phone, such as a personal computer, a mobile device, and a viewfinder. An attached camera, a pager, a POS terminal, an electronic notebook, a navigation device, and the like can be given.

It is a schematic explanatory drawing of the liquid crystal device with which this invention is applied. FIG. 2 is a block diagram of the X driver IC shown in FIG. 1. It is a wave form diagram which shows the signal potential supplied to one segment electrode from the liquid crystal drive circuit shown in FIG. FIG. 3 is a characteristic diagram showing a temperature gradient of an output voltage of the power supply circuit shown in FIG. 2. FIG. 3 is a characteristic diagram showing temperature dependence characteristics of a liquid crystal applied voltage V _LCD obtained by adjusting a first electronic volume switch shown in FIG. 2. It is a characteristic view which shows the temperature dependence characteristic of an oscillation frequency. It is a characteristic view which shows the temperature dependence characteristic of the frame frequency obtained by adjustment of a 2nd electronic volume switch. FIG. 2 is a block diagram showing specific examples of the gradation pulse width correction circuit, the PWM clock generation circuit, and the gradation pulse generation circuit 80. 9 is an operation timing chart of the circuit shown in FIG. It is a characteristic view which shows the applied voltage-transmittance characteristic of the liquid crystal in normal temperature and low temperature. (A)-(D) is a wave form diagram which shows the gradation pulse of a different pulse width used in order to obtain the same transmittance | permeability at the time of normal temperature and low temperature. It is a top view of the liquid crystal unit which has the driver IC mounted on the glass substrate by COG. It is a part of glass substrate shown in FIG. 12, and is an enlarged plan view which expands and shows the area | region where driver IC is mounted. FIG. 14 is an enlarged plan view of a conventional example showing a region corresponding to FIG. 13.

Explanation of symbols

10 liquid crystal panel, 12 first electrode, 14 second electrode, 20 MPU,
22 X driver IC (master), 24 X driver IC (slave),
26 Y driver IC, 30 power supply circuit, 30A first power supply circuit,
30B second power supply circuit, 32A first power supply voltage output unit,
32B second power supply voltage output unit, 34A first amplifier, 34B second amplifier,
36 temperature gradient selection circuit, 38 temperature gradient selection register, 40 voltage generation circuit,
42 4th amplifier, 50 memory | storage part (RAM), 60 oscillation circuit,
70 PWM clock generation circuit, 80 gradation pulse generation circuit,
90 PWM decoder, 100 liquid crystal drive circuit, 110 third amplifier 120 temperature detector, 122 frequency divider, 124 counter, 126 comparator,
128 temperature setting register, 130 first electronic volume switch control unit 132 first correction table, 134 first register, 136 first adder,
140 a second electronic volume switch control unit;
142 second correction table, 144 second register, 146 second adder,
150 gradation control pulse width correction circuit, 152 third correction table,
154 third register, 156 third adder, 200 liquid crystal unit,
210 first glass substrate, 212 second glass substrate, 220 driver IC,
230 bumps, R1-R6 resistors, R1A, R2A, R4A feedback resistors,
The resistance selected by the R4B first electronic volume switch;
SW1 temperature gradient selection switch, SW2 first electronic volume switch,
SW3 temperature detection switch, SW4 temperature detection switch,
SW5 Second electronic volume switch

Claims (5)

In a driver IC that drives an electro-optic element,
An oscillator,
A grayscale clock generator for generating a grayscale clock based on the oscillation frequency from the oscillator;
A gradation pulse generating section for generating a plurality of gradation pulses having different pulse widths according to gradation values based on the gradation clock from the gradation clock generating section;
A temperature detector for detecting the environmental temperature;
A correction table for storing a gradation pulse width correction value corresponding to the temperature detected by the temperature detection unit;
A power circuit;
Have
The power supply circuit is
A first power supply circuit having a first temperature-voltage characteristic;
A second power supply circuit having a second temperature-voltage characteristic;
A temperature gradient selection circuit that outputs a voltage according to a voltage characteristic having a desired temperature gradient based on output voltages from the first and second power supply circuits;
Have
The temperature detector detects an actual temperature based on the first and second temperature-voltage characteristics,
The gradation pulse generation unit varies the pulse width of the plurality of gradation pulses based on the gradation pulse width correction value in the correction table corresponding to the actual temperature detected by the temperature detection unit. A driver IC characterized by that. In claim 1,
The first power supply circuit includes a first constant voltage source and a first amplifier that amplifies and outputs the output voltage of the first constant voltage source based on the resistance value of the first feedback resistor. And
The second power supply circuit includes a second constant voltage source and a second amplifier that amplifies and outputs the output voltage of the second constant voltage source based on the resistance value of the second feedback resistor. And
The driver IC, wherein the first and second temperature-voltage characteristics depend on characteristics of elements constituting the first and second constant voltage sources. In claim 2,
The temperature detector is
A first temperature detection switch connected to the first feedback resistor;
A second temperature detection switch connected to the second feedback resistor;
A comparator that compares the voltages input via the first and second temperature detection switches while moving one contact of the first and second temperature detection switches;
And a driver IC that detects an actual temperature based on an output of the comparator. A driver IC according to any one of claims 1 to 3;
A panel having an electro-optic element driven by the driver IC;
An electro-optical device comprising:   An electronic apparatus comprising the electro-optical device according to claim 4.

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