JP2005031508A - Flat display device and method for manufacturing flat display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an area on a substrate relating to setting of gamma, etc., smaller so that the gamma value, etc., can be set in a simple manner by applying a flat display device and a method for manufacturing the flat display device to a liquid crystal display apparatus integrally formed with a driving circuit on, for example, an insulating substrate. <P>SOLUTION: At the time of forming a plurality of reference voltages V0 to V63 to be subjected to digital-to-analog conversion processing by resistance voltage division, the resistance values of voltage dividing resistors R0 and R63 relating to the resistance voltage division are changed over. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flat display device and a flat display device manufacturing method, and can be applied to, for example, a liquid crystal display device in which a drive circuit is integrally formed on an insulating substrate. In the present invention, when a plurality of reference voltages to be subjected to digital-analog conversion processing are generated by resistance voltage division, the resistance value of the voltage dividing resistor related to the resistance voltage division is switched to thereby change the gamma and the like on the substrate. The area can be reduced, and a gamma value or the like can be easily set.

  In recent years, in a liquid crystal display device which is a flat display device applied to a portable terminal device such as a PDA or a mobile phone, a driving circuit for the liquid crystal display panel is integrated on a glass substrate which is an insulating substrate constituting the liquid crystal display panel. What is configured is to be provided.

  In such a liquid crystal display device, each pixel is formed by a liquid crystal cell, a polysilicon TFT (Thin Film Transistor) which is a switching element of the liquid crystal cell, and a storage capacitor, and the pixels are arranged in a matrix to display a display unit. Is formed. In this type of liquid crystal display device, each pixel forming this display portion is connected to a horizontal drive circuit and a vertical drive circuit by a signal line (column line) and a gate line (row line), respectively. Is selected and the gradation of each pixel is set by a drive signal from a horizontal drive circuit.

  For this reason, in the horizontal driving circuit, gradation data of each pixel that is sequentially input is sampled cyclically and digital-to-analog conversion processing is performed in units of rows. In a conventional liquid crystal display device, a predetermined reference voltage is used. The digital-to-analog conversion processing is executed by dividing the voltage by a series circuit using a voltage dividing resistor to generate a plurality of reference voltages and selecting the plurality of reference voltages according to the gradation data. Yes.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 10-333648, such a liquid crystal display device is configured to perform gamma correction by setting a plurality of reference voltages generated in this way.

  In a conventional liquid crystal display device, a plurality of voltage dividing circuits are provided on a substrate for such gamma correction by resistance voltage division, and various voltage gammas are selected by using an aluminum mask. A liquid crystal display device based on values was constructed and used for sample products and the like.

By the way, when preparing a plurality of voltage dividing circuits for generating a reference voltage for digital-analog conversion in this way and selecting the voltage dividing circuit to set a gamma value, the plurality of voltage dividing circuits are provided. Occupies a large area on the substrate, which increases the size of the substrate. Further, when actually switching the gamma value, there is a problem that a corresponding mask is required.
JP-A-10-333648

  The present invention has been made in consideration of the above points, and it is possible to reduce the area on the substrate related to the setting of gamma and the like, and the manufacture of a flat display device and a flat display device that can easily set the gamma value and the like We are going to propose a method.

  In order to solve this problem, in the first aspect of the present invention, the horizontal drive circuit is applied to a flat display device, and the horizontal drive circuit generates a plurality of reference voltages by dividing the generated reference voltage by a series circuit of voltage dividing resistors. A voltage generation circuit, and a reference voltage selector that generates a drive signal by selecting one reference voltage from a plurality of reference voltages according to gradation data indicating the gradation of the pixel, and includes at least a plurality of voltage dividing resistors One voltage dividing resistor is set so that the resistance value can be switched.

  According to a sixth aspect of the present invention, in the method for manufacturing a flat display device, the horizontal drive circuit includes a reference voltage generation circuit that generates a plurality of reference voltages by dividing a generated reference voltage by a series circuit of voltage dividing resistors. And a reference voltage selector that generates a drive signal by selecting one reference voltage from a plurality of reference voltages according to gradation data indicating the gradation of the pixel. By switching the resistance value of at least one voltage dividing resistor of the resistor, the potentials of the plurality of reference voltages are adjusted.

  According to the configuration of the first aspect of the present invention, the horizontal driving circuit is applied to the flat display device, and the horizontal drive circuit resistance-divides the generated reference voltage by a series circuit of voltage dividing resistors to generate a plurality of reference voltages, and the pixel A reference voltage selector that generates a drive signal by selecting one reference voltage from a plurality of reference voltages according to gradation data indicating a gradation, and at least one voltage dividing resistor of the plurality of voltage dividing resistors is: If the resistance value is set so that it can be switched, it is possible to change the reference voltage by switching the resistance value and change the gamma as necessary without providing multiple voltage dividers on the board. Thus, the area on the substrate related to the setting of gamma or the like can be reduced, and the gamma value or the like can be set easily.

  Thus, according to the configuration of the sixth aspect, it is possible to provide a method of manufacturing a flat display device that can reduce the area on the substrate related to the setting of gamma and the like and can easily set the gamma value and the like.

  According to the present invention, when generating a plurality of reference voltages to be subjected to digital-analog conversion processing by resistance voltage division, by switching the resistance value of the voltage dividing resistor related to the resistance voltage division, the substrate relating to the setting of gamma or the like The upper area can be reduced, and a gamma value or the like can be easily set.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

(1) Configuration of Embodiment FIG. 2 is a block diagram showing a liquid crystal display device according to an embodiment of the present invention. In the liquid crystal display device 1, each pixel is formed by a liquid crystal cell 2, a polysilicon TFT 3 that is a switching element of the liquid crystal cell 2, and a storage capacitor (not shown), and each pixel is arranged in a matrix and has a rectangular shape. A display unit 4 is formed. In the liquid crystal display device 1, the red, green, and blue pixels R, G, and B are sequentially and cyclically repeated in the horizontal direction by arranging the color filter on each pixel formed in the display unit 4 in this manner. The pixels in the horizontal direction are formed by 240 sets of these red, green, and blue pixels R, G, and B, and the display unit 4 is formed. In the liquid crystal display device 1, 6-bit gradation data R 0 to R 5, G 0 to G 5, and B 0 to B 5 that indicate the gradations of the red, green, and blue pixels R, G, and B are rasterized simultaneously and in parallel. Input is made in accordance with the scanning order, and each pixel is driven by the gradation data D1 (R0 to R5, G0 to G5, B0 to B5) to display a desired image.

  In the liquid crystal display device 1, the signal line SL and the gate line SG of the display unit 4 are connected to the horizontal drive circuit 5 and the vertical drive circuit 6, respectively. The vertical drive circuit 6 outputs a drive signal for the pixel corresponding to SL, and the vertical drive circuit 6 controls the gate line SG in response to the output of the drive signal to the signal line SL by the horizontal drive circuit 5. Select a pixel. Thereby, in the liquid crystal display device 1, each pixel of the display unit 4 is driven by the horizontal drive circuit 5 and the vertical drive circuit 6 to display a desired image.

  Specifically, the horizontal driving circuit 5 sequentially and cyclically corresponds to the bits R0 to R6 and G0 corresponding to the gradation data D1 by a sampling latch circuit (SL) 8 provided corresponding to the arrangement of the pixels in the horizontal direction. By sampling .about.G6 and B0 to B6, the gradation data D1 is collected in units of one line and output to the corresponding reference voltage selector 9. The reference voltage selector 9 selects the reference voltages V0 to V63 output from the reference voltage generation circuit 10 according to the output data of the sampling latch circuit 8, respectively, thereby driving the corresponding gradation data by digital-analog conversion processing. Output a signal. The buffer circuit 11 outputs this drive signal to the corresponding signal line SL. Accordingly, the horizontal drive circuit 5 selects a plurality of reference voltages V0 to V63 according to the gradation data, thereby generating a drive signal for driving each pixel and driving the display unit 4. .

  The reference voltage generation circuit 10 generates and outputs a plurality of reference voltages V0 to V63 which are selection targets of the reference voltage selector 9. FIG. 1 is a block diagram showing a detailed configuration of the reference voltage generation circuit 10. The reference voltage generation circuit 10 generates a plurality of reference voltages V0 to V63 by resistance-dividing the generated reference voltage by the series circuit 12 of the voltage dividing resistors R0 to R63.

  In this embodiment, the liquid crystal display device 1 is configured to drive the display unit 4 by so-called line inversion. For this reason, in the reference voltage generation circuit 10, the generated reference voltage is generated every one horizontal scanning period by the switch circuits 13 and 14. The polarity of is switched. That is, in the switch circuit 13, one ends of the switch circuits 13A and 13B that are complementarily switched on and off by the switching signal SEL are connected to the reference voltage line and the ground line of the voltage 3 [V], respectively, and the switch circuits 13A and 13B The other end is connected to one end of the series circuit 12. In addition, one end of each of the switch circuits 14A and 14B that are switched on and off in a complementary manner by the switching signal SEL is connected to the reference voltage line and the ground line of the voltage 3 [V], respectively, and the switch circuits 14A and 14B The other end is connected to the other end of the series circuit 12. The switch circuits 13 and 14 select the reference voltage line and the ground line complementarily by the switch circuits 13A and 13B and the switch circuits 14A and 14B.

  Thereby, in the reference voltage generating circuit 10, the polarity of the generated reference voltage applied to the series circuit 12 is switched every horizontal scanning period, and the generated reference voltage having this switched polarity is divided into the voltage dividing resistors R0 to R0. A plurality of reference voltages V0 to V63 are generated by dividing the resistance by the series circuit 12 of R63.

  Therefore, the series circuit 12 including the voltage dividing resistors R0 to R63 is connected so as to output the reference voltages V0 and V63 from both ends of the series circuit 12, and the resistors R0 and R63 at both ends are respectively connected to the series circuits of the resistors R0A and R0B. The resistors R63A and R63B are formed by a series circuit, and both ends of the inner resistors R0B and R63A in the series circuit 12 are short-circuited by the wiring patterns A and B, respectively. In addition, the wiring patterns A and B are created so that they can be disconnected by trimming by laser beam irradiation, respectively, so that the voltage dividing resistors R0 and R63 related to the wiring patterns A and B are resistances as necessary. The value can be switched.

  When the value of the gradation data D1 is sequentially changed in such a state that both ends of the resistors R0A and R0B are short-circuited by the wiring patterns A and B as described above, the series circuit 12 responds as shown by a symbol L0 in FIG. The resistance values of the voltage dividing resistors R0 to R63 are set so that the transmittance in the pixel changes according to a predetermined characteristic, and the change in transmittance due to the predetermined characteristic is a change in luminance due to a predetermined gamma value. Is set.

  When the wiring pattern A or B is disconnected by laser trimming, the characteristics relating to the change in transmittance change as indicated by the symbols L1 and L2, respectively. The changed characteristic is a change in luminance due to a predetermined gamma value. Set to be. In this embodiment, the gamma values related to these codes L0, L1, and L2 are set to 2.2, 1.9, and 2.5, respectively. Thus, in this embodiment, reference voltages V0 to V0 by voltage dividing resistors R0 to R63 are set. The gamma value of an image displayed on the display unit 4 is set by setting V63, and the gamma value can be changed by laser trimming of the wiring pattern A or B. According to the example shown in FIG. 3, in the series circuit 12, when the black level side wiring pattern B is laser-trimmed and the resistor R63B is inserted on the black level side, the gamma value becomes small. When the white level wiring pattern A is laser-trimmed and a resistor R0A is inserted on the white level side, the gamma value is increased.

(2) Operation of Example In the above configuration, in the liquid crystal display device 1 (FIG. 2), gradation data D1 by continuous data indicating the gradation of each pixel to be displayed is input to the horizontal drive circuit 5, Here, the gradation data D1 is sequentially sampled by the sampling latch circuit 8 and grouped in units of lines, and the reference voltage V0 to V63 corresponding to each gradation data is selected by the subsequent reference voltage selector 9. In the liquid crystal display device 1, a drive signal for driving each pixel is generated by selecting the reference voltages V0 to V63, and this drive signal is supplied to the display unit 4 through the signal line SL, and the pixel selected by the vertical drive circuit 6 is selected. This drive signal is applied to the circuit. Thereby, in the liquid crystal display device 1, each pixel of the display unit 4 is driven by the corresponding gradation data D1 to display a desired image.

  In the horizontal drive circuit 5 that drives the display unit 4 in this way, a plurality of reference voltages V0 to V63 to be selected based on such gradation data D1 are generated by the reference voltage generation circuit 10, and this reference voltage generation is performed. In the circuit 10 (FIG. 1), a reference voltage generated by line inversion input via the switch circuits 13 and 14 is divided by a series circuit 12 of voltage dividing resistors R0 to R63 to generate a plurality of reference voltages V0 to V63. Is done.

  In the liquid crystal display device 1, the gamma in the display unit 4 is set by setting the reference voltages V0 to V63, so that the configuration related to gamma correction can be simplified.

  In the liquid crystal display device 1, in the series circuit 12 used to generate the reference voltages V0 to V63, the voltage dividing resistors R0 and R63 at both ends are respectively formed by a series circuit of resistors R0A and R0B and a series circuit of resistors R63A and R63B. Further, the internal resistors R0B and R63A in this series circuit are created by being short-circuited by the wiring patterns A and B. Thereby, in the liquid crystal display device 1, the wiring pattern A or B is disconnected by laser trimming, so that the resistance values of the voltage dividing resistors R0 and R63 constituting the series circuit 12 can be switched to set various gamma values. Has been made.

  That is, in this liquid crystal display device 1, when the gamma value is set to 2.2, the reference voltage V0 to V63 is generated by the series circuit 12 without trimming the wiring patterns A and B, and the gamma value is set to 2. 2 can be set. On the other hand, when the gamma value is set to 2.5, the gamma value can be set to 2.5 only by laser trimming the wiring pattern A on the white level side, whereas the gamma value is set to 1.9. In the case of setting, the gamma value can be set to 1.9 by laser trimming the wiring pattern B on the black level side.

  Thereby, in this liquid crystal display device 1, the gamma value can be set easily. Further, by simply providing extra resistors R0A and R63B short-circuited by the wiring patterns A and B to a part of the voltage dividing resistors R0 and R63 of one voltage dividing circuit as described above, various gamma values can be obtained. By being able to set, the area occupied on the substrate of the part related to the setting of gamma is reduced as compared with the case where a plurality of voltage dividing circuits are created on the substrate and selectively used according to the gamma value. be able to. As a result, in this embodiment, the area on the substrate related to the setting of gamma is reduced, and the gamma value can be set easily.

  In practice, such a change in the gamma value is often performed at the stage of product development, and according to this embodiment, the gamma value can be set variously by simply laser trimming the wiring patterns A and B. As a result, the time required for development can be shortened, and waste of mask preparation can be prevented.

  In addition, when the resistance values of the voltage dividing resistors are switched in this way and the reference voltages V0 to V63 are switched, in the liquid crystal display device 1, the reference voltages V0 and V63 are also applied from both ends of the series circuit 12 related to the voltage dividing resistors R0 to R63. The resistance values are switched in the resistors R0 and R63 at both ends of the series circuit 12 so that the gamma value is switched by this, and the maximum and minimum values of the reference voltages V0 to V63 are changed. Can be held at a constant voltage, and the gamma-related transmittance characteristics can be set appropriately, which makes it possible to easily and reliably perform gamma adjustment by effectively avoiding changes in the black level and white level. Can do. Further, in the manufacturing process of the liquid crystal display device 1, for example, mass production of products with various gamma characteristics relating to a small amount of mass production can be performed only by exchanging the masks relating to the wiring patterns A and B relating to the switching of the resistance value. This also makes it possible to effectively avoid mask waste.

(3) Effects of the embodiment According to the above configuration, when generating a plurality of reference voltages to be subjected to digital-analog conversion processing by resistance voltage division, by switching the resistance value of the voltage dividing resistor related to this resistance voltage division, The area on the substrate related to the setting of gamma and the like can be reduced, and the gamma value and the like can be set easily.

  In addition, since the voltage dividing resistor set so that the resistance value can be switched is a voltage dividing resistor provided at both ends of the series circuit by the voltage dividing resistor, the variation of the white level and the black level can be effectively performed. By avoiding this, gamma adjustment can be performed easily and reliably.

  Further, since the switching of the resistance value of the voltage dividing resistor is switching by trimming, the gamma value and the like can be easily set by applying to a small-volume product such as a sample product.

  FIG. 4 is a connection diagram showing a reference voltage generating circuit applied to the liquid crystal display device according to the second embodiment of the present invention in comparison with FIG. The liquid crystal display device according to the second embodiment is configured the same as the liquid crystal display device 1 according to the first embodiment except that the configuration related to the reference voltage generation circuit 20 is different. In this reference voltage generation circuit 20, the same components as those of the reference voltage generation circuit 10 described above with reference to FIG.

  The reference voltage generating circuit 20 generates a plurality of reference voltages V0 to V63 by resistance-dividing the generated reference voltage by the series circuit 22. Therefore, the series circuit 22 is configured by connecting voltage dividing resistors R0 to R63 in series, and is connected so as to output the reference voltages V0 and V63 from both ends of the series circuit 22.

  The series circuit 22 includes a plurality of resistors RA to RN in which one of the voltage dividing resistors R0 to R63 is set to be short-circuited at both ends by setting the switch circuits 23A to 23N, respectively. Formed by a series circuit. As a result, the reference voltage generating circuit 20 can switch the resistance value of the voltage dividing resistor R63 by setting the switch circuits 23A to 23N. In the liquid crystal display device of this embodiment, the gamma value is thereby set. Can be set in various ways.

  Accordingly, in the liquid crystal display device, the switch circuits 23A to 23N can be set by the gamma setting data Dγ output from the host controller, thereby displaying an image with a gamma value desired by the designer of the liquid crystal display device. It is made like that.

  According to this embodiment, since the switching of the resistance value of the voltage dividing resistor is switching by the setting of the switch circuit, the gamma value can be set more easily and more easily.

(4) Other Embodiments In the above-described first embodiment, the case where the resistance value is switched by laser trimming has been described. However, the present invention is not limited to this, and there are various cases such as when the wiring pattern by a fuse is blown. The wiring pattern cutting method can be widely applied.

  In the second embodiment, the case where the gamma value is set by the controller is described. However, the present invention is not limited to this, and the optical characteristics of the light source such as the backlight and the front light are detected by the sensor. The switch circuit may be set by the controller according to the detection result. In this way, it is possible to always display an image with an optimal gamma value by correcting such variations in light sources, changes with time, and the like.

  In the above-described embodiments, the case where the present invention is applied to a TFT liquid crystal formed by forming a display portion on a glass substrate has been described. However, the present invention is not limited to this, and a CGS (Continuous Grain Silicon) liquid crystal or the like. It can be widely applied to various flat display devices such as various liquid crystal display devices and EL (Electro Luminescence) display devices.

  The present invention relates to a flat display device and a flat display device manufacturing method, and can be applied to, for example, a liquid crystal display device in which a drive circuit is integrally formed on an insulating substrate.

It is a connection diagram which shows the reference voltage generation circuit of the liquid crystal display device which concerns on embodiment of this invention. FIG. 2 is a block diagram illustrating a liquid crystal display device according to the reference voltage generation circuit of FIG. 1. It is a characteristic curve figure with which it uses for description of the reference voltage generation circuit of FIG. 6 is a connection diagram illustrating a reference voltage generation circuit according to Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 4 ... Display part, 5 ... Horizontal drive circuit, 9 ... Reference voltage selector, 10, 20 ... Reference voltage generation circuit

Claims (6)

A display unit in which pixels are arranged in a matrix, a vertical drive circuit for sequentially selecting pixels of the display unit by gate lines, and a drive signal for driving the pixels selected by the gate lines as signal lines of the display unit In a flat display device formed on a substrate integrally with a horizontal drive circuit that outputs to
The horizontal drive circuit includes:
A reference voltage generation circuit that generates a plurality of reference voltages by resistance-dividing the generated reference voltage by a series circuit of voltage dividing resistors;
A reference voltage selector that selects one reference voltage from the plurality of reference voltages according to gradation data indicating the gradation of the pixel and generates the drive signal;
The flat display device characterized in that at least one voltage dividing resistor of the plurality of voltage dividing resistors is set so that a resistance value can be switched. A gamma value is set by setting the potential of the plurality of reference voltages,
The flat display device according to claim 1, wherein the gamma value is changed by changing a potential of the plurality of reference voltages by switching the resistance value. The voltage dividing resistor set so that the resistance value can be switched is a voltage dividing resistor provided at one end or both ends of the series circuit of the voltage dividing resistors. A flat display device according to claim 1. The flat display device according to claim 1, wherein the switching of the resistance value of the voltage dividing resistor is switching by trimming. The flat display device according to claim 1, wherein switching of the resistance value of the voltage dividing resistor is switching by setting of a switch circuit. A display unit in which pixels are arranged in a matrix, a vertical drive circuit for sequentially selecting pixels of the display unit by gate lines, and a drive signal for driving the pixels selected by the gate lines as signal lines of the display unit In a manufacturing method of a flat display device formed on a substrate integrally with a horizontal drive circuit that outputs to
The horizontal drive circuit includes:
A reference voltage generation circuit that generates a plurality of reference voltages by resistance-dividing the generated reference voltage by a series circuit of voltage dividing resistors;
A reference voltage selector that selects one reference voltage from the plurality of reference voltages according to gradation data indicating the gradation of the pixel and generates the drive signal;
The method of manufacturing the flat display device is as follows:
A method of manufacturing a flat display device, wherein the resistance value of at least one voltage dividing resistor of the plurality of voltage dividing resistors is switched to adjust the potential of the plurality of reference voltages.

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