JP2001249645A - Alternating balance adjusting circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alternating balance adjusting circuit capable of adjusting flicker without using a variable resistance which is provided with variable elements and whose size is large. SOLUTION: At the time of constituting an alternating balance adjusting circuit which optimizes the alternating balances of liquid crystal driving voltages while adjusting a common electrode potential to be applied to common electrodes 201 of a TFT liquid crystal panel, in short, adjusts flicker, ITO (indium tin oxide) electrode parts 601 whose resistance values are adjustable by laser irradiation are arranged. As a result, the package space of components for adjusting flicker is reduced and cost of the components and cost of a package are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alternating balance adjustment circuit used for a monitor device, a television receiver, and the like.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device has been used for a monitor device, a television receiver, and the like.
Some have a TFT liquid crystal panel as schematically shown in FIG. In FIG. 7, reference numeral 101 denotes an array-side substrate;
Is a common electrode side substrate, 103 is a drive circuit board, 104 is an FPC (flexible printed circuit) for electrically connecting the array side substrate 101 and the drive circuit board 103, and 105 is an array side substrate 101 and the common electrode side substrate 1.
02 is a conductive paste provided between them to electrically connect them to each other, 106 is a common electrode potential wiring formed on the drive circuit substrate 103, and 107 is an array-side wiring formed on the array-side substrate 101 It is.

The vicinity of the conductive paste 105 has a structure as shown in an enlarged sectional view of FIG. The common electrode side substrate 102 is made of ITO (INDIUM, TIN, OXI
(CIDE).

As shown in FIG. 9, a common electrode potential generating circuit formed on a drive circuit board 103 includes a variable resistor (hereinafter referred to as a volume) 3 having a resistor 301 and a movable element.
02 and a resistor 303 are connected to a power supply terminal 30.
4, a common electrode potential 306 that is formed between the GND potential 305 and is applied to the common electrode 201.
2 is variable.

In such a TFT liquid crystal panel, the driving waveform and the common electrode potential 306 have the relationship shown in the waveform diagram of FIG. In FIG. 10, reference numeral 401 denotes a part of the driving waveform of the TFT liquid crystal panel, and reference numerals 402, 403, and 404 denote the upper limit, the median, and the lower limit of the common electrode potential 306, respectively. Reference numeral 407 denotes an amplitude between the power supply side potential in the drive waveform 401 and the common electrode potential 306 (402, 403, 404) (hereinafter referred to as positive drive voltage amplitude), and 408 denotes a GND side potential in the drive waveform 401 and the common electrode potential. Potential 306
(402, 403, 404) (hereinafter referred to as the negative drive voltage amplitude).

In other words, in this TFT liquid crystal panel, as can be understood from the waveform diagram, by adjusting the volume 302, the common electrode potential 306 is displaced between the upper limit value 402 and the lower limit value 404 to drive the positive side. The voltage amplitude 407 and the drive voltage amplitude 408 on the negative side are made to coincide with each other, so that the alternating current balance of the liquid crystal drive voltage can be optimized (flicker adjustment).

[0007]

However, since the volume 302 used for flicker adjustment in the above-described conventional configuration has a large component thickness and a relatively high component cost, a space for mounting the volume 302 is secured. However, it is not easy, and it has hindered the reduction of the apparatus cost.

In view of the foregoing, it is an object of the present invention to realize an alternating current balance adjusting circuit capable of adjusting flicker without using a volume.

[0009]

In order to solve the above problems, the present invention uses a laser trimmer resistor whose resistance can be adjusted by laser irradiation, instead of a volume conventionally used for flicker adjustment. As a result, mounting space and component costs are reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 is a TFT
This is an AC balance adjustment circuit that adjusts the common electrode potential applied to the common electrode of the liquid crystal panel to optimize the AC voltage balance of the liquid crystal drive voltage, and has a laser trimmer resistor whose resistance can be adjusted by laser irradiation. It is characterized by the following. According to this configuration, since the optimization of the alternating current balance of the liquid crystal drive voltage, that is, the flicker adjustment is performed by the laser trimmer resistor, the mounting space and the component cost can be reduced as compared with the conventional configuration using a volume.

According to a second aspect of the present invention, in the configuration of the first aspect, the laser trimmer resistor is a resistor whose resistance value changes by forming a laser hole. Since the resistor has a simple configuration and can be mounted in a small mounting space, it is easy to secure a mounting space for other components.

According to a third aspect of the present invention, in the configuration according to the first or second aspect, the laser trimmer resistor is provided on a drive circuit board on which a drive circuit for driving a TFT liquid crystal panel is formed. It is characterized by being arranged.

According to a fourth aspect of the present invention, in the configuration of the first or second aspect, the laser trimmer resistor is disposed on the TFT liquid crystal panel.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect, a laser trimmer resistor is disposed on the TFT array side substrate. According to a sixth aspect of the present invention, in the configuration of the fourth aspect, a laser trimmer resistor is arranged on the common electrode side substrate.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. (Embodiment 1) The alternating current balance adjusting circuit according to Embodiment 1 of the present invention is arranged in a liquid crystal display device as described above with reference to FIGS.

As shown in FIG. 1, an alternating-current balance adjusting circuit which constitutes a part of a common electrode potential generating circuit formed on a drive circuit board 103 is replaced with a conventional volume.
It has a laser trimmer resistor 501 whose resistance can be adjusted by laser irradiation, and forms a voltage dividing circuit of the resistors 301 and 303 and the laser trimmer resistor 501.

Therefore, as can be understood from FIG. 10, by adjusting the resistance value of the laser trimmer resistor 501 by laser irradiation, the common electrode potential 306 can be changed through the common electrode potential generation circuit, and the positive drive The flicker adjustment can be performed by making the voltage amplitude 407 coincide with the negative drive voltage amplitude 408.

Since the laser trimmer resistor 501 is smaller than the volume, the mounting space can be reduced as compared with the conventional liquid crystal display device in which the volume is mounted, and the parts cost and the mounting cost can be reduced. . (Embodiment 2) An AC balance adjustment circuit according to Embodiment 2 of the present invention is arranged in a liquid crystal display device as described above with reference to FIGS. ing.

Arranged as the laser trimmer resistor 501 in this alternating balance adjustment circuit is an ITO electrode portion 601 formed on a TFT liquid crystal panel as shown in FIGS. The ITO electrode unit 601 is
It is arranged on an array-side wiring 107a formed on the periphery of the array-side substrate 101 so as to be connected to a common electrode potential generating circuit on the drive circuit substrate 103, and is irradiated with a laser as shown in an enlarged sectional view of FIG. As a result, the ITO is removed and the hole 801 is formed, so that the area changes and the resistance value changes.

Therefore, in this liquid crystal display device, the resistance value is adjusted by irradiating the ITO electrode portion 601 with a laser, and the common electrode potential 306 can be changed through the common electrode potential generation circuit. The voltage amplitude 407 and the drive voltage amplitude 408 on the negative side can be matched to perform flicker adjustment.

Since the ITO electrode portion 601 is very small,
As shown, the array side substrate 101 and the common electrode side substrate 1
02, it is possible to reduce the mounting space as compared with a conventional liquid crystal display device in which a volume is mounted, and it is also possible to reduce component costs and mounting costs. (Embodiment 3) An AC balance adjustment circuit according to Embodiment 3 of the present invention is arranged in a liquid crystal display device as described above with reference to FIGS. ing.

In this alternating balance adjusting circuit, the laser trimmer resistor 501 is arranged on the periphery of the common electrode side substrate 102 as shown in FIGS. This is the formed ITO electrode portion 901. The ITO electrode portion 901 is connected to an array-side wiring 107a formed on the array-side substrate 101 so as to be connected to the common electrode potential generating circuit of the drive circuit substrate 103.
Are connected via a conductive paste 105. This I
The TO electrode portion 901 is also configured such that the ITO is removed by laser irradiation to form a hole (not shown).

Therefore, also in this liquid crystal display device, the flicker can be adjusted by adjusting the resistance value of the ITO electrode portion 901 by laser irradiation. Also, I
Since the TO electrode portion 901 is arranged on the common electrode side substrate 102, the mounting space on the array side substrate 101 is smaller than that in the second embodiment, and a COG (chip on glass) is provided on the array side substrate 101. It is possible to secure a space for mounting a semiconductor IC and an FPC (flexible printed circuit).

In the second and third embodiments, the ITO electrodes 601 and 901 are used as resistors. However, if the resistance value can be adjusted by forming a hole by laser irradiation and changing the area, other than ITO. The same effect can be obtained by forming the resistor from the above material, for example, aluminum.

[0025]

As described above, according to the present invention, a laser trimmer resistor whose resistance value can be adjusted by laser irradiation is arranged to perform flicker adjustment. The component mounting space for adjustment can be reduced, and the component cost and the mounting cost can also be reduced.

The laser trimmer resistor may be arranged on a drive circuit board, or may be arranged on a TFT liquid crystal panel. If it is arranged on the common electrode side substrate of the TFT liquid crystal panel, a large array wiring space can be secured, and CO
A mounting space for the IC for G and the FPC can be secured.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an alternating-current balance adjusting circuit according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view of a liquid crystal display device having an AC balance adjustment circuit according to Embodiment 2 of the present invention.

FIG. 3 is a cross-sectional view of the liquid crystal display device of FIG.

FIG. 4 is a plan view of the laser trimmer resistance portion.

FIG. 5 is a schematic plan view of a liquid crystal display device having an AC balance adjustment circuit according to Embodiment 3 of the present invention.

6 is a sectional view taken along the line BB showing a laser trimmer resistance portion of the liquid crystal display device of FIG.

FIG. 7 is a schematic plan view of a conventional liquid crystal display device.

8 is an XX cross-sectional view showing an end of a TFT liquid crystal panel of the liquid crystal display device of FIG. 7;

9 is a circuit diagram showing a common electrode potential generation circuit of the liquid crystal display device of FIG.

10 is a waveform chart showing a relationship between a driving waveform of a TFT liquid crystal panel of the liquid crystal display device of FIG. 7 and a common electrode potential.

[Explanation of symbols]

 101 Array side substrate 102 Common electrode side substrate 103 Drive circuit board 201 Common electrode 306 Common electrode potential 501 Laser trimmer resistance 601 ITO electrode part 801 Hole 901 ITO electrode part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/66 102 H04N 5/66 102B F-term (Reference) 2H092 GA50 HA04 JA24 MA47 NA27 NA29 NA30 PA06 2H093 NC34 ND10 ND54 ND60 5C006 AC26 AF52 BB16 BC20 BF49 FA23 FA41 FA51 5C058 AA06 AB06 BA09 5C080 AA10 BB05 DD06 FF11 JJ03 JJ04 JJ06

Claims (6)

[Claims] 1. An alternating-current balance adjusting circuit for adjusting a common electrode potential applied to a common electrode of a TFT liquid crystal panel to optimize an alternating current balance of a liquid crystal driving voltage, wherein a laser whose resistance value can be adjusted by laser irradiation. An alternating-current balance adjustment circuit comprising a trimmer resistor. 2. The alternating-current balance adjustment circuit according to claim 1, wherein the laser trimmer resistor is a resistor whose resistance value changes when a laser hole is formed. 3. The alternating-current balance according to claim 1, wherein the laser trimmer resistor is disposed on a drive circuit board on which a drive circuit for driving the TFT liquid crystal panel is formed. Adjustment circuit. 4. The alternating-current balance adjustment circuit according to claim 1, wherein the laser trimmer resistor is disposed on the TFT liquid crystal panel. 5. The circuit according to claim 4, wherein the laser trimmer resistor is arranged on the TFT array side substrate. 6. The alternating-current balance adjusting circuit according to claim 4, wherein the laser trimmer resistor is disposed on the common electrode side substrate.