A Gamma switching circuit for liquid crystal glass panels

Abstract

The present invention provides a liquid crystal glass panel gamma switching circuit, belonging to the field of liquid crystal display, including a liquid crystal glass panel TFT-LCD, a gamma module, and six source chip-on-film (S-COF)s, wherein the six S-COFs are electrically connected to the TFT-LCD; three adjacent S-COFs on one side are connected in series via a first routing line, and three adjacent S-COFs on the other side are connected in series via a second routing line; two middle S-COFs are connected in series via a third routing line, which passes through the TFT-LCD; and the gamma module is connected to one end of the third routing line. By connecting different S-COFs in series and connecting the two middle S-COFs in series via the third routing line, which passes through the TFT-LCD, the present invention reduces the number of connectors, realizes gamma routing on the panel, reduces the number of connector pins and the number of FFC pins, and reduces the manufacturing and production costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid crystal display, and in particular relates to a Gamma switching circuit for a liquid crystal glass panel. Background Art

[0002] In the TV display driver architecture, the Source Cof is the main component of the source line that drives the TFTL CD. The Source Cof power supply system usually has 14 sets of gamma voltages. The GAMMA trace is where the gamma IC outputs multiple sets of gamma voltages to the S-COF. Therefore, the gamma IC is now placed on the XL connector (the XL connector is connected to the left PCBA board). The trace is as follows: Figure 1 The gamma trace is output from the XL connector, passes through the FFC, and then enters the XR connector (the XR connector is connected to the right PCBA board) to supply power to the COF on the XR.

[0003] As market demand for panel sizes increases, XB lengths are also increasing. However, the current industry bonding machine limit is approximately 570mm. XBs exceeding this length cannot be bonded. Therefore, the common practice is to divide XBs into smaller sections and increase the number of XBs to address machine limitations. As the number of XBs increases, the number of XB connectors also increases, increasing connector costs. XB is a general term for XR and XL. It is an expansion board for CB, containing components and connected to the LCD glass panel via S-COF.

[0004] Furthermore, current gamma trace routing is primarily based on PCB routing, which is then fed into a COF and then onto a panel. This results in a high number of connector pins and FFC pins, increasing costs. Damage to the gamma trace on the PCB is irreparable and requires removing the COF and rebonding a new PCB, a time-consuming and costly process. Summary of the Invention

[0005] In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a Gamma switching circuit for a liquid crystal glass panel.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A liquid crystal glass panel Gamma switching circuit, comprising a liquid crystal glass panel TFT LCD, a GAMMA module and six source-chip-on-film (S-COF)s;

[0008] All six S-COFs are electrically connected to the TFT LCD;

[0009] Three adjacent S-COFs on one side are connected in series via a first wiring, and three adjacent S-COFs on the other side are connected in series via a second wiring.

[0010] The two middle S-COFs are connected in series via a third trace, which passes through the TFT LCD.

[0011] The GAMMA module is connected to one end of the third wiring. The GAMMA module divides the analog voltage VDDA into multiple groups of gamma voltages and provides them to six S-COFs. The six S-COFs transmit the processed signals to the TFT LCD.

[0012] Preferably, it also includes an XL connector and an XR connector, three adjacent S-COFs on one side are connected to the XL connector, and three adjacent S-COFs on the other side are connected to the XR connector, the XL connector and the XR connector are connected through a flat cable FFC, and the GAMMA module is arranged on the XL connector.

[0013] Preferably, two S-COFs connected to the XL connector and close to the XR connector are connected in series via a fourth trace, the fourth trace is connected in series with the third trace, and the fourth trace passes through the TFT LCD.

[0014] Preferably, the third wiring includes a repair line and two parallel main lines, two ends of the repair line are respectively connected to two ends of the two main lines, and two ends of the two main lines and two ends of the repair line are connected in series with resistors.

[0015] Preferably, the third wiring includes a repair line and two parallel main lines, one end of the repair line is connected to one end of the two main lines located on the XR connector side, and the repair line and the main lines located on the XR connector side are both connected in series with resistors;

[0016] The GAMMA module has two ports. The two main lines are located on the XL connector side and are connected to the two ports of the GAMMA module through a Coad control switch. The repair line is located on the XL connector side and is connected to the Coad control switch as a spare channel.

[0017] The liquid crystal glass panel gamma switching circuit provided by the present invention has the following beneficial effects:

[0018] The present invention connects different S-COFs in series, and simultaneously connects two intermediate S-COFs in series via a third line that passes through a TFT LCD. This reduces the number of connectors and implements gamma routing for the panel. As TV panels tend to be larger in size, the number of pins in the XB to XB connector and the number of FFC pins are reduced, thereby lowering manufacturing and production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more clearly illustrate the embodiments of the present invention and its design, the following briefly introduces the drawings required for this embodiment. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0020] Figure 1 The circuit structure of the existing crystal glass panel;

[0021] Figure 2 The liquid crystal glass panel Gamma switching circuit provided in Examples 1 and 2 of the present invention;

[0022] Figure 3 The liquid crystal glass panel Gamma switching circuit provided in Examples 3 and 4 of the present invention;

[0023] Figure 4 This is a schematic diagram of XL and XR impedance matching;

[0024] Figure 5 This is another schematic diagram of XL and XR impedance matching. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solution of the present invention and to be able to implement it, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention.

[0026] Example 1

[0027] The present invention provides a liquid crystal glass panel Gamma switching circuit, specifically Figure 2 and Figure 4 As shown, it includes a liquid crystal glass panel TFT LCD, a GAMMA module and six source-chip-on-films (S-COF).

[0028] Among them, all six S-COFs are electrically connected to the TFT LCD; three adjacent S-COFs on one side are connected in series via a first trace, and three adjacent S-COFs on the other side are connected in series via a second trace; the two middle S-COFs are connected in series via a third trace, which passes through the TFT LCD; a gamma module is connected to one end of the third trace, and the gamma module divides the analog voltage VDDA into multiple groups of gamma voltages and provides them to the six S-COFs, which then transmit the processed signals to the TFT LCD.

[0029] Specifically, this embodiment also includes an XL connector and an XR connector. Three adjacent S-COFs on one side are connected to the XL connector, and three adjacent S-COFs on the other side are connected to the XR connector. The XL connector and the XR connector are connected through a flat cable FFC, and the GAMMA module is set on the XL connector.

[0030] Furthermore, in this embodiment, the third routing line includes a repair line and two parallel main lines, both ends of the repair line are connected to both ends of the two main lines respectively, and both ends of the two main lines and both ends of the repair line are connected in series with resistors.

[0031] Example 2

[0032] The present invention provides a liquid crystal glass panel Gamma switching circuit, specifically Figure 2 and Figure 5 As shown, it includes a liquid crystal glass panel TFT LCD, a GAMMA module and six source-chip-on-films (S-COF).

[0033] Among them, all six S-COFs are electrically connected to the TFT LCD; three adjacent S-COFs on one side are connected in series via a first trace, and three adjacent S-COFs on the other side are connected in series via a second trace; the two middle S-COFs are connected in series via a third trace, which passes through the TFT LCD; a gamma module is connected to one end of the third trace, and the gamma module divides the analog voltage VDDA into multiple groups of gamma voltages and provides them to the six S-COFs, which then transmit the processed signals to the TFT LCD.

[0034] Specifically, this embodiment also includes an XL connector and an XR connector. Three adjacent S-COFs on one side are connected to the XL connector, and three adjacent S-COFs on the other side are connected to the XR connector. The XL connector and the XR connector are connected through a flat cable FFC, and the GAMMA module is set on the XL connector.

[0035] Furthermore, in this embodiment, the third routing includes a repair line and two parallel main lines, one end of the repair line is connected to one end of the two main lines on the XR connector side, and the repair line and the main lines on the XR connector side are both connected in series with resistors; the GAMMA module has two ports, the two main lines on the XL connector side are respectively connected to the two ports of the GAMMA module through the Coad control switch, and the repair line on the XL connector side is connected to the Coad control switch as a backup channel. In this embodiment, the Coad control switch is a dual-control switch.

[0036] Example 3

[0037] The present invention provides a liquid crystal glass panel Gamma switching circuit, specifically as follows Figure 3 and Figure 4 As shown, it includes a liquid crystal glass panel TFT LCD, a GAMMA module and six source-chip-on-films (S-COF).

[0038] Among them, all six S-COFs are electrically connected to the TFT LCD; three adjacent S-COFs on one side are connected in series via a first trace, and three adjacent S-COFs on the other side are connected in series via a second trace; the two middle S-COFs are connected in series via a third trace, which passes through the TFT LCD; a gamma module is connected to one end of the third trace, and the gamma module divides the analog voltage VDDA into multiple groups of gamma voltages and provides them to the six S-COFs, which then transmit the processed signals to the TFT LCD.

[0039] Specifically, this embodiment also includes an XL connector and an XR connector. Three adjacent S-COFs on one side are connected to the XL connector, and three adjacent S-COFs on the other side are connected to the XR connector. The XL connector and the XR connector are connected through a flat cable FFC, and the GAMMA module is set on the XL connector.

[0040] Furthermore, in this embodiment, the two S-COFs connected to the XL connector and near the XR connector are connected in series via a fourth trace. This fourth trace is connected in series with the third trace and passes through the TFT LCD. This fourth trace creates symmetry between the gamma traces on both sides. After the gamma traces are routed to the panel, the impedance of the gamma traces on the XR and XL are matched, ensuring consistent voltage line losses on the XL and XR screens and consistent XL / XR and source COF input voltages, thus preventing split-screen anomalies caused by inconsistent grayscales on the left and right displays.

[0041] Furthermore, in this embodiment, the third routing line includes a repair line and two parallel main lines, both ends of the repair line are connected to both ends of the two main lines respectively, and both ends of the two main lines and both ends of the repair line are connected in series with resistors.

[0042] Example 4

[0043] The present invention provides a liquid crystal glass panel Gamma switching circuit, specifically Figure 3 and Figure 5 As shown, it includes a liquid crystal glass panel TFT LCD, a GAMMA module and six source-chip-on-films (S-COF).

[0044] Among them, all six S-COFs are electrically connected to the TFT LCD; three adjacent S-COFs on one side are connected in series via a first trace, and three adjacent S-COFs on the other side are connected in series via a second trace; the two middle S-COFs are connected in series via a third trace, which passes through the TFT LCD; a gamma module is connected to one end of the third trace, and the gamma module divides the analog voltage VDDA into multiple groups of gamma voltages and provides them to the six S-COFs, which then transmit the processed signals to the TFT LCD.

[0045] Specifically, this embodiment also includes an XL connector and an XR connector. Three adjacent S-COFs on one side are connected to the XL connector, and three adjacent S-COFs on the other side are connected to the XR connector. The XL connector and the XR connector are connected through a flat cable FFC, and the GAMMA module is set on the XL connector.

[0046] Furthermore, in this embodiment, the two S-COFs connected to the XL connector and near the XR connector are connected in series via a fourth trace. This fourth trace is connected in series with the third trace and passes through the TFT LCD. This fourth trace creates symmetry between the gamma traces on both sides. After the gamma traces are routed to the panel, the impedance of the gamma traces on the XR and XL are matched, ensuring consistent voltage line losses on the XL and XR screens and consistent XL / XR and source COF input voltages, thus preventing split-screen anomalies caused by inconsistent grayscales on the left and right displays.

[0047] Furthermore, in this embodiment, the third routing includes a repair line and two parallel main lines, one end of the repair line is connected to one end of the two main lines on the XR connector side, and the repair line and the main lines on the XR connector side are both connected in series with resistors; the GAMMA module has two ports, the two main lines on the XL connector side are respectively connected to the two ports of the GAMMA module through the Coad control switch, and the repair line on the XL connector side is connected to the Coad control switch as a backup channel. In this embodiment, the Coad control switch is a dual-control switch.

[0048] like Figure 4 and Figure 5As shown, the repair line serves as a backup trace. The two main traces provided in Examples 1 and 3 of the present invention are G1 and G2, respectively. The resistors at both ends of G1 are R4 and R8, respectively. The resistors at both ends of G2 are R2 and R6, respectively. The resistors at the ends of the repair line connecting to G1 and G2 are NU / R3 and NU / R1, respectively. The resistors at the ends of the repair line connecting to G1 and G2 are NU / R7 and NU / R5, respectively. During PCB layout, ensure that the Gamma trace paths on the XL and XR boards are identical to achieve impedance matching on the XL and XR boards.

[0049] like Figure 4 As shown, the present invention reserves some traces in the panel segment. For example, when G1 or G2 is short-circuited or open-circuited, G1 / G2 is switched to the spare traces through the corresponding spare traces and circuits of the circuit board XR / XL. Figure 4 If G1 is short-circuited or open-circuited: remove R4 and R8; replace R3 and R7.

[0050] Or as Figure 5 As shown, through the software, the output channel of Gamma is changed and the output line of Gamma is switched to the backup line, thereby solving the problem of open circuit or short circuit caused by foreign matter. Figure 5 If G1 / G2 is shorted or open, the Gamma output channel can be modified through software to replace the Gamma output circuit by installing resistors R1 or R3 and removing resistors R2 or R4. By changing the Gamma IC code through software and switching the Gamma voltage output channel switch, the output channel can be changed to solve the problem of shorts or shorts caused by foreign matter, greatly reducing pre-production losses and saving costs.

[0051] The present invention adds 15 groups of ByPass lines on the S-COF and reserves lines at the panel end. When gamma1 or gamma2 is short-circuited or open-circuited, G1 / G2 is switched to the spare lines through the corresponding spare lines and circuits of the circuit board XR / XL. Or through software, such as Figure 5 , change the Gamma output channel. Switch the Gamma output line to the backup line to solve the problem of open circuit or short circuit caused by foreign matter.

[0052] The circuit manufacturing process of the display panel disclosed in the embodiment of the present invention is as follows (the entire process needs to be carried out in a dust-free environment):

[0053] 1) Select a piece of glass with a smooth surface and no impurities. Glass is the main raw material for manufacturing TFT glass substrates. Before production, the glass must be cleaned with a special cleaning solution, then dehydrated and dried.

[0054] 2) To coat a glass substrate with a metal film, the metal material must first be placed in a vacuum chamber. After the special gas on the metal generates plasma, the atoms on the metal will be knocked toward the glass, and then layers of metal films will be formed.

[0055] 3) After the metal film is plated, the present invention also coats a non-conductive layer and a semi-conductive layer. In a vacuum chamber, the glass plate is first heated, and then a special gas is sprayed through a high-voltage sprayer to allow electrons and the gas to generate plasma. After a chemical reaction, a non-conductive layer and a semiconductor layer are formed on the glass.

[0056] 4) After the film is formed, the present invention creates a gamma trace pattern at a fixed location on the glass. First, the film is sprayed with a highly sensitive photoresist solution in a yellow light chamber. Then, a mask is placed on the film and exposed to blue-violet light. Finally, the film is sent to a developing area where developer is sprayed. This removes the light-exposed photoresist and allows the resist layer to set.

[0057] 5) After the photoresist is patterned, the present invention can use wet etching to expose the useless film, or dry etching can be performed using a chemical reaction of plasma. After etching, the remaining photoresist is removed with a slip solution, and finally a gamma circuit pattern is generated on the surface.

[0058] 6) Once the in-plane traces are created, the same traces need to be laid out on the PCB. To ensure impedance matching of the trace diameters, the present invention also requires ensuring the Gamma trace position on the FFC, ensuring that the XL trace diameter is equal to the XR trace diameter.

[0059] While ensuring that the Gamma wire diameters of XR and XL are the same, it is also necessary to avoid disconnection or short circuit of the Gamma in-plane wiring caused by in-plane foreign matter.

[0060] In the panel circuit manufacturing process, a spare circuit is reserved to repair the open circuit or short circuit of the wiring in the Gamma surface. If there is a foreign object at the panel end wiring position, such as Figure 4 and Figure 5 The breakpoint marks of G1 and G2 will cause the gamma1 and gamma2 traces to be short-circuited or open-circuited.

[0061] While ensuring impedance matching on the PCB, the addition of 14 gamma voltages and one repair trace on the COF must also be addressed. The challenge lies in controlling the in-plane gamma trace diameter and the distance between the two gamma traces. If a foreign object is encountered within the panel, such as a short or open circuit on G1 or G2, G1 / G2 can be switched to the backup traces using the corresponding backup traces and circuitry on the XR / XL board. Alternatively, the gamma voltage output channel can be changed to the backup channel using the gamma IC's code settings. This resolves shorts or open circuits caused by foreign objects. Since the COF is not required for driving, only 15 bypass traces need to be added to the COF. Furthermore, implementing in-plane traces at the COF requires careful consideration of the panel manufacturing process. The in-plane gamma traces are already pre-fabricated during glass manufacturing. Finally, during bonding, the COF pins corresponding to the glass and the corresponding PCB pins must be bonded.

[0062] The present invention uses Gamma routing on large-size panels to replace Gamma routing on connectors and FFCs with routing at the panel end, thereby reducing the number of connectors, reducing the number of connector PINs and the number of FFC PINs, and lowering costs. The Gamma routing in the plane changes the path of the Gamma routing in the plane by changing the resistance on the peripheral circuit, achieving impedance matching of XR and X and repairing the problems of partial short circuits and open circuits in the Gamma routing plane. At the same time, it solves the voltage anomaly caused by process foreign matter and improves the yield.

[0063] The above-described embodiments are only preferred specific implementation methods of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention fall within the protection scope of the present invention.

Claims

1. A liquid crystal glass panel gamma switching circuit, characterized in that: Including liquid crystal glass panel TFT LCD, GAMMA module and six source-chip-on-film (S-COF); All six S-COFs are electrically connected to the TFT LCD; Three adjacent S-COFs on one side are connected in series via a first wiring, and three adjacent S-COFs on the other side are connected in series via a second wiring. The two middle S-COFs are connected in series via a third trace, which passes through the TFT LCD. The GAMMA module is connected to one end of the third wiring. The GAMMA module divides the analog voltage VDDA into multiple groups of gamma voltages and provides them to six S-COFs. The six S-COFs transmit the processed signals to the TFT LCD. It also includes an XL connector and an XR connector, three adjacent S-COFs on one side are connected to the XL connector, and three adjacent S-COFs on the other side are connected to the XR connector, the XL connector and the XR connector are connected via a flat cable FFC, and the GAMMA module is provided on the XL connector; Two S-COFs connected to the XL connector and close to the XR connector are connected in series via a fourth trace, the fourth trace is connected in series with the third trace, and the fourth trace passes through the TFT LCD; The third wiring includes a repair line and two parallel main lines. Two ends of the repair line are respectively connected to two ends of the two main lines. Both ends of the two main lines and two ends of the repair line are connected in series with resistors.

2. The liquid crystal glass panel Gamma switching circuit according to claim 1, characterized in that: The third routing includes a repair line and two parallel main lines, one end of the repair line is connected to one end of the two main lines located on the XR connector side, and the repair line and the main lines located on the XR connector side are both connected in series with resistors; The GAMMA module has two ports. The two main lines are located on the XL connector side and are connected to the two ports of the GAMMA module through a Coad control switch. The repair line is located on the XL connector side and is connected to the Coad control switch as a spare channel.

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