WO2018214376A1

WO2018214376A1 - Smart tablet with capacitive touch screen

Info

Publication number: WO2018214376A1
Application number: PCT/CN2017/104958
Authority: WO
Inventors: 马正; 邬营杰; 刘天保; 陶炳俊
Original assignee: 广州视源电子科技股份有限公司; 广州视睿电子科技有限公司
Priority date: 2017-05-26
Filing date: 2017-09-30
Publication date: 2018-11-29
Also published as: CN207115375U

Abstract

Disclosed is a smart tablet (100) with a capacitive touch screen. The smart tablet comprises: a complete machine (10), a capacitive touch screen (20), a liquid crystal display panel (30) and an I2C isolator (40). The liquid crystal display panel (30) is arranged between the complete machine (10) and the capacitive touch screen (20), wherein the complete machine (10) comprises a complete machine backboard, a power source (11), a TV main board (12), a capacitive touch screen control board (13) and a liquid crystal screen drive board (14); the power source (11) is connected to the TV main board (12); the liquid crystal screen drive board (14) is connected to the liquid crystal display panel (30) and the TV main board (12); the capacitive touch screen control board (13) is hung on the complete machine backboard, and is connected to the capacitive touch screen (20); and the capacitive touch screen control board (13) is provided with a first I2C interface, the TV main board (12) is provided with a second I2C interface, and the first I2C interface is connected to the second I2C interface by means of the I2C isolator (40). By means of adding the I2C isolator (40) to isolate the complete machine (10) from the capacitive touch screen (20), the grounding interference suffered by the complete machine (10) cannot be transferred to the capacitive touch screen (20), thus ensuring stable operation of the capacitive touch screen (20).

Description

Capacitive screen smart tablet

Technical field

The utility model relates to the field of smart plates, in particular to a capacitive screen smart tablet.

Background technique

The smart tablet is an integrated device that controls the content displayed on the display tablet through touch technology to realize human-computer interaction. The smart tablet integrates various functions of projector, electronic whiteboard, curtain, audio, TV, video conferencing terminal, and is suitable for group communication occasions. It solves the problem of remote audio and video communication in conferences and high-definition display of conference documents in various formats. Systematic meeting requirements such as video file playback, live audio, screen writing, document labeling, saving, printing and distribution are widely used in education, business meetings, business presentations, etc., which can effectively improve the communication environment and improve group communication efficiency.

Currently, the commonly used smart tablets can be roughly classified into an infrared screen smart tablet and a capacitive screen smart tablet according to the type of touch. Infrared Touch Screen Technology consists of a touch screen and infrared transmitting and receiving sensing elements mounted on the outer frame of the touch screen. The infrared emitting and receiving sensing elements form an infrared detecting net on the surface of the screen, and any touch object can change the contact. Touch screen operation is achieved by infrared rays. The capacitive screen works with the current sensing of the human body. The advantage of the infrared touch screen is that it is cheap and free from current, voltage and static interference, and is suitable for harsh environmental conditions. The disadvantage is that the resolution is low, and the thickness of the whole machine is increased due to the increase of the outer frame. The advantage of the capacitive screen is that the writing experience is smooth, the resolution is high, and the whole machine can be made thin, but the disadvantage of the capacitive screen is that it is easily disturbed by the interference of the external environment, resulting in inaccurate touch or inability to touch and write. For example, when the ambient temperature and humidity change, it will cause the capacitive screen to drift, resulting in inaccurate touch. The drift of the capacitive screen is a technically insufficiency. The environmental potential surface (including the user's body) is farther away from the capacitive touch screen, but much larger than the finger area. These factors directly affect the determination of the touch position.

Utility model content

However, the inventor found in the process of applying a capacitive screen to a smart tablet, especially a large-sized smart tablet, even if the influence of external environmental interference is eliminated, the capacitive screen may still have a jump point or a written interruption, and this phenomenon There are no reasonable explanations for the reasons at present. Through further research, the utility model found that the main reason for the jump point is that the noise signal of the external power grid and the liquid crystal display panel and the whole machine interfere with the grounding of the whole machine during operation, because the whole machine and the capacitive screen are performed. I2C communication and the need to supply power to the capacitive screen, the grounding of the whole machine and the grounding of the capacitive screen need to be connected, which causes the interference of the grounding of the whole machine to be conducted to the grounding of the capacitive screen, and the capacitive screen needs to be grounded by itself. Reference, so when the ground is disturbed, it may cause a change in the reference, resulting in a capacitive screen jump point.

In view of the above problems, the object of the present invention is to provide a capacitive screen smart panel, which can avoid the interference of the grounding of the whole machine to the grounding of the capacitive screen, and solve the jumping point phenomenon of the capacitive screen due to grounding interference.

The utility model provides a capacitive screen smart panel, comprising: a whole machine, a capacitive screen, a liquid crystal display panel and an I2C isolator, wherein the liquid crystal display panel is disposed between the whole machine and the capacitive screen; The whole machine includes a whole machine backboard, a power supply, a TV main board, a capacitive screen control board and a liquid crystal panel driving board;

The power supply is connected to the TV main board; the liquid crystal display driving board is connected to the liquid crystal display panel and the TV main board; the capacitive screen control board is hung on the whole machine back board, and is Capacitive screen connection;

The capacitive screen control board has a first I2C interface, and the TV main board has a second I2C interface, and the first I2C interface and the second I2C interface are connected by the I2C isolator.

Preferably, the I2C isolator has a signal isolation function.

Preferably, the capacitive screen smart tablet further includes an AD conversion module; the capacitive screen is connected to the capacitive screen control board through a capacitive screen receiving line and a capacitive screen output line, and the AD conversion module is connected to the capacitive screen to receive on-line.

Preferably, the AD conversion module is disposed on the capacitive screen receiving line and connected to the capacitive screen One end.

Preferably, the capacitive screen receiving line and the capacitive screen output line are routed along an inner wall of the whole machine backplane; wherein the capacitor receiving line and the capacitor output line comprise a conductor layer, and the conductor layer is wrapped a first insulating layer and a shielding layer disposed outside the first insulating layer.

Preferably, the shielding layer is insulated from the inner wall of the whole machine backboard

Preferably, a second insulating layer surrounding the shielding layer is disposed outside the shielding layer.

Preferably, an insulating spacer is interposed between the shielding layer and an inner wall of the whole machine backboard.

Preferably, a portion of the inner wall of the whole machine back plate that is in contact with the shielding layer is affixed with an insulating tape.

Preferably, a power isolator is further included, and the power source is connected to the capacitive screen control board through the power isolator.

The capacitive screen smart tablet provided by the embodiment of the present invention adds an I2C isolator between the second I2C interface of the TV main board and the first I2C interface of the capacitive screen control board, thereby The capacitive screen is grounded and isolated, so that the interference received by the grounding end of the whole machine does not affect the grounding end of the capacitive screen, thereby avoiding the phenomenon that the capacitive screen is bumped due to interference of the grounding end, thereby improving the phenomenon. The operational stability of the capacitive screen.

DRAWINGS

In order to explain the technical solutions of the present invention more clearly, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without paying any creative work.

FIG. 1 is a schematic structural diagram of a capacitive screen smart tablet according to an embodiment of the present invention.

2 is a schematic view of a connection of the whole machine provided by the embodiment of the present invention.

FIG. 3 is a schematic diagram of the whole machine and the capacitive screen isolated by the I2C isolator according to the embodiment of the present invention.

FIG. 4 is a schematic diagram of a connection between interfaces based on an I2C protocol according to an embodiment of the present invention.

FIG. 5 is a schematic diagram of a connection between a whole machine and a capacitive screen control board according to an embodiment of the present invention.

6 is a schematic cross-sectional view of a capacitive screen receiving line provided by an embodiment of the present invention.

FIG. 7 is another schematic diagram of the connection between the whole machine and the capacitive screen control board according to the embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. example. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Referring to FIG. 1 to FIG. 3 , an embodiment of the present invention provides a capacitive screen smart panel 100, including: a whole machine 10, a capacitive screen 20, a liquid crystal display panel 30, and an I2C isolator 40. The liquid crystal display panel 30 is configured. Between the whole machine 10 and the capacitive screen 20. The whole machine 10 includes a whole machine backboard (not shown), a power source 11, a TV main board 12, a capacitive screen control board 13, and a liquid crystal panel driving board 14. The power source 11 is connected to the TV main board 12, the liquid crystal panel driving board 14 is connected to the liquid crystal display panel 30 and the TV main board 12, and the capacitive screen control board 13 is hung on the whole machine back board. And connected to the capacitive screen 20; the capacitive screen control board 13 has a first I2C interface, the TV main board 12 has a second I2C interface, and the first I2C interface and the second I2C interface pass through The I2C isolator 40 is connected.

In the embodiment of the present invention, the power source 11 supplies power to the TV main board 12, and the liquid crystal panel driving board 14 is connected to the liquid crystal display panel 30, and thus the grounding end of the power source 11 and the grounding of the TV main board 12 The terminals are connected to the ground ends of the liquid crystal display panel 30. In the prior art, the TV main board 12 and the capacitive screen control board 13 are directly connected through an I2C interface for communication. As shown in Figure 4, the I2C bus is very simple in physical connection, consisting of SDA (serial data line) and SCL (serial clock line) and pull-up resistors. The communication principle is based on the control of the high and low timing of the SCL and SDA lines. The signals required by the I2C bus protocol are used for data transfer. In the bus idle state, the two wires are generally pulled high by the pull-up resistor connected above, and remain high. Each module circuit connected on the bus is both a master (the master must have a CPU) The logic module) (or the controller) is the transmitter (or receiver), but there is only one host in the system, and the clock signal is generated by the host.

In the prior art, since the capacitive screen control board 13 and the capacitive screen 20 are also directly connected, the grounding end of the whole machine 10, the grounding end of the liquid crystal display panel 30, and the capacitive screen 20 are actually The ground terminals are all connected. In the actual working process, the noise signal of the external power grid and the liquid crystal display panel 30 and the whole machine 10 may all work on the grounding end of the whole machine 10 (the actual grounding end of the whole machine 10 is the whole machine 10). The backplane of the machine is disturbed. Since the grounding end of the whole machine 10 is connected to the grounding end of the capacitive screen 20, the interference of the grounding end of the whole machine 10 is transmitted to the grounding end of the capacitive screen 20, and the When the capacitive screen 20 is in operation, the level of the grounding terminal of the capacitive screen 20 is used as a reference. Therefore, when the grounding end of the capacitive screen 20 is disturbed, a change in the reference level may be caused, causing the capacitive screen 20 to be in the touch process. A jump point appears. In particular, when applied to a large-sized capacitive screen, this interference is more pronounced due to an increase in the operating voltage. In severe cases, the capacitive screen may not be written.

In the embodiment of the present invention, in order to prevent interference of the grounding end of the whole machine 10 from being transmitted to the grounding end of the capacitive screen 20, the second I2C interface of the TV main board 12 and the capacitive screen control board 13 The I2C isolator 40 is added between the first I2C interfaces. The I2C isolator 40 is provided with a signal isolation function, that is, the TV main board 12 and the capacitive screen control board 13 are electrically connected under the premise of ensuring normal communication between the TV main board 12 and the capacitive screen control board 13. Isolated, independent, ungrounded equipment. Among them, the techniques for implementing signal isolation include, but are not limited to, transformer isolation, coil isolation, magnetic isolation, optocoupler isolation, etc., and the present invention is not specifically limited.

In summary, the capacitive screen smart panel 100 provided by the embodiment of the present invention adds the I2C isolation between the second I2C interface of the TV motherboard 12 and the first I2C interface of the capacitive screen control panel 13. The device 40 grounds the TV main board and the capacitive screen control board 13 so that the interference received by the ground end of the whole machine 10 is not transmitted to the ground end of the capacitive screen 20, thereby avoiding the capacitance. The phenomenon that the screen 20 generates a jump point due to interference of the ground end improves the operational stability of the capacitive screen 20.

In order to facilitate the understanding of the present invention, some preferred embodiments of the present invention will be further described below.

Preferably, as shown in FIG. 5, the capacitive screen smart tablet 100 further includes an AD conversion module 50; the capacitive screen 20 is connected to the capacitive screen control board 13 through a capacitive screen receiving line 21 and a capacitive screen output line 22. The AD conversion module 50 is connected to the capacitive screen receiving line 21.

As shown in FIG. 3, RX1, RX2, and RX3 shown in FIG. 3 are part of the capacitive screen receiving line 21, and the capacitive screen receiving line 21 is used to detect a touch signal (analog signal) detected by the capacitive screen 20. Transmitted to the capacitive screen control panel 13, the capacitive screen control panel 13 generates touch coordinate information according to the touch signal, and transmits the touch coordinate information to the TV motherboard 12, which is to be The touch coordinate information is converted into a touch coordinate value and sent to an external device 60 (such as a PC module or an Android module), and the external device 60 responds according to the touch coordinate value, and sends the image information generated after the response to The TV main board 12 transmits the image signal and the screen driving command to the liquid crystal display driving board 14 , and the liquid crystal display driving board 14 drives the liquid crystal display panel 30 according to the driving command. And the image information is finally displayed by the display.

In a practical situation, in a smart tablet, especially a large-sized smart tablet, the capacitive screen receiving line 21 may be relatively long due to wiring requirements, which may result in transmission within the capacitive screen receiving line 21. The signal is subject to large interference. In particular, when the transmitted signal is an analog signal, it will generate distortion and superimposed clutter after being interfered, and such distortion and superimposed clutter are difficult to eliminate and recover, and thus may cause touch. The coordinate information is inaccurate, resulting in inaccurate final touch position determination.

To this end, in the embodiment of the present invention, the AD conversion module 50 is added to each of the capacitive screen receiving lines 21, and the AD conversion module 50 can convert an analog signal into a digital signal, although the digital signal is transmitted. In the process, there may also be a problem of error caused by interference, but such error can be eliminated by prior anti-interference coding, thereby ensuring the accuracy of touch coordinate information and improving the accuracy of touch position determination.

Preferably, the AD conversion module 50 is disposed at one end of the capacitive screen receiving line 21 connected to the capacitive screen 20.

In the preferred embodiment, the AD conversion module 50 is disposed at one end of the capacitive screen receiving line 21 connected to the capacitive screen 20, that is, the analog signal is just generated and transmitted on the capacitive screen receiving line 21. When it is converted into a digital signal, the problem that the analog signal is difficult to recover after being interfered by the interference can be minimized, and the accuracy of the touch point judgment is improved.

At present, it should be understood that the AD conversion module 50 can also be disposed at one end of the capacitive screen receiving line 21 close to the capacitive screen 20, which is not specifically limited by the present invention.

Preferably, the capacitive screen receiving line 21 and the capacitive screen output line 22 are taken out from the capacitive screen control board 13 and connected to the capacitive screen along the inner wall of the whole backplane; The capacitive screen receiving line 21 and the capacitive screen output line 22 have a conductor layer, a first insulating layer encasing the conductor layer, and a shielding layer disposed outside the first insulating layer.

In this embodiment, the back plate of the whole machine is made of a metal material, and on the one hand, functions as a fixed support, and the TV circuit board 12, the capacitive screen control board 13 and various circuit board covers are fixed at the whole. On the back of the machine. On the other hand, as described above, the whole machine backplane is also the largest ground in the whole machine 10, in the sense of the circuit. In the prior art, the capacitive screen receiving line 21 and the capacitive touch screen emitting line 24 are closely aligned with the inner wall of the whole machine backplane. During the working process, the whole backplane may be subjected to the liquid crystal display. The panel 30 interferes, and the entire backplane is disturbed to generate spatial radiation that interferes with signals transmitted within the capacitive screen receiving line 21 and the capacitive screen output line 22.

For this reason, please refer to FIG. 6 , taking the capacitive screen receiving line 21 as an example. In the embodiment, the capacitive screen receiving line 21 has a conductor layer 211 and a first insulating layer enclosing the conductor layer 211 . 212 and a shielding layer 213 disposed outside the first insulating layer 212.

In this embodiment, the conductor layer 211 is used for signal transmission, the first insulating layer 212 functions to insulate the conductor layer 211, and the shielding layer 213 may be a metal shielding layer. The interference of the spatial radiation of the entire backplane to the signals transmitted within the conductor layer 211 can be shielded.

In this embodiment, since the shielding layer 233 is a metal shielding layer, the shielding layer 213 needs to be insulated. Specifically, a second insulating layer 214 surrounding the shielding layer 213 may be disposed outside the shielding layer 213, or may be insulated between the shielding layer 213 and the whole backplane. The spacer layer 213 is physically separated from the whole machine backplane, and may be insulated by attaching an insulating tape to a portion of the whole machine backplane that is in contact with the shielding layer 213, wherein preferably A second insulating layer 214 surrounding the shielding layer 213 may be disposed outside the shielding layer 213 to achieve a better insulation effect.

Similarly, the capacitive screen output line 22 is also subjected to similar insulation treatment, and the present invention will not be described herein.

Preferably, the smart tablet 100 further includes a power isolator 70, and the power source 11 is connected to the capacitive screen control board 13 through the power isolator 70.

In this embodiment, the TV motherboard 12 cannot directly supply power to the capacitive screen control board 13 through the I2C interface. Therefore, the capacitive screen 13 needs to be powered by the power source 11. To this end, as shown in FIG. 7, in the preferred embodiment, a power isolator 70 is connected between the power source 11 and the capacitive screen control board 13 for implementing the power source 11 and the capacitive screen. The power supply between the control boards 13 is isolated, so that the grounding of the power supply 11, the TV main board 12 and the ground of the capacitive screen 20 are no longer connected, and the grounding interference received by the grounding end of the whole machine 10 is prevented from affecting the capacitive screen. 20 ground terminal.

It should be noted that the liquid crystal panel driving board 14 has two power supply modes. For a small-sized smart tablet, the liquid crystal panel driving board 14 can be powered by the TV main board 12, and for a large-sized smart tablet, The liquid crystal panel driving board 14 is powered by the power source 11.

The above is only a few preferred embodiments of the present invention, and of course, the scope of the present invention is not limited thereto, and those skilled in the art can understand all or part of the process of implementing the above embodiments, and Equivalent changes made by the new claims are still within the scope of the utility model.

One of ordinary skill in the art can understand that all or part of the process of implementing the foregoing embodiments can be completed by a computer program to instruct related hardware, and the program can be stored in a computer readable storage medium. When executed, the flow of an embodiment of the methods as described above may be included. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

Claims

A capacitive screen smart panel, comprising: a whole machine, a capacitive screen, a liquid crystal display panel and an I2C isolator, wherein the liquid crystal display panel is disposed between the whole machine and the capacitive screen; wherein The whole machine includes the whole machine backplane, power supply, TV motherboard, capacitive screen control board and LCD driver board;

The power supply is connected to the TV main board; the liquid crystal display driving board is connected to the liquid crystal display panel and the TV main board; the capacitive screen control board is hung on the whole machine back board, and is Capacitive screen connection;

The capacitive screen control board has a first I2C interface, and the TV main board has a second I2C interface, and the first I2C interface and the second I2C interface are connected by the I2C isolator.
The capacitive screen smart tablet according to claim 1, wherein the I2C isolator has a signal isolation function.
The capacitive screen smart tablet according to claim 1, wherein the capacitive screen smart tablet further comprises an AD conversion module; the capacitive screen is connected to the capacitive screen control board through a capacitive screen receiving line and a capacitive screen output line. The AD conversion module is connected to the capacitive screen receiving line.
The capacitive screen smart tablet according to claim 3, wherein the AD conversion module is disposed at one end of the capacitive screen receiving line connected to the capacitive screen.
The capacitive screen smart panel according to claim 4, wherein the capacitive screen receiving line and the capacitive screen output line are routed along an inner wall of the whole machine backplane; wherein the capacitor receiving line and the The capacitor output line includes a conductor layer, a first insulating layer encasing the conductor layer, and a shielding layer disposed outside the first insulating layer.
The capacitive screen smart panel according to claim 5, wherein the shielding layer is insulated from the inner wall of the whole backplane.
The capacitive screen smart panel according to claim 6, wherein a second insulating layer surrounding the shielding layer is disposed outside the shielding layer.
The capacitive screen smart panel according to claim 6, wherein an insulating spacer is interposed between the shielding layer and an inner wall of the whole machine backboard.
The capacitive screen smart panel according to claim 6, wherein a portion of the inner wall of the whole machine backplane that is in contact with the shielding layer is affixed with an insulating tape.
The capacitive screen smart tablet according to any one of claims 1 to 9, further comprising a power isolator, wherein the power source is connected to the capacitive screen control board through the power isolator.