Infrared touch frame and infrared touch screen

Abstract

The embodiment of the utility model provides an infrared touch board circuit board, an infrared touch frame and an infrared touch screen, and the infrared touch frame circuit board comprises a mainboard and a plurality of slave boards, the mainboard comprises a signal conditioning circuit; the signal conditioning circuit comprises a plurality of sampling resistors and an operational amplifier circuit; the slave board comprises an infrared receiving circuit; the infrared receiving circuit comprises a plurality of optical signal receiving tubes and a plurality of amplifier tubes; the first end of each optical signal receiving tube is used for receiving an optical signal receiving tube enable signal; the second end of each optical signal receiving tube is connected with the signal input end of one amplifier tube; the first connecting end of the amplifier tube is grounded; a second connecting end of the amplifier tube is connected with a first end of a sampling resistor through an analog signal bus; the sampling resistor is further connected with the input end of the operational amplifier circuit and connected with the power supply end. According to the invention, interference is prevented from being introduced on each slave board along with wiring of each amplifier tube, noise interference is reduced, and the signal-to-noise ratio is improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of infrared touch, and in particular to an infrared touch frame and an infrared touch screen. Background Art

[0002] With the development of electronic technology, infrared touch devices are widely used in interactive tablets due to their fast response speed and high cost-effectiveness. The working principle of infrared touch devices is to deploy infrared transmitting circuits and / or infrared receiving circuits within each frame of the infrared touch frame. The infrared transmitting circuits are controlled to transmit infrared signals, while the infrared receiving circuits receive infrared signals. The signal processing circuit then performs a series of stabilization adjustments on the infrared signals and performs A / D (analog-to-digital converter) sampling on the infrared signals to determine the touch position and perform the corresponding touch operation.

[0003] Therefore, it can be seen that the quality of the infrared receiving signal will directly affect the accuracy of infrared touch detection. In the related art, the infrared touch frame is easy to introduce noise interference, has poor anti-interference ability, and has a low signal-to-noise ratio. Summary of the Invention

[0004] In order to overcome the problems existing in the related art, the present application provides an infrared touch frame and an infrared touch screen, which can reduce noise interference, improve anti-interference ability, and improve signal-to-noise ratio.

[0005] According to a first aspect of an embodiment of the present application, an infrared touch frame is provided, comprising a frame, a main board disposed within the frame, and a plurality of slave boards; the main board comprising a signal conditioning circuit and an A / D sampling circuit; the signal conditioning circuit comprising a plurality of sampling resistors and an operational amplifier circuit; the slave boards comprising an infrared receiving circuit; the infrared receiving circuit comprising a plurality of optical signal receiving tubes and a plurality of amplifier tubes;

[0006] The first end of each optical signal receiving tube is used to receive an optical signal receiving tube enable signal; the second end of each optical signal receiving tube is connected to the signal input end of one of the amplifier tubes; the first connection end of the amplifier tube is grounded; the second connection end of the amplifier tube is connected to the first end of one of the sampling resistors via an analog signal bus; the second end of the sampling resistor is connected to the power supply end; the first end of the sampling resistor is also connected to the input end of the operational amplifier circuit; and the output end of the operational amplifier circuit is connected to the input end of the A / D sampling circuit.

[0007] The amplifier tubes in the embodiment of the present application are uniformly connected to the power supply terminal of the main board, and there is no need to lay out a power supply for each amplifier tube on the slave board. This can avoid the introduction of interference caused by the power supply wiring of each amplifier tube on each slave board, improve the anti-interference capability, and improve the signal-to-noise ratio.

[0008] In an optional embodiment, the operational amplifier circuit includes an operational amplifier, a first resistor, a first capacitor, a second resistor, and a feedback resistor;

[0009] The inverting input terminal of the operational amplifier is connected to the first end of the sampling resistor via a first resistor and a first capacitor; the inverting input terminal of the operational amplifier is also connected to a reference power supply via a second resistor; the non-inverting input terminal of the operational amplifier is connected to the reference power supply; and the output terminal of the operational amplifier is connected to the inverting input terminal of the operational amplifier via a feedback resistor.

[0010] When the inverting proportional operational amplifier of the embodiment of the present application amplifies and processes weak signals, only differential-mode signals are present. Compared with the inverting proportional operational amplifier, it has stronger anti-interference performance and can further improve the signal-to-noise ratio.

[0011] In an optional embodiment, the operational amplifier circuit further includes a feedback capacitor connected in parallel across the feedback resistor to prevent the operational amplifier from self-oscillating and to suppress high-frequency noise.

[0012] According to a second aspect of the embodiments of the present application, an infrared touch screen, a display screen, and the infrared touch frame described above are provided; the infrared touch frame is arranged around the display screen.

[0013] The amplifier tubes in the embodiment of the present application are uniformly connected to the power supply terminal of the main board, and there is no need to lay out a power supply for each amplifier tube on the slave board. This can avoid the introduction of interference caused by the power supply wiring of each amplifier tube on each slave board, improve the anti-interference capability, and improve the signal-to-noise ratio.

[0014] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application.

[0015] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 This is a schematic diagram of the circuit structure of the infrared touch frame in the related art of this application;

[0018] Figure 2This is a schematic block diagram of the structure of an infrared touch frame shown in one embodiment of the present application;

[0019] Figure 3 This is a schematic diagram of the circuit structure of an infrared touch frame according to an embodiment of the present application;

[0020] Figure 4 This is a schematic diagram of the circuit structure of an infrared touch frame according to another embodiment of the present application;

[0021] Figure 5 This is a schematic diagram of the circuit structure of a signal conditioning circuit according to one embodiment of the present application;

[0022] Figure 6 This is a schematic block diagram of the structure of an infrared touch screen according to one embodiment of the present application. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of this application more clear, the embodiments of this application will be further described in detail below with reference to the accompanying drawings. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0024] It should be understood that the embodiments described in the following examples do not represent all embodiments consistent with this application. Rather, they are merely examples of devices and methods consistent with certain aspects of this application, as detailed in the appended claims. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of this application without inventive effort are intended to fall within the scope of protection of this application.

[0025] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a" and "the" used in this application are also intended to include plural forms, unless the context clearly indicates otherwise. In addition, in the description of this application, unless otherwise stated, "a plurality" refers to two or more. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone; the character " / " generally indicates that the objects associated before and after are in an "or" relationship.

[0026] It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, this information should not be limited to these terms. Moreover, these terms are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood to indicate or imply relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. Depending on the context, the words "if" / "if" used in this application can be interpreted as "at the time of" or "when" or "in response to determining".

[0027] With the development of electronic technology, infrared touch devices are widely used in interactive tablets due to their fast response speed and high cost-effectiveness. The working principle of infrared touch devices is to deploy infrared transmitting circuits and / or infrared receiving circuits within each frame of the infrared touch frame. The infrared transmitting circuits are controlled to transmit infrared signals, while the infrared receiving circuits receive infrared signals. The signal processing circuit then performs a series of stabilization adjustments on the infrared signals and performs A / D (analog-to-digital converter) sampling on the infrared signals to determine the touch position and perform the corresponding touch operation.

[0028] Specifically, several infrared touch panels are provided on the four sides of the infrared touch frame. Each infrared touch panel houses an infrared touch frame circuit board, which in turn houses an infrared transmitter circuit and / or infrared receiver circuit. The infrared transmitter circuit houses several infrared transmitters, while the infrared receiver circuit houses several infrared receivers. The infrared transmitters emit infrared signals, while the infrared receivers receive them, forming a horizontally and vertically intersecting infrared detection network on the screen. When a user's finger or other object touches the screen, it blocks or reflects the passing infrared signal, causing the infrared signal received by the infrared receiver to change. The touch point is then located based on the changed infrared signal.

[0029] According to different functions and positions, the infrared touch panels on the infrared touch frame are divided into a master panel and multiple slave panels. An analog signal bus, a digital signal bus and a power signal bus are connected between the master panel and the slave panels.

[0030] The master board and the slave board share a power signal bus to provide power signals, that is, power supply, to their connected infrared transmitters and infrared receivers.

[0031] The mainboard sends control signals via the digital signal bus to control the operating status of the infrared transmitters and receivers on each slave board. The slave board's infrared receiver receives infrared light signals, converts them into analog electrical signals, and then loads these signals onto the analog signal bus to transmit back to the mainboard. The mainboard detects the analog electrical signals from each slave board on the analog signal bus and converts them into digital signals. The mainboard uses these digital signals to calculate the corresponding touch object coordinates. Alternatively, the mainboard transmits these digital signals to a host computer (such as an Android or Windows motherboard), which then calculates the touch object coordinates.

[0032] In the related art, there are two main ways to set infrared transmitters and infrared receivers on the four sides of the infrared touch frame: one is to set the infrared transmitter and infrared receiver on opposite sides of the infrared touch frame respectively; the other is to arrange the infrared transmitter and infrared receiver in an alternating manner on the same side of the infrared touch frame.

[0033] The structure of the infrared touch frame will be further described below by taking an example where the infrared transmitter and the infrared receiver are respectively arranged on two opposite sides of the infrared touch frame.

[0034] The slave board equipped with an infrared receiver includes an infrared receiver selection circuit and an infrared receiving circuit; the infrared receiver selection circuit includes a shift register; the shift register includes multiple output terminals; a number of infrared receivers are provided in the infrared receiving circuit, and the shift register outputs an infrared receiver enable signal at the corresponding output terminal to control the corresponding infrared receiver to turn on according to the control signal sent by the master MCU; the turned-on infrared receiver receives the infrared light signal, converts the infrared light signal into an analog electrical signal, and then loads the analog electrical signal onto the analog signal bus and transmits it back to the signal conditioning circuit of the host board.

[0035] The mainboard is equipped with a signal conditioning circuit, an A / D sampling circuit, and a main MCU (Microcontroller Unit, or MCU), which are connected in sequence. The main MCU outputs control signals via a digital control bus to turn each infrared emitter and / or infrared receiver on or off. The signal conditioning circuit is connected to the analog signal bus and is used to detect and amplify the analog electrical signal from the analog signal bus. The A / D sampling circuit performs A / D sampling on the amplified analog electrical signal to obtain a digital signal, which is then transmitted to the main MCU via a set protocol. The main MCU analyzes and processes the digital signal obtained by A / D sampling to calculate the touch position.

[0036] Specifically, the slave board is provided with a shift register (not shown) and an infrared receiving circuit; the infrared receiving circuit includes a plurality of infrared receivers, a plurality of amplifier tubes and a plurality of bias resistors. Figure 1 In the following example, an infrared receiving circuit 11 includes an infrared receiver PD1, an amplifier Q1, and a bias resistor R1. The infrared receiver PD1 is a light signal receiving tube, specifically a photodiode; the amplifier Q1 is a transistor, specifically an NPN transistor. V1 is the infrared receiver enable signal that controls whether the infrared receiver PD1 is turned on or off.

[0037] The shift register's input is connected to the motherboard's main MCU via a digital signal bus to receive control signals. The shift register's output is connected to the cathode of a photodiode PD1, which outputs an infrared receiver enable signal V1 based on the control signal. The anode of photodiode PD1 is connected to the base of an NPN transistor Q1, whose collector is connected to the power supply VCC_R. The emitter of NPN transistor Q1 is connected to the analog signal bus and then to the motherboard's signal conditioning circuitry.

[0038] The signal conditioning circuit includes a sampling resistor RH1, an operational amplifier U1C, a first capacitor C1, a first resistor RV1, a second resistor RK1, a feedback resistor RF1, and a feedback capacitor CJ1. The non-inverting input of the operational amplifier U1C is connected to the first end of the sampling resistor RH1 via the first capacitor C1. The first end of the sampling resistor RH1 is connected to the emitter of the NPN transistor Q1 via the analog signal bus. The second end of the sampling resistor RH1 is grounded. The non-inverting input of the operational amplifier U1C is also connected to the reference power supply VREF via the first resistor RV1. The inverting input of the operational amplifier U1C is connected to the reference power supply VREF via the second resistor RK1. The output of the operational amplifier is also connected to the inverting input of the operational amplifier via the parallel feedback resistor RF1 and feedback capacitor CJ1. The output of the operational amplifier is connected to the A / D sampling circuit.

[0039] When the photodiode PD1 receives the infrared receiver enable signal and turns on, the photodiode PD1 senses the infrared light signal and generates a photocurrent. The photocurrent is amplified by the NPN transistor Q1 and transmitted to the analog signal bus. The photocurrent is transmitted to the main board via the analog signal bus. After the current-voltage conversion is performed on the sampling resistor RH1 of the main board, the infrared receiving signal is obtained. The infrared receiving signal is transmitted to the operational amplifier U1C for amplification and input into the A / D sampling circuit for sampling and processing.

[0040] In the related art, an infrared touch frame is composed of multiple infrared touch panels. Each slave board used to receive infrared signals includes at least one infrared receiving circuit. The infrared receiving signal detected by the infrared receiving circuit is transmitted to the signal conditioning module via an analog signal bus. Each NPN transistor in the infrared receiving circuit requires a stable and clean power supply VCC_R. The power supply VCC_R on each NPN transistor is a single-point connection to the power signal bus, which means that the power signal bus must run through all infrared touch panels. The power supply VCC_R on each NPN transistor also needs to be routed along the distribution of each NPN transistor, which easily introduces noise interference on the slave board and reduces the signal-to-noise ratio. In addition, the infrared receiving signal after amplification by the NPN transistor is still very weak. The signal conditioning circuit in the related art uses a non-inverting input connection method, which easily generates a common-mode input signal and has low anti-interference ability.

[0041] In the embodiment of the present application, the circuit is redesigned. Instead of providing a power supply for each amplifier tube on the slave board, the power supply terminal of each amplifier tube is uniformly connected to the power supply terminal of the master board. This avoids running the power signal bus through each slave board, reduces interference, and improves the signal-to-noise ratio. At the same time, the operational amplifier of the signal conditioning circuit adopts an inverting input connection method to avoid the generation of common-mode input signals and improve anti-interference capabilities.

[0042] The following will be combined with the Figures 2 to 5 , the infrared touch frame circuit board provided in the embodiment of the present application is introduced in detail.

[0043] An infrared touch frame provided in an embodiment of the present application includes: a frame, a main board disposed within the frame, and multiple slave boards; the main board includes a signal conditioning circuit 202 and an A / D sampling circuit 203; the signal conditioning circuit 202 includes a plurality of sampling resistors RH1-RHn and an operational amplifier circuit 2021; the slave boards include an infrared receiving circuit 201; the infrared receiving circuit 201 includes a plurality of optical signal receiving transistors PD1-PDmn and a plurality of amplifier transistors Q1-Qmn.

[0044] The first end of each optical signal receiving transistor PD1-PDmn is used to receive an optical signal receiving transistor enable signal V1-Vm; the second end of each optical signal receiving transistor PD1-PDmn is connected to the signal input end of an amplifier transistor Q1-Qmn; the first connection end of the amplifier transistor Q1-Qmn is grounded; the second connection end of the amplifier transistor Q1-Qmn is connected to the first end of a sampling resistor RH1-RHn via an analog signal bus; the second end of the sampling resistor RH1-RHn is connected to the power supply end; and the first end of the sampling resistor RH1-RHn is also connected to the input end of the operational amplifier circuit 2021.

[0045] The optical signal receiving tube may be a photodiode or a photosensitive receiving tube or other device capable of detecting optical signals and performing photoelectric conversion, and the amplifier tube may be a triode or a field effect tube or other device capable of amplifying.

[0046] Please continue reading Figure 2 In an optional embodiment, a plurality of optical signal receiving tubes are arranged in a matrix of M rows and N columns, and the first ends of the optical signal receiving tubes in the same row receive the same optical signal receiving tube enable signal, so as to reduce wiring complexity, simplify control, and reduce design costs; wherein M and N are both integers greater than 0, and M and N may be equal or unequal.

[0047] Please continue reading Figure 2 In an optional embodiment, a plurality of optical signal receiving tubes are arranged in a matrix of M rows and N columns, and the second ends of the amplifying tubes corresponding to the optical signal receiving tubes in the same column are connected to the same sampling resistor to simplify wiring, reduce the number of sampling resistors, and lower costs; wherein M and N are both integers greater than 0, and M and N may be equal or unequal.

[0048] In an optional embodiment, the main board also includes a main MCU; the main MCU includes a control signal output end; the slave board also includes an optical signal receiving tube selection circuit; the optical signal receiving tube selection circuit includes a shift register; the shift register includes an input end and multiple output ends; the input end of the shift register is connected to the control signal output end of the main MCU via an analog signal bus or a digital signal bus, for receiving a control signal; each output end of the shift register is connected to the first end of at least one optical signal receiving tube, for outputting an optical signal receiving tube enable signal according to the control signal.

[0049] It is understandable that the above solution is applicable to the scenario where the infrared transmitter and the infrared receiver (optical signal receiving tube) are respectively arranged on opposite sides of the infrared touch frame, that is, only the infrared transmitter is provided on the slave board, or only the infrared receiver is provided on the slave board. For the slave board with only the infrared receiver, the above infrared receiver selection circuit is provided.

[0050] The embodiments of the present application use a shift register to quickly perform data shift operations based on control signals, thereby quickly changing the working state of the optical signal receiving tube and improving the response speed of the optical signal receiving tube. Moreover, since one shift register can control multiple optical signal receiving tubes, compared to a microcontroller, the use of a shift register can reduce the number of input / output ports required by the microcontroller, thereby reducing costs.

[0051] In another optional embodiment, the main board also includes a main MCU; the main MCU includes a control signal output end; the slave board also includes a slave MCU and an infrared transmitting circuit; the infrared transmitting circuit includes a plurality of infrared transmitters; the slave MCU includes an input end and an output end; the input end of the slave MCU is connected to the control signal output end of the main MCU via an analog signal bus or a digital signal bus for receiving a control signal; the output end of the slave MCU is connected to the first end of at least one optical signal receiving tube for outputting an optical signal receiving tube enable signal according to the control signal.

[0052] It can be understood that when the above solution is applicable to the scenario where the infrared transmitter and the infrared receiver (optical signal receiving tube) are staggered and arranged on the same side of the infrared touch frame, that is, the infrared transmitter and the infrared receiver are arranged on the slave board, at this time, the slave board controls the working status of the infrared transmitter through the slave MCU.

[0053] Before scanning begins, the master board sends scanning data to each slave board via a digital signal bus, controlling the infrared emitter and receiver. Each slave board then uses the shared digital signal bus to retrieve its own scanning data and control its own infrared emitter and receiver to perform scanning operations. This scanning data includes the location of the infrared receiver and emitter connected to each slave board, as well as the corresponding scanning logic.

[0054] After scanning begins, the master board transmits synchronization signals to each slave board via a synchronization signal bus to control the corresponding slave board's scanning. The synchronization signal includes a control signal. Specifically, after receiving the synchronization signal sent by the master board, the slave board triggers the start of scanning based on the synchronization signal. The slave board reads its own stored scan data and controls the operating status of the connected infrared receiver and infrared transmitter based on the control signal in the synchronization signal. The synchronization signal bus can be an analog signal bus or a digital signal bus.

[0055] This application controls the state of the infrared receiver (optical signal receiving tube) from the MCU, which can avoid the deployment of additional control components on the slave board and reduce costs. In addition, based on the powerful data processing capabilities of the slave MCU, precise timing control and synchronization control can be achieved.

[0056] In the embodiment of the present application, when the optical signal receiving tube of the slave board 21 receives an optical signal receiving tube enable signal and is turned on, the optical signal receiving tube senses the infrared light signal emitted by the infrared emitter and generates a photocurrent. After the photocurrent is amplified by the amplifier tube, it is transmitted to the main board 22 via the analog signal bus. After current-to-voltage conversion is performed on the sampling resistor of the main board 22, an infrared receiving signal is obtained. The infrared receiving signal is then amplified by the operational amplifier circuit 2021 and input into the A / D sampling circuit for sampling processing.

[0057] In the embodiment of the present application, the amplifier tubes are uniformly connected to the power supply terminal of the main board, and there is no need to lay a power supply for each amplifier tube on the slave board. This can avoid running a power signal bus through each slave board, avoid interference introduced by wiring each amplifier tube, and improve the signal-to-noise ratio.

[0058] In an alternative embodiment, see Figure 3 The optical signal receiving tubes PD1-PDmn are photodiodes; their first terminals serve as the cathodes of the photodiodes; their second terminals serve as the anodes of the photodiodes. The amplifier tubes Q1-Qmn are NPN transistors; their signal input terminals serve as the bases of the NPN transistors; their first connection terminals serve as the emitters of the NPN transistors; and their second connection terminals serve as the collectors of the NPN transistors.

[0059] Alternatively, the optical signal receiving tubes PD1-PDmn are photodiodes; the first ends of the optical signal receiving tubes PD1-PDmn serve as the cathodes of the photodiodes; the second ends of the optical signal receiving tubes PD1-PDmn serve as the anodes of the photodiodes. The amplifier tubes Q1-Qmn are N-type field-effect transistors (N-FETs); the signal input ends of the amplifier tubes Q1-Qmn serve as the gates of the N-FETs; the first connection ends of the amplifier tubes Q1-Qmn serve as the sources of the N-FETs; and the second connection ends of the amplifier tubes Q1-Qmn serve as the drains of the N-FETs.

[0060] When the optical signal receiving tube enable signal received by the anode of the photodiode on the main board 21 is a high-level signal, the photodiode is turned on, and the photodiode senses the infrared light signal emitted by the infrared emitter, generating a photocurrent. The photocurrent flows into the signal input end of the amplifier tube (NPN or N-type field-effect transistor), is amplified by the amplifier tube, and is transmitted to the analog signal bus. After current-voltage conversion is performed on the sampling resistor of the main board 22, an infrared receiving signal is obtained.

[0061] The embodiments of the present application match a photodiode with an NPN transistor or a photodiode with an N-type field-effect transistor, thereby avoiding the need to provide a power supply for each amplifier tube on the board on the basis of normal detection and amplification of infrared light signals, thereby reducing wiring difficulty and design costs.

[0062] In another alternative embodiment, see Figure 4The optical signal receiving tubes PD1-PDmn are photodiodes; their first terminals serve as the anodes of the photodiodes; their second terminals serve as the cathodes. The amplifier tubes Q1-Qmn are PNP transistors; their signal input terminals serve as the bases of the PNP transistors; their first connection terminals serve as the collectors of the PNP transistors; and their second connection terminals serve as the emitters of the PNP transistors.

[0063] Alternatively, the optical signal receiving tubes PD1-PDmn are photodiodes; the first terminals of the optical signal receiving tubes PD1-PDmn serve as the anodes of the photodiodes; the second terminals of the optical signal receiving tubes PD1-PDmn serve as the cathodes of the photodiodes. The amplifier tubes Q1-Qmn are P-type field-effect transistors (P-FETs); the signal input terminals of the amplifier tubes Q1-Qmn serve as the gates of the P-FETs; the first connection terminals of the amplifier tubes Q1-Qmn serve as the drains of the P-FETs; and the second connection terminals of the amplifier tubes Q1-Qmn serve as the sources of the N-FETs.

[0064] When the optical signal receiving tube enable signal received by the anode of the photodiode on the slave board 21 is a low-level signal, the photodiode turns on, senses the infrared light signal emitted by the infrared emitter, and generates photocurrent. The photocurrent flows into the control end of the amplifier tube (PNP transistor or P-type field-effect transistor), is amplified by the amplifier tube, and is transmitted to the analog signal bus. After current-voltage conversion is performed on the sampling resistor of the main board, an infrared receiving signal is obtained.

[0065] In the embodiments of the present application, by matching a photodiode with a PNP transistor or a photodiode with a P-type field-effect transistor, it is possible to avoid laying a power supply for each amplifier tube on the board on the basis of normal detection and amplification of infrared light signals, thereby reducing wiring difficulty and design costs.

[0066] In an optional embodiment, please also refer to Figures 2 to 5 The signal conditioning circuit 202 includes an operational amplifier U1C, a first resistor RK1, a first capacitor C1, a second resistor RV1, and a feedback resistor RF1. It should be noted that, in order to simplify the drawings, Figure 5 In the figure, only a photodiode PD1, an amplifier tube Q1 and a sampling resistor RH1 are used as examples for illustration.

[0067] The inverting input of the operational amplifier U1C is connected to the first end of the sampling resistor RH1 via the first resistor RK1 and the first capacitor C1. The inverting input of the operational amplifier U1C is also connected to the reference power supply VREF via the second resistor RV1. The non-inverting input of the operational amplifier U1C is connected to the reference power supply VREF. The output of the operational amplifier is connected to the inverting input of the operational amplifier via the feedback resistor RF1. The output of the operational amplifier is connected to the A / D sampling circuit 13.

[0068] Please continue reading Figure 5 When the photodiode PD1 is turned on and the infrared signal irradiates the photodiode, photogenerated electron-hole pairs are generated, resulting in an increase in reverse current. When this reverse current passes through the sampling resistor RH1, a voltage signal is generated at both ends of the sampling resistor RH1. This voltage signal reflects the infrared received signal, but the phase is inverted. The operational amplifier circuit of the present application, as an inverting proportional operational amplifier circuit, not only corrects the phase of the voltage signal, but also, because the inverting proportional operational amplifier circuit only has a differential mode signal when amplifying and processing weak signals, it has stronger anti-interference performance than the in-phase proportional operational amplifier circuit in the related art, and can further improve the signal-to-noise ratio.

[0069] Optionally, the signal conditioning circuit 202 further includes a feedback capacitor CJ1 connected in parallel across the feedback resistor RF1 to prevent the operational amplifier U1C from self-oscillating and to suppress high-frequency noise.

[0070] See also Figure 6 , which is a schematic diagram of the structure of an infrared touch screen provided in the second embodiment of this application. This infrared touch screen includes: a display screen 32 and an infrared touch frame 31; the infrared touch frame 31 is disposed around the display screen 32. The infrared touch screen can be used on various terminal devices. The display screen 32 can display screen content, and the infrared touch frame 31 has a touch positioning function, enabling the terminal device to have touch functionality. The infrared touch frame of this embodiment of the application has the structure of any of the above embodiments and is not further described here.

[0071] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0072] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. An infrared touch frame, characterized in that: include: A frame, a main board and a plurality of slave boards arranged in the frame; the main board includes a signal conditioning circuit and an A / D sampling circuit; the signal conditioning circuit includes a plurality of sampling resistors and an operational amplifier circuit; the slave boards include an infrared receiving circuit; the infrared receiving circuit includes a plurality of optical signal receiving tubes and a plurality of amplifier tubes; The first end of each optical signal receiving tube is used to receive an optical signal receiving tube enable signal; the second end of each optical signal receiving tube is connected to the signal input end of one of the amplifier tubes; the first connection end of the amplifier tube is grounded; the second connection end of the amplifier tube is connected to the first end of one of the sampling resistors via an analog signal bus; the second end of the sampling resistor is connected to the power supply end; the first end of the sampling resistor is also connected to the input end of the operational amplifier circuit; and the output end of the operational amplifier circuit is connected to the input end of the A / D sampling circuit.

2. The infrared touch frame according to claim 1, characterized in that: The operational amplifier circuit includes an operational amplifier, a first resistor, a first capacitor, a second resistor and a feedback resistor; The inverting input terminal of the operational amplifier is connected to the first end of the sampling resistor via a first resistor and a first capacitor; the inverting input terminal of the operational amplifier is also connected to a reference power supply via a second resistor; the non-inverting input terminal of the operational amplifier is connected to the reference power supply; and the output terminal of the operational amplifier is connected to the inverting input terminal of the operational amplifier via a feedback resistor.

3. The infrared touch frame according to claim 2, characterized in that: The operational amplifier circuit further includes a feedback capacitor; the feedback capacitor is connected in parallel across the feedback resistor.

4. The infrared touch frame according to any one of claims 1 to 3, characterized in that: The optical signal receiving tubes are distributed in a matrix of M rows and N columns, and the first ends of the optical signal receiving tubes in the same row receive the same optical signal receiving tube enable signal; wherein M and N are both integers greater than 0.

5. The infrared touch frame according to any one of claims 1 to 3, characterized in that: The optical signal receiving tubes are distributed in a matrix of M rows and N columns, and the second ends of the amplifier tubes corresponding to the optical signal receiving tubes in the same column are connected to the same sampling resistor; wherein M and N are both integers greater than 0.

6. The infrared touch frame according to any one of claims 1 to 3, characterized in that: The main board also includes a master MCU; the master MCU includes a control signal output terminal; the slave board also includes an optical signal receiving tube selection circuit; the optical signal receiving tube selection circuit includes a shift register; the shift register includes an input terminal and multiple output terminals; the input terminal of the shift register is connected to the control signal output terminal of the master MCU via a digital signal bus for receiving a control signal; each output terminal of the shift register is connected to the first terminal of at least one optical signal receiving tube for outputting an optical signal receiving tube enable signal according to the control signal.

7. The infrared touch frame according to any one of claims 1 to 3, characterized in that: The main board further includes a master MCU; the master MCU includes a control signal output terminal; the slave board further includes a slave MCU and an infrared transmitting circuit; the infrared transmitting circuit includes a plurality of infrared transmitters; the slave MCU includes an input terminal and an output terminal; the input terminal of the slave MCU is connected to the control signal output terminal of the master MCU via an analog signal bus or a digital signal bus for receiving a control signal; The output end of the slave MCU is connected to the first end of at least one of the optical signal receiving tubes, and is used to output an optical signal receiving tube enable signal according to a control signal.

8. The infrared touch frame according to any one of claims 1 to 3, characterized in that: The optical signal receiving tube is a photosensitive diode; the first end of the optical signal receiving tube is the cathode of the photosensitive diode; the second end of the optical signal receiving tube is the anode of the photosensitive diode; The amplifier tube is an NPN transistor; the signal input end of the amplifier tube is the base of the NPN transistor; the first connection end of the amplifier tube is the emitter of the NPN transistor; the second connection end of the amplifier tube is the collector of the NPN transistor; or, the amplifier tube is an N-type field effect transistor; the signal input end of the amplifier tube is the gate of the N-type field effect transistor; the first connection end of the amplifier tube is the source of the N-type field effect transistor; and the second connection end of the amplifier tube is the drain of the N-type field effect transistor.

9. The infrared touch frame according to any one of claims 1 to 3, characterized in that: The optical signal receiving tube is a photosensitive diode; the first end of the optical signal receiving tube is the anode of the photosensitive diode; the second end of the optical signal receiving tube is the cathode of the photosensitive diode; The amplifier tube is a PNP transistor; the signal input end of the amplifier tube is the base of the PNP transistor; the first connection end of the amplifier tube is the collector of the PNP transistor; the second connection end of the amplifier tube is the emitter of the PNP transistor; or, the amplifier tube is a P-type field effect transistor; the signal input end of the amplifier tube is the gate of the P-type field effect transistor; the first connection end of the amplifier tube is the drain of the P-type field effect transistor; and the second connection end of the amplifier tube is the source of the P-type field effect transistor.

10. An infrared touch screen, characterized in that: A display screen and the infrared touch frame according to any one of claims 1 to 9; the infrared touch frame is arranged around the display screen.

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