Infrared signal amplifying circuit, infrared signal processing circuit and infrared touch screen

Abstract

The utility model provides an infrared signal amplification circuit, a processing circuit and an infrared touch screen. The amplification circuit comprises an infrared signal input end, a triode, a transimpedance amplification module, a direct current feedback module and an amplification signal output end. A base electrode of the triode is connected with an infrared signal input end, a collector electrode of the triode is connected with an input end of the transimpedance amplification module, an output end of the transimpedance amplification module is connected with an amplification signal output end, an input end of the direct current feedback module is connected with an output end of the transimpedance amplification module, and an output end of the direct current feedback module is connected with a collector electrode of the triode. The emitter of the triode is grounded. According to the utility model, the direct-current feedback module is used for feeding back direct-current compensation current to the triode, so that direct current generated during irradiation of an incandescent lamp cannot flow through the transimpedance amplification module too much, and the anti-interference performance of the incandescent lamp and the signal-to-noise ratio of an output signal are effectively improved; and the transimpedance value of the transimpedance amplification module can be increased to enhance the strength of the output signal.

Description

Technical Field

[0001] The utility model relates to the technical field of touch screens, in particular to an infrared signal amplification circuit, a processing circuit and an infrared touch screen. Background Art

[0002] In an infrared touch screen, an infrared signal amplification circuit is used to receive and amplify weak infrared signals captured by an infrared sensor or an infrared receiving diode, so that these infrared signals can be recognized and processed to achieve touch control of the screen. The existing infrared signal amplification circuit usually consists of a triode and a transimpedance amplifier. When irradiated by an incandescent lamp, the interference signal generated is close to the DC state and is amplified by the transimpedance amplifier, so that the amplified infrared signal is affected. Therefore, the existing infrared signal amplification circuit has poor anti-incandescent lamp interference performance, low signal-to-noise ratio of the output signal, and weak output signal intensity. Summary of the Utility Model

[0003] The utility model provides an infrared signal amplification circuit, a processing circuit and an infrared touch screen, which have the characteristics of strong anti-incandescent lamp interference performance, high signal-to-noise ratio of the output signal and strong output signal intensity.

[0004] To solve the above technical problems, in the first aspect of the embodiment of the utility model, an infrared signal amplification circuit is provided, which includes an infrared signal input end, a triode, a transimpedance amplification module, a DC feedback module and an amplified signal output end;

[0005] The base of the triode is connected to the infrared signal input end, the collector of the triode is connected to the input end of the transimpedance amplification module, the output end of the transimpedance amplification module is connected to the amplified signal output end, the input end of the DC feedback module is connected to the output end of the transimpedance amplification module, the output end of the DC feedback module is connected to the collector of the triode, and the emitter of the triode is grounded.

[0006] As a preferred solution, the DC feedback module includes a low-pass filtering unit and a DC feedback adjustment unit;

[0007] The input end of the low-pass filtering unit is connected to the output end of the transimpedance amplification module, the output end of the low-pass filtering unit is connected to the input end of the DC feedback adjustment unit, and the output end of the DC feedback adjustment unit is connected to the collector of the triode.

[0008] As a preferred solution, the low-pass filtering unit includes a first resistor and a capacitor;

[0009] One end of the first resistor is connected to the output end of the transimpedance amplification module, the other end of the first resistor is connected to one end of the capacitor, one end of the capacitor is connected to the input end of the DC feedback adjustment unit, and the other end of the capacitor is grounded.

[0010] As a preferred solution, the DC feedback adjustment unit includes a first operational amplifier, a second resistor, a third resistor, and a fourth resistor;

[0011] The non-inverting input end of the first operational amplifier is connected to the output end of the low-pass filter unit, the inverting input end of the first operational amplifier is connected to one end of the second resistor, the other end of the second resistor is grounded, one end of the third resistor is connected to the inverting input end of the first operational amplifier, the other end of the third resistor is connected to the output end of the first operational amplifier, the output end of the first operational amplifier is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the collector of the triode.

[0012] As a preferred solution, the transimpedance amplification module includes a second operational amplifier and a fifth resistor;

[0013] The inverting input end of the second operational amplifier is connected to the collector of the triode, the non-inverting input end of the second operational amplifier is connected to a voltage source, one end of the fifth resistor is connected to the inverting input end of the second operational amplifier, the other end of the fifth resistor is connected to the output end of the second operational amplifier, and the output end of the second operational amplifier is respectively connected to the amplified signal output end and the input end of the DC feedback module.

[0014] As a preferred solution, the triode is an NPN triode.

[0015] In the second aspect of the embodiments of the present invention, an infrared signal processing circuit is provided, including a detection circuit and the infrared signal amplification circuit according to any one of the first aspect; the input end of the detection circuit is connected to the amplified signal output end of the infrared signal amplification circuit.

[0016] In the third aspect of the embodiments of the present invention, an infrared touch screen is provided, including the infrared signal processing circuit according to the second aspect.

[0017] Compared with the prior art, the beneficial effects of the embodiments of the present invention are that by setting a DC feedback module in the infrared signal amplification circuit, a DC compensation current can be fed back to the triode, ensuring that the DC current generated during the incandescent lamp irradiation does not flow through the transimpedance amplification module too much, effectively improving the anti-incandescent lamp interference performance and the signal-to-noise ratio of the output signal, and the transimpedance value of the transimpedance amplification module can be increased to enhance the output signal strength. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of a preferred embodiment of the infrared signal amplification circuit provided by the present utility model;

[0019] Figure 2 It is a schematic structural diagram of another preferred embodiment of the infrared signal amplification circuit provided by the present utility model;

[0020] Figure 3 It is a schematic connection diagram of the infrared signal amplification circuit in the embodiment of the present utility model. Specific embodiments

[0021] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. The purpose of providing these embodiments is to make the disclosure of the present utility model more thorough and comprehensive. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present utility model.

[0022] In the description of the present application, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined with "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0023] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. The terms "vertical", "horizontal", "left", "right", "up", "down" and similar expressions used herein are only for the purpose of illustration, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present utility model. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0024] In the description of the present application, it should be noted that unless otherwise defined, all technical and scientific terms used in the present utility model have the same meaning as commonly understood by those skilled in the technical field to which this belongs. The terms used in the specification of the present utility model are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0025] See Figures 1 to 3 , the first aspect of the embodiment of the present utility model provides an infrared signal amplification circuit, including an infrared signal input end, a triode Q1, a transimpedance amplification module, a DC feedback module, and an amplified signal output end Vout;

[0026] The base of the triode Q1 is connected to the infrared signal input end, the collector of the triode Q1 is connected to the input end of the transimpedance amplification module, the output end of the transimpedance amplification module is connected to the amplified signal output end Vout, the input end of the DC feedback module is connected to the output end of the transimpedance amplification module, the output end of the DC feedback module is connected to the collector of the triode Q1, and the emitter of the triode Q1 is grounded.

[0027] Specifically, Figure 1 The circuit within the dashed box in Figure 1As shown, the infrared signal input terminal is used to connect to the infrared receiving diode D1. The cathode of the infrared receiving diode D1 is connected to the external voltage source V1, and the anode is connected to the infrared signal input terminal. When it receives an infrared signal, it converts the infrared signal into a current and inputs it to the infrared signal amplification circuit in this embodiment through the infrared signal input terminal. Further, the input current flows through the triode Q1 for the first amplification. The amplified current flows out from the collector of the triode Q1, and then is converted into a voltage through the transimpedance amplification module and the voltage is amplified. Finally, it is output through the amplified signal output terminal Vout. It should be noted that the effective output signal in this embodiment is a signal with a relatively high frequency. Since the existing infrared signal amplification circuit is only composed of the triode Q1 and the transimpedance amplifier, the interference signal generated when irradiated by an incandescent lamp is close to the DC state, so it will be amplified by the transimpedance amplifier, causing the operational amplifier output of the second operational amplifier U2 in the transimpedance amplifier to saturate to the maximum output voltage, submerging the high-frequency effective output signal, resulting in a low signal-to-noise ratio of the output signal. Moreover, it is difficult to increase the transimpedance value of the transimpedance amplifier. The reason is that if the transimpedance value of the transimpedance amplifier is large, the interference signal generated when irradiated by an incandescent lamp will also increase, further reducing the signal-to-noise ratio of the output signal. If the transimpedance value of the transimpedance amplifier is low, it will cause the output signal strength to be weak, affecting the subsequent recognition and processing of the infrared signal and resulting in low touch control sensitivity of the screen. Therefore, this embodiment additionally sets up a DC feedback module, which can feedback a DC compensation current to the triode Q1 to ensure that the DC current generated when irradiated by an incandescent lamp does not flow through the transimpedance amplification module too much, ensuring that the high-frequency effective output signal is not submerged, effectively improving the anti-incandescent lamp interference performance and the signal-to-noise ratio of the output signal, and the transimpedance value of the transimpedance amplification module can be increased to enhance the output signal strength.

[0028] As a preferred solution, the DC feedback module includes a low-pass filtering unit and a DC feedback adjustment unit;

[0029] The input end of the low-pass filtering unit is connected to the output end of the transimpedance amplification module, the output end of the low-pass filtering unit is connected to the input end of the DC feedback adjustment unit, and the output end of the DC feedback adjustment unit is connected to the collector of the triode Q1.

[0030] It should be noted that the DC feedback module in this embodiment further includes a low-pass filtering unit and a DC feedback adjustment unit. Since the finally amplified effective output signal is a signal with a relatively high frequency, the low-pass filtering unit is used to filter out the high-frequency signals in the signal output by the transimpedance amplification module, obtain a DC signal and input it to the DC feedback adjustment unit. The DC feedback adjustment unit can adjust the magnitude of the DC compensation current fed back to the triode Q1, thereby being able to adjust the anti-incandescent lamp interference performance of the infrared signal amplification circuit.

[0031] As a preferred solution, the low-pass filter unit includes a first resistor R1 and a capacitor C1;

[0032] One end of the first resistor R1 is connected to the output end of the transimpedance amplification module, the other end of the first resistor R1 is connected to one end of the capacitor C1, one end of the capacitor C1 is connected to the input end of the DC feedback adjustment unit, and the other end of the capacitor C1 is grounded.

[0033] Specifically, in this embodiment, the high-frequency signals in the signals output by the transimpedance amplification module are filtered by the low-pass filter unit composed of the first resistor R1 and the capacitor C1, and the capacitor C1 outputs a DC voltage to the DC feedback adjustment unit after charging is completed.

[0034] As a preferred solution, the DC feedback adjustment unit includes a first operational amplifier U1, a second resistor R2, a third resistor R3, and a fourth resistor R4;

[0035] The non-inverting input terminal of the first operational amplifier U1 is connected to the output end of the low-pass filter unit, the inverting input terminal of the first operational amplifier U1 is connected to one end of the second resistor R2, the other end of the second resistor R2 is grounded, one end of the third resistor R3 is connected to the inverting input terminal of the first operational amplifier U1, the other end of the third resistor R3 is connected to the output end of the first operational amplifier U1, the output end of the first operational amplifier U1 is connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the collector of the triode Q1.

[0036] Specifically, in this embodiment, according to loop regulation, when the first operational amplifier U1 outputs an amplified signal in phase with the input signal, by adjusting the size of the fourth resistor R4 within the output capacity range of the operational amplifier through the DC compensation current, the size of the DC compensation current fed back to the triode Q1 can be changed, thereby adjusting the anti-incandescent lamp interference performance of the infrared signal amplification circuit. It should be noted that the closed-loop gain of the first operational amplifier U1 is 1 + R2 / R1.

[0037] As a preferred solution, the transimpedance amplification module includes a second operational amplifier U2 and a fifth resistor R5;

[0038] The inverting input terminal of the second operational amplifier U2 is connected to the collector of the triode Q1, the non-inverting input terminal of the second operational amplifier U2 is connected to the voltage source V2, one end of the fifth resistor R5 is connected to the inverting input terminal of the second operational amplifier U2, the other end of the fifth resistor R5 is connected to the output end of the second operational amplifier U2, and the output end of the second operational amplifier U2 is respectively connected to the amplified signal output terminal Vout and the input end of the DC feedback module.

[0039] Specifically, after the first amplification of the current by the triode Q1, since the inverting input terminal of the second operational amplifier U2 is connected to the collector of the triode Q1, and both ends of the fifth resistor R5 are respectively connected to the inverting input terminal and the output terminal of the second operational amplifier U2 to form a feedback circuit, the input current can be converted into a voltage and amplified for the second time.

[0040] As a preferred solution, the triode Q1 is an NPN triode Q1.

[0041] The infrared signal amplification circuit provided by the embodiment of the present invention can feedback a DC compensation current to the triode Q1 by setting a DC feedback module in the infrared signal amplification circuit, ensuring that the DC current generated when the incandescent lamp irradiates will not flow through the transimpedance amplification module too much, effectively improving the anti-incandescent lamp interference performance and the signal-to-noise ratio of the output signal, and the transimpedance value of the transimpedance amplification module can be increased to enhance the output signal strength.

[0042] The second aspect of the embodiment of the present invention provides an infrared signal processing circuit, including a detection circuit and the infrared signal amplification circuit as described in any one of the first aspects; the input terminal of the detection circuit is connected to the amplified signal output terminal of the infrared signal amplification circuit.

[0043] Specifically, the infrared signal amplification circuit sends the amplified voltage to the detection circuit through the amplified signal output terminal. The detection circuit is used to judge whether the infrared receiving diode receives an infrared signal. Since the infrared signal amplification circuit is used to amplify the infrared signal, the detection range of the infrared signal is increased.

[0044] The third aspect of the embodiment of the present invention provides an infrared touch screen, including the infrared signal processing circuit as described in the second aspect.

[0045] The infrared signal amplification circuit, processing circuit and infrared touch screen provided by the embodiment of the present invention can feedback a DC compensation current to the triode by setting a DC feedback module in the infrared signal amplification circuit, ensuring that the DC current generated when the incandescent lamp irradiates will not flow through the transimpedance amplification module too much, effectively improving the anti-incandescent lamp interference performance and the signal-to-noise ratio of the output signal, and the transimpedance value of the transimpedance amplification module can be increased to enhance the output signal strength.

[0046] The above is the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. An infrared signal amplification circuit, characterized in that It includes an infrared signal input terminal, a triode, a transimpedance amplification module, a DC feedback module, and an amplified signal output terminal; The base of the triode is connected to the infrared signal input terminal, the collector of the triode is connected to the input terminal of the transimpedance amplification module, the output terminal of the transimpedance amplification module is connected to the amplified signal output terminal, the input terminal of the DC feedback module is connected to the output terminal of the transimpedance amplification module, the output terminal of the DC feedback module is connected to the collector of the triode, and the emitter of the triode is grounded.

2. The infrared signal amplification circuit according to claim 1, characterized in that, The DC feedback module includes a low-pass filtering unit and a DC feedback adjustment unit; The input terminal of the low-pass filtering unit is connected to the output terminal of the transimpedance amplification module, the output terminal of the low-pass filtering unit is connected to the input terminal of the DC feedback adjustment unit, and the output terminal of the DC feedback adjustment unit is connected to the collector of the triode.

3. The infrared signal amplification circuit according to claim 2, wherein The low-pass filtering unit includes a first resistor and a capacitor; One end of the first resistor is connected to the output terminal of the transimpedance amplification module, the other end of the first resistor is connected to one end of the capacitor, one end of the capacitor is connected to the input terminal of the DC feedback adjustment unit, and the other end of the capacitor is grounded.

4. The infrared signal amplification circuit according to claim 2, characterized in that The DC feedback adjustment unit includes a first operational amplifier, a second resistor, a third resistor, and a fourth resistor; The non-inverting input terminal of the first operational amplifier is connected to the output terminal of the low-pass filtering unit, the inverting input terminal of the first operational amplifier is connected to one end of the second resistor, the other end of the second resistor is grounded, one end of the third resistor is connected to the inverting input terminal of the first operational amplifier, the other end of the third resistor is connected to the output terminal of the first operational amplifier, the output terminal of the first operational amplifier is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the collector of the triode.

5. The infrared signal amplification circuit according to claim 1, wherein The transimpedance amplification module includes a second operational amplifier and a fifth resistor; The inverting input terminal of the second operational amplifier is connected to the collector of the triode, the non-inverting input terminal of the second operational amplifier is connected to a voltage source, one end of the fifth resistor is connected to the inverting input terminal of the second operational amplifier, the other end of the fifth resistor is connected to the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is respectively connected to the amplified signal output terminal and the input terminal of the DC feedback module.

6. The infrared signal amplification circuit according to any one of claims 1 to 5, characterized in that, The triode is an NPN triode.

7. An infrared signal processing circuit, characterized in that It includes a detection circuit and the infrared signal amplification circuit according to any one of claims 1 to 6; the input terminal of the detection circuit is connected to the amplified signal output terminal of the infrared signal amplification circuit.

8. An infrared touch screen, characterized in that, It includes the infrared signal processing circuit according to claim 7.

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