Photoelectric detection circuit, optical trigger tag and radio frequency identification system

Abstract

This utility model discloses a photoelectric detection circuit, a light-triggered tag, and a radio frequency identification system. The photoelectric detection circuit includes: a photoelectric conversion module, a transimpedance amplification module, a comparator module, and a switch module. One end of the photoelectric conversion module is connected to the first input terminal of the transimpedance amplification module, and the other end is grounded. The photoelectric conversion module converts optical signals into electrical signals. A clamping voltage is connected to the second input terminal of the transimpedance amplification module. One end of the switch module is connected to the first input terminal of the transimpedance amplification module, and the second end of the switch module is connected to the output terminal of the transimpedance amplification module. The output terminal of the transimpedance amplification module is connected to the first input terminal of the comparator module, and an adjustable reference voltage is connected to the second input terminal of the comparator module. The output terminal of the comparator module outputs the light detection result. The technical solution provided by this utility model embodiment can detect a wide range of light-triggered signals; and the photoelectric detection circuit has low power consumption, which can reduce the impact on the sensitivity of the photoelectric tag.

Description

Technical Field

[0001] This utility model relates to the field of photoelectric conversion technology, and in particular to a photoelectric detection circuit, a light-triggered tag, and a radio frequency identification system. Background Technology

[0002] Radio frequency identification (RFID) technology, also known as electronic tag technology, is widely used in logistics management, supply chain, item identification and tracking, and wireless sensors. Its basic working principle utilizes the coupling transmission characteristics of radio frequency signals and inductive or electromagnetic fields to power the tag chip while simultaneously reading its information, thus achieving automatic object identification. In complex logistics environments, such as express delivery and air baggage tracking and sorting, there are various interference sources, including metal objects and electromagnetic radiation. Furthermore, with multiple tags within the same radio frequency field, tag reading can easily lead to missed reads and cross-referencing.

[0003] As an innovative achievement in RFID technology, optically triggered tags organically combine photoelectric sensing technology with traditional RFID technology. The tag is equipped with a light detection circuit module, which only initiates the corresponding reading operation when it detects specific light exceeding a preset threshold. This optical event-driven working mode enables optically triggered tags to effectively resist various interferences in complex environments, significantly improving identification efficiency. The light detection module mainly consists of a photosensitive device and a trigger circuit, which work together to achieve accurate detection and response to light. However, in different usage scenarios, the ambient light intensity varies, and therefore the light trigger signal strength also varies. This necessitates setting different photoelectric detection circuits to adapt to the light environment of the optically triggered tag in different environments. Utility Model Content

[0004] This invention provides a photoelectric detection circuit, a light-triggered tag, and a radio frequency identification system. The light detection circuit has a configurable trigger threshold and can detect a wide range of light-triggered signals. Furthermore, the photoelectric detection circuit has low power consumption, which reduces the impact on the sensitivity of the photoelectric tag.

[0005] According to one aspect of this utility model, a photoelectric detection circuit is provided for use in light-triggered electronic tags; the photoelectric detection circuit includes: a photoelectric conversion module, a transimpedance amplification module, a comparison module, and a switching module;

[0006] One end of the photoelectric conversion module is connected to the first input terminal of the transimpedance amplifier module, and the other end is grounded. The photoelectric conversion module is used to convert optical signals into electrical signals. The second input terminal of the transimpedance amplifier module is connected to a clamping voltage.

[0007] One end of the switching module is connected to the first input terminal of the transimpedance amplifier module, and the second end of the switching module is connected to the output terminal of the transimpedance amplifier module.

[0008] The output terminal of the transimpedance amplifier module is connected to the first input terminal of the comparator module, and the second input terminal of the comparator module is connected to an adjustable reference voltage; the output terminal of the comparator module outputs the light detection result.

[0009] Optionally, the transimpedance amplifier module includes: an operational amplifier and a first capacitor;

[0010] One end of the photoelectric conversion module is connected to the inverting input of the operational amplifier, the non-inverting input of the operational amplifier is connected to the clamping voltage, and the output of the operational amplifier is connected to the first input of the comparator module; the first end of the first capacitor is connected to the inverting input of the operational amplifier, and the second end of the first capacitor is connected to the output of the operational amplifier.

[0011] Optionally, the switching module includes a switching transistor;

[0012] The first terminal of the switching transistor is connected to the first terminal of the first capacitor, the second terminal of the switching transistor is connected to the second terminal of the first capacitor, and the control terminal of the switching transistor is connected to a control signal.

[0013] Optionally, the photoelectric detection circuit further includes a capacitive digital-to-analog converter, which is connected to the second input terminal of the comparison module; the capacitive digital-to-analog converter is used to provide an adjustable reference voltage.

[0014] Optionally, the comparison module includes a comparison amplifier;

[0015] The non-inverting input of the comparator amplifier is connected to the output of the transimpedance amplifier module, the inverting input of the comparator amplifier is connected to the capacitive digital-to-analog converter, and the output of the comparator amplifier outputs the comparison result.

[0016] Optionally, the photoelectric detection circuit further includes a latch output module; the input terminal of the latch output module is connected to the output terminal of the comparison module, and the output terminal of the latch output module outputs the photoelectric detection result.

[0017] Optionally, the photoelectric conversion module includes a photodiode, the anode of which is connected to the input terminal of the transimpedance amplifier module, and the cathode of which is grounded.

[0018] Optionally, the switching transistor may include a MOSFET or an IGBT.

[0019] According to a second aspect of the present invention, a light-triggered electronic tag is provided, comprising the photoelectric detection circuit described in any one of the first aspects of the present invention.

[0020] According to a third aspect of the present invention, a radio frequency identification system is provided, comprising a plurality of electronic tags and readers as described in the second aspect of the present invention; the readers are used to emit optical signals to the electronic tags to identify the electronic tags.

[0021] The technical solution provided by this utility model enables the photoelectric conversion module to output a stable conversion current through the clamping voltage connected to the transimpedance amplification module. Then, the magnitude of the amplified output voltage of the conversion current is controlled by the on / off cycle of the switching module. The amplified output voltage can be connected to the first input terminal of the comparator module, and the second input terminal of the comparator module is connected to an adjustable reference voltage. By adjusting the magnitude of the reference voltage, the judgment standard of the comparator module for photoelectric detection results is changed, thereby enabling the detection circuit to have a configurable trigger threshold and detect a wide range of light trigger signals. Furthermore, the switching module can control the amplification factor of the conversion current by the transimpedance amplification module through the on / off cycle, reducing the power consumption of the photoelectric detection circuit, thereby reducing the thermal noise of the photoelectric detection circuit, improving the signal-to-noise ratio, and thus reducing the impact on the sensitivity of the light-triggered electronic tag. The technical solution provided by this utility model can ultimately achieve light intensity detection with a minimum power consumption of 40nW and a maximum of 64 threshold configurations, reaching a minimum of 101ux.

[0022] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A photoelectric detection circuit provided for an embodiment of this utility model;

[0025] Figure 2 Another photoelectric detection circuit provided in this embodiment of the utility model;

[0026] Figure 3 Another photoelectric detection circuit provided in this embodiment of the utility model;

[0027] Figure 4 A signal timing diagram of a photoelectric detection circuit provided for an embodiment of this utility model;

[0028] Figure 5 Another photoelectric detection circuit provided in this embodiment of the utility model;

[0029] Figure 6 Another photoelectric detection circuit provided in this embodiment of the utility model;

[0030] Figure 7 A schematic diagram of the structure of a light-triggered electronic tag provided by this utility model;

[0031] Figure 8 This is a schematic diagram of the structure of a radio frequency identification system provided by this utility model. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0033] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0034] Figure 1 This invention provides a photoelectric detection circuit according to an embodiment of the present invention. The photoelectric detection circuit provided in this embodiment can be applied to photoelectric detection on light-triggered electronic tags. See also... Figure 1The photoelectric detection circuit includes: a photoelectric conversion module 100, a transimpedance amplification module 200, a comparison module 300, and a switching module 400; one end of the photoelectric conversion module 100 is connected to the first input terminal of the transimpedance amplification module 200, and the other end is grounded; the photoelectric conversion module 200 is used to convert optical signals into electrical signals; the second input terminal of the transimpedance amplification module 200 is connected to a clamping voltage Vref; one end of the switching module 400 is connected to the first input terminal of the transimpedance amplification module 200, and the second end of the switching module 400 is connected to the output terminal of the transimpedance amplification module 200; the output terminal of the transimpedance amplification module 200 is connected to the first input terminal of the comparison module 300, and the second input terminal of the comparison module 300 is connected to an adjustable reference voltage Vcmp; the output terminal of the comparison module 300 outputs the light detection result.

[0035] Specifically, the photoelectric conversion module 100 can convert optical signals into current signals for transmission. The first terminal of the photoelectric conversion module 100 can be grounded, and the second terminal can be connected as an output terminal to the first input terminal of the transimpedance amplifier module 200. A clamping voltage Vref can be connected to the second input terminal of the transimpedance amplifier module 200. This clamping voltage controls the voltage Vph at the first input terminal of the transimpedance amplifier module 200 to remain at the value of Vref, thus allowing the photoelectric conversion module to maintain a stable output of the converted current Iph. The transimpedance amplifier module 200 has an integration amplification function, which can amplify the current Iph converted by the photoelectric conversion module 100 and output a voltage Vint. The switching module 400 can be connected in parallel with the transimpedance amplifier module 200, controlling the amplification factor of the converted current Iph by the transimpedance amplifier module 200 through its on and off cycles. In other words, the switching module 400 can control the magnitude of the voltage Vint output by the transimpedance amplifier module 200 through its own on and off times. The voltage Vint output by the transimpedance amplifier module 200 can be connected to the first input terminal of the comparator module 300; the second input terminal of the comparator module 300 can be connected to an adjustable reference voltage Vcmp. For example, when the voltage Vint output by the transimpedance amplifier module 200 is greater than the reference voltage Vcmp, the comparator module 300 outputs a photoelectric detection result indicating that a light signal has been detected; when the voltage Vint output by the transimpedance amplifier module 200 is less than or equal to the reference voltage Vcmp, the comparator module 300 outputs a photoelectric detection result indicating that no light signal has been detected. The magnitude of the reference voltage Vcmp can be adjusted according to the operating environment of the photoelectric detection circuit to match the amplified output voltage Vint of the transimpedance amplifier module 200, so that the photoelectric detection circuit has a configurable trigger threshold and can detect a wide range of light trigger signals.

[0036] The technical solution provided by this utility model embodiment enables the photoelectric conversion module to output a stable conversion current through the clamping voltage connected to the transimpedance amplification module. Then, the magnitude of the amplified output voltage of the conversion current is controlled by the on / off cycle of the switching module. The amplified output voltage can be connected to the first input terminal of the comparator module, and the second input terminal of the comparator module is connected to an adjustable reference voltage. By adjusting the magnitude of the reference voltage, the judgment standard of the comparator module for photoelectric detection results is changed, thereby enabling the detection circuit to have a configurable trigger threshold and detect a wide range of light-triggered signals. Furthermore, the switching module can control the amplification factor of the conversion current by the transimpedance amplification module through its on / off cycle, eliminating the need for a high-power circuit to increase the current amplification factor, thus reducing the power consumption of the photoelectric detection circuit. Further, because the photoelectric detection circuit provided by this utility model has low power consumption, it can reduce the thermal noise of the photoelectric detection circuit and improve the signal-to-noise ratio, thereby reducing the impact on the sensitivity of the light-triggered electronic tag while reducing power consumption.

[0037] Furthermore, by selecting appropriate components in the technical solution provided by this utility model, it is possible to achieve light intensity detection with a minimum power consumption of 40nW and a maximum of 101ux and 64 threshold configurations.

[0038] Optionally, Figure 2 This invention provides yet another photoelectric detection circuit as an embodiment of the present utility model. Based on the above embodiments, see [link to related documentation]. Figure 2 The transimpedance amplifier module 200 includes an operational amplifier 210 and a first capacitor C1. One end of the photoelectric conversion module 100 is connected to the inverting input of the operational amplifier 210, the non-inverting input of the operational amplifier 210 is connected to a clamping voltage Vref, and the output of the operational amplifier 210 is connected to the first input of the comparator module 300. The first end of the first capacitor C1 is connected to the inverting input of the operational amplifier 210, and the second end of the first capacitor C1 is connected to the output of the operational amplifier 210.

[0039] Specifically, a clamping voltage Vref is connected to the non-inverting input of operational amplifier 210. Through the virtual short principle of the operational amplifier, the voltage Vph at the inverting input of operational amplifier 210 can be clamped and controlled to be Vref, thereby ensuring that the photoelectric conversion module 100 can output a stable conversion current Iph. The conversion current Iph allows charge to continuously accumulate on the first capacitor C1, enabling the transimpedance module 200 to integrate and amplify the relatively small conversion current Iph, achieving a larger voltage gain. The output voltage Vint after integration and amplification by operational amplifier 210 can be calculated using the following formula:

[0040]

[0041] Where Cint is the capacitance of the first capacitor C1, and Vint is the voltage output after integration and amplification by the operational amplifier 210.

[0042] Optionally, Figure 3 This is yet another photoelectric detection circuit provided in an embodiment of the present utility model. Figure 4 This is a signal timing diagram of a photoelectric detection circuit provided in an embodiment of the present invention. Based on the above embodiment, see [link to embodiment]. Figure 3 and Figure 4 The switching module 400 includes a switching transistor T1; the first end of the switching transistor T1 is connected to the first end of the first capacitor C1, the second end of the switching transistor T1 is connected to the second end of the first capacitor C1, and the control terminal of the switching transistor T1 is connected to the control signal Rst.

[0043] Specifically, the switching transistor T1 can be a MOS (Metal-Oxide Semiconductor Field Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor). The control terminal of the switching transistor T1 can be connected to a control signal Rst. According to formula (1), the longer the turn-off time of the switching transistor T1, the longer the integration time of the operational amplifier 210, and the larger the amplified output voltage Vint. Therefore, the amplification factor of the operational amplifier 210 can be controlled by controlling the turn-on and turn-off times of the switching transistor T1 according to the control signal Rst. For example, as shown... Figure 3 As shown, the switching transistor T1 can be an N-type MOSFET. When the Rst signal is low, the switching transistor T1 is turned off, and the operational amplifier 210 performs integration amplification. Charge gradually accumulates on capacitor C1, and the output voltage Vint gradually increases. When the Rst signal is high, the switching transistor T1 is turned on, the operational amplifier 210 is short-circuited, the operational amplifier 210 is cleared, the integration amplification process stops, and the output voltage Vint drops sharply to the voltage Vref at the inverting input terminal of the operational amplifier 210. It should be noted that, under the same on / off period of the switching transistor T1, the greater the light intensity, the greater the conversion current Iph generated by the photoelectric conversion module 100, and the greater the output voltage Vint after integration amplification. Therefore, in scenarios requiring a high light trigger threshold, the amplification factor of the transimpedance amplifier module 200 can be reduced or the reference voltage Vcmp can be increased to raise the trigger threshold of the photoelectric detection circuit; in scenarios requiring a low light trigger threshold, the amplification factor of the transimpedance amplifier module 200 can be increased or the reference voltage Vcmp can be decreased to lower the trigger threshold of the photoelectric detection circuit, so that the photoelectric detection circuit has a configurable trigger threshold and can detect a wide range of light trigger signals.

[0044] Optionally, Figure 5 This invention provides another photoelectric detection circuit according to an embodiment of the present invention. Based on the above embodiment, it further includes a capacitive digital-to-analog converter 500, which is connected to the second input terminal of the comparison module 300; the capacitive digital-to-analog converter 500 is used to provide an adjustable reference voltage Vcmp. The comparison module 300 includes a comparison amplifier 310; the non-inverting input terminal of the comparison amplifier 310 is connected to the output terminal of the transimpedance amplifier module 200, the inverting input terminal of the comparison amplifier 310 is connected to the capacitive digital-to-analog converter 500, and the output terminal of the comparison amplifier 310 outputs the comparison result.

[0045] Specifically, the capacitive digital-to-analog converter (CDAC) can provide a multi-level adjustable reference voltage Vcmp. The CDAC's output voltage settling time is short, allowing it to respond to sudden changes in light intensity and avoiding missed detections due to reference voltage Vcmp lag, thus improving the stability and reliability of the photoelectric detection circuit. Furthermore, the CDAC has a small area, making it easy to integrate into the light-triggered tag. When the output voltage Vint is greater than the reference voltage Vcmp, the comparator amplifier 310 determines that a light signal has been detected; when the output voltage Vint is less than or equal to the reference voltage Vcmp, the comparator amplifier 310 determines that no light signal has been detected.

[0046] Optionally, based on the above embodiments, see below. Figure 5 The photoelectric conversion module 100 includes a photodiode D1, the anode of which is connected to the input terminal of the transimpedance amplifier module 200, and the cathode of which is grounded.

[0047] Specifically, photodiode D1 converts ambient light signals into current signals for transmission. The anode of photodiode D1 can be connected to the inverting input of transimpedance amplifier 210, and the cathode of photodiode D1 can be grounded, thus setting photodiode D1 to a reverse-biased configuration. Reverse-biasing photodiode D1 improves its sensitivity to light, making it suitable for more precise optical measurement environments.

[0048] Optionally, Figure 6 This invention provides yet another photoelectric detection circuit as an embodiment of the present utility model. Based on the above embodiments, see [link to related documentation]. Figure 4 and Figure 6 The photoelectric detection circuit also includes a latch output module 600; the input terminal of the latch output module 600 is connected to the output terminal of the comparison module 300, and the output terminal of the latch output module 600 outputs the photoelectric detection result.

[0049] Specifically, the input terminal of the output module 600 can receive the comparison result from the comparison module 300. Within one detection cycle, when the comparison result of the comparison module 300 indicates that a light signal has been detected, the latch output module 600 can lock this result and continuously output a high-level voltage Vout. Until the next detection cycle, when the comparison result of the comparison module 300 indicates that a light signal has not been detected, the latch output module 600 can lock the result of not detecting a light signal and continuously output a low-level voltage Vout, and this cycle repeats. For example, as shown... Figure 4 As shown, when the switching transistor T1 is turned off when the Rst signal is low, the operational amplifier 210 performs integration and amplification, and charge gradually accumulates on the capacitor C1, causing the output voltage Vint to gradually increase. However, when the output voltage Vint is less than the reference voltage Vref, the comparison result output by the comparison module 300 is that no light signal is detected, and the output voltage Vout of the latch output module 600 remains low. Until the output voltage Vint gradually increases and exceeds the reference voltage Vref, the comparison result output by the comparison module 300 is that a light signal is detected, and the output voltage Vout of the latch output module 600 remains high.

[0050] Figure 7 This is a schematic diagram of the structure of a light-triggered electronic tag provided by this utility model. The light-triggered electronic tag 20 includes the photoelectric detection circuit provided in any embodiment of this utility model. The light-triggered electronic tag 20 can be a tag chip based on RFID (Radio Frequency Identification) technology. It can utilize the coupling transmission characteristics of radio frequency signals and inductive or electromagnetic space to power the tag chip while reading chip information, thereby realizing automatic identification of objects.

[0051] Figure 8 This is a schematic diagram of a radio frequency identification (RFID) system provided by this utility model, including a light trigger 20 and a reader / writer 30 as provided in this embodiment; the reader / writer 30 is used to emit light signals to the light trigger 20 to identify electronic tags. The RFID system provided by this utility model has the same beneficial effects as the photoelectric detection circuit in any of the above embodiments, and will not be described in detail here.

[0052] It should be understood that the various forms of the process shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this utility model can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this utility model can be achieved, and this is not limited herein.

[0053] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A photodetection circuit, characterized by, Applied to light-triggered electronic tags; the photoelectric detection circuit includes: a photoelectric conversion module, a transimpedance amplification module, a comparison module, and a switching module; One end of the photoelectric conversion module is connected to the first input terminal of the transimpedance amplifier module, and the other end is grounded. The photoelectric conversion module is used to convert optical signals into electrical signals. The second input terminal of the transimpedance amplifier module is connected to a clamping voltage. One end of the switching module is connected to the first input terminal of the transimpedance amplifier module, and the second end of the switching module is connected to the output terminal of the transimpedance amplifier module. The output terminal of the transimpedance amplifier module is connected to the first input terminal of the comparator module, and the second input terminal of the comparator module is connected to an adjustable reference voltage; the output terminal of the comparator module outputs the light detection result.

2. The photodetection circuit of claim 1, wherein, The transimpedance amplifier module includes: an operational amplifier and a first capacitor; One end of the photoelectric conversion module is connected to the inverting input of the operational amplifier, the non-inverting input of the operational amplifier is connected to the clamping voltage, and the output of the operational amplifier is connected to the first input of the comparator module; the first end of the first capacitor is connected to the inverting input of the operational amplifier, and the second end of the first capacitor is connected to the output of the operational amplifier.

3. The photodetection circuit of claim 2, wherein, The switching module includes a switching transistor; The first terminal of the switching transistor is connected to the first terminal of the first capacitor, the second terminal of the switching transistor is connected to the second terminal of the first capacitor, and the control terminal of the switching transistor is connected to a control signal.

4. The photodetection circuit of claim 1, wherein, It also includes a capacitive digital-to-analog converter, which is connected to the second input terminal of the comparator module; the capacitive digital-to-analog converter is used to provide an adjustable reference voltage.

5. The photodetection circuit of claim 4, wherein, The comparison module includes a comparison amplifier; The non-inverting input of the comparator amplifier is connected to the output of the transimpedance amplifier module, the inverting input of the comparator amplifier is connected to the capacitive digital-to-analog converter, and the output of the comparator amplifier outputs the comparison result.

6. The photodetection circuit of claim 1, wherein, It also includes a latch output module; the input terminal of the latch output module is connected to the output terminal of the comparison module, and the output terminal of the latch output module outputs the photoelectric detection result.

7. The photoelectric detection circuit according to claim 1, characterized in that, The photoelectric conversion module includes a photodiode, the anode of which is connected to the input terminal of the transimpedance amplifier module, and the cathode of which is grounded.

8. The photodetection circuit of claim 3, wherein, The switching transistor includes a MOSFET or an IGBT.

9. An optically triggered electronic tag, characterized by Includes the photoelectric detection circuit according to any one of claims 1-8.

10. A radio frequency identification system, characterized by The device includes multiple electronic tags and readers as described in claim 9; the reader is used to emit light signals to the electronic tag to identify the electronic tag.

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