An infrared receiving circuit suitable for a smart meter

Abstract

The utility model relates to circuit technical field discloses an infrared receiving circuit suitable for intelligent electric meter, including infrared diode, first resistance, second resistance, fourth resistance, first transistor, infrared diode is used for receiving infrared head emission's light signal and will it convert into current, the cathode of infrared diode connects power, the anode passes through second resistance and fifth resistance ground in proper order, one end of fourth resistance connects the common end of second resistance and fifth resistance, and the other end is connected with the base of first crystal end, the collector of first transistor passes through first resistance and is connected with power, and the emitter ground, the collector of first transistor and the common end of first resistance are used as the receiving port of intelligent electric meter, and the receiving port is used for resolving infrared communication signal, the utility model discloses can reduce cost and satisfy standard requirement.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, in particular to an infrared receiving circuit suitable for smart electric meters. Background Art

[0002] At present, low-cost smart electric meters are being rapidly deployed worldwide, and all electric meters are integrated with a local infrared communication interface. For the infrared communication interface, the international standard IEC 62056-21 stipulates that (defining the radiation intensity of an infrared head as Ee / T) when the radiation intensity emitted by the infrared head satisfies 500<Ee / T<5 000 uW / cm², the receiving circuit of the terminal (electric meter) shall be able to receive and parse the signal to conduct infrared communication with the infrared head.

[0003] Basically, the infrared receiving circuits used in electric meters in the industry can only achieve communication within the range of 500<Ee / T<3000 uW / cm², which cannot meet the IEC standard. Summary of Utility Model

[0004] In view of the above, in order to solve the technical problems existing in the foregoing prior art, the utility model provides an infrared receiving circuit suitable for smart electric meters, which is low in cost and can meet the requirements of the IEC standard.

[0005] An infrared receiving circuit suitable for a smart electric meter comprises an infrared diode, a first resistor, a second resistor, a fourth resistor and a first transistor; the infrared diode is configured to receive an optical signal emitted by an infrared head and convert the optical signal into current; a cathode of the infrared diode is connected to a power supply, and an anode of the infrared diode is grounded sequentially through the second resistor and a fifth resistor; one end of the fourth resistor is connected to a common terminal of the second resistor and the fifth resistor, and the other end of the fourth resistor is connected to a base of the first transistor; a collector of the first transistor is connected to the power supply through the first resistor, and an emitter of the first transistor is grounded; a common terminal of the collector of the first transistor and the first resistor serves as a receiving port of the smart electric meter; the receiving port is configured to parse an infrared communication signal.

[0006] Further, when the infrared diode receives an optical signal emitted by the infrared head, the infrared diode is conducted, the power supply drives the first transistor to conduct through the infrared diode, the second resistor and the fourth resistor, and the receiving port of the smart electric meter receives a low-level signal.

[0007] Further, when the infrared diode does not receive the optical signal emitted by the infrared head, that is, when the infrared head does not emit an optical signal, the infrared diode is not conducted, the power supply cannot drive the first transistor to conduct through the infrared diode, the second resistor and the fourth resistor, that is, the first transistor is cut off, and the receiving port of the smart electric meter receives a high-level signal.

[0008] Further, the circuit further comprises a third resistor and a second transistor; one end of the third resistor is connected to the common terminal of the second resistor and the fifth resistor, and the other end is connected to the base of the second transistor; the emitter of the second transistor is grounded, and the collector is suspended.

[0009] Further, the first transistor and the second transistor have the same model.

[0010] Further, by adjusting the parameters of the second resistor, the third resistor, the fourth resistor and the fifth resistor, it is ensured that under different light intensity environments and different saturated currents of the infrared diode, through the clamping of the PN junction of the second transistor, the first transistor can be turned on and off correctly and timely, so that the waveform received by the system meets the requirements.

[0011] Further, the third resistor is used for current limiting.

[0012] Due to the adoption of the above technical solutions, the present utility model has the following advantages: the present utility model can balance low cost and meet standard requirements, and increases the flexibility of on-site adapted infrared heads (as long as the emission intensity of the infrared head meets the requirement: 500<Ee / T<5 000 uW / cm², the receiving port of the smart meter can normally parse infrared communication signals), and no additional separate configuration of the infrared head is required. Description of Drawings

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present utility model, and those of ordinary skill in the art can also obtain other drawings based on these accompanying drawings.

[0014] Figure 1 is a structural schematic diagram of an infrared receiving circuit suitable for a smart meter provided by an embodiment of the present utility model. Detailed Description

[0015] It should be noted that terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also elements inherent to such process, method, article or apparatus.

[0016] The features and properties of the present utility model will be further described in detail below with reference to the embodiments.

[0017] It balances low cost, meets standard requirements, and increases the flexibility of on-site adaptation of infrared heads (as long as the emitted light intensity of the infrared head meets the requirement of 500<Ee / T<5 000 uW / cm², the electric meter's receiving port can normally parse infrared communication signals), eliminating the need to separately configure infrared heads for corresponding markets. As Figure 1 shown, the present utility model provides an embodiment of an infrared receiving circuit suitable for smart electric meters, which comprises: an infrared diode D1, a first resistor R1, a second resistor R2, a fourth resistor R4, and a first transistor Q1; the infrared diode D1 is configured to receive an optical signal emitted by an infrared head and convert it into current; a cathode of the infrared diode D1 is connected to a power supply, and an anode is grounded sequentially through the second resistor R2 and a fifth resistor R5; one end of the fourth resistor R4 is connected to a common terminal of the second resistor R2 and the fifth resistor R5, and the other end is connected to a base of the first transistor; a collector of the first transistor Q1 is connected to the power supply through the first resistor R1, and an emitter of the first transistor Q1 is grounded; the common terminal of the collector of the first transistor Q1 and the first resistor R1 serves as the receiving port of the smart electric meter; the receiving port is configured to parse the infrared communication signal.

[0018] Optionally, when the infrared diode D1 receives the optical signal emitted by the infrared head, the infrared diode D1 conducts, the power supply drives the first transistor Q1 to conduct through the infrared diode D1, the second resistor R2 and the fourth resistor R4, and the receiving port of the smart electric meter receives a low level signal.

[0019] Optionally, when the infrared diode D1 does not receive the optical signal emitted by the infrared head, that is, when the infrared head does not emit an optical signal, the infrared diode D1 does not conduct, the power supply cannot drive the first transistor Q1 to conduct through the infrared diode D1, the second resistor R2 and the fourth resistor R4, that is, the first transistor Q1 is cut off, and the receiving port of the smart electric meter receives a high level signal.

[0020] Optionally, the circuit further comprises a third resistor R3 and a second transistor Q2; one end of the third resistor R3 is connected to the common terminal of the second resistor R2 and the fifth resistor R5, and the other end is connected to a base of the second transistor Q2; an emitter of the second transistor Q2 is grounded, and a collector of the second transistor Q2 is suspended.

[0021] Optionally, the first transistor Q1 and the second transistor Q2 have the same model.

[0022] Optionally, by adjusting the parameters of the second resistor R2, the third resistor R3, the fourth resistor R4 and the fifth resistor R5, it is ensured that under different light intensity environments and different saturation current conditions of the infrared diode D1, through the clamping of the PN junction of the second transistor Q2, the first transistor Q1 can be turned on and off correctly and timely, so that the waveform received by the system meets the requirements.

[0023] Optionally, the third resistor R3 is used for current limiting.

[0024] Based on the above embodiment, when the infrared receiving diode (infrared diode) receives an optical signal transmitted by the infrared emitter of an external device (with an optical intensity of 500<Ee / T<5 000 uW / cm²), D1 is turned on, the system power supply (power supply) drives the first transistor to conduct through D1 / R2 / R4, and the system receiving IO port (the receiving port of the smart electricity meter) receives a low-level signal; When the infrared emitter of the external device does not transmit an optical signal, that is, the optical intensity is close to 0 uW / cm², the infrared receiving diode is not turned on, at this time no electrical signal flows through D1 / R2 / R4, the first transistor Q1 is not turned on, and the system receiving IO port receives a high-level signal; Due to differences in manufacturing processes, the saturation current of D1 varies among different batches, different manufacturers and different production times. When R2 / R5 / R4 are fixed, the voltage drop across D1 will also be different, the voltage at the intersection node of R4 / R5 (the common terminal of R4 and R5) will have great differences. Superimposed with the characteristics of the internal PN junction of Q1, the positive pulse width and negative pulse width of the waveform received by the system receiving IO port cannot meet the requirement that the pulse width is ≥ standard pulse width of 80%; In the technical solution of the present utility model, a second transistor Q2 of the same model as Q1 and a third resistor R3 for current limiting are added between the base of Q1 and the ground to minimize the difference between Q1 and Q2. By adjusting the values of R2 / R3 / R4 / R5, it can be ensured that under different light intensity environments and different saturation currents of D1, through the clamping of the PN junction of Q2, Q1 can be turned on and off correctly and timely, so that the waveform received by the system satisfies that the positive pulse width or negative pulse width ± pulse width of the waveform is ≥ standard pulse width of 80%.

[0025] The above described embodiments only express the specific implementation of the present utility model, and the description thereof is relatively specific and detailed, but it should not be construed as limiting the protection scope of the present utility model. It should be noted that, for those skilled in the art, without departing from the concept of the technical solution of the present utility model, several variations and improvements can be made, which all belong to the protection scope of the present utility model.

Claims

1. An infrared receiving circuit suitable for smart meters, characterized in that, The device includes an infrared diode, a first resistor, a second resistor, a fourth resistor, and a first transistor. The infrared diode receives the light signal emitted by the infrared head and converts it into current. The cathode of the infrared diode is connected to a power supply, and the anode is grounded through the second and fifth resistors in sequence. One end of the fourth resistor is connected to the common terminal of the second and fifth resistors, and the other end is connected to the base of the first transistor. The collector of the first transistor is connected to the power supply through the first resistor, and the emitter is grounded. The common terminal of the collector of the first transistor and the first resistor serves as the receiving port of the smart meter. The receiving port is used to analyze the infrared communication signal.

2. The infrared receiving circuit for smart meters according to claim 1, characterized in that, When the infrared diode receives the light signal emitted by the infrared head, the infrared diode turns on. The power supply drives the first transistor to turn on through the infrared diode, the second resistor, and the fourth resistor, and the receiving port of the smart meter receives a low-level signal.

3. The infrared receiving circuit for smart meters according to claim 1, characterized in that, When the infrared diode does not receive the light signal emitted by the infrared head, that is, when the infrared head does not emit a light signal, the infrared diode is not conducting. The power supply cannot drive the first transistor to conduct through the infrared diode, the second resistor, and the fourth resistor. That is, the first transistor is cut off, and the receiving port of the smart meter receives a high-level signal.

4. The infrared receiving circuit for smart meters according to claim 1, characterized in that, It also includes a third resistor and a second transistor; one end of the third resistor is connected to the common terminal of the second and fifth resistors, and the other end is connected to the base of the second transistor; the emitter of the second transistor is grounded, and the collector is left floating.

5. The infrared receiving circuit for smart meters according to claim 4, characterized in that, The first transistor and the second transistor have the same model number.

6. The infrared receiving circuit for smart meters according to claim 2, characterized in that, By adjusting the second, third, fourth, and fifth resistors, it is ensured that under different light intensity environments and with different saturation currents of the infrared diode, the clamping of the PN junction of the second transistor enables the first transistor to be correctly and timely turned on and off, so that the waveform received by the system meets the requirements.

7. The infrared receiving circuit for smart meters according to claim 4, characterized in that, The third resistor is used for current limiting.

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