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EP-4475417-B1 - POWER SUPPLY CIRCUIT

EP4475417B1EP 4475417 B1EP4475417 B1EP 4475417B1EP-4475417-B1

Inventors

  • GUO, QIAOSHI

Dates

Publication Date
20260506
Application Date
20230216

Claims (5)

  1. A power supply circuit comprising a device (Q1), of which a second electrode (2) and a third electrode (3) are configured to form a first series circuit with a load requiring for power supply, the power supply circuit having a positive power source (V+) and a power ground, wherein the positive power source is connected to the second electrode (2), wherein the power supply circuit further comprises a light-emitting element (LD) and a receiving element (BT), the receiving element is a photoelectric converting element, the light-emitting element (LD) is configured to provide the receiving element (BT) with optical signals, the electrical signals produced by the receiving element (BT) are amplified by the device (Q1) and provided to the load, the device (Q1) is configured to operate in its amplification region, wherein the power supply circuit further comprises a voltage-stabilizing unit (Z1) which is configured to be connected to the load in parallel, wherein one end of the voltage-stabilizing unit (Z1) is connected to the third electrode (3) and another end of the voltage-stabilizing unit (Z1) is connected to the power ground of the power supply circuit; wherein the second electrode (2), the first electrode (1), and the receiving element (BT) are connected in series to form a driver circuit for the device (Q1); wherein one end of the receiving element (BT) is connected to a first electrode (1) of the device (Q1), and another end of the receiving element (BT) is connected either to the power ground or to the third electrode (3).
  2. The power supply circuit according to claim 1, wherein the device (Q1) is configured for constant current.
  3. The power supply circuit according to claim 1, wherein the light-emitting element (LD) is an LED.
  4. The power supply circuit according to claim 1, wherein the photoelectric converting element is a photodiode.
  5. The power supply circuit according to claim 1, wherein the voltage-stabilizing unit (Z1, Z2) is a zener diode or a transistor circuit.

Description

TECHNICAL FIELD The present invention relates generally to a power supply circuit, and more specifically, to a power supply circuit that can output pure current (voltage) for power supply of an audio circuit. BACKGROUND The current (voltage) outputted by power supply circuits of conventional electronic circuits can be readily affected by the influence of the voltage of input power sources (e.g., ripple, ultra-low-frequency voltage fluctuations, harmonics, and electromagnetic interference), and there also exist problems that electric grid interference can be easily introduced and the normal operation of a circuit can be affected by impure output current (voltage). US 4 652 764 A and US 4 450 517 A disclose prior art power supply circuits. SUMMARY The objects of the present invention is to solve the problems mentioned in Background and to provide a power supply circuit that can output pure current (voltage). An apparatus according to the invention is defined in the appended independent claim. Preferred embodiments are defined in the dependent claims. As shown in FIG. 1, a power supply circuit comprises a device Q1, a light-emitting element LD, and a receiving element BT (which may be a photodiode or photocell). A second electrode 2 and a third electrode 3 of the device Q1 are used to form a first series circuit with a load (i.e. the load connected to Output Terminal VO+; the load is an amplification circuit) requiring for power supply. The light-emitting element LD provides the receiving element BT, which is connected to a first electrode of the device Q1, with optical signals. The electrical signals produced by the receiving element BT are amplified by the device Q1 operating in its amplification region and provided to the load. Since the output current of the device Q1 is dependent on the counterpart of the receiving element BT, so that the purity (stability) of the output current can be realized. The present invention is reasonable in design, having the advantage of high purity (namely, hardly to be affected by the influence of the power quality of input power sources and electromagnetic interference) of output current (voltage). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a power supply circuit as well as a schematic diagram 1 of Embodiment 1 of the present invention.FIG. 2 is schematic diagram 2 of Embodiment 1 of a power supply circuit of the present invention.FIG. 3 is schematic diagram of Comparative Example 1 of a power supply circuit useful to understand the present invention.FIG. 4 is schematic diagram 1 of Comparative Example 2 of a power supply circuit useful to understand the present invention.FIG. 5 is schematic diagram 2 of Comparative Example 2 of a power supply circuit of the present invention. DETAILED DESCRIPTION Embodiments and comparative examples of a power supply circuit are shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5. A power supply circuit comprises a device Q1, a light-emitting element LD, and a receiving element BT. A second electrode 2 and a third electrode 3 of the device Q1 are used to form a first series circuit with a load (i.e. the load connected to Output Terminal VO+ or VO-; the load is an amplification circuit) requiring for power supply. The light-emitting element LD provides the receiving element BT, which is connected to a first electrode of the device Q1, with optical signals. The electrical signals produced by the receiving element BT is amplified by the device Q1 operating in its amplification region and provided to the load. Since the output current of the device Q1 is dependent on the counterpart of the receiving element BT, so that the purity (stability) of the output current can be realized. Embodiment 1 of the present invention: FIG. 1 and FIG. 2. are schematic diagram 1 and schematic diagram 2 of the present embodiment, respectively. A second electrode 2, a first electrode 1, and a receiving element BT are connected in series to form a driver circuit for device Q1; the driver circuit is connected to an input power source in parallel (as shown in FIG.1). FIG.2 shows that the two ends of the receiving element BT are connected to the first electrode 1 and a third electrode 3, respectively. The main advantage in FIG.1 and FIG.2 is that operational requirements can be still readily satisfied even if the receiving element BT has extremely small output voltage, wherein the receiving element BT can adopt a single photodiode. As shown in FIG.3, in Comparative Example 1 useful to understand the present invention, the two ends of the receiving element BT are connected to the first electrode 1 and the second electrode 2, respectively. The output voltage of the receiving element BT is required to be high enough to drive the device Q1 into amplification state (without entering into saturation state, however). The receiving element BT may adopt a plurality of photodiodes used in a way of serial connection, with the main advantage of overcoming th