A digitally adjustable current limiting circuit for adjusting the brightness of fill lights

Abstract

This invention provides a digitally adjustable current-limiting circuit for adjusting the brightness of a fill light, including a current-limiting chip main circuit, a first analog switch resistor connection circuit, a second analog switch resistor connection circuit, and a third analog switch resistor connection circuit. The input terminal of the current-limiting chip main circuit is connected to a power supply, and the output terminal is connected to the fill light power supply. The first, second, and third analog switch resistor connection circuits are connected in series, and their output terminals are connected to the input terminal of the current-limiting chip main circuit. The input terminals of the first, second, and third analog switch resistor connection circuits can receive control signals from external software. The advantages of this invention are: it enables direct digital adjustment of the current in the fill light circuit, significantly improving the user experience.

Description

Technical Field

[0001] This utility model relates to the field of circuit technology, specifically to a digitally adjustable current limiting circuit for adjusting the brightness of a fill light. Background Technology

[0002] Photographic fill lights are devices used in photography to increase illumination and improve lighting conditions. They help photographers take better photos in low-light or less-than-ideal environments. Fill lights can be continuous light sources (such as LED lights) or non-continuous light sources (such as flash units), each with its specific application scenarios and technical characteristics.

[0003] As a component providing light for camera devices, supplementary lighting is also widely used in POS machines, palm vein recognition devices, and other similar applications. The brightness of supplementary lighting must vary depending on the external environment. Current supplementary lighting primarily adjusts brightness by changing the duty cycle of the PWM control signal. However, this method results in the supplementary lighting operating in a discontinuous on-off manner, thus regulating its brightness. For high-speed or certain specialized cameras, this discontinuous illumination can negatively impact image quality, leading to a less than ideal user experience. Utility Model Content

[0004] To address the problems in existing technologies, this utility model provides a digitally adjustable current-limiting circuit for adjusting the brightness of a fill light. By incorporating a cooperating current-limiting chip main circuit, a first analog switch resistor access circuit, a second analog switch resistor access circuit, and a third analog switch resistor access circuit, the control signal from external software can control the resistance values ​​output from these circuits to the current-limiting chip main circuit, thereby adjusting the final current-limiting value. This enables direct digital adjustment of the current in the fill light circuit. This method ensures that the fill light is always on, without affecting the camera's imaging effect, significantly improving the user experience and solving the problem in existing technologies where PWM control signals affecting fill light brightness adjustment negatively impact camera imaging.

[0005] This utility model provides a digitally adjustable current limiting circuit for adjusting the brightness of a fill light, comprising a current limiting chip main circuit, a first analog switch resistor connection circuit, a second analog switch resistor connection circuit, and a third analog switch resistor connection circuit. The input terminal of the current limiting chip main circuit is connected to a power supply, and the output terminal of the current limiting chip main circuit is connected to the fill light power supply. The first, second, and third analog switch resistor connection circuits are connected in series, and their output terminals are connected to the input terminal of the current limiting chip main circuit. The input terminals of the first, second, and third analog switch resistor connection circuits can receive control signals from external software. The control signals from the external software can control the resistance values ​​of the first, second, and third analog switch resistor connection circuits output to the current limiting chip main circuit, thereby adjusting the final current limiting value output by the current limiting chip main circuit.

[0006] This utility model is further improved in that the main circuit of the current limiting chip is provided with a current limiting chip U1 and a capacitor C1. The current limiting chip U1 has 6 pins. The 4th pin of the current limiting chip U1 is connected to the power supply of the fill light. The 3rd pin of the current limiting chip U1 is connected to the output terminal of the first analog switch resistor access circuit. The 4th pin of the current limiting chip U1 is connected to the 6th pin of the current limiting chip U1, one end of the capacitor C1, and the power supply. The 2nd pin of the current limiting chip U1 and the other end of the capacitor C1 are grounded.

[0007] This utility model is further improved in that the first analog switch resistor access circuit is provided with an analog switch chip U2 and a resistor R1. The analog switch chip U2 has 10 pins. The 8th pin of the analog switch chip U2 is connected to one end of the resistor R1, the 9th pin of the analog switch chip U2 is connected to the other end of the resistor R1, the 2nd pin of the analog switch chip U2 can receive control signals from external software, the 3rd pin of the analog switch chip U2 is connected to the 3rd pin of the current limiting chip U1, and the 4th pin of the analog switch chip U2 is connected to the output terminal of the second analog switch resistor access circuit.

[0008] This utility model is further improved in that the second analog switch resistor access circuit is provided with an analog switch chip U3 and a resistor R2. The analog switch chip U3 has 10 pins. The 8th pin of the analog switch chip U3 is connected to one end of the resistor R2, the 9th pin of the analog switch chip U3 is connected to the other end of the resistor R2, the 2nd pin of the analog switch chip U3 can receive control signals from external software, the 3rd pin of the analog switch chip U3 is connected to the 4th pin of the analog switch chip U2, and the 4th pin of the analog switch chip U3 is connected to the output terminal of the third analog switch resistor access circuit.

[0009] This utility model is further improved in that the third analog switch resistor access circuit is provided with an analog switch chip U4 and a resistor R3. The analog switch chip U4 has 10 pins. The 8th pin of the analog switch chip U4 is connected to one end of the resistor R3, the 9th pin of the analog switch chip U4 is connected to the other end of the resistor R3, the 2nd pin of the analog switch chip U4 can receive control signals from external software, the 3rd pin of the analog switch chip U4 is connected to the 4th pin of the analog switch chip U3, and the 4th pin of the analog switch chip U4 is grounded.

[0010] This utility model is further improved, and the current limiting chip U1 is model number LP3321.

[0011] In a further improvement to this invention, the analog switch chip U2 is model SGM7227_MSOP10, and the resistance of the resistor R1 is 0.1Ω.

[0012] In a further improvement to this invention, the analog switch chip U3 is model SGM7227_MSOP10, and the resistance of resistor R2 is 0.2Ω.

[0013] In a further improvement to this invention, the analog switch chip U4 is model SGM7227_MSOP10, and the resistance of resistor R3 is 0.4Ω.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows: It provides a digitally adjustable current limiting circuit for adjusting the brightness of a fill light. By setting up a cooperating current limiting chip main circuit, a first analog switch resistor access circuit, a second analog switch resistor access circuit, and a third analog switch resistor access circuit in the digitally adjustable current limiting circuit for adjusting the brightness of the fill light, the control signal of the external software can control the resistance of the first analog switch resistor access circuit, the second analog switch resistor access circuit, and the third analog switch resistor access circuit to the current limiting chip main circuit, thereby adjusting the final output current limiting value of the current limiting chip main circuit. This enables direct digital adjustment of the current in the fill light circuit. By using a binary mathematical method, the current limiting resistor value connected to the current limiting chip main circuit is digitally changed, thereby changing the fill light current and achieving the effect of adjusting the brightness. Compared with the working method of controlling the fill light with PWM signal to turn on and off, this method can ensure that the fill light is always on at all times, without affecting the imaging effect of the camera, greatly improving the user experience, and solving the problem that the imaging effect of the camera is affected by the adjustment of the brightness of the fill light by the PWM control signal in the prior art. Attached Figure Description

[0015] To more clearly illustrate the solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a circuit diagram of a digitally adjustable current limiting circuit for adjusting the brightness of a fill light, according to the present invention. Detailed Implementation

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this invention are used to distinguish different objects, not to describe a particular order.

[0018] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0020] like Figure 1 As shown, this utility model provides a digitally adjustable current limiting circuit for adjusting the brightness of a fill light, including a current limiting chip main circuit, a first analog switch resistor connection circuit, a second analog switch resistor connection circuit, and a third analog switch resistor connection circuit. The input terminal of the current limiting chip main circuit is connected to a power supply, and the output terminal of the current limiting chip main circuit is connected to the fill light power supply. The first analog switch resistor connection circuit, the second analog switch resistor connection circuit, and the third analog switch resistor connection circuit are connected in series, and their output terminals are connected to the input terminal of the current limiting chip main circuit. The input terminals of the first analog switch resistor connection circuit, the second analog switch resistor connection circuit, and the third analog switch resistor connection circuit can receive control signals from external software. The control signals from the external software can control the resistance values ​​of the first analog switch resistor connection circuit, the second analog switch resistor connection circuit, and the third analog switch resistor connection circuit output to the current limiting chip main circuit, thereby adjusting the final current limiting value output by the current limiting chip main circuit. In this embodiment, the control signal from the external software can control the resistance values ​​of the first analog switch resistor input circuit, the second analog switch resistor input circuit, and the third analog switch resistor input circuit, which are output to the main circuit of the current limiting chip. This adjusts the final current limiting value output by the main circuit of the current limiting chip, enabling direct digital adjustment of the current in the fill light circuit. By using a binary mathematical method, the current limiting resistor value connected to the main circuit of the current limiting chip is digitally changed, thereby changing the fill light current and adjusting the brightness. Compared with the PWM signal-controlled fill light operation that turns the fill light on and off intermittently, this method ensures that the fill light is always on, without affecting the camera's imaging effect, and significantly improves the user experience.

[0021] like Figure 1As shown, the main circuit of the current limiting chip includes a current limiting chip U1 and a capacitor C1. The current limiting chip U1 is an LP3321 with six pins. Pin 4 of the current limiting chip U1 is connected to the power supply of the fill light. Pin 3 of the current limiting chip U1 is connected to the output terminal of the first analog switch resistor circuit. Pin 4 of the current limiting chip U1 is connected to pin 6 of the current limiting chip U1, one end of capacitor C1, and the power supply. Pin 2 of the current limiting chip U1 and the other end of capacitor C1 are grounded. In this embodiment, the main circuit of the current limiting chip is used to connect to the power supply of the fill light. The current limiting chip U1 acts as the driver IC for the fill light. The current driving the fill light is determined by the resistance between pin 3 and ground. The voltage between pin 3 and ground is fixed at 0.2V. Therefore, the operating current of the fill light I = 0.2 / R, where R is the resistance between pin 3 and ground. By changing the value of R, the current of the lamp can be changed.

[0022] like Figure 1As shown, the first analog switch resistor connection circuit includes an analog switch chip U2 and a resistor R1. The analog switch chip U2 is an SGM7227_MSOP10, and the resistor R1 has a resistance of 0.1Ω. The analog switch chip U2 has 10 pins. Pin 8 of the analog switch chip U2 is connected to one end of the resistor R1, pin 9 of the analog switch chip U2 is connected to the other end of the resistor R1, pin 2 of the analog switch chip U2 can receive control signals from external software, pin 3 of the analog switch chip U2 is connected to pin 3 of the current limiting chip U1, and pin 4 of the analog switch chip U2 is connected to the output terminal of the second analog switch resistor connection circuit. The second analog switch resistor connection circuit includes an analog switch chip U3 and a resistor R2. The analog switch chip U3 is an SGM7227_MSOP10, and the resistor R2 has a resistance of 0.2Ω. The analog switch chip U3 has 10 pins, and pin 8 of the analog switch chip U3 is connected to the other end of the resistor R1. One end of R2 is connected, pin 9 of analog switch chip U3 is connected to the other end of resistor R2, pin 2 of analog switch chip U3 can receive control signals from external software, pin 3 of analog switch chip U3 is connected to pin 4 of analog switch chip U2, and pin 4 of analog switch chip U3 is connected to the output terminal of the third analog switch resistor access circuit; the third analog switch resistor access circuit is equipped with analog switch chip U4 and resistor R3, wherein the model of analog switch chip U4 is SGM7227_MSOP10, the resistance value of resistor R3 is 0.4Ω, analog switch chip U4 has 10 pins, pin 8 of analog switch chip U4 is connected to one end of resistor R3, pin 9 of analog switch chip U4 is connected to the other end of resistor R3, pin 2 of analog switch chip U4 can receive control signals from external software, pin 3 of analog switch chip U4 is connected to pin 4 of analog switch chip U3, and pin 4 of analog switch chip U4 is grounded. In this embodiment, the first analog switch resistor connection circuit, the second analog switch resistor connection circuit, and the third analog switch resistor connection circuit are connected in series and output the final resistor to pin 3 of the current limiting chip U1. When SET_0 is high, resistor R1 is connected to the circuit; when SET_0 is low, analog switch chip U2 is connected to the circuit in a short-circuit manner. Similarly, SET_1 and SET_2 determine whether resistors R2 and R3 are connected to the circuit, or whether analog switch chips U3 and U4 are connected to the circuit in a short-circuit manner. It can be seen that resistors R1, R2, and R3 are selected in binary multiples of 0.1 ohms. The advantage of this is that they can be combined in binary to form any natural number.When we need to set the current of the fill light, we first calculate the value of R using the formula I = 0.2 / R. Then, we convert the value of R into binary, which means we can set the levels of SET_0, SET_1, and SET_2 to make the resistance between pin 3 of the current limiting chip U1 and ground reach the calculated value of R. In this way, we can achieve digitally adjustable current.

[0023] As can be seen from the above, this utility model provides a digitally adjustable current limiting circuit for adjusting the brightness of a fill light. By setting up a cooperating current limiting chip main circuit, a first analog switch resistor access circuit, a second analog switch resistor access circuit, and a third analog switch resistor access circuit in the digitally adjustable current limiting circuit for adjusting the brightness of the fill light, the control signal of external software can control the resistance values ​​of the first, second, and third analog switch resistor access circuits output to the current limiting chip main circuit, thereby adjusting the final output current limiting value of the current limiting chip main circuit. This enables direct digital adjustment of the current in the fill light circuit. Utilizing a binary mathematical method, the current limiting resistor value connected to the current limiting chip main circuit is digitally changed, thereby changing the fill light current and achieving the effect of adjusting brightness. Compared with the PWM signal-controlled fill light's on-off operation, this method ensures that the fill light is always on, without affecting the camera's imaging effect, significantly improving the user experience and solving the problem in the prior art where PWM control signals affecting the fill light's brightness affects the camera's imaging effect.

[0024] The specific embodiments described above are preferred embodiments of this utility model, and are not intended to limit the specific scope of this utility model. The scope of this utility model includes but is not limited to the specific embodiments described above. All equivalent changes made in accordance with this utility model are within the protection scope of this utility model.

Claims

1. A digitally adjustable current limiting circuit for adjusting the brightness of a fill light, characterized in that: The device includes a current-limiting chip main circuit, a first analog switch resistor connection circuit, a second analog switch resistor connection circuit, and a third analog switch resistor connection circuit. The input terminal of the current-limiting chip main circuit is connected to a power supply, and the output terminal is connected to the power supply of a supplementary light. The first, second, and third analog switch resistor connection circuits are connected in series, and their output terminals are connected to the input terminal of the current-limiting chip main circuit. The input terminals of the first, second, and third analog switch resistor connection circuits can receive control signals from external software. The control signals from the external software can control the resistance values ​​of the first, second, and third analog switch resistor connection circuits output to the current-limiting chip main circuit, thereby adjusting the final current-limiting value output by the current-limiting chip main circuit.

2. The digitally adjustable current limiting circuit for regulating the brightness of a fill light of claim 1, wherein: The main circuit of the current limiting chip includes a current limiting chip U1 and a capacitor C1. The current limiting chip U1 has 6 pins. The 4th pin of the current limiting chip U1 is connected to the power supply of the fill light. The 3rd pin of the current limiting chip U1 is connected to the output terminal of the first analog switch resistor access circuit. The 4th pin of the current limiting chip U1 is connected to the 6th pin of the current limiting chip U1, one end of the capacitor C1, and the power supply. The 2nd pin of the current limiting chip U1 and the other end of the capacitor C1 are grounded.

3. The digitally adjustable current limiting circuit for regulating the brightness of a fill light of claim 2, wherein: The first analog switch resistor access circuit includes an analog switch chip U2 and a resistor R1. The analog switch chip U2 has 10 pins. The 8th pin of the analog switch chip U2 is connected to one end of the resistor R1, the 9th pin of the analog switch chip U2 is connected to the other end of the resistor R1, the 2nd pin of the analog switch chip U2 can receive control signals from external software, the 3rd pin of the analog switch chip U2 is connected to the 3rd pin of the current limiting chip U1, and the 4th pin of the analog switch chip U2 is connected to the output terminal of the second analog switch resistor access circuit.

4. The digitally adjustable current limiting circuit for regulating the brightness of a fill light of claim 3, wherein: The second analog switch resistor access circuit includes an analog switch chip U3 and a resistor R2. The analog switch chip U3 has 10 pins. The 8th pin of the analog switch chip U3 is connected to one end of the resistor R2, the 9th pin of the analog switch chip U3 is connected to the other end of the resistor R2, the 2nd pin of the analog switch chip U3 can receive control signals from external software, the 3rd pin of the analog switch chip U3 is connected to the 4th pin of the analog switch chip U2, and the 4th pin of the analog switch chip U3 is connected to the output terminal of the third analog switch resistor access circuit.

5. The digitally adjustable current limiting circuit for regulating the brightness of a fill light of claim 4, wherein: The third analog switch resistor access circuit includes an analog switch chip U4 and a resistor R3. The analog switch chip U4 has 10 pins. The 8th pin of the analog switch chip U4 is connected to one end of the resistor R3, the 9th pin of the analog switch chip U4 is connected to the other end of the resistor R3, the 2nd pin of the analog switch chip U4 can receive control signals from external software, the 3rd pin of the analog switch chip U4 is connected to the 4th pin of the analog switch chip U3, and the 4th pin of the analog switch chip U4 is grounded.

6. The digitally adjustable current limiting circuit for adjusting the brightness of a fill light of claim 5, wherein: The current limiting chip U1 is model LP3321.

7. The digitally adjustable current limiting circuit for regulating the brightness of a fill light of claim 6, wherein: The analog switch chip U2 is model SGM7227_MSOP10, and the resistor R1 has a resistance of 0.1Ω.

8. The digitally adjustable current limiting circuit for regulating the brightness of a fill light of claim 7, wherein: The analog switch chip U3 is model SGM7227_MSOP10, and the resistor R2 has a resistance of 0.2Ω.

9. The digitally adjustable current limiting circuit for regulating the brightness of a fill light of claim 8, wherein: The analog switch chip U4 is model SGM7227_MSOP10, and the resistor R3 has a resistance of 0.4Ω.

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