LED driving device and electronic equipment

Abstract

The present invention relates to an LED driving device and an electronic device, which comprises: a power supply circuit for providing a power supply voltage, a control circuit for generating brightness indication information, a signal conversion circuit for converting the brightness indication information into a corresponding analog voltage signal, and a MOS tube arranged on a power supply circuit of an LED. Based on the transfer characteristic curve of the MOS tube, when the power supply voltage remains unchanged, the drain current of the MOS tube is controlled by controlling the voltage of the analog voltage signal applied to the gate of the MOS tube, so as to control the current variation amplitude through the LED power supply circuit within a preset range, so that the LED stably emits the brightness corresponding to the brightness indication information. The MOS tube is used as a current control device, and the current flowing through the LED is adjusted by controlling the analog voltage value applied to the gate of the MOS tube, thereby realizing brightness adjustment. The stable voltage applied to the gate makes the current flowing through the LED stable and avoids unnecessary fluctuations.

Description

Technical Field

[0001] The present invention relates to the field of lighting technology, and in particular to an LED driving device and an electronic device. Background Art

[0002] A light emitting diode (LED) is a semiconductor light source that emits light when a forward current passes through it, and the brightness of the light is positively correlated with the current passing through it. Compared with traditional light sources, light emitting diodes have the advantages of high luminous efficiency, long service life, and small size, and are therefore widely used in various devices as light sources.

[0003] Traditional LED brightness adjustment is based on analog signals. It adjusts the current through the LED by controlling the reference voltage applied to the LED power supply circuit to provide the desired brightness. However, this analog dimming method cannot achieve digital control, and the adjustment effect is difficult to guarantee.

[0004] In addition to the traditional analog dimming method, there is also a technical solution that uses pulse width modulation (PWM) to adjust the brightness of LEDs. It adjusts the average current through the LED by adjusting the duty cycle and changing the ratio of the switching time, thereby adjusting the brightness of the LED. However, the PWM dimming method is usually only suitable for high-brightness and high-power LEDs, etc. For application scenarios that are not sensitive to flicker and current stability, the naturally existing flicker defects caused by its dimming principle are not conducive to application in some low-brightness scenarios. Summary of the invention

[0005] The LED driving device and electronic device provided in the embodiments of the present application are intended to solve at least some of the defects of the existing LED driving devices.

[0006] In the first aspect, an embodiment of the present application provides an LED driving device. The LED driving device includes: a power supply circuit configured to provide a power supply voltage for the LED; a control circuit configured to generate brightness indication information corresponding to a user operation; a signal conversion circuit configured to convert the brightness indication information into a corresponding analog voltage signal; and a regulating circuit, wherein the regulating circuit includes: a MOS tube arranged on the power supply circuit of the LED; wherein, based on the transfer characteristic curve of the MOS tube, when the power supply voltage remains unchanged, the drain current of the MOS tube is controlled by controlling the voltage of the analog voltage signal applied to the gate of the MOS tube, so that the current variation amplitude through the LED power supply circuit is controlled within a preset range, so that the LED stably emits the brightness corresponding to the brightness indication information.

[0007] Optionally, the LED driving device also includes: a peripheral unit, which is configured to: convert into a corresponding operation electrical signal in response to the application of a user operation; wherein the control circuit is communicatively connected to the peripheral unit and is configured to: generate brightness indication information represented by a digital signal according to the operation electrical signal; the peripheral unit is selected from one or more of the following devices: a knob, a button, a touch display screen and a host computer.

[0008] Optionally, the power supply circuit is further configured to: provide a reference voltage; the signal conversion circuit includes: an adjustable voltage divider whose resistance value can vary within a preset range; wherein the reference voltage is provided to the input end of the adjustable voltage divider, and the output end of the adjustable voltage divider is connected to the gate of the MOS tube; the adjustable voltage divider is configured to: change the resistance value between the input end and the output end according to the received brightness indication information, so that the output end forms an analog voltage signal corresponding to the brightness indication information.

[0009] Optionally, the power supply circuit is also configured to: provide a reference voltage; the signal conversion circuit includes: a digital-to-analog converter; the digital-to-analog converter has a digital signal input terminal and an analog signal output terminal; wherein the reference voltage is provided to the digital-to-analog converter so that the brightness indication information received at the digital signal input terminal is converted into a corresponding analog voltage signal and output from the analog signal output terminal.

[0010] Optionally, the regulating circuit further includes: a controllable switch connected in series with the LED; wherein the controllable switch is configured to switch between an on state and an off state according to a received synchronization signal, so as to interrupt or connect a power supply circuit of the LED.

[0011] Optionally, the MOS transistor and the controllable switch are discrete electronic devices; or the MOS transistor and the controllable switch are integrated into the same chip.

[0012] Optionally, the regulation circuit further includes: a logic gate circuit; wherein the logic gate circuit is an AND gate, configured to: modulate the received synchronization signal and the analog voltage signal to generate a modulation signal; and provide the modulation signal to the gate of the MOS tube.

[0013] Optionally, the LED driving device further comprises: a level conversion circuit; wherein the level conversion circuit is configured to: convert a received initial synchronization signal into the synchronization signal, and provide the synchronization signal to the controllable switch.

[0014] Optionally, the power supply circuit comprises: a low voltage dropout linear regulator; wherein the low voltage dropout linear regulator is configured to: form the power supply voltage for powering the LED.

[0015] In a second aspect, an embodiment of the present application further provides an electronic device, which includes: an LED; and the LED driving device as described above; wherein the LED driving device is connected to the LED to control the light luminance of the LED.

[0016] At least one advantageous aspect of the LED driving device provided in the embodiment of the present application is: utilizing the transfer characteristic curve of the metal oxide semiconductor field effect transistor (MOS), connecting the MOS tube as a current control device to the power supply circuit of the LED, and adjusting the current flowing through the LED by controlling the analog voltage value applied to the gate of the MOS tube to achieve brightness adjustment. The stable voltage applied to the gate makes the current flowing through the LED stable and avoids unnecessary fluctuations.

[0017] In addition, the analog voltage value applied to the gate of the MOS tube can be generated by an additional signal conversion circuit according to the received digital control signal, thereby realizing the control of the LED brightness by the digital signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0019] Figure 1 This is the waveform of the current flowing through the LED in the PWM control mode;

[0020] Figure 2 A functional block diagram of an LED driving device provided in an embodiment of the present application;

[0021] Figure 3 It is a schematic diagram of the transfer characteristic curve of a typical MOS tube;

[0022] Figure 4 A functional block diagram of an LED driving device provided by another embodiment of the present application;

[0023] Figure 5 A circuit schematic diagram showing the connection between the knob and the low-pass filter provided in an embodiment of the present application;

[0024] Figure 6 A circuit schematic diagram of a signal conversion chip provided in an embodiment of the present application;

[0025] Figure 7 A functional block diagram of a signal conversion circuit provided in an embodiment of the present application;

[0026] Figure 8A circuit schematic diagram of a signal conversion circuit provided in an embodiment of the present application;

[0027] Fig. 9 A functional block diagram of a signal conversion circuit provided by another embodiment of the present application;

[0028] Fig.10 A circuit schematic diagram of a signal conversion circuit provided in another embodiment of the present application;

[0029] Fig.11 A functional block diagram of a MOS tube and a controllable switch connected in series provided in an embodiment of the present application;

[0030] Fig.12 A circuit schematic diagram of a MOS tube and a controllable switch integrated into a driver according to an embodiment of the present application;

[0031] Fig.13 A functional block diagram of a logic gate circuit provided in an embodiment of the present application;

[0032] Fig.14 A circuit schematic diagram showing the connection between the level conversion circuit and the regulating circuit provided in an embodiment of the present application;

[0033] Fig.15 A functional block diagram of a low voltage drop linear regulator is provided for a power supply circuit provided in an embodiment of the present application;

[0034] Fig.16 A circuit schematic diagram of a low voltage dropout linear regulator provided in an embodiment of the present application;

[0035] Fig.17 A circuit schematic diagram of a control circuit provided in an embodiment of the present application;

[0036] Fig.18 A circuit schematic diagram of a first linear voltage regulator provided in an embodiment of the present application;

[0037] Fig.19 This is a circuit schematic diagram of the second linear voltage regulator provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present invention, the present invention is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom" etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present invention and simplifying the description, 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 therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0039] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification and in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0040] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] In the process of implementing this application, the applicant found that the existing analog dimming method of changing the resistance value through a potentiometer cannot achieve digital control, which is not conducive to the precise adjustment of the brightness of the light source. The brightness adjustment method based on the PWM signal is to adjust the average current, so there will be a problem of current fluctuation. Especially in the application scenario with lower brightness, the fluctuation of LED light brightness due to current fluctuation will be more obvious, which will cause the light source to work unstable and unable to provide stable brightness.

[0042] For example, Figure 1 The current waveform under the control of the LED driver model TPS92515 is shown in Figure 1. Figure 1 As shown, there are obvious fluctuations in its current waveform.

[0043] Accordingly, the embodiment of the present application provides a new LED driving device, which can achieve digital dimming while ensuring the stability of the current passing through the LED, reducing the current fluctuation as much as possible so that the light source can provide stable and reliable brightness.

[0044] The LED driver uses the transfer characteristic curve of the metal oxide semiconductor field effect transistor (MOS) and connects the MOS tube as a current control device into the power supply circuit of the LED. Specifically, the transfer characteristic of the MOS tube refers to the control effect of the gate-source voltage (VGS) on the drain current (ID).

[0045] like Figure 3 As shown in the transfer characteristic curve of the MOS tube, under a fixed drain-source voltage (VDS), there is a positive correlation between the gate voltage (VGS) and the drain current (ID). Therefore, while keeping the voltage of the power supply circuit unchanged, the drain current (ID) can be controlled by controlling the gate voltage (VGS). Therefore, the current flowing through the LED can be accurately controlled and adjusted by changing the analog voltage value applied to the gate of the MOS tube to ensure the stability of the LED brightness.

[0046] In addition, the analog voltage value applied to the gate of the MOS tube can be generated by an additional signal conversion circuit according to the received digital control signal, thereby realizing the control of the LED brightness by the digital signal.

[0047] Those skilled in the art can understand that, based on similar principles, the LED driving device provided in the embodiment of the present application can also be applied to any suitable type of lighting scene that requires a stable light source.

[0048] Figure 2 The functional block diagram of the LED driving device provided in the embodiment of the present application is as follows: Figure 2 As shown, the LED driving device 20 includes: a power supply circuit 21 , a control circuit 22 , a signal conversion circuit 23 and a regulating circuit 24 .

[0049] The power supply circuit 21 is a power supply circuit used to provide a suitable power supply voltage to support the operation of the LED and the functional circuits in the LED driving device. It can provide a suitable number of target voltages according to actual conditions. For example, the DC voltage (5V and 3.3V) for powering electronic devices such as chips, the reference voltage for digital-to-analog conversion or comparator operation, and the forward voltage for driving the LED to light up.

[0050] In this application, for the convenience of explanation and description, the voltage provided by the power supply circuit is referred to as supply voltage, reference voltage, base voltage, etc. according to its different functions. The voltage prefix is ​​only used to indicate the function of the voltage and is not used to limit the specific voltage value.

[0051] It is understood by those skilled in the art that, based on the needs of practical applications, a variety of different electronic circuits can be used to provide a specific target voltage. For example, in order to facilitate access to the mains network, the power supply circuit may include an AC to DC and DC to DC voltage conversion circuit to provide a suitable operating voltage (e.g., 5V or 3.3V) for most logic devices, and for electronic devices in functional circuits that have high requirements for voltage noise, an LDO circuit may be further added to power such electronic devices to provide a more stable voltage.

[0052] Preferably, in order to ensure the stability of the LED brightness as much as possible, a high-current low-voltage dropout linear regulator can be used to generate a supply voltage to power the LED. In other words, the voltage in the LED power supply circuit is generated by a high-current low-voltage dropout linear regulator.

[0053] Similarly, in order to improve the reliability of signal conversion, the reference voltage or base voltage used by the signal conversion circuit when performing analog voltage signal conversion can be provided by a precision reference voltage source.

[0054] The control circuit 22 is a control core for performing logic operations. It can be a microprocessor or a single-chip microcomputer, which can convert the user's operation instructions into corresponding brightness indication information and provide it to the signal conversion circuit 23. Specifically, the brightness indication information is electronic information represented in the form of a digital signal.

[0055] The signal conversion circuit 23 is a functional circuit capable of forming an analog voltage signal. It receives the brightness indication information from the control circuit 22 and converts it into a corresponding analog voltage signal. In the present application, "corresponding" means that there is a one-to-one mapping relationship between two signals.

[0056] The regulating circuit 24 is a functional circuit disposed in the power supply circuit of the LED to regulate the brightness of the LED. In this embodiment, the regulating circuit 24 at least includes a MOS tube.

[0057] Please continue reading Figure 2 The gate of the MOS tube is connected to the output end of the signal conversion circuit 23, and the formed analog voltage signal will be applied to the MOS tube. Correspondingly, the MOS tube will form a drain current corresponding to the analog voltage signal. Such a control method can ensure that the current variation amplitude through the LED is controlled within a smaller preset range. The smaller preset range refers to a very small current value difference that is technically acceptable. For example, a difference of 5% or less. In other words, the drain current of the MOS tube is stable.

[0058] In actual use, by changing the output brightness indication information, the size of the analog voltage signal applied to the gate of the MOS tube can be changed, thereby changing the drain current of the MOS tube (that is, the current passing through the LED), so that the LED can stably emit the brightness corresponding to the brightness indication information.

[0059] In some embodiments, in order to collect and receive user operations, Figure 4 As shown, the LED driving device 20 may further include: a peripheral unit 25 .

[0060] The peripheral unit 25 is an electronic device for collecting user operations and converting them into corresponding electrical signals. It can be any suitable type of interactive device according to actual needs, as long as it can respond to user operations and convert them into corresponding operation electrical signals.

[0061] For example, the peripheral unit 25 may be one or more of a knob, a button, and a touch screen. Further, the peripheral unit 25 may also be a host computer, and the control circuit 22 directly receives instruction information generated by the host computer.

[0062] In some embodiments, Figure 5 As shown, when the peripheral unit 25 is a knob, the LED driving device 20 may further include: a low-pass filter.

[0063] The low-pass filter is disposed between the knob KNOB and the control circuit 22, and can perform noise filtering on the operation electrical signal generated by the knob to improve the reliability of the operation electrical signal.

[0064] Specifically, Figure 5 As shown, the low-pass filter includes a resistor R1, a resistor R21 and a capacitor C25. The knob KNOB is powered by a DC voltage source VCC.

[0065] The electrical signal output pin of the knob KNOB is connected to the first end of the resistor R21, and can output an operation electrical signal. The ground pin of the knob KNOB is connected to the reference ground GND, and the power pin of the knob KNOB is connected to the DC voltage source VCC. The resistor R21 is respectively connected to the first end of the resistor R1, the first end of the capacitor C25, and the control circuit 22. The first end of the resistor R1 is connected to the control circuit 22, the second end of the resistor R1 is connected to the reference ground GND, the first end of the capacitor C25 is connected to the control circuit 22, and the second end of the capacitor C25 is connected to the reference ground GND.

[0066] In some embodiments, Figure 6 As shown, when the peripheral unit 25 is a touch screen or a host computer, the LED driving device 20 further includes: a signal conversion chip U1.

[0067] Among them, the signal conversion chip U1 can be arranged between the peripheral unit 25 and the control circuit 22. When the peripheral unit 25 and the control circuit 22 communicate through the USB data line, the operation electrical signal represented by the USB signal is converted into an operation electrical signal represented by the serial port signal, thereby realizing the brightness setting of the LED through the touch display screen or the host computer.

[0068] Specifically, Figure 6 As shown, the signal conversion chip can be a USB to serial port chip CH340N, wherein pin 1 (UD+) is connected to the DD+ data line of the USB bus, pin 2 (UD-) is connected to the DD- data line of the USB bus, pin 3 (GND) is connected to the ground GND, pin 5 (VCC) is respectively connected to the power supply, the first end of capacitor C32 and the first end of capacitor C31, the second end of capacitor C32 and the second end of capacitor C31 are both connected to the ground GND, pin 6 (TXD) and pin 7 (RXD) are both connected to the control circuit 22 for outputting an operating electrical signal in the form of a serial port signal, pin 8 (V3) is connected to the first end of capacitor C30, and the second end of capacitor C30 is connected to the ground GND.

[0069] In order to fully describe the inventive concept of the present application, the specific implementation of the signal conversion circuit is described in detail below, and a variety of different specific implementation methods are provided. Figure 7 and Figure 8 is a functional block diagram of a signal conversion circuit provided in an embodiment of the present application, showing a signal conversion circuit implemented based on an adjustable voltage divider (eg, a potentiometer). Fig. 9 and Fig.10 It is a functional block diagram of a signal conversion circuit provided in another embodiment of the present application, showing a signal conversion circuit implemented based on a digital-to-analog converter.

[0070] In some embodiments, based on the reference voltage provided by the power supply circuit, such as Figure 7 As shown, the signal conversion circuit 23 includes: an adjustable voltage divider 232.

[0071] The adjustable voltage divider 232 has an input terminal 2321 and an output terminal 2322. The resistance value between the input terminal 2321 and the output terminal 2322 can vary within a preset range.

[0072] The reference voltage provided by the power supply circuit can be provided to the input terminal 2321 of the adjustable voltage divider. The resistance value between the input terminal 2321 and the output terminal 2322 of the adjustable voltage divider 232 is adjusted to a suitable value according to the brightness indication information, so that the output terminal 2322 generates a corresponding analog voltage signal.

[0073] Specifically, Figure 8As shown, the adjustable voltage divider 232 includes: a variable resistor POT and a fixed resistor R01.

[0074] The first end of the variable resistor POT is connected to the second voltage VREF, the second end of the variable resistor POT is connected to the first end of the fixed resistor R01, and the second end of the fixed resistor R01 is connected to the reference ground GND. The sliding end of the variable resistor serves as the output end of the adjustable voltage divider 232 to form a corresponding analog voltage signal.

[0075] Specifically, when the variable resistor uses a potentiometer, assuming that the total resistance of the potentiometer is r1, the fixed resistance is r2, and the resistance of the potentiometer input to the output is r3. Based on the principle of resistor series voltage division, it can be calculated that the ratio between the output analog voltage signal and the reference voltage VREF is r3 / (r1+r2).

[0076] Alternatively, the potentiometer may be a conventional analog potentiometer, a digital potentiometer, or any other suitable type of electronic device capable of achieving a change in resistance value.

[0077] The reference voltage VREF can select a suitable value according to the requirements of the signal conversion circuit, which determines the maximum value of the analog voltage signal. The fixed resistor R01 determines the minimum value of the analog voltage signal, which can select a suitable resistance value according to the requirements of the signal conversion circuit.

[0078] In some embodiments, based on the reference voltage provided by the power supply circuit, such as Fig. 9 As shown, the signal conversion circuit 23 includes: a digital-to-analog converter 233 .

[0079] The digital-to-analog converter 233 has a digital signal input terminal 2331 and an analog signal output terminal 2332. The reference voltage formed by the power supply circuit is provided to the digital-to-analog converter 233 so that the brightness indication information received by the digital signal input terminal 2331 is converted into a corresponding analog voltage signal and output from the analog signal output terminal 2332.

[0080] Alternatively, in addition to using the reference voltage formed by the power supply circuit as the external reference voltage of the digital-to-analog converter 233, a voltage provided by a reference voltage source directly integrated inside the digital-to-analog converter 233 may also be used as the reference voltage.

[0081] Specifically, Fig.10As shown, the part of the power supply circuit that forms the reference voltage may include: power management chip U2 (model AD586KRZ), voltage regulator diode D1, capacitor C1, capacitor C2, inductor L3, capacitor C3, capacitor C5 and capacitor C6. The signal conversion circuit 23 specifically includes: digital-to-analog converter U3 (model DAC8552), resistor R2, resistor R3 and resistor R7.

[0082] Among them, pin 2 of the power management chip U2 is respectively connected to the first end of the capacitor C2 and the first end of the inductor U3, for receiving the input voltage VIN, the second end of the capacitor C2 is connected to the reference ground GND, the second end of the inductor L3 is respectively connected to the first end of the capacitor C1 and the cathode of the Zener diode D1, the anode of the Zener diode D1 is connected to the input voltage VIN, the second end of the capacitor C1 is connected to the reference ground GND, pin 4 of the power management chip U2 is connected to the reference ground GND, pin 8 of the power management chip U1 is connected to the first end of the capacitor C3, the second end of the capacitor C3 is connected to GND, and pin 6 of the power management chip U2 outputs a third voltage, which is provided to the digital-to-analog converter U3 for use.

[0083] Pin 6 of the power management chip U2 is respectively connected to the first end of capacitor C5, the first end of capacitor C6, pin 1 (VDD) and pin 2 of the digital-to-analog converter U3, and the second end of capacitor C5 and the second end of capacitor C6 are both connected to the reference ground GND.

[0084] Pin 7 of the digital-to-analog converter U3 is connected to the first end of the resistor R2, the second end of the resistor R2 is connected to the control circuit 22, and pin 7 is used to receive brightness indication information. Pin 6 of the digital-to-analog converter U2 is connected to the first end of the resistor R3, the second end of the resistor R3 is connected to the control circuit 22, and pin 6 is used to receive a clock signal. Pin 5 of the digital-to-analog converter U3 is connected to the first end of the resistor R7, the second end of the resistor R7 is connected to the control circuit 22, and pin 5 is used to receive a synchronous clock signal. Pin 8 of the digital-to-analog converter U3 is connected to the reference ground GND, and pin 4 of the digital-to-analog converter U3 is connected to the gate of the MOS tube, and the analog voltage signal corresponding to the brightness indication information received by pin 7 is applied to the gate of the MOS tube.

[0085] In some embodiments, as described above, in order to meet the requirement of synchronization between the light source and the camera during the shooting process, such as Fig.11 As shown, the regulating circuit 24 may further include: a controllable switch K.

[0086] The controllable switch K refers to an electronic device that can switch between an on state and an off state according to a received control signal, and can be arranged in a power supply circuit of an LED in a serial connection to control the on and off state of the power supply circuit.

[0087] In this application, the control signal provided to the controllable switch K is called a "synchronization signal". It is synchronized with the camera shooting action, so that the controllable switch K can be switched to the on state when the camera is shooting, so that the LED is lit, and at the same time, it is switched to the off state when the camera is not shooting, interrupting the power supply circuit of the LED.

[0088] In other embodiments, different from Fig.11 As shown, the MOS tube and the controllable switch K are independent electronic devices, which are arranged in the power supply circuit in a serial connection. The MOS tube and the controllable switch can be integrated into the same functional circuit and implemented by an integrated chip. Fig.12 As shown, a driver chip model IC-HN3 can be used.

[0089] Specifically, Fig.12 As shown, the driver chip IC-HN3 also includes: a control pin CI, two input pins (a positive input pin EP and a negative input pin EN), two ground pins (GND) and two cathode pins (LDK). The driver chip IC-HN3 also includes a power input pin (VDD), wherein the control pin CI is respectively connected to the signal conversion circuit 23 and the MOS tube, and is used to transmit the received analog voltage signal to the control end of the MOS tube, the positive input pin EP and the negative input pin EN are both connected to the controllable switch K1, and are both used to receive the synchronization signal, the two ground pins (GND) are respectively connected to the controllable switch K1 and the positive pole LED+ of the LED, the two cathode pins (LDK) are respectively connected to the MOS tube and the negative pole LED- of the LED, and the connection method of other components in the driver chip IC-HN3 is the same as the existing one, which will not be repeated here.

[0090] In other embodiments, signal modulation can also be used to meet the requirement of synchronizing the light source lighting and camera shooting. Fig.13 As shown, the regulation circuit also includes additional logic gate circuits.

[0091] The logic gate circuit is an AND gate. One input end of the AND gate is connected to the signal conversion circuit 23 to receive an analog voltage signal, and the other input end receives a synchronization signal. The output end of the AND gate is connected to the control end of the MOS tube.

[0092] In actual use, the analog voltage signal and the synchronization signal are modulated by the AND gate, and the modulated signal formed at the output end of the AND gate will maintain a low level in the low level phase of the synchronization signal, and only retain the level signal in the high level phase of the synchronization signal.

[0093] Therefore, when the synchronization signal is in the low level stage, the modulation signal will cause the MOS tube to be in the cut-off state, thereby achieving an effect similar to that of the controllable switch K (interrupting the power supply circuit of the LED), and realizing the synchronization of light source lighting and camera shooting.

[0094] In some embodiments, the level standard of the initial synchronization signal generated by the camera shooting may be different from the level standard of the adjustment circuit. Therefore, in order to achieve coordination between different level standards, the LED driving device 20 further includes: a level conversion circuit.

[0095] Among them, the level conversion circuit can convert a signal of one level standard (initial synchronization signal) into a signal of another level standard (synchronization signal) to ensure that the signal can be correctly transmitted and processed between different level systems.

[0096] For example, the initial synchronization signal input externally has different level standards, such as TTL (transistor-transistor logic) and LVTTL (low voltage transistor-transistor logic). The received initial synchronization signal needs to be converted into a synchronization signal through a level conversion circuit. The synchronization signal is a signal with a level standard suitable for the adjustment circuit.

[0097] As an example but not limitation, the level conversion circuit may be a circuit composed of a MOS tube and other components, a circuit composed of an optocoupler and other components, or a circuit composed of a level conversion chip and other components.

[0098] Specifically, Fig.14 As shown, the level conversion circuit includes a level conversion chip U4 (model DSLVDS1001DBVR) and a resistor R5. Correspondingly, the adjustment circuit 24 also includes: a resistor R6, a capacitor CCI1, a resistor R12, a capacitor CVDD3, a capacitor CVDD4 and a capacitor CL5.

[0099] Among them, the first end of the resistor R6 is connected to the signal conversion circuit 23 for receiving the analog voltage signal, the second end of the resistor R6 is respectively connected to the first end of the capacitor CCI1 and the first end of the resistor R12, the second end of the capacitor CCI1 is connected to the reference ground GND, the second end of the resistor R12 is connected to the control pin CI of the driver IC-HN3, the first end of the capacitor CVDD3 is respectively connected to the DC voltage VCC1, the first end of the capacitor CVDD4 and the power input pin (VDD) of the driver IC-HN3, the first end of the capacitor CVDD4 is respectively connected to the 5V power supply and the power input pin (VDD), the second end of the capacitor CVDD3 and the second end of the capacitor CVDD4 are both connected to the reference ground GND.

[0100] The level conversion chip U4 has a level signal input pin TTL-IN, a positive signal output pin OUT+, a negative signal output pin OUT- and a power input pin VDD. Among them, the level signal input pin TTL-IN is used to receive the initial synchronization signal, the positive signal output pin OUT+ is used to output the positive phase differential signal, and the negative signal output pin OUT- is used to output the negative phase differential signal. The positive phase differential signal and the negative phase differential signal constitute the synchronization signal.

[0101] The positive signal output pin OUT+ is respectively connected to the first end of the resistor R5 and the negative input pin EN of the driver IC-HN3, and the reverse signal output pin OUT- is respectively connected to the second end of the resistor R5 and the positive input pin EP of the driver IC-HN3, thereby transmitting opposite signals on two lines to realize data transmission, which can effectively reduce electromagnetic interference and suppress crosstalk, thereby improving the signal's anti-interference ability.

[0102] The two ground pins (GND) of the driver chip IC-HN3 are connected to the first end of the capacitor CL5, the second end of the capacitor CL5 is connected to the positive electrode LED+ of the LED and the power supply respectively, and the two cathode pins (LDK) of the driver IC-HN3 are connected to the negative electrode LED- of the LED.

[0103] In some embodiments, Fig.15 As shown, the power supply circuit 21 includes: a low voltage dropout linear regulator. The low voltage dropout linear regulator is a DC voltage converter that can convert a higher input voltage into a stable lower output voltage to provide a stable and reliable forward driving voltage (ie, the above-mentioned power supply voltage) for the LED.

[0104] Specifically, Fig.16 As shown, the low voltage drop linear regulator U5 can use a low voltage drop linear regulator of model LM1084, which supports large current. The power supply circuit 21 also includes: a capacitor C4, a resistor R23, a resistor R24 ​​and a capacitor C7.

[0105] Among them, pin 3 (IN) of the low-voltage difference linear regulator LM1084 is respectively connected to the third DC voltage source VCC3 (for example, 12V) and the first end of the capacitor C4, the second end of the capacitor C4 is connected to the reference ground GND, pin 4 (OUT) of the low-voltage difference linear regulator LM1084 is respectively connected to the first end of the resistor R24, the first end of the capacitor C7 and the positive electrode LED+ of the LED, the second end of the capacitor C7 is connected to the reference ground GND, and pin 1 (ADJ / GND) of the low-voltage difference linear regulator U5 is respectively connected to the second end of the resistor R24 ​​and the first end of the resistor R23, and the second end of the resistor R23 is connected to the reference ground GND.

[0106] Specifically, the control circuit 22 may be composed of a control chip and its peripheral circuits. Fig.17 As shown, the control chip U6 is a microcontroller of model STM32f103C6T6, and the peripheral circuits include: crystal oscillator X1 (frequency is 8MHz) and matching capacitors.

[0107] Among them, pin 1 (VBAT) of the microcontroller U6 is connected to the power supply, pin 11 (PA1) of the microcontroller is connected to the peripheral unit 25 (such as a knob, a button) for receiving an operation electrical signal, pin 30 (PA9) and pin 31 (PA10) of the microcontroller are connected to the peripheral unit 25 (such as a touch screen, a host computer) for receiving an operation electrical signal, pin 26 (PB13) of the microcontroller U6 is connected to pin 7 (DIN) of the digital-to-analog converter U3 for outputting brightness indication information, pin 27 (PB14) is connected to pin 6 (SCLK) of the digital-to-analog converter U3, and pin 28 (PB15) is connected to pin 5 (SYNC#) of the digital-to-analog converter U3 , pin 5 (PD0-OSC_IN) of the microcontroller U6 is connected to pin 3 (OSCIN) of the crystal oscillator X1, pin 6 (PD0-OSC_OUT) of the microcontroller U6 is connected to pin 1 (OSCOUT) of the crystal oscillator X1, pin 4 and pin 2 of the crystal oscillator X1 are both connected to the reference ground GND, pin 5 (PD0-OSC_IN) of the microcontroller U6 is also connected to the first end of the capacitor C23 and the first end of the resistor R20 respectively, pin 6 (PD0-OSC_OUT) of the microcontroller U6 is also connected to the first end of the capacitor C24 and the second end of the resistor R20 respectively, the second end of the capacitor C23 and the second end of the capacitor C24 are both connected to the reference ground GND.

[0108] In some embodiments, the power supply circuit may further include: a first linear voltage regulator and a second linear voltage regulator. The first linear voltage regulator and the second linear voltage regulator may respectively provide the required operating voltages for different functional circuits to support the operation of the entire LED driving device. For example, the first linear voltage regulator may provide a constant voltage of 3.3V to provide the required operating voltage for the above-mentioned microcontroller STM32f103C6T6, etc., while the second linear voltage regulator may provide a constant voltage of 5V to provide the required operating voltage for the knob KNOB, the USB to serial port chip CH340N and the driver IC-HN3, etc.

[0109] Specifically, Fig.18As shown, the first linear voltage regulator includes: a first linear voltage regulator U7, a capacitor C22, a capacitor C21, a capacitor C16, a capacitor C34, a capacitor C33 and a resistor R25, wherein a pin 3 (VIN) of the first linear voltage regulator is respectively connected to a 5V DC voltage supply node VCC2 and a first end of the capacitor C22, a pin 2 (VOUT) of the first linear voltage regulator is respectively connected to a 3.3V DC voltage supply node VCC1 (providing a 3.3V voltage for the DC voltage supply node VCC1), a first end of the capacitor C21, a first end of the capacitor C16, a first end of the capacitor C34, a first end of the capacitor C33 and a first end of the resistor R25, a second end of the resistor R25 is connected to a pin 1 (VBAT) of the microcontroller, and a pin 1 (ADJ) of the first linear voltage regulator, a second end of the capacitor C22, a second end of the capacitor C21, a second end of the capacitor C16, a second end of the capacitor C34 and a second end of the capacitor C33 are all connected to a reference ground GND.

[0110] Specifically, Fig.19 As shown, the second linear voltage regulator source includes: a second linear voltage regulator U8 and a resistor R15.

[0111] Among them, pin 3 (IN) of the second linear regulator is connected to the 12V DC voltage supply node VCC3, and pin 2 (OUT) of the second linear regulator is connected to the 5V DC voltage supply node VCC2, providing 5V voltage for the DC voltage supply node VCC1. Pin 4 (TAB) of the second linear regulator is also connected to the DC voltage supply node VCC2. Pin 1 (ADJ / GND) of the second linear regulator is connected to the reference ground GND through resistor R15, and pin 1 (ADJ / GND) of the second linear regulator is also connected to the digital circuit reference ground DGND.

[0112] Based on the LED driving device provided in the embodiment of the present application, the embodiment of the present application further provides an electronic device. The electronic device includes an LED and the above-mentioned LED driving device. The LED driving device generates brightness indication information corresponding to the user operation through a control circuit, and then converts the brightness indication information into a corresponding analog voltage signal through a signal conversion circuit. Finally, the analog voltage signal is applied to the control end of the MOS tube, so that the LED can stably emit the brightness corresponding to the brightness indication information.

[0113] The LED driving device provided in the embodiment of the present application realizes adjusting the brightness of the LED by applying an analog voltage signal to the control end of the MOS tube, and stably maintaining the brightness of the LED at the target brightness. It utilizes the device characteristics of the MOS tube, can avoid brightness fluctuations during the lighting process in principle, realizes digital recording of the brightness value of the microscopic imaging, can communicate through the host computer, can store the detection work records, facilitate later tracing, and avoid the problem of lighting flickering during low-brightness imaging.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An LED driving device for microscopic imaging, characterized in that: include: The power supply circuit is configured to: provide a power supply voltage for powering the LED; The power supply circuit is further configured to: provide a reference voltage; The control circuit is configured to: generate brightness indication information corresponding to the user operation; the brightness indication information is information represented in the form of a digital signal and is also stored as a brightness value of the detection work record; The signal conversion circuit is configured to: convert the brightness indication information into a corresponding analog voltage signal; The signal conversion circuit comprises: a digital-to-analog converter; the digital-to-analog converter has a digital signal input terminal and an analog signal output terminal; Wherein, the reference voltage is provided to the digital-to-analog converter, so that the brightness indication information received by the digital signal input terminal is converted into a corresponding analog voltage signal, and output from the analog signal output terminal; A regulating circuit, the regulating circuit comprising: a MOS tube arranged on an LED power supply circuit; The regulating circuit further includes: a logic gate circuit; the logic gate circuit is an AND gate, configured to: modulate the received synchronization signal and the analog voltage signal to generate a modulation signal; and provide the modulation signal to the gate of the MOS tube; The modulation signal formed at the output end of the AND gate will maintain a low level in the low level phase of the synchronization signal, so that the MOS tube is in a cut-off state, and only the level signal in the high level phase of the synchronization signal is retained; Wherein, based on the transfer characteristic curve of the MOS tube, when the power supply voltage remains unchanged, the drain current of the MOS tube is controlled by controlling the voltage of the analog voltage signal applied to the gate of the MOS tube, so that the current variation amplitude through the LED power supply circuit is controlled within a preset range, so that the LED stably emits the brightness corresponding to the brightness indication information; The LED driving device further includes: a level conversion circuit; Wherein, the level conversion circuit is configured to: convert the received initial synchronization signal into the synchronization signal, and provide it to the input end of the AND gate; The level conversion circuit comprises a level conversion chip, wherein the level conversion chip has a level signal input pin, a forward signal output pin, a reverse signal output pin and a power input pin; Among them, the level signal input pin is used to receive the initial synchronization signal, the forward signal output pin is used to output the positive phase differential signal, and the reverse signal output pin is used to output the reverse phase differential signal. The positive phase differential signal and the reverse phase differential signal constitute the synchronization signal.

2. The LED driving device according to claim 1, characterized in that: The LED driving device further includes: a peripheral unit; The peripheral unit is configured to: in response to the application of a user operation, convert into a corresponding operation electrical signal; Wherein, the control circuit is in communication connection with the peripheral unit and is configured to: generate brightness indication information represented in the form of a digital signal according to the operation electrical signal; The peripheral unit is selected from one or more of the following devices: a knob, a button, a touch screen, and a host computer.

3. The LED driving device according to any one of claims 1 to 2, characterized in that: The regulating circuit further comprises: a controllable switch connected in series with the LED; The controllable switch is configured to switch between an on state and an off state according to a received synchronization signal, so as to interrupt or connect the power supply circuit of the LED.

4. The LED driving device according to claim 3, characterized in that: The MOS transistor and the controllable switch are discrete electronic devices; or the MOS transistor and the controllable switch are integrated in the same chip.

5. The LED driving device according to claim 1, characterized in that: The power supply circuit includes: a low voltage drop linear regulator; Wherein, the low voltage difference linear regulator is configured to form the power supply voltage for powering the LED.

6. An electronic device, characterized in that: include: LED; And the LED driving device according to any one of claims 1 to 5; Wherein, the LED driving device is connected to the LED and is used to control the light emitting brightness of the LED.

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