Switching device and light-emitting equipment

Abstract

The invention relates to a switching device and light-emitting equipment. The switching device comprises a switching control circuit, a constant-current driving circuit and an auxiliary driving circuit, the first end of the switch control circuit is connected with the first end of the constant-current driving circuit, the second end of the switch control circuit is connected with the first end of the auxiliary driving circuit, and the second end of the constant-current driving circuit is connected with the second end of the auxiliary driving circuit and the light-emitting unit. The third end of the constant current driving circuit is connected with the third end of the auxiliary driving circuit; the switch control circuit is used for providing a voltage signal for the constant-current driving circuit; the constant-current driving circuit is used for determining driving current according to the voltage signal, the driving current is used for driving the light-emitting unit, and the driving current is in positive correlation with the corresponding voltage of the voltage signal; and the auxiliary driving circuit is used for providing a current signal for the constant-current driving circuit to ensure that the constant-current driving circuit is in a working state when the driving current is smaller than a preset current threshold value. The light-emitting equipment comprises the switching device.

Description

Technical Field

[0001] The present application relates to the field of circuit technologies, and particularly to a switching device and a lighting device. Background Art

[0002] With the rapid development of electronic technologies, lighting devices using light-emitting diodes (LEDs) have widely appeared in everyone's life. During the use of an LED, it is necessary to frequently switch the state between the on state and the off state. Therefore, the turn-on speed and turn-off speed of the LED are crucial for the display effect of the LED, and the state switching speed of the LED is determined by an LED driving chip.

[0003] Currently, in traditional circuits, the turn-on and turn-off of an LED are achieved through a switching control circuit. However, during the turn-on and turn-off processes of the LED, the operational amplifier in the switching control circuit also turns on and off along with the LED. Since the response speed of the operational amplifier is limited, the turn-on speed and turn-off speed of the LED will be affected. Therefore, it is impossible to precisely control the turn-on speed and turn-off speed of the LED only through the switching control circuit in the traditional circuit. Obviously, if the turn-on speed and turn-off speed of the LED cannot be kept constant, it will be unfavorable for improving the display effect of the LED. Summary of the Invention

[0004] Based on this, it is necessary to provide a switching device and a lighting device that can keep the turn-on speed and turn-off speed of a lighting unit constant.

[0005] In a first aspect, the present application provides a switching device. The switching device includes a switching control circuit, a constant-current driving circuit, and an auxiliary driving circuit; a first end of the switching control circuit is connected to a first end of the constant-current driving circuit, a second end of the switching control circuit is connected to a first end of the auxiliary driving circuit, a second end of the constant-current driving circuit is respectively connected to a second end of the auxiliary driving circuit and a lighting unit, and a third end of the constant-current driving circuit is connected to a third end of the auxiliary driving circuit;

[0006] The switching control circuit is configured to provide a voltage signal to the constant-current driving circuit;

[0007] The constant-current driving circuit is configured to determine a driving current according to the voltage signal and drive the lighting unit with the driving current. The driving current is positively correlated with the voltage corresponding to the voltage signal;

[0008] The auxiliary driving circuit is configured to provide a current signal to the constant-current driving circuit to ensure that the constant-current driving circuit is in a working state when the driving current is less than a preset current threshold.

[0009] In a second aspect, the present application provides a light-emitting device, which includes a light-emitting unit and a switching device as described in any one of the first aspects of the present application. The light-emitting unit is connected to the switching device.

[0010] In the above-mentioned switching device and light-emitting device, after the switching control circuit is used to provide a voltage signal to the constant-current driving circuit, the constant-current driving circuit can determine a driving current that is positively correlated with the voltage corresponding to the voltage signal according to the voltage signal, and use the driving current to drive the light-emitting unit. At the same time, the auxiliary driving circuit can provide a current signal to the constant-current driving circuit to ensure that the constant-current driving circuit is in a working state when the driving current is less than a preset current threshold. Since the driving current used to drive the light-emitting unit is always positively correlated with the voltage corresponding to the voltage signal, and the voltage signal changes linearly whether during the turning-on process or the turning-off process of the light-emitting unit, correspondingly, the driving current also changes linearly. Therefore, the driving current used to drive the light-emitting unit changes with a constant slope. Thus, both the turning-on speed and the turning-off speed of the light-emitting unit can be kept constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0012] Figure 1 It is a schematic structural diagram of a switching circuit;

[0013] Figure 2 It is a schematic structural diagram of a switching device provided in this embodiment;

[0014] Figure 3 It is a schematic structural diagram of another switching device provided in this embodiment;

[0015] Figure 4 It is a schematic structural diagram of an auxiliary driving switching circuit provided in this embodiment;

[0016] Figure 5 It is a schematic structural diagram of a switching control driving circuit provided in this embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] To facilitate the understanding of the present application, the following will provide a more comprehensive description of the present application with reference to the relevant drawings. Embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0019] It can be understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, the first end may be referred to as the second end, and similarly, the second end may be referred to as the first end. Both the first end and the second end are ends, but they are not the same end.

[0020] It can be understood that for "connection" in the following embodiments, if there is a transmission of electrical signals or data between the connected circuits, modules, units, etc., it should be understood as "electrical connection", "communication connection", etc.

[0021] It can be understood that "at least one" means one or more, and "a plurality" means two or more. "At least part of an element" means part or all of the element.

[0022] As used herein, the singular forms "a", "an", and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprise / include" or "have", etc. specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0023] This application is made by the inventors based on the recognition and research of the following problems:

[0024] Both the turn-on speed and the turn-off speed of an LED will affect the display effect of the LED. Generally, the turn-on speed and the turn-off speed of an LED are determined by an LED driving chip, and essentially, the turn-on speed and the turn-off speed of an LED are respectively the rising speed and the falling speed of the LED driving current. As Figure 1As shown, in a traditional switching circuit for an LED, when switch S1' is closed and switch S2' is open, operational amplifier A0 starts to respond. The gate voltage of switch transistor M1', which is the output of operational amplifier A0, starts to rise from 0V. The inverting input of operational amplifier A0 starts to rise from 0V. The driving current of LED' starts to rise from 0mA until the voltage at the inverting input of operational amplifier A0 rises to the voltage VR at the non-inverting input. At this time, operational amplifier A0 reaches a stable state, and the driving current of LED' reaches the set value and enters the on state. This is the traditional turn-on process of the LED. Conversely, when switch S1' is open and switch S2' is closed, the gate voltage of switch transistor M1' starts to be pulled down by switch transistor M3'. The voltage at the inverting input of operational amplifier A0 drops from VR. The driving current of the LED starts to drop from the set value until the gate voltage of switch transistor M1' is pulled down to 0V and the voltage at the inverting input of operational amplifier A0 drops to 0V. At this time, the driving current of LED' drops to 0mA and enters the off state. This is the traditional turn-off process of the LED.

[0025] It can be seen that during the turn-on and turn-off processes of the LED, there are charge and discharge processes for the gate voltage of switch transistor M1', that is, the turn-on and turn-off processes of the operational amplifier. Therefore, the turn-on speed and turn-off speed of the LED are always affected by the response of the operational amplifier, resulting in the inability to keep the turn-on speed and turn-off speed of the LED constant. That is to say, the driving current used to drive the LED to turn on or off does not change with a constant slope. Consequently, the turn-on speed and turn-off speed of the LED cannot be kept constant, which will significantly affect the display effect of the LED.

[0026] Based on this, the present embodiment provides a switching device, as Figure 2 shown. The switching device includes a switch control circuit 202, a constant current driving circuit 204, and an auxiliary driving circuit 206. The first end of the switch control circuit 202 is connected to the first end of the constant current driving circuit 204. The second end of the switch control circuit 202 is connected to the first end of the auxiliary driving circuit 206. The second end of the constant current driving circuit 204 is respectively connected to the second end of the auxiliary driving circuit 206 and the light-emitting unit. The third end of the constant current driving circuit 204 is connected to the third end of the auxiliary driving circuit 206.

[0027] The switch control circuit 202 is configured to provide a voltage signal to the constant current driving circuit 204.

[0028] The constant current driving circuit 204 is configured to determine a driving current according to the voltage signal and use the driving current to drive the light-emitting unit. The driving current is positively correlated with the voltage corresponding to the voltage signal.

[0029] An auxiliary drive circuit 206 is used to provide a current signal to the constant current drive circuit 204 to ensure that the constant current drive circuit 204 is in an operating state when the drive current is less than a preset current threshold.

[0030] Among them, a light-emitting unit can generate and emit light under the action of a drive current. The light-emitting unit may include an LED, an organic light-emitting diode (OLED), a liquid crystal display (LCD), or other devices capable of emitting light.

[0031] Specifically, the switch control circuit 202 is further configured to receive a status switching enable signal for the light-emitting unit. The status switching enable signal is used to enable the light-emitting unit to switch between an on state and an off state. That is to say, by applying the status switching enable signal to the switch control circuit 202, the light-emitting unit can be switched from the on state to the off state, and during this process, the drive current for driving the light-emitting unit will decrease from large to small, or the light-emitting unit can be switched from the off state to the on state, and during this process, the drive current will increase from small to large.

[0032] Specifically, the drive current is positively correlated with the voltage of the voltage signal, and it can ensure that the drive current for driving the light-emitting unit maintains a constant slope change during the state switching of the light-emitting unit. Thus, both the turn-on speed and the turn-off speed of the light-emitting unit can be kept constant.

[0033] Specifically, during the process of the light-emitting unit switching from the on state to the off state, the drive current will gradually decrease. Then, when the drive current is less than the preset current threshold, the driving ability of the constant current drive circuit 204 for the light-emitting unit decreases. If the constant current drive circuit 204 cannot maintain a normal operating state, it will cause the drive current for driving the light-emitting unit to fail to maintain a constant slope change. Therefore, in this case, the auxiliary drive circuit 206 provides a current signal to the constant current drive circuit 204 to ensure that the constant current drive circuit 204 remains in an operating state. And, during the process of the light-emitting unit switching from the off state to the on state, the drive current will gradually increase. Then, when the drive current is greater than the preset current threshold, the driving ability of the constant current drive circuit 204 for the light-emitting unit increases, and the constant current drive circuit 204 starts to be in a normal operating state, and the auxiliary drive circuit 206 is turned off. Thus, the constant current drive circuit 204 can be in a normal operating state under any circumstances.

[0034] It should be noted that during the process of the light-emitting unit switching from the on state to the off state, the driving current gradually decreases, changing from a relatively large driving current to a driving current smaller than the preset current threshold until the light-emitting unit completely enters the off state. As long as the driving current is smaller than the preset current threshold, the auxiliary driving circuit 206 can provide a current signal to the constant-current driving circuit 204 to ensure that the constant-current driving circuit 204 is in the working state. Therefore, the auxiliary driving circuit 206 can ensure that the constant-current driving circuit 204 remains in the normal working state even when the light-emitting unit is in the off state.

[0035] For the above-mentioned switching device, since the constant-current driving circuit 204 is in the normal working state under any circumstances, accordingly, the voltage signal provided by the switch control circuit to the constant-current driving circuit is the only factor affecting the magnitude of the driving current. That is to say, the driving current for driving the light-emitting unit is always positively correlated with the voltage corresponding to the voltage signal. Moreover, the voltage signal changes linearly both during the turning-on process and the turning-off process of the light-emitting unit. Correspondingly, the driving current also changes linearly. Therefore, the driving current for driving the light-emitting unit changes with a constant slope, and thus, the turning-on speed and the turning-off speed of the light-emitting unit can both be kept constant.

[0036] In an exemplary embodiment, as Figure 3 shown, the constant-current driving circuit 204 includes a first switching transistor M1, a second switching transistor M2, and a first operational amplifier A1.

[0037] The first end of the first switching transistor M1 is connected to the output end of the first operational amplifier A1. The second end of the first switching transistor M1 is connected to the light-emitting unit LED. The third end of the first switching transistor M1 is respectively connected to the second end of the second switching transistor M2 and the inverting input end of the first operational amplifier A1.

[0038] The first end of the second switching transistor M2 is connected to the first end of the switch control circuit 202. The third end of the second switching transistor M2 is connected to the ground terminal.

[0039] The non-inverting input end of the first operational amplifier A1 is connected to the first power supply VR.

[0040] Among them, the first switching transistor M1 and the second switching transistor M2 are Metal-Oxide-Semiconductor Field-Effect Transistors (MOS). Further, the first switching transistor M1 and the second switching transistor M2 are N-channel Metal-Oxide-Semiconductor Field-Effect Transistors (NMOS). The first end of the first switching transistor M1 is the gate terminal, the second end is the drain terminal, and the third end is the source terminal. At the same time, the first end of the second switching transistor M2 is the gate terminal, the second end is the drain terminal, and the third end is the source terminal.

[0041] Specifically, the magnitude of the driving current used to drive the light-emitting unit LED is determined by the second switching transistor M2. Further, since the driving current is positively correlated with the voltage corresponding to the voltage signal, the magnitude of the driving current is determined by the voltage corresponding to the voltage signal. The larger the voltage corresponding to the voltage signal, the larger the driving current; the smaller the voltage corresponding to the voltage signal, the smaller the driving current.

[0042] In this embodiment, the constant-current driving circuit includes a first switching transistor, a second switching transistor, and a first operational amplifier. The third end of the second switching transistor is connected to the ground terminal, that is, there is no voltage at the source terminal of the second switching transistor. Under the combined action of the first operational amplifier and the first switching transistor, the drain voltage of the second switching transistor can be clamped at a fixed voltage value. Therefore, the settings of the first operational amplifier and the first switching transistor can ensure that the magnitude of the driving current is only positively correlated with the voltage corresponding to the voltage signal provided by the switching control circuit to the constant-current driving circuit.

[0043] In an exemplary embodiment, as Figure 3 shown, the switching control circuit 202 includes a constant current source I, a second operational amplifier A2, a third switching transistor M3, a first switch S1, and a second switch S2.

[0044] One end of the constant current source I is connected to the second power supply VDD. The other end of the constant current source I is respectively connected to the inverting input terminal and the output terminal of the second operational amplifier A2, the first end of the first switch S1, and the first end of the auxiliary driving circuit.

[0045] The non-inverting input terminal of the second operational amplifier A2 is connected to the third power supply VREF.

[0046] The first end of the third switching transistor M3 is connected to the fourth power supply VBN. The second end of the third switching transistor M3 is connected to the second end of the first switch S1 and the first end of the constant-current driving circuit through the second switch S2. The third end of the third switching transistor M3 is connected to the ground terminal.

[0047] Among them, the third switching transistor M3 is a MOS transistor. Further, the third switching transistor M3 is an NMOS transistor, the first end of the third switching transistor M3 is the gate terminal, the second end is the drain terminal, and the third end is the source terminal.

[0048] Specifically, when the first switch S1 is turned on, the second switch S2 is turned off, and when the first switch S1 is turned off, the second switch S2 is turned on. That is to say, the operating states of the first switch S1 and the second switch S2 are opposite.

[0049] Specifically, the third switching transistor M3 turns off the second switching transistor M2 by pulling down the gate voltage of the second switching transistor M2, so as to achieve the purpose of turning off the switching unit. During the process of turning off the second switching transistor M2, the third switching transistor M3 is equivalent to another constant current source I. The pulling-down speed of the gate voltage of the second switching transistor M2 by the third switching transistor M3 is uniform. The pulling-down speed determines the switching speed of the light-emitting unit LED entering the off state. The faster the pulling-down speed, the faster the switching speed; the slower the pulling-down speed, the slower the switching speed. By adjusting the voltage magnitude of the fourth power supply VBN and / or the size of the third switching transistor M3, the pulling-down speed can be adjusted. That is to say, by adjusting the voltage magnitude of the fourth power supply VBN and / or the size of the third switching transistor M3, the switching speed of the light-emitting unit LED can be adjusted.

[0050] Specifically, the second operational amplifier A2 and the constant current source I act together to charge the gate of the second switching transistor M2. During the charging process, the constant current source I charges the gate of the second switching transistor M2 uniformly. The second operational amplifier A2 ensures that the gate voltage of the second switching transistor M2 can be charged to the set voltage value, so as to ensure that the driving current for turning on the light-emitting unit LED can be consistent with the set current value. It can be seen that the charging speed of charging the gate voltage of the second switching transistor M2 to the set voltage value determines the switching speed of the light-emitting unit LED entering the on state. The faster the charging speed, the faster the switching speed; the slower the charging speed, the slower the switching speed. That is to say, by adjusting the current magnitude of the constant current source I, the switching speed of the light-emitting unit LED can be adjusted.

[0051] In an exemplary embodiment, the switching speed of the light-emitting unit LED is determined based on the magnitude of the constant current source I; the switching speed of the light-emitting unit LED is determined based on the voltage magnitude of the fourth power supply VBN and / or the size of the third switching transistor M3.

[0052] In this embodiment, the switch control circuit includes a constant current source, a second operational amplifier, a third switch transistor, a first switch, and a second switch. By adjusting the current magnitude of the constant current source, the charging speed of the gate terminal voltage of the second switch transistor can be adjusted to regulate the opening speed. Moreover, by adjusting the voltage magnitude of the fourth power supply and / or the size of the third switch transistor, the pulling-down speed of the gate terminal voltage of the second switch transistor by the third switch transistor can be adjusted to regulate the closing speed. Thus, in addition to providing a voltage signal to the constant current driving circuit, the switch control circuit can also control the opening speed and the closing speed of the light-emitting unit.

[0053] In an exemplary embodiment, as Figure 3 shown, the auxiliary driving circuit 206 includes a third switch S3, a fourth switch S4, a fifth switch S5, a sixth switch S6, a fourth switch transistor M4, and a fifth switch transistor M5.

[0054] The first terminal of the fourth switch transistor M4 is connected to the second terminal of the switch control circuit 202 through the third switch S3. The second terminal of the fourth switch transistor M4 is connected to the third terminal of the constant current driving circuit through the fourth switch S4. The third terminal of the fourth switch transistor M4 is connected to the ground terminal.

[0055] The first terminal of the fifth switch transistor M5 is respectively connected to the first terminal of the fifth switch S5 and the first terminal of the sixth switch S6. The second terminal of the fifth switch transistor M5 is respectively connected to the second terminal of the fifth switch S5 and the second terminal of the constant current driving circuit. The third terminal of the fifth switch transistor M5 is respectively connected to the second terminal of the sixth switch S6 and the second power supply VDD.

[0056] Among them, the fourth switch transistor M4 and the fifth switch transistor M5 are MOS transistors. Further, the fourth switch transistor M4 is an NMOS transistor. The first terminal of the fourth switch transistor M4 is the gate terminal, the second terminal is the drain terminal, and the third terminal is the source terminal. The fifth switch transistor M5 is a P-channel Metal-Oxide-Semiconductor Field-Effect Transistor (PMOS). The first terminal of the fifth switch transistor M5 is the gate terminal, the second terminal is the drain terminal, and the third terminal is the source terminal.

[0057] Specifically, in order to keep the drain voltage of the second switching transistor M2 constant, the first operational amplifier A1 and the first switching transistor M1 are required to jointly clamp the drain voltage of the second switching transistor M2, so as to ensure that the voltage signal provided by the switching control circuit 202 to the constant current driving circuit has a positive correlation between the corresponding voltage and the driving current magnitude, that is, to ensure that the voltage signal corresponding voltage and the driving current magnitude are linearly correlated. If the first operational amplifier A1 is in a non-operating state, it may cause the drain voltage of the second switching transistor M2 to fluctuate, thereby resulting in an unstable driving current magnitude. Obviously, the auxiliary driving circuit 206 should enable the first operational amplifier A1 to maintain an operating state when the light-emitting unit LED is turned off, that is, when the driving current is less than the preset current threshold. Therefore, at this time, the auxiliary driving circuit 206 provides a current signal to the constant current driving circuit to ensure that the first operational amplifier A1 is in an operating state.

[0058] Specifically, since the auxiliary driving circuit 206 enters the operating state only when the driving current is less than the preset current threshold, and the situation where the driving current is less than the preset current threshold is the situation where the light-emitting unit LED enters the off state. In order to prevent the fourth switching transistor M4 from providing an excessive current signal to the light-emitting unit LED during the process of the light-emitting unit LED entering the off state to hinder the state switching of the light-emitting unit LED. Therefore, on the one hand, the current generated by the fourth switching transistor M4 should be much smaller than the current generated by the second switching transistor M2. When the third switch S3 and the fourth switch S4 are closed, the gate voltages of the second switching transistor M2 and the fourth switching transistor M4 are the same, and the drain voltage of the second switching transistor M2 provides a voltage signal to the drain of the fourth switching transistor M4. Thus, the drain voltage of the second switching transistor M2 is the same as the drain voltage of the fourth switching transistor M4. Furthermore, at this time, the current magnitudes of the second switching transistor M2 and the fourth switching transistor M4 are determined only by the dimensions respectively. On the other hand, the current generated by the fourth switching transistor M4 should not flow through the light-emitting unit LED, but should flow through the fifth switching transistor M5 to ensure that the light-emitting unit LED has no current flowing through after entering the off state while the first operational amplifier A1 is still in the operating state.

[0059] In an exemplary embodiment, the size of the fourth switching transistor M4 is smaller than the size of the second switching transistor M2.

[0060] In an exemplary embodiment, the equivalent resistance of the fifth switching transistor M5 is smaller than the resistance of the light-emitting unit LED.

[0061] In this embodiment, the auxiliary driving circuit includes a third switch, a fourth switch, a fifth switch, a sixth switch, a fourth switching transistor, and a fifth switching transistor. The fourth switching transistor can provide a current signal to the constant-current driving circuit when the driving current is less than a preset current threshold, so as to maintain the operating state of the first operational amplifier in the constant-current driving circuit. Thus, by ensuring that the drain voltage of the second switching transistor remains fixed, it can be ensured that the driving current for driving the light-emitting unit always changes linearly. Moreover, the current signal provided by the fourth switching transistor to the constant-current driving circuit finally flows through the fifth switching transistor and does not flow through the light-emitting unit. Furthermore, the setting of the fourth switching transistor that ensures the driving current of the light-emitting unit changes with a constant slope does not affect the state switching of the light-emitting unit.

[0062] In an exemplary embodiment, the device further includes an auxiliary driving switch circuit; the auxiliary driving switch circuit is connected to the auxiliary driving circuit.

[0063] The auxiliary driving switch circuit is configured to control the auxiliary driving circuit to turn on when the voltage corresponding to the voltage signal is less than a preset voltage threshold, and control the auxiliary driving circuit to turn off when the voltage corresponding to the voltage signal is greater than or equal to the preset voltage threshold. The preset voltage threshold corresponds to the preset current threshold.

[0064] In an exemplary embodiment, the preset voltage threshold is determined based on one or more of a fifth power supply VBP, the size of a sixth switching transistor M6, and the size of a seventh switching transistor M7.

[0065] Wherein, the auxiliary driving switch circuit is a circuit for controlling the switching state of the auxiliary driving circuit.

[0066] Specifically, the preset voltage threshold corresponds to the preset current threshold, that is to say, when the driving current is less than the preset current threshold, the voltage corresponding to the voltage signal is less than the preset voltage threshold, and vice versa. When the driving current is greater than or equal to the preset current threshold, the voltage corresponding to the voltage signal is greater than or equal to the preset voltage threshold.

[0067] Specifically, the auxiliary driving switch circuit can detect the magnitude of the voltage corresponding to the voltage signal provided by the switch control circuit 202 to the constant-current driving circuit, so as to decide to control the auxiliary driving circuit to turn on or control the auxiliary driving circuit to turn off under different magnitudes of the voltage corresponding to the voltage signal.

[0068] In an exemplary embodiment, as Figure 4 shown, the auxiliary driving switch circuit includes a sixth switching transistor M6, a seventh switching transistor M7, a transmission gate control module, and a first inverter INV1.

[0069] The first terminal of the sixth switching transistor M6 is connected to the fifth power supply VBP, the second terminal of the sixth switching transistor M6 is connected to the input terminal of the transmission gate control module and the second terminal of the seventh switching transistor M7, and the third terminal of the sixth switching transistor M6 is connected to the second power supply VDD.

[0070] The first terminal of the seventh switching transistor M7 is connected to the first terminal of the switch control circuit 202, and the third terminal of the seventh switching transistor M7 is connected to the ground terminal.

[0071] The first output terminal of the transmission gate control module is respectively connected to the third switch S3, the fourth switch S4 and the fifth switch S5, and the second output terminal of the transmission gate control module is connected to the sixth switch S6 through the first inverter INV1.

[0072] Wherein, the transmission gate control module is used to control the third switch S3, the fourth switch S4 and the fifth switch S5 to conduct and the sixth switch S6 to turn off when the voltage corresponding to the voltage signal is less than the preset voltage threshold; and to control the third switch S3, the fourth switch S4 and the fifth switch S5 to turn off and the sixth switch S6 to conduct when the voltage corresponding to the voltage signal is greater than or equal to the preset voltage threshold.

[0073] Wherein, the sixth switching transistor M6 and the seventh switching transistor M7 are MOS transistors. Further, the sixth switching transistor M6 is a PMOS transistor, the first terminal of the sixth switching transistor M6 is the gate terminal, the second terminal is the drain terminal and the third terminal is the source terminal; the seventh switching transistor M7 is an NMOS transistor, the first terminal of the seventh switching transistor M7 is the gate terminal, the second terminal is the drain terminal and the third terminal is the source terminal.

[0074] Specifically, when the third switch S3, the fourth switch S4 and the fifth switch S5 conduct and the sixth switch S6 turns off, the current generated by the fourth switching transistor M4 can flow through the fifth switching transistor M5, thereby realizing maintaining the working state of the first operational amplifier A1 when the voltage corresponding to the voltage signal is less than the preset voltage threshold.

[0075] Specifically, the transmission gate control module may include a first transmission gate, a second transmission gate, a third transmission gate and a fourth transmission gate. The output terminal of the first transmission gate is connected to the third switch S3, the output terminal of the second transmission gate is connected to the fourth switch S4, the output terminal of the third transmission gate is connected to the fifth switch S5, and the output terminal of the fourth transmission gate is connected to the sixth switch S6 through the first inverter INV1.

[0076] Specifically, the first terminal of the seventh switching transistor M7 is connected to the first terminal of the switch control circuit 202. If the voltage corresponding to the voltage signal provided by the switch control circuit 202 to the constant current driving circuit 204 is denoted as VG, then it can be regarded that the first terminal of the seventh switching transistor M7 is connected to the power supply VG.

[0077] Specifically, the control signals received by the third switch S3, the fourth switch S4, and the fifth switch S5 from the transmission gate control module are opposite to the control signal received by the sixth switch S6 from the transmission gate control module. The transmission gate control module is configured to, when the voltage corresponding to the voltage signal is less than the preset voltage threshold, turn on the third switch S3, the fourth switch S4, and the fifth switch S5 based on the K signal, and turn off the sixth switch S6 based on the K_NOT signal; when the voltage corresponding to the voltage signal is greater than or equal to the preset voltage threshold, turn off the third switch S3, the fourth switch S4, and the fifth switch S5 based on the K signal, and turn on the sixth switch S6 based on the K_NOT signal.

[0078] In this embodiment, the auxiliary driving switch circuit includes a sixth switching transistor, a seventh switching transistor, a transmission gate control module, and a first inverter. Thus, it can be ensured that the sixth switch is turned off when the third, fourth, and fifth switches are turned on, and the sixth switch is turned on when the third, fourth, and fifth switches are turned off. Thus, the auxiliary driving circuit connected to the auxiliary driving switch circuit can provide a current signal to the constant current driving circuit to ensure that the constant current driving circuit is in an operating state when the voltage corresponding to the voltage signal is less than the preset voltage threshold.

[0079] In an exemplary embodiment, the auxiliary driving switch circuit further includes a second inverter INV2 and a third inverter INV3.

[0080] The second inverter INV2 and the third inverter INV3 are connected in series between the second terminal of the sixth switching transistor M6 and the input terminal of the transmission gate control module in sequence.

[0081] In this embodiment, since the transmission gate control module includes multiple transmission gates, to ensure that the transmission gate control module can drive the third, fourth, fifth, and sixth switches in a timely manner, the driving ability of the transmission gate control module should be ensured. Therefore, a second inverter and a third inverter are also provided in the auxiliary driving switch circuit, which can significantly reduce the voltage drop between the sixth switching transistor and the transmission gate control module to improve the driving ability of the output terminal of the transmission gate control module and ensure the response timeliness of the auxiliary driving circuit.

[0082] In an exemplary embodiment, the device further includes a switch control driving circuit; the switch control driving circuit is respectively connected to the first switch S1 and the second switch S2. The switch control driving circuit is configured to, in response to a state switching enable signal, control the first switch S1 to be turned on and the second switch S2 to be turned off when the state switching signal indicates that the light emitting unit LED is turned on, and control the first switch S1 to be turned off and the second switch S2 to be turned on when the state switching signal indicates that the light emitting unit LED is turned off.

[0083] In an exemplary embodiment, as Figure 5 shown, the switch control driving circuit includes a fourth inverter INV4, a fifth inverter INV5, a sixth inverter INV6, and a fifth transmission gate TG; the input end of the switch control driving circuit is used to receive a state switching enable signal PWMO, and the fourth inverter INV4 and the fifth inverter INV5 are connected in series between the input end of the switch control driving circuit and the fifth transmission gate TG in sequence; the first output end of the fifth transmission gate TG is connected to the first switch S1, and the second output end of the fifth transmission gate is connected to the second switch S2 through the sixth inverter INV6.

[0084] Among them, the control signals received by the first switch S1 and the second switch S2 from the fifth transmission gate TG are opposite. Specifically, the fifth transmission gate TG is used to control the first switch S1 to conduct based on the K1 signal and control the second switch S2 to turn off based on the K1_NOT signal when the state switching signal indicates to turn on the light-emitting unit LED; when the state switching signal indicates to turn off the light-emitting unit LED, it controls the first switch S1 to turn off based on the K1 signal and controls the second switch S2 to conduct based on the K1_NOT signal.

[0085] As Figure 3 shown, the application process of the above switch device is described below in combination with a detailed embodiment, as follows:

[0086] (1) When the light-emitting unit LED changes from the on state to the off state, at this time, the first switch S1 is turned off, the second switch S2 is turned on, the third switch S3 is turned off, the fourth switch S4 is turned off, the fifth switch S5 is turned off, and the sixth switch S6 is turned on. The gate voltage of the second switching transistor M2 begins to be pulled down by the third switching transistor M3, and the driving current flowing through the second switching transistor M2 becomes smaller. When the driving current is less than the preset current threshold, the gate voltage of the second switching transistor M2 is also less than the preset voltage threshold. At this time, the auxiliary driving switch circuit controls the third switch S3 to conduct, the fourth switch S4 to conduct, the fifth switch S5 to conduct, and the sixth switch S6 to turn off. The constant current source I starts to charge the gate terminal of the fourth switching transistor M4, and the fourth switching transistor M4 starts to generate a current signal. Finally, the gate voltage of the second switching transistor M2 is pulled down to 0 by the third switching transistor M3, and the gate voltage of the fourth switching transistor M4 is charged to the same voltage magnitude as the voltage signal provided by the switch control circuit 202 to the constant current driving circuit. Thus, the light-emitting unit LED completely enters the off state. During this process, there is always current flowing through the first switching transistor M1. Therefore, the first operational amplifier A1 is always in a normal working state, and thus, the drain voltage of the second switching transistor M2 always remains consistent.

[0087] (2) When the light-emitting unit LED enters the on state from the off state, the first switch S1 is turned on, the second switch S2 is turned off, the third switch S3 is turned on, the fourth switch S4 is turned on, the fifth switch S5 is turned on, and the sixth switch S6 is turned off. The gate end of the second switch tube M2 begins to be charged by the constant current source I, and the driving current increases. When the driving current reaches the preset current threshold, the auxiliary driving switch circuit controls the third switch S3 to be turned off, the fourth switch S4 to be turned off, the fifth switch S5 to be turned off, and the sixth switch S6 to be turned on. Finally, the current flowing through the fourth switch tube M4 becomes 0, and the gate voltage of the second switch tube M2 is charged to the same voltage as the voltage signal corresponding to the voltage signal provided by the switch control circuit 202 to the constant current driving circuit. At this point, the light-emitting unit LED completely enters the on state. In this process, the first switch tube M1 always has current flowing through it, so the first operational amplifier A1 is always in a normal working state, so that the drain voltage of the second switch tube M2 always remains consistent.

[0088] In this embodiment, the driving current used to drive the light-emitting unit will only change with the change of the gate voltage of the second switch tube, and the gate voltage of the second switch tube changes linearly whether the light-emitting unit enters the on state or the off state. Therefore, the driving current used to drive the light-emitting unit also changes linearly. That is to say, this embodiment achieves the goal of constant slope change of the driving current, which can keep the on speed and off speed of the light-emitting unit constant and have a better display effect.

[0089] It can be understood that the above-mentioned switching device can also adopt other forms, and is not limited to the forms mentioned in the above-mentioned embodiments, as long as it can achieve the function of linearly controlling the constant current driving circuit with a single variable in the two processes of the light-emitting unit switching from the on state to the off state and from the off state to the on state, so that the driving current used to drive the light-emitting unit also changes linearly, thereby keeping the opening speed and closing speed of the light-emitting unit constant.

[0090] The switch device can be applied to lamps, display screens or other lighting devices.

[0091] In an exemplary embodiment, a light emitting device is further provided. The light emitting device includes a light emitting unit and a switch device as described in any one of the above switch device embodiments. The light emitting unit is connected to the switch device.

[0092] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0093] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0094] The above-described embodiments only represent several implementation manners of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A switch device, characterized in that: It includes a switch control circuit, a constant current drive circuit and an auxiliary drive circuit; the first end of the switch control circuit is connected to the first end of the constant current drive circuit, the second end of the switch control circuit is connected to the first end of the auxiliary drive circuit, the second end of the constant current drive circuit is respectively connected to the second end of the auxiliary drive circuit and the light-emitting unit, and the third end of the constant current drive circuit is connected to the third end of the auxiliary drive circuit; The switch control circuit is used to provide a voltage signal to the constant current drive circuit; The constant current driving circuit is used to determine a driving current according to the voltage signal, and use the driving current to drive the light-emitting unit, wherein the driving current is positively correlated with a voltage corresponding to the voltage signal; The auxiliary driving circuit is used to provide a current signal to the constant current driving circuit to ensure that the constant current driving circuit is in a working state when the driving current is less than a preset current threshold.

2. The device according to claim 1, characterized in that The constant current driving circuit includes a first switch tube, a second switch tube and a first operational amplifier; The first end of the first switch tube is connected to the output end of the first operational amplifier, the second end of the first switch tube is connected to the light-emitting unit, and the third end of the first switch tube is respectively connected to the second end of the second switch tube and the reverse input end of the first operational amplifier; The first end of the second switch tube is connected to the first end of the switch control circuit, and the third end of the second switch tube is connected to the ground end; A positive input terminal of the first operational amplifier is connected to a first power supply.

3. The device according to claim 1, characterized in that The switch control circuit includes a constant current source, a second operational amplifier, a third switch tube, a first switch and a second switch; One end of the constant current source is connected to the second power supply, and the other end of the constant current source is respectively connected to the inverting input end and the output end of the second operational amplifier, the first end of the first switch, and the first end of the auxiliary driving circuit; The positive input terminal of the second operational amplifier is connected to a third power supply; The first end of the third switch tube is connected to the fourth power supply, the second end of the third switch tube is connected to the second end of the first switch and the first end of the constant current drive circuit through the second switch, and the third end of the third switch tube is connected to the ground.

4. The device according to claim 1, characterized in that The auxiliary driving circuit includes a third switch, a fourth switch, a fifth switch, a sixth switch, a fourth switch tube and a fifth switch tube; The first end of the fourth switch tube is connected to the second end of the switch control circuit through the third switch, the second end of the fourth switch tube is connected to the third end of the constant current drive circuit through the fourth switch, and the third end of the fourth switch tube is connected to the ground; The first end of the fifth switch tube is respectively connected to the first end of the fifth switch and the first end of the sixth switch, the second end of the fifth switch tube is respectively connected to the second end of the fifth switch and the second end of the constant current drive circuit, and the third end of the fifth switch tube is respectively connected to the second end of the sixth switch and the second power supply.

5. The device according to claim 4, characterized in that The equivalent resistance of the fifth switch tube is smaller than the resistance of the light emitting unit.

6. The device according to claim 1 or 4, characterized in that: The device further comprises an auxiliary driving switch circuit; the auxiliary driving switch circuit is connected to the auxiliary driving circuit; The auxiliary drive switching circuit is used to control the auxiliary drive circuit to be turned on when the voltage corresponding to the voltage signal is less than a preset voltage threshold, and to control the auxiliary drive circuit to be turned off when the voltage corresponding to the voltage signal is greater than or equal to the preset voltage threshold, and the preset voltage threshold corresponds to the preset current threshold.

7. The device according to claim 6, characterized in that The auxiliary driving switch circuit includes a sixth switch tube, a seventh switch tube, a transmission gate control module and a first inverter; The first end of the sixth switch tube is connected to the fifth power supply, the second end of the sixth switch tube is connected to the input end of the transmission gate control module and the second end of the seventh switch tube, and the third end of the sixth switch tube is connected to the second power supply; The first end of the seventh switch tube is connected to the first end of the switch control circuit, and the third end of the seventh switch tube is connected to the ground end; The first output end of the transmission gate control module is connected to the third switch, the fourth switch and the fifth switch respectively, and the second output end of the transmission gate control module is connected to the sixth switch through the first inverter; Among them, the transmission gate control module is used to control the third switch, the fourth switch and the fifth switch to be turned on, and the sixth switch to be turned off when the voltage corresponding to the voltage signal is less than the preset voltage threshold; and to control the third switch, the fourth switch and the fifth switch to be turned off, and the sixth switch to be turned on when the voltage corresponding to the voltage signal is greater than or equal to the preset voltage threshold.

8. The device according to claim 7, characterized in that The auxiliary drive switch circuit also includes a second inverter and a third inverter; The second inverter and the third inverter are connected in series in sequence between the second end of the sixth switch tube and the input end of the transmission gate control module.

9. The device according to claim 3, characterized in that The turning-on speed of the light-emitting unit is determined based on the size of the constant current source; the turning-off speed of the light-emitting unit is determined based on the voltage size of the fourth power supply and / or the size of the third switch tube.

10. A light emitting device, characterized in that: The light emitting device comprises a light emitting unit and a switch device according to any one of claims 1 to 9, wherein the light emitting unit is connected to the switch device.

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