TWI711338B - Driving device - Google Patents

Abstract

A driving device for driving a lighting-emitting element includes a bridge rectifier, a first capacitor, a transformer, a power switch element, an output stage circuit, and a controller. The bridge rectifier generates a rectified voltage according to a first input voltage and a second input voltage. The transformer includes a main coil, a secondary coil, and an auxiliary coil. The main coil receives the rectified voltage. The secondary coil generates a transformation voltage. The main coil is coupled through the power switch element to a ground voltage. The output stage circuit generates an output voltage according to the transformation voltage, thereby controlling the lighting-emitting element. The output stage circuit further compares the output voltage with a threshold voltage. If the output voltage is higher than the threshold voltage, the output stage circuit will reduce an output current flowing through the lighting-emitting element.

Description

Drive device

The present invention relates to a driving device, and more particularly to a driving device that can drive a light-emitting element.

In the lighting application of light-emitting elements, the most common problem is flicker, which means that the brightness of light will periodically change over time. Generally speaking, when the switching frequency of light is below 60Hz, the human eye can easily perceive the flicker of the light source, and when the switching frequency of light is above 60Hz, although the human eye cannot easily detect it, it still easily causes eye fatigue And discomfort. In view of this, it is necessary to propose a new solution to overcome the shortcomings faced by the prior art.

In a preferred embodiment, the present invention provides a driving device for driving a light-emitting element, and includes: a bridge rectifier, which generates a rectified potential according to a first input potential and a second input potential; and a first capacitor , Store the rectified potential; a transformer, including a main coil, a secondary coil, and an auxiliary coil, wherein the main coil is used to receive the rectified potential, and the secondary coil is used to generate a variable voltage; a power A switch, wherein the main coil is coupled to a ground potential via the power switch, and the power switch performs a switching operation according to a clock potential; an output stage circuit generates an output potential according to the variable voltage , Wherein the light-emitting element determines whether to generate a light according to the output potential; and a controller generates the clock potential; wherein the output stage circuit compares the output potential with a critical potential, and if the output potential is high At the critical potential, the output stage circuit reduces the output current through one of the light-emitting elements.

In order to make the purpose, features and advantages of the present invention more comprehensible, specific embodiments of the present invention are specifically listed below, and are described in detail in conjunction with the accompanying drawings.

Certain words are used in the specification and the scope of patent applications to refer to specific elements. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and the scope of the patent application do not use differences in names as a way to distinguish elements, but use differences in functions as a criterion for distinction. The terms "include" and "include" mentioned in the entire specification and the scope of the patent application are open-ended terms and should be interpreted as "including but not limited to". The term "approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and achieve the basic technical effect. In addition, the term "coupling" includes any direct and indirect electrical connection means in this specification. Therefore, if it is described that a first device is coupled to a second device, it means that the first device can be directly electrically connected to the second device, or indirectly electrically connected to the second device through other devices or connection means. Two devices.

FIG. 1 is a schematic diagram of a driving device 100 according to an embodiment of the invention. The driving device 100 is used to drive a light emitting element 190. For example, the driving device 100 can be applied to a desktop computer, a notebook computer, or an integrated computer. As shown in FIG. 1, the driving device 100 includes: a bridge rectifier 110, a first capacitor C1, a transformer 130, a power switch 140, an output stage circuit 150, and a controller 160. It should be noted that although not shown in Figure 1, the driving device 100 may further include other components, such as a voltage regulator or (and) a negative feedback circuit.

The bridge rectifier 110 generates a rectified potential VR according to a first input potential VIN1 and a second input potential VIN2. Both the first input potential VIN1 and the second input potential VIN2 can come from an external power source, wherein an AC voltage of any frequency and any amplitude can be formed between the first input potential VIN1 and the second input potential VIN2. For example, the frequency of the AC voltage may be about 50 Hz or 60 Hz, and the root mean square value of the AC voltage may be about 110V or 220V, but it is not limited to this. The first capacitor C1 can be used to store the rectified potential VR. The transformer 130 includes a main winding 131, a secondary winding 132, and an auxiliary winding 133. The primary winding 131 and the auxiliary winding 133 can be located on the same side of the transformer 130, and the secondary winding 132 can be located on the opposite side of the transformer 130 . The main coil 131 is used to receive the rectified potential VR, and as a response to the rectified potential VR, the auxiliary coil 132 can be used to generate a variable voltage potential VS. The auxiliary coil 133 is coupled to the controller 160. In addition, the main coil 131 is coupled to a ground potential VSS (for example, 0V) via the power switch 140. The power switch 140 performs a switching operation according to a clock potential VA, which can be turned on or off alternately. The output stage circuit 150 generates an output potential VOUT according to the variable potential VS. The light-emitting element 190 determines whether to generate a light according to the output potential VOUT. For example, if the output potential VOUT is at a high logic level, the light emitting element 190 will generate light, and if the output potential VOUT is at a low logic level, the light emitting element 190 will not generate any light. The controller 160 may be a control integrated circuit, where the controller 160 is used to generate the clock potential VA. The clock potential VA can be maintained at a fixed potential when the driving device 100 is initialized, and a periodic clock waveform can be provided after the driving device 100 enters the normal use stage. In a preferred embodiment, the output stage circuit 150 further compares the output potential VOUT with a threshold potential VTH, and if the output potential VOUT is higher than the threshold potential VTH, the output stage circuit 150 reduces the output current IOUT through one of the light emitting elements 190; Conversely, if the output potential VOUT is lower than or equal to the threshold potential VTH, the output stage circuit 150 will not reduce the output current IOUT through the light emitting element 190 (that is, the output current IOUT may remain unchanged or increase). According to the actual measurement results, this circuit design method can reduce the non-ideal stroboscopic phenomenon, so using the light-emitting element 190 of the driving device 100 will not easily cause eye fatigue of the user.

The following embodiments will introduce the detailed structure and operation of the driving device 100. It must be understood that these drawings and descriptions are only examples and are not used to limit the scope of the present invention.

FIG. 2 is a schematic diagram showing the driving device 200 according to an embodiment of the invention. In the embodiment of FIG. 2, the driving device 200 has a first input node NIN1, a second input node NIN2, and an output node NOUT, and includes a bridge rectifier 210, a first capacitor C1, a transformer 230, A power switch 240, an output stage circuit 250, and a controller 260. The first input node NIN1 and the second input node NIN2 of the driving device 200 can receive a first input potential VIN1 and a second input potential VIN2 respectively from an external power source, and the output node NOUT of the driving device 200 can be used to output an output potential VOUT to a light-emitting element 290.

The bridge rectifier 210 includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The anode of the first diode D1 is coupled to the first input node NIN1, and the cathode of the first diode D1 is coupled to a first node N1 to output a rectified potential VR. The anode of the second diode D2 is coupled to a ground potential VSS, and the cathode of the second diode D2 is coupled to the first input node NIN1. The anode of the third diode D3 is coupled to the second input node NIN2, and the cathode of the third diode D3 is coupled to the first node N1. The anode of the fourth diode D4 is coupled to the ground potential VSS, and the cathode of the fourth diode D4 is coupled to the second input node NIN2.

The first terminal of the first capacitor C1 is coupled to the first node N1 to receive and store the rectified potential VR, and the second terminal of the first capacitor C1 is coupled to the ground potential VSS.

The transformer 230 includes a main coil 231, a secondary coil 232, and an auxiliary coil 233. The first end of the main coil 231 is coupled to the first node N1 to receive the rectified potential VR, and the second end of the main coil 231 is coupled to a second node N2. The first end of the auxiliary coil 232 is coupled to a third node N3 to output a variable voltage potential VS, and the second end of the auxiliary coil 232 is coupled to the ground potential VSS. The first end of the auxiliary coil 233 is coupled to the controller 260 to receive a supply potential VCC, and the second end of the auxiliary coil 233 is coupled to the ground potential VSS. For example, the supply potential VCC can be a fixed potential.

The power switch 240 includes a first transistor M1. The first transistor M1 can be an N-type metal oxide half field effect transistor. The control terminal of the first transistor M1 is used to receive a clock potential VA, the first terminal of the first transistor M1 is coupled to the ground potential VSS, and the second terminal of the first transistor M1 is coupled to the second Node N2. The controller 260 is used to generate the clock potential VA. The clock potential VA can be maintained at a fixed potential (for example, the ground potential VSS) when the driving device 200 is initialized, and a periodic clock waveform can be provided after the driving device 200 enters the normal use phase.

The output stage circuit 250 includes a monitoring circuit 251, a first comparator 252, a second comparator 253, a fifth diode D5, a sixth diode D6, a second capacitor C2, a second capacitor Crystal M2, a third transistor M3, a first resistor R1, a second resistor R2, and a third resistor R3. For example, the monitoring circuit 221 may include a voltage detector and an arithmetic circuit (not shown), the first comparator 251 and the second comparator 252 may each be an operational amplifier, and the second transistor M2 and the third transistor M3 can each be an N-type MOSFET.

The anode of the fifth diode D5 is coupled to the third node N3 to receive the variable voltage potential VS, and the cathode of the fifth diode D5 is coupled to the output node NOUT. The first end of the second capacitor C2 is coupled to the output node NOUT, and the second end of the second capacitor C2 is coupled to the ground potential VSS.

The monitoring circuit 251 can detect the output potential VOUT. The monitoring circuit 251 replicates and generates the output potential VOUT at a fourth node N4, and generates a threshold at a fifth node N5 according to the output potential VOUT and a target flicker percentage. Potential VTH. The positive input terminal of the first comparator 252 is coupled to the fourth node N4, the negative input terminal of the first comparator 252 is coupled to the fifth node N5, and the output terminal of the first comparator 252 is coupled to a sixth node. A first control potential VC1 is output at the node N6. The positive input terminal of the second comparator 253 is coupled to the fifth node N5, the negative input terminal of the second comparator 253 is coupled to the fourth node N4, and the output terminal of the second comparator 253 is coupled to a seventh node. A second control potential VC2 is output at the node N7. The first control potential VC1 and the second control potential VC2 may have complementary logic levels. For example, if the output potential VOUT is higher than the threshold potential VTH, the first control potential VC1 can be a high logic level and the second control potential VC2 can be a low logic level; conversely, if the output potential VOUT is lower than the threshold potential VTH, then The first control potential VC1 can be a low logic level and the second control potential VC2 can be a high logic level.

The first end of the first resistor R1 is coupled to the output node NOUT, and the second end of the first resistor R1 is coupled to an eighth node N8. The control terminal of the second transistor M2 is coupled to the sixth node N6, the first terminal of the second transistor M2 is coupled to a ninth node N9, and the second terminal of the second transistor M2 is coupled to The eighth node N8. The first end of the second resistor R2 is coupled to the ninth node N9, and the second end of the second resistor R2 is coupled to the ground potential VSS. The first resistor R1, the second transistor M2, and the second resistor R2 can jointly form an auxiliary current path, which can be selectively turned on or off according to the first control potential VC1.

The anode of the sixth diode D6 is coupled to a sixth node N6, and the cathode of the sixth diode D6 is coupled to a tenth node N10. The control terminal of the third transistor M3 is coupled to the seventh node N7, the first terminal of the third transistor M3 is coupled to the ground potential VSS, and the second terminal of the third transistor M3 is coupled to the tenth node. Node N10. The sixth diode D6 and the third transistor M3 can jointly form a fast discharge path, which can selectively pull down or maintain the level of the first control potential VC1 according to the second control potential VC2. The first end of the third resistor R3 is coupled to an eleventh node N11, and the second end of the third resistor R3 is coupled to the ground potential VSS.

The light emitting element 290 may include one or a plurality of light emitting diodes connected in series between the output node NOUT and the eleventh node N11. The total number of light-emitting diodes is not particularly limited in the present invention. In other embodiments, the aforementioned light-emitting diodes can also be changed to sub-millimeter light-emitting diodes (Mini LED), micro-light-emitting diodes (Micro LED), or organic light-emitting diodes (Organic LED, OLED) , But not limited to this. For example, if the output potential VOUT is at a high logic level, the light emitting element 290 will generate light, and if the output potential VOUT is at a low logic level, the light emitting element 290 will not generate any light. In detail, the flicker percentage of the light-emitting element 290 can be as described in the following equation (1):

…………………………………………….(1)其中「P」代表發光元件290之閃爍百分比，「A」代表輸出電位VOUT之極大值，而「B」代表輸出電位VOUT之極小值。

………………………………………. (1) “P” represents the flicker percentage of the light-emitting element 290, “A” represents the maximum value of the output potential VOUT, and “B” represents the output The minimum value of the potential VOUT.

」之結論，亦即，輸出電位VOUT之目標極大值可等於輸出電位VOUT之極小值之1.5倍，而臨界電位VTH可設定為輸出電位VOUT之目標極大值。一般來說，若發光元件290之閃爍百分比越低(例如：低於或等於20%)，則人眼將越不容易察覺其頻閃現象。 In some embodiments, the monitoring circuit 251 may first detect the minimum value of the output potential VOUT, and then estimate the target maximum value of the output potential VOUT based on the target flicker percentage and the minimum value of the output potential VOUT, which can be set as the aforementioned The critical potential VTH. For example, if the target flicker percentage is set to 20%, according to equation (1), the monitoring circuit 251 will be able to deduce

"The conclusion is that the target maximum value of the output potential VOUT can be equal to 1.5 times the minimum value of the output potential VOUT, and the critical potential VTH can be set as the target maximum value of the output potential VOUT. Generally speaking, if the flicker percentage of the light-emitting element 290 is lower (for example, less than or equal to 20%), the human eyes will be less likely to perceive the stroboscopic phenomenon.

In some embodiments, the operating principle of the driving device 200 may be as described below. If the output potential VOUT is higher than the threshold potential VTH, the first control potential VC1 can be a high logic level and the second control potential VC2 can be a low logic level, so that the second transistor M2 is enabled and the third transistor M3 is disabled . At this time, a branch current IDIV will flow from the output node NOUT through the first resistor R1, the second transistor M2, and the second resistor R2 (that is, the aforementioned auxiliary current path) to the ground potential VSS, so that it passes through the light emitting element One of the 290 output current IOUT decreases. Conversely, if the output potential VOUT is lower than the threshold potential VTH, the first control potential VC1 can be a low logic level and the second control potential VC2 can be a high logic level to disable the second transistor M2 and enable the third Transistor M3. At this time, the aforementioned branch current IDIV will quickly drop to zero, so that the output current IOUT through the light-emitting element 290 increases.

Fig. 3 shows a waveform diagram of the output current IOUT of the driving device 200 according to an embodiment of the present invention. A first curve CC1 represents the output current IOUT of the driving device 200 when the output stage circuit 250 is not used. The second curve CC2 represents the output current IOUT when the driving device 200 has used the output stage circuit 250. Fig. 4 is a waveform diagram showing the output potential VOUT of the driving device 200 according to an embodiment of the present invention. A third curve CC3 represents the output potential VOUT of the driving device 200 when the output stage circuit 250 is not used, and a first The four-curve CC4 represents the output potential VOUT when the driving device 200 has used the output stage circuit 250. According to the measurement results in Figures 3 and 4, after the output stage circuit 250 is used to dynamically fine-tune the output current IOUT, the maximum values of the output current IOUT and the output potential VOUT of the driving device 200 both decrease at the same time. Therefore, the light-emitting element 290 can have a lower blinking percentage (which approaches the target blinking percentage).

In some embodiments, the component parameters of the driving device 200 may be as described below. The resistance value of the first resistor R1 may be between 9kΩ and 11kΩ, preferably 10kΩ. The resistance value of the second resistor R2 may be between 45kΩ and 55kΩ, preferably 50kΩ. The resistance value of the third resistor R3 can be between 423Ω and 517Ω, preferably 470Ω. The capacitance value of the first capacitor C1 can be between 96 μF and 144 μF, preferably 120 μF. The capacitance value of the second capacitor C2 can be between 1200 μF and 1800 μF, preferably 1500 μF. The ratio of the number of turns of the primary coil 231 to the secondary coil 232 can be between 1 and 40, preferably 20. The turns ratio of the auxiliary coil 232 to the auxiliary coil 233 may be between 1 and 3, preferably 1.33. The above parameter ranges are obtained based on the results of many experiments, which help optimize the conversion efficiency of the driving device 200 and effectively suppress the stroboscopic phenomenon.

The present invention provides a novel driving device, which includes an output stage circuit that can limit the flicker percentage of the light-emitting element. According to the actual measurement results, the use of the aforementioned output stage circuit can suppress the non-ideal flicker of the corresponding light-emitting elements, thereby reducing the user's eye fatigue and discomfort. Generally speaking, the driving device of the present invention is not susceptible to the negative effects of general low-frequency noise from the mains, so it is very suitable for use in various electronic devices.

It should be noted that the above-mentioned potential, current, resistance value, inductance value, capacitance value, and other component parameters are not the limiting conditions of the present invention. The designer can adjust these settings according to different needs. The driving device of the present invention is not limited to the state illustrated in FIGS. 1-4. The present invention may only include any one or more of the features of any one or more of the embodiments shown in FIGS. 1-4. In other words, not all the features shown in the figures need to be implemented in the driving device of the present invention at the same time. Although the embodiment of the present invention uses metal oxide half field effect transistors as an example, the present invention is not limited to this. Those skilled in the art can use other types of transistors, such as junction field effect transistors or fins. Type field effect transistors, etc., without affecting the effect of the present invention.

The ordinal numbers in this specification and the scope of the patent application, such as "first", "second", "third", etc., do not have a sequential relationship between them. They are only used to distinguish between two having the same Different components of the name.

Although the present invention is disclosed as above in a preferred embodiment, it is not intended to limit the scope of the present invention. Anyone familiar with the art can make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention shall be subject to those defined by the attached patent scope.

100, 200: drive device 110, 210: Bridge rectifier 130, 230: Transformer 131, 231: main coil 132, 232: secondary coil 133, 233: auxiliary coil 140, 240: power switch 150, 250: output stage circuit 160, 260: Controller 190, 290: light-emitting element 251: Monitoring circuit 252: first comparator 253: second comparator C1: The first capacitor C2: second capacitor CC1: the first curve CC2: second curve CC3: third curve CC4: fourth curve D1: The first diode D2: The second diode D3: The third diode D4: The fourth diode D5: Fifth diode D6: The sixth diode IDIV: branch current IOUT: output current M1: The first transistor M2: second transistor M3: third transistor N1: the first node N2: second node N3: third node N4: Fourth node N5: fifth node N6: sixth node N7: seventh node N8: Eighth node N9: Ninth node N10: Tenth node N11: Tenth node NIN1: the first input node NIN2: second input node NOUT: output node R1: first resistor R2: second resistor R3: third resistor VA: clock potential VC1: The first control potential VC2: second control potential VCC: supply potential VIN1: first input potential VIN2: second input potential VOUT: output potential VR: Rectified potential VS: Variable voltage potential VSS: Ground potential VTH: critical potential

Figure 1 is a schematic diagram showing a driving device according to an embodiment of the present invention. Figure 2 is a schematic diagram showing the driving device according to an embodiment of the present invention. Fig. 3 is a waveform diagram showing the output current of the driving device according to an embodiment of the invention. FIG. 4 is a waveform diagram showing the output potential of the driving device according to an embodiment of the invention.

100: Drive

110: Bridge rectifier

130: Transformer

131: main coil

132: Secondary coil

133: auxiliary coil

140: power switch

150: output stage circuit

160: Controller

190: Light-emitting element

C1: The first capacitor

IOUT: output current

VA: clock potential

VIN1: first input potential

VIN2: second input potential

VOUT: output potential

VR: Rectified potential

VS: Variable voltage potential

VSS: Ground potential

VTH: critical potential

Claims (10)

A driving device for driving a light-emitting element, and comprising: a bridge rectifier, which generates a rectified potential according to a first input potential and a second input potential; a first capacitor, which stores the rectified potential; and a transformer, including A main coil, a sub-coil, and an auxiliary coil, wherein the main coil is used to receive the rectified potential, and the sub-coil is used to generate a variable voltage potential; a power switch, wherein the main coil is through the The power switch is coupled to a ground potential, and the power switch performs switching operations according to a clock potential; an output stage circuit generates an output potential according to the variable voltage potential, and the light-emitting element is based on the output potential To determine whether to generate a light, and the output stage circuit at least includes a first comparator and a second comparator; and a controller to generate the clock potential; wherein the output stage circuit compares the output potential with a Critical potential, and if the output potential is higher than the critical potential, the output stage circuit reduces the output current through one of the light-emitting elements. According to the driving device described in claim 1, wherein the bridge rectifier includes: a first diode having an anode and a cathode, wherein the anode of the first diode is coupled to a first diode An input node to receive the first input potential, and the cathode of the first diode is coupled to a first node to output the rectified potential; A second diode having an anode and a cathode, wherein the anode of the second diode is coupled to the ground potential, and the cathode of the second diode is coupled to the first input Node; a third diode having an anode and a cathode, wherein the anode of the third diode is coupled to a second input node to receive the second input potential, and the third diode The cathode is coupled to the first node; and a fourth diode having an anode and a cathode, wherein the anode of the fourth diode is coupled to the ground potential, and the fourth diode The cathode of the polar body is coupled to the second input node; wherein the first capacitor has a first terminal and a second terminal, and the first terminal of the first capacitor is coupled to the first node to receive The rectified potential, and the second terminal of the first capacitor is coupled to the ground potential. As for the driving device described in claim 2, wherein the main coil has a first end and a second end, and the first end of the main coil is coupled to the first node to receive the rectified potential, The second end of the main coil is coupled to a second node, the auxiliary coil has a first end and a second end, and the first end of the auxiliary coil is coupled to a third node to output the Variable voltage, the second end of the auxiliary coil is coupled to the ground potential, the auxiliary coil has a first end and a second end, the first end of the auxiliary coil is received by the controller Supply potential, and the second end of the auxiliary coil is coupled to the ground potential. The driving device described in item 3 of the scope of patent application, wherein the power switch includes: A first transistor has a control terminal, a first terminal, and a second terminal, wherein the control terminal of the first transistor is used to receive the clock potential, and the first transistor of the first transistor The terminal is coupled to the ground potential, and the second terminal of the first transistor is coupled to the second node. According to the driving device described in claim 3, the output stage circuit further comprises: a fifth diode having an anode and a cathode, wherein the anode of the fifth diode is coupled to the The third node receives the variable voltage potential, and the cathode of the fifth diode is coupled to an output node to output the output potential; and a second capacitor having a first terminal and a second terminal, The first terminal of the second capacitor is coupled to the output node, and the second terminal of the second capacitor is coupled to the ground potential. For the driving device described in item 5 of the scope of patent application, the output stage circuit further includes: a monitoring circuit for detecting the output potential, wherein the monitoring circuit generates the output potential at a fourth node, and according to the The output potential and a target flicker percentage generate the critical potential at a fifth node; wherein the first comparator has a positive input terminal, a negative input terminal, and an output terminal, the positive input terminal of the first comparator Is coupled to the fourth node, the negative input terminal of the first comparator is coupled to the fifth node, and the output terminal of the first comparator outputs a first control at a sixth node Potential; and wherein the second comparator has a positive input terminal, a negative input terminal, and an output Terminal, the positive input terminal of the second comparator is coupled to the fifth node, the negative input terminal of the second comparator is coupled to the fourth node, and the output terminal of the second comparator A second control potential is output at a seventh node. According to the driving device described in claim 6, wherein the output stage circuit further includes: a first resistor having a first end and a second end, wherein the first end of the first resistor is Is coupled to the output node, and the second terminal of the first resistor is coupled to an eighth node; a second transistor has a control terminal, a first terminal, and a second terminal, wherein The control terminal of the second transistor is coupled to the sixth node, the first terminal of the second transistor is coupled to a ninth node, and the second terminal of the second transistor is coupled Connected to the eighth node; and a second resistor having a first end and a second end, wherein the first end of the second resistor is coupled to the ninth node, and the second resistor The second terminal of the device is coupled to the ground potential. According to the driving device described in claim 7, wherein the output stage circuit further comprises: a sixth diode having an anode and a cathode, wherein the anode of the sixth diode is coupled to the A sixth node, and the cathode of the sixth diode is coupled to a tenth node; and a third transistor having a control terminal, a first terminal, and a second terminal, wherein the third The control terminal of the transistor is coupled to the seventh node, and the third transistor The first terminal is coupled to the ground potential, and the second terminal of the third transistor is coupled to the tenth node. According to the driving device described in claim 8, wherein the output stage circuit further includes: a third resistor having a first terminal and a second terminal, wherein the first terminal of the third resistor is Is coupled to an eleventh node, and the second terminal of the third resistor is coupled to the ground potential. According to the driving device described in claim 9, wherein the light-emitting element includes one or more light-emitting diodes connected in series between the output node and the eleventh node.

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