Light emission driving device

Abstract

A light emission driving device according to the present technology comprises: a first accumulation selection unit that selects, in accordance with a charge signal, whether or not to perform charge accumulation in a first charge accumulation unit using a power supply; a second accumulation selection unit that selects, in accordance with a charge signal, whether or not to perform charge accumulation in a second charge accumulation unit using the power supply; and an output selection unit that selects, in accordance with a boost signal, whether or not to connect the first charge accumulation unit and the second charge accumulation unit in series on a path of light emission current to a light emission unit.

Description

Light-emitting driving device

[0001] This technology relates to a technology for a light-emitting driving device that makes the light-emitting intensity of a light-emitting part variable.

[0002] For example, in a LiDAR (Light Detection And Ranging) device, there is a desire to adaptively change the light-emitting intensity of the light-emitting part. In Patent Document 1 below, a configuration for changing the light-emitting intensity of the light-emitting part using a diode charge pump circuit is disclosed.

[0003] Japanese Patent Application Laid-Open No. 2017-139704

[0004] However, in the configuration described in Patent Document 1, since the capacitance of the capacitor Cchg connected to a plurality of capacitors described as C1 to C6 in the figure is constant, there is a problem that it takes time to charge and the pulse width of the light emission widens due to the increase in the voltage applied to the light-emitting part, and there is room for improvement from the viewpoint of eye safety.

[0005] Therefore, an object of this technology is to propose a configuration that makes the light-emitting intensity variable without excessively widening the pulse width of the light emission.

[0006] The light-emitting driving device according to this technology includes a first charge accumulation selection unit that selects whether to accumulate charge in a first charge accumulation unit by a power source according to a charge signal, a second charge accumulation selection unit that selects whether to accumulate charge in a second charge accumulation unit by the power source according to the charge signal, and an output selection unit that selects whether to connect the first charge accumulation unit and the second charge accumulation unit in series on the light-emitting current path for the light-emitting part according to a boost signal. The boost signal is, for example, a signal that becomes "H (Hi)" when the light-emitting part emits strong light (boost light emission). According to the above configuration, when the boost signal is "H", the first charge accumulation unit and the second charge accumulation unit are connected in series.

[0007] This is a block diagram showing an overview of the sensing system, control system, and vehicle system including the light-emitting drive device of this technology. This is a flowchart showing an example of the determination process performed by the boost signal supply unit. This is a diagram showing a first circuit configuration example of a light-emitting unit having a light-emitting drive device. This is a diagram showing the operation of the light-emitting drive device in the first state. This is a diagram showing the operation of the light-emitting drive device in the second state. This is a diagram showing the operation of the light-emitting drive device in the third state. This is a diagram showing the operation of the light-emitting drive device in the fourth state. This is an example of a timing chart related to the light emission of the light-emitting unit. This is a diagram showing a second configuration example of the light-emitting drive device. This is a diagram for explaining the switching mode of the connection switching unit in the second configuration example of the light-emitting drive device. This is a diagram showing an example in which the light-emitting unit has an array configuration. This is a diagram showing an example of the configuration of the third switch in an example in which the light-emitting unit has an array configuration.

[0008] The embodiments will be described below in the following order: <1. System Configuration> <2. First Configuration Example of Light-Emitting Drive Device> <3. Operation of Light-Emitting Drive Device> <3-1. First State> <3-2. Second State> <3-3. Third State> <3-4. Fourth State> <4. Timing Chart> <5. Second Configuration Example of Light-Emitting Drive Device> <6. Example of Light-Emitting Unit with Array Configuration> <7. Modified Examples> <8. Summary> <9. This Technology>

[0009] <1. System Configuration> The light-emitting drive device 1 of this technology is mounted on a sensing system Sys, which performs sensing to measure the distance to a subject using, for example, LiDAR (Light Detection And Ranging). The sensing system Sys is controlled by a control system 100 that performs various processing such as object detection and object recognition using the distance measurement results related to the subject.

[0010] Furthermore, the control system 100 is linked to, for example, a vehicle system 200 that controls the entire vehicle.

[0011] Figure 1 shows a block diagram illustrating the outlines of the light-emitting drive device 1, the sensing system Sys, the control system 100, and the vehicle system 200.

[0012] The vehicle system 200 performs various controls necessary for the vehicle's operation, such as accelerator control and brake control, as well as controls that ensure passenger comfort, such as in-cabin air conditioning control and audio control.

[0013] The vehicle system 200 is a system that works in conjunction with various ECUs (Electronic Control Units), and may be the main ECU, such as a VCU (Vehicle Control Unit) or a VDCU (Vehicle Dynamics Control Unit).

[0014] Among the various ECUs that work in conjunction with the vehicle system 200, there is a control system 100 that uses a sensing system Sys. Examples of the control system 100 include a recognition ECU that detects and recognizes obstacles outside the vehicle, pedestrians, and other vehicles.

[0015] The vehicle system 200 supplies time information, location information, speed information, illumination information, and the like to the control system 100. The vehicle system 200 also receives the results of the recognition process from the control system 100.

[0016] The control system 100 includes a recognition processing unit 101 and a boost instruction unit 102.

[0017] The recognition processing unit 101 receives distance measurement results for the subject from the sensing system Sys and performs the process of recognizing the subject. The recognition results are supplied to the vehicle system 200 and the boost instruction unit 102 as appropriate.

[0018] The boost instruction unit 102 performs a process to instruct the intensity of light to be irradiated onto the subject based on the recognition result of the recognition processing unit 101. In the following description, the emission at the basic emission intensity will be referred to as "reference emission," and emission with a higher intensity than the reference emission will be referred to as "boost emission." In addition, the instruction that the boost instruction unit 102 supplies to the sensing system Sys, which indicates whether or not to perform boost emission, will be referred to as "boost instruction."

[0019] In other words, the boost instruction unit 102 can be rephrased as an indicator that determines whether or not to perform boost illumination.

[0020] The boost indicator unit 102 provides instructions for boost illumination based on, for example, time information, vehicle location information such as latitude and longitude, vehicle speed information, and illumination information.

[0021] The boost instruction may be an instruction to perform standard illumination or boost illumination, or it may be an instruction to indicate the illumination intensity when boost illumination is performed.

[0022] The sensing system Sys comprises a light-emitting unit 2 having a light-emitting drive device 1, a light-receiving unit 3, a signal processing unit 4, and a control unit 5.

[0023] The light-emitting unit 2 realizes the emission of laser light in response to instructions from the control unit 5. The control unit 5 supplies the light-emitting unit 2 with a "charge signal Sc" that can distinguish between, for example, a "light emission period Te" which is the period during which laser light is emitted, and a "charge period Tc" for accumulating charge for light emission. That is, the light-emitting unit 2 is configured to include a light-emitting drive device 1 that switches between the light emission period Te and the charge period Tc based on the charge signal Sc supplied from the control unit 5.

[0024] Furthermore, the control unit 5 supplies a boost signal Sb to the light-emitting unit 2. The boost signal Sb may be the boost instruction signal itself supplied from the control system 100 to the sensing system Sys, or it may be a signal that reflects the control result from the control unit 5.

[0025] The light-emitting unit 2 comprises a light-emitting drive device 1, a charge storage unit 6, a light-emitting unit 7, and a power supply unit 8. In Figure 1, the charge storage unit 6 is not shown.

[0026] The light-emitting drive device 1 is configured to include a switching unit such as a switch. The power supply unit 8 supplies the power supply voltage VDD to the light-emitting drive device 1.

[0027] The charge storage unit 6 is a capacitor or the like, which stores and discharges charge by the light-emitting drive device 1. In this embodiment, the charge storage unit 6 is provided with at least two capacitors.

[0028] The light-emitting part 7 is, for example, a light-emitting element such as a laser diode.

[0029] The light-receiving unit 3 is composed of optical lenses, light-receiving elements, circuits, etc. The light-receiving unit 3 receives the reflected light from the subject after the laser light emitted from the light-emitting section 7 of the light-emitting unit 2 has been reflected, and supplies the light-receiving results, such as a histogram, to the signal processing unit 4. The light-receiving unit 3 uses a light-receiving trigger signal Sr to control the exposure timing of each pixel. The light-receiving trigger signal Sr is supplied from the control unit 5.

[0030] The signal processing unit 4 receives the light reception result output from the light receiving unit 3 and generates distance measurement data. The generated distance measurement data is output to the control system 100 as the distance measurement result.

[0031] The signal processing unit 4 calculates the amount of background light and interference light related to the subject based on the light reception result received from the light receiving unit, and supplies the result to the control unit 5.

[0032] The control unit 5 supplies a charge signal Sc and a boost signal Sb to the light-emitting unit 2, and a light-receiving trigger signal Sr to the light-receiving unit 3.

[0033] The control unit 5 includes a boost signal supply unit 9.

[0034] The boost signal supply unit 9 determines whether or not to perform boost emission based on information about the amount of background light and interference light received from the signal processing unit 4. The boost signal supply unit 9 may also determine the emission intensity when it decides to perform boost emission.

[0035] The boost signal supply unit 9 determines whether or not to actually perform boost emission based on information about the amount of background light and interference light or noise, and the boost instruction received from the boost instruction unit 102 of the control system 100, and supplies a boost signal Sb to the light emission unit 2.

[0036] The boost signal Sb may be a 1-bit signal capable of identifying whether or not to perform boost illumination. Alternatively, the boost signal Sb may be a 2-bit or more signal capable of distinguishing between cases where reference illumination is performed and cases where boost illumination is performed, and capable of specifying the illumination intensity when boost illumination is performed.

[0037] Figure 2 shows an example of the determination process performed by the boost signal supply unit 9.

[0038] In step S101, the boost signal supply unit 9 determines whether or not it has received a boost instruction from the boost instruction unit 102.

[0039] If it is determined that no boost instruction has been received, the boost signal supply unit 9 proceeds to step S102 and determines whether the amount of background light and interference light is above a threshold.

[0040] If the determination process in step S101 and step S102 both result in a "No" determination, the boost signal supply unit 9 proceeds to step S103 and decides to perform reference illumination. At this time, in the following step S105, the boost signal supply unit 9 supplies a boost signal Sb that is set to "L (Low)".

[0041] On the other hand, if the result in either step S101 or step S102 is "Yes", the boost signal supply unit 9 proceeds to step S104 and decides to perform boost illumination. At this time, in the following step S105, the boost signal supply unit 9 supplies a boost signal Sb which is set to "H (Hi)".

[0042] Note that supplying an "L" or "H" signal as the boost signal Sb to the light-emitting unit 2 is an example where the boost signal Sb is a 1-bit signal. If the boost signal Sb also includes information on light emission intensity, a signal of 2 bits or more will be output.

[0043] For example, if the boost signal Sb is a 2-bit signal, the boost signal supply unit 9 can output four types of signals: "0", "1", "2", and "3". In the example where the boost signal Sb is 2 bits, the signal output when performing reference light emission is set as "L(0)", and the signals output when performing boost light emission are set as "H(1)", "H(2)", and "H(3)" in ascending order of low emission intensity.

[0044] <2. First Configuration Example of Light Emission Driving Device> A first circuit configuration example of the light emission unit 2 having the light emission driving device 1 is shown in FIG. 3. In this example, assuming that the voltage applied to the light emitting unit 7 during reference light emission is the reference voltage V, the voltage applied to the light emitting unit 7 during boost light emission is set to a voltage twice the reference voltage V (= 2V).

[0045] Also, the boost signal Sb is a 1-bit signal indicating whether to perform boost light emission.

[0046] The light emission unit 2 is configured to include a light emission driving device 1, a first charge storage unit 21, a second charge storage unit 22, and a light emitting unit 7.

[0047] The light emission driving device 1 includes a first storage selection unit 31 that selects whether to store charge in the first charge storage unit 21, a second storage selection unit 32 that selects whether to store charge in the second charge storage unit 22, and an output selection unit 33 that can select the emission intensity of the light emitting unit 7 by selecting the emission current path for the light emitting unit 7.

[0048] The output selection unit 33 further includes a connection switching unit 34 that switches the connection mode of the second charge storage unit 22, and a power multiplexer 35 that selects the voltage applied to the light emitting unit 7 by selecting one from a plurality of inputs.

[0049] The connection switching unit 34 includes a first switch 36 that switches whether to connect the first charge storage unit 21 and the second charge storage unit 22 in series, and a second switch 37 that selects whether to ground one end of the second charge storage unit 22.

[0050] The light-emitting drive device 1 also includes a third switch 38 that switches whether or not to actually apply the output voltage selected by the power multiplexer 35 of the output selection unit 33 to the light-emitting unit 7.

[0051] Since the first storage selection unit 31 and the second storage selection unit 32 have similar configurations, the specific configuration of the second storage selection unit 32 is not shown in the diagram. The first storage selection unit 31 and the second storage selection unit 32 each have a p-type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) 39, an n-type MOSFET 40, and two resistors 41 and 42. In the diagram, the gate of the MOSFET is denoted as "G", the source as "S", and the drain as "D".

[0052] In the following description, the p-type MOSFET 39, n-type MOSFET 40, resistor 41, and resistor 42 provided in the first storage selection unit 31 will be referred to as p-type MOSFET 39A, n-type MOSFET 40A, resistor 41A, and resistor 42A, respectively.

[0053] Similarly, the p-type MOSFET 39, n-type MOSFET 40, resistor 41, and resistor 42 in the second storage selection unit 32 are changed to p-type MOSFET 39B, n-type MOSFET 40B, resistor 41B, and resistor 42B, respectively.

[0054] The source terminal of the p-type MOSFET 39A is connected to the positive terminal of the power supply unit 8, and the gate terminal is connected to the drain terminal of the n-type MOSFET 40A via a resistor 41A. The resistor 41A is the gate resistor of the p-type MOSFET 39A.

[0055] A resistor 42A is inserted between the source terminal and gate terminal of the p-type MOSFET 39A. Resistor 42A is considered to be the gate-source resistance of the p-type MOSFET 39A.

[0056] The voltage between the gate and source terminals of the p-type MOSFET 39A is divided by the gate resistor 41A and the gate-source resistor 42A. The resistance values ​​of resistors 41A and 42A are set so that the voltage between the gate and source terminals exceeds the on-threshold of the p-type MOSFET 39A.

[0057] The drain terminal of the p-type MOSFET 39A is grounded via the first charge storage unit 21.

[0058] The drain terminal of the p-type MOSFET 39A and the connection point of the first charge storage unit 21 are connected to the first input terminal 35a(1) of the power multiplexer 35.

[0059] The source terminal of the n-type MOSFET 40A is grounded. Additionally, a charge signal Sc is applied to the gate terminal of the n-type MOSFET 40A.

[0060] When a high ("H") charge signal Sc is applied to the n-type MOSFET 40A, an ON voltage is applied between the gate and source, and it is controlled to be in the ON state.

[0061] As a result, an ON voltage is applied between the gate and source of the p-type MOSFET 39A, and the p-type MOSFET 39A is also controlled to be in the ON state.

[0062] Furthermore, when a low ("L") charge signal Sc is applied to the n-type MOSFET 40A, the voltage between its gate and source falls below the ON voltage, thus controlling it to the OFF state. As a result, the voltage between the gate and source of the p-type MOSFET 39A also falls below the ON voltage, and the p-type MOSFET 39A is also controlled to the OFF state.

[0063] In other words, the first storage selection unit 31 functions as a switch that is controlled to be ON when an "H" signal is applied as the charge signal Sc, and controlled to be OFF when an "L" signal is applied as the charge signal Sc.

[0064] The first switch 36 includes a p-type MOSFET 43, an n-type MOSFET 44, and resistors 45 and 46. The second switch 37 includes an n-type MOSFET 47.

[0065] The source terminal of the p-type MOSFET 43 is connected to the connection point between the drain terminal of the p-type MOSFET 39A and the first charge storage unit 21.

[0066] The drain terminal of the p-type MOSFET 43 is connected to the second input terminal 35a(2) of the power multiplexer 35 via the second charge storage unit 22.

[0067] The gate terminal of the p-type MOSFET 43 is connected to the drain terminal of the n-type MOSFET 44 via a resistor 45. The resistor 45 is the gate resistor of the p-type MOSFET 43.

[0068] A resistor 46 is inserted between the source terminal and the gate terminal of the p-type MOSFET 43. Resistor 46 is considered to be the gate-source resistance of the p-type MOSFET 43.

[0069] The source terminal of the n-type MOSFET 44 is grounded. Additionally, the gate terminal of the n-type MOSFET 44 is subjected to the logical AND of the inverted charge signal Sc and the boost signal Sb.

[0070] In other words, when the charge signal Sc is set to "L" and the boost signal Sb is set to "H", the n-type MOSFET 44 is controlled to the ON state, and consequently the p-type MOSFET 43 is also controlled to the ON state. That is, the first switch 36 is controlled to the ON state when the charge signal Sc is set to "L" and the boost signal Sb is set to "H", and to the OFF state otherwise.

[0071] The drain terminal of the n-type MOSFET 47 is connected to the connection point between the drain terminal of the p-type MOSFET 43 and the second charge storage unit 22.

[0072] The source terminal of the n-type MOSFET 47 is grounded. Additionally, the logical AND of the charge signal Sc and the boost signal Sb is applied to the gate terminal of the n-type MOSFET 47.

[0073] In other words, the second switch 37 is controlled to be ON when both the charge signal Sc and the boost signal Sb are set to "H", thereby controlling the n-type MOSFET 47 to be ON, and otherwise controlled to be OFF.

[0074] The source terminal of the p-type MOSFET 39B is connected to the positive terminal of the power supply unit 8 that supplies the power supply voltage VDD, and the drain terminal is connected to the connection point between the second charge storage unit 22 and the second input terminal 35a(2) of the power multiplexer 35.

[0075] The power multiplexer 35 is supplied with a boost signal Sb as a control signal. When the boost signal Sb is "L", the power multiplexer 35 selects the input to the first input terminal 35a (1) as the output from output terminal 35b. On the other hand, when the boost signal Sb is "H", the power multiplexer 35 selects the input to the second input terminal 35a (2) as the output from output terminal 35b.

[0076] The third switch 38 is composed of a p-type MOSFET 48, an n-type MOSFET 49, and resistors 50 and 51.

[0077] The source terminal of the p-type MOSFET 48 is connected to the output terminal 35b of the power multiplexer 35.

[0078] The drain terminal of the p-type MOSFET 48 is connected to the anode of the light-emitting unit 7. The cathode of the light-emitting unit 7 is grounded.

[0079] The gate terminal of the p-type MOSFET 48 is connected to the drain terminal of the n-type MOSFET 49 via a resistor 50.

[0080] A resistor 51 is inserted between the source terminal and the gate terminal of the p-type MOSFET 48. Resistor 51 is considered to be the gate-source resistance of the p-type MOSFET 48.

[0081] The source terminal of the n-type MOSFET 49 is grounded.

[0082] An inverted signal of the charge signal Sc is applied to the gate terminal of the n-type MOSFET 49.

[0083] In other words, when the charge signal Sc is set to "L", the n-type MOSFET 49 is controlled to the ON state, and consequently, the p-type MOSFET 48 is also controlled to the ON state. That is, the third switch 38 is controlled to the ON state when the charge signal Sc is set to "L", and to the OFF state otherwise. Note that when the charge signal Sc is set to "L", it corresponds to the light emission period Te.

[0084] When the third switch 38 is controlled to the ON state, the voltage output from the output terminal 35b of the power multiplexer 35 is applied to the anode of the light-emitting unit 7, causing the light-emitting unit 7 to emit light.

[0085] <3. Operation of the Light-Emitting Drive Device> The light-emitting drive device 1 controls the energy storage of the first charge storage unit 21 and the second charge storage unit 22 and the light emission of the light-emitting unit 7 based on the charge signal Sc and the boost signal Sb. The charge signal Sc and the boost signal Sb each have two states: "H" and "L". Therefore, there are four possible combinations of the states of the charge signal Sc and the boost signal Sb.

[0086] In the diagrams used in this explanation, for the sake of ease of understanding, the specific structures of the first storage selection unit 31 and the second storage selection unit 32, as well as the specific structures of the first switch 36, the second switch 37, and the third switch 38, have been omitted.

[0087] <3-1. First State> The state in which the charge signal Sc is set to "H" and the boost signal Sb is set to "L" is defined as the "first state St1". Figure 4 shows the operation of the light-emitting drive device 1 in the first state St1.

[0088] When the charge signal Sc is set to "H", the first storage selection unit 31 connects the positive terminal of the power supply unit 8 to the positive side of the first charge storage unit 21. In addition, the first switch 36 of the connection switching unit 34 is controlled to the OFF state.

[0089] Therefore, a path is formed in which the positive terminal of the power supply unit 8 is connected to the positive electrode side of the first charge storage unit 21, and the negative electrode side of the first charge storage unit 21 is grounded, and charge is stored in the first charge storage unit 21. This path is referred to as the "first charging current path RC1".

[0090] Furthermore, when the boost signal Sb is set to "L", the second switch 37 of the connection switching unit 34 is controlled to the OFF state.

[0091] Therefore, the positive terminal side of the second charge storage unit 22 is connected to the positive terminal of the power supply unit 8, while the negative terminal side of the second charge storage unit 22 is not grounded and is not connected to the positive terminal side of the first charge storage unit 21.

[0092] As a result, no charge is accumulated in the second charge storage unit 22.

[0093] Furthermore, when the charge signal Sc is set to "H", the inverted signal of the charge signal Sc becomes "L", and the third switch 38 is controlled to the OFF state. Consequently, the output terminal 35b of the power multiplexer 35 and the anode of the light-emitting unit 7 are not connected, and the output selected by the power multiplexer 35 is not applied to the light-emitting unit 7. In other words, the light-emitting unit 7 is in a non-emitting state.

[0094] In other words, the first state St1 is defined as a charge period Tc in which charge is accumulated only in the first charge storage unit 21 of the two charge storage units 22. The first state St1 can be rephrased as the charge period Tc for reference emission.

[0095] <3-2. Second State> The state in which the charge signal Sc is set to "L" and the boost signal Sb is set to "L" is defined as the "second state St2". Figure 5 shows the operation of the light-emitting drive device 1 in the second state St2.

[0096] When the charge signal Sc is set to "L", the first storage selection unit 31 prevents the positive terminal of the power supply unit 8 from connecting to the positive side of the first charge storage unit 21.

[0097] Furthermore, by setting the boost signal Sb to "L", the first switch 36 is controlled to the OFF state, so that the first charge storage unit 21 and the second charge storage unit 22 are not connected in series. A signal based on the charge stored in the first charge storage unit 21 is input to the first input terminal 35a(1) of the power multiplexer 35.

[0098] Furthermore, by setting the boost signal Sb to "L", the second switch 37 is controlled to the OFF state. As a result, the negative electrode side of the second charge storage unit 22 is not grounded and is not connected to the positive electrode side of the first charge storage unit 21.

[0099] Furthermore, when the boost signal Sb is set to "L", the first input terminal 35a(1) is selected in the power multiplexer 35.

[0100] Furthermore, when the charge signal Sc is set to "L", the inverted signal of the charge signal Sc becomes "H", and the third switch 38 is controlled to the ON state. Consequently, the output terminal 35b of the power multiplexer 35 and the anode of the light-emitting unit 7 are connected, and the voltage output based on the selection in the power multiplexer 35 is applied to the light-emitting unit 7. That is, the light-emitting unit 7 is set to a light-emitting state.

[0101] As can be understood from the above, the second state St2 corresponds to the emission period Te in which the light-emitting unit 7 emits light using only the charge accumulated in the first charge-accumulating unit 21 of the two charge-accumulating units 22. The second state St2 can be rephrased as the emission period Te in which the reference emission is performed.

[0102] The path through which the light-emitting unit 7 emits light using the charge stored in the first charge storage unit 21 is referred to as the "first light-emitting current path RD1". On the first light-emitting current path RD1, only the first charge storage unit 21 is included among the first charge storage unit 21 and the second charge storage unit 22.

[0103] <3-3. Third State> The state in which the charge signal Sc is set to "H" and the boost signal Sb is set to "H" is defined as the "third state St3". Figure 6 shows the operation of the light-emitting drive device 1 in the third state St3.

[0104] When the charge signal Sc is set to "H", the first storage selection unit 31 connects the positive terminal of the power supply unit 8 to the positive side of the first charge storage unit 21. In addition, the first switch 36 of the connection switching unit 34 is controlled to the OFF state.

[0105] Therefore, a first charging current path RC1 is formed, in which the positive terminal of the power supply unit 8 is connected to the positive electrode side of the first charge storage unit 21, and the negative electrode side of the first charge storage unit 21 is grounded.

[0106] Furthermore, in the second storage selection unit 32, when the charge signal Sc is set to "H", the positive terminal of the power supply unit 8 and the positive electrode side of the second charge storage unit 22 are connected.

[0107] Furthermore, the second switch 37 of the connection switching unit 34 is controlled to the ON state when both the charge signal Sc and the boost signal Sb are set to "H". In addition, the first switch 36 of the connection switching unit 34 is controlled to the OFF state when both the charge signal Sc and the boost signal Sb are set to "H", causing the inverted signal of the charge signal Sc to be set to "L".

[0108] Therefore, the positive terminal side of the second charge storage unit 22 is connected to the positive terminal of the power supply unit 8, and the negative terminal side of the second charge storage unit 22 is grounded, and charge is stored in the second charge storage unit 22. This path is referred to as the "second charging current path RC2".

[0109] Furthermore, since the inverted signal of the charge signal Sc becomes "L", the third switch 38 is controlled to the OFF state. Consequently, the output terminal 35b of the power multiplexer 35 and the anode of the light-emitting unit 7 are not connected, and the output selected by the power multiplexer 35 is not applied to the light-emitting unit 7. In other words, the light-emitting unit 7 is in a non-emitting state.

[0110] In other words, the third state St3 is defined as the charge period Tc during which charge is accumulated in both the first charge storage unit 21 and the second charge storage unit 22. The third state St3 can be rephrased as the charge period Tc for boost light emission.

[0111] <3-4. Fourth State> The state in which the charge signal Sc is set to "L" and the boost signal Sb is set to "H" is defined as the "fourth state St4". Figure 7 shows the operation of the light-emitting drive device 1 in the fourth state St4.

[0112] When the charge signal Sc is set to "L", the first storage selection unit 31 prevents the positive terminal of the power supply unit 8 from connecting to the positive side of the first charge storage unit 21, and the second storage selection unit 32 prevents the positive terminal of the power supply unit 8 from connecting to the positive side of the second charge storage unit 22.

[0113] Furthermore, when the charge signal Sc is set to "L" (i.e., the inverted signal of the charge signal Sc is set to "H"), and the boost signal Sb is set to "H", the first switch 36 is controlled to the ON state. Also, when the charge signal Sc is set to "L", the second switch 37 is controlled to the OFF state.

[0114] Therefore, the first charge storage unit 21 and the second charge storage unit 22 are connected in series.

[0115] Furthermore, when the boost signal Sb is set to "H", the second input terminal 35a(2) is selected in the power multiplexer 35.

[0116] Furthermore, when the charge signal Sc is set to "L", the inverted signal of the charge signal Sc becomes "H", and the third switch 38 is controlled to the ON state. Consequently, the output terminal 35b of the power multiplexer 35 and the anode of the light-emitting unit 7 are connected, and the voltage output based on the selection in the power multiplexer 35 is applied to the light-emitting unit 7. That is, the light-emitting unit 7 is set to a light-emitting state.

[0117] As can be understood from the above, the fourth state St4 corresponds to the light emission period Te in which the light emission unit 7 emits light using the charges accumulated in both the first charge storage unit 21 and the second charge storage unit 22, by connecting the first charge storage unit 21 and the second charge storage unit 22 in series. The fourth state St4 can be rephrased as the light emission period Te in which boost light emission is performed.

[0118] The path through which the light-emitting unit 7 emits light using the charges accumulated in both the first charge storage unit 21 and the second charge storage unit 22 is referred to as the "second light-emitting current path RD2". On the second light-emitting current path RD2, the first charge storage unit 21 and the second charge storage unit 22 are connected in series.

[0119] <4. Timing Chart> An example of a timing chart related to the light emission of the light-emitting unit 7 is shown in Figure 8. Figure 8 schematically shows the changes in the charge signal Sc, the boost signal Sb, the positive electrode side potential of the first charge storage unit 21, the positive electrode side potential of the second charge storage unit 22, and the light emission power of the light-emitting unit 7.

[0120] First, the charge signal Sc changes between "H" and "L" at regular intervals. Furthermore, the duration for which the charge signal Sc is "H" is longer than the duration for which it is "L". The period when the charge signal Sc is "H" is defined as the charge period Tc, and the period when it is "L" is defined as the light emission period Te.

[0121] Here, a period containing one period where the charge signal Sc is "H" and one period where it is "L" is referred to as a "period period Cp". The first period period Cp is denoted as period period Cp1, and the nth period period Cp is denoted as period period Cpn.

[0122] Next, the boost signal Sb is randomly switched between "H" and "L". Specifically, period Cp1 is set to "L", period Cp2 is set to "H", period Cp3 is set to "L" again, period Cp4 and period Cp5 are set to "H", and period Cp6 is set to "L".

[0123] The voltage on the positive electrode side of the first charge storage unit 21 rises from 0 volts to V volts at the start of the charging period Tc. Then, this voltage gradually decreases from V volts to 0 volts at the start of the light emission period Te. That is, this voltage undergoes a similar change in each period Cp.

[0124] The voltage on the positive electrode side of the second charge storage unit 22 remains at 0 volts during both the charging period Tc and the light emission period Te in periodic periods Cp1, Cp3, and Cp6, when the boost signal Sb is set to "L". Furthermore, during periodic periods Cp2, Cp4, and Cp5, when the boost signal Sb is set to "H", the voltage on the positive electrode side of the second charge storage unit 22 rises from 0 volts at the start of the charging period Tc, reaching V volts. Then, at the start of the light emission period Te, this voltage instantaneously rises from V volts to 2V volts, before gradually decreasing to 0 volts.

[0125] Furthermore, the light-emitting power of the light-emitting unit 7 increases almost simultaneously with the start of the voltage drop on the positive electrode side of each charge storage unit, and then gradually decreases as the voltage drops. Also, the maximum value of the light-emitting power of the light-emitting unit 7 is approximately twice as high when the boost signal Sb is set to "H" compared to when it is set to "L".

[0126] As can be seen from Figure 8, focusing on the voltage change on the positive electrode side of the second charge storage unit 22, charge is stored in the second charge storage unit 22 only when the boost signal Sb is "H", and the charge stored in the second charge storage unit 22 is used for the emission of light by the light-emitting unit 7 only when the boost signal Sb is "H". This enables efficient light emission operation of the light-emitting unit 7 with reduced power consumption.

[0127] <5. Second Configuration Example of the Light-Emitting Drive Device> The first configuration example of the light-emitting drive device 1 was an example in which the voltage supplied to the light-emitting unit 7 for illumination was limited to two options: V volts and 2V volts. In other words, the first configuration example illustrates a configuration in which the light-emitting power of the light-emitting unit 7 is adjusted in two stages.

[0128] The second configuration example of the light-emitting drive device 1X has a configuration that allows the light-emitting power of the light-emitting unit 7 to be adjusted in N steps. In the following description, the parts described in the first configuration example will be omitted as appropriate.

[0129] Let's explain this in detail with reference to Figure 9.

[0130] The light-emitting unit 2X comprises a light-emitting drive device 1X, one first charge storage unit 21, multiple second charge storage units 22, and a light-emitting unit 7.

[0131] Specifically, the light-emitting unit 2X is equipped with N charge storage units to adjust the light-emitting power of the light-emitting section 7 in N steps. The light-emitting unit 2X is equipped with one first charge storage unit 21 and (N-1) second charge storage units 22. The (N-1) second charge storage units 22 are designated as second charge storage unit 22(1), second charge storage unit 22(2), ..., second charge storage unit 22(N-1).

[0132] Furthermore, the light-emitting drive device 1X of the light-emitting unit 2X includes one first charge storage selection unit 31 that selects whether or not to connect the positive electrode side of the first charge storage unit 21 to the positive terminal of the power supply unit 8.

[0133] Furthermore, the light-emitting drive device 1X is equipped with a second storage selection unit 32 for each of the (N-1) second charge storage units 22, which selects whether or not to connect the positive terminal side of the second charge storage unit 22 to the positive terminal of the power supply unit 8. The second storage selection unit 32 corresponding to the second charge storage unit 22(1) is designated as the second storage selection unit 32(1), the second storage selection unit 32 corresponding to the second charge storage unit 22(2) is designated as the second storage selection unit 32(2), and the second storage selection unit 32 corresponding to the second charge storage unit 22(N-1) is designated as the second storage selection unit 32(N-1).

[0134] Each second charge storage selection unit 32 selects to connect the positive terminal of the second charge storage unit 22 to the positive terminal of the power supply unit 8 when storing charge in the target second charge storage unit 22.

[0135] Furthermore, the light-emitting drive device 1X is equipped with (N-1) connection switching units 34. A connection switching unit 34 that switches whether or not to connect the first charge storage unit 21 and the second charge storage unit 22(1) in series is designated as connection switching unit 34(1), and a connection switching unit 34 that switches whether or not to connect the second charge storage unit 22(1) and the second charge storage unit 22(2) in series is designated as connection switching unit 34(2).

[0136] Similarly, the connection switching unit 34 that switches whether or not to connect the second charge storage unit 22(N-2) and the second charge storage unit 22(N-1) in series is designated as the connection switching unit 34(N-1).

[0137] The first charge storage selection unit 31 is inserted between the positive terminal of the power supply unit 8 and the positive electrode side of the first charge storage unit 21.

[0138] If the variable n is any number from 1 to (N-1), the second storage selection unit 32(n) is inserted between the positive terminal of the power supply unit 8 and the positive electrode side of the second charge storage unit 22(n).

[0139] First, let's explain the case where the variable n is 1. A connection switching unit 34(1) is inserted between the positive electrode side of the first charge storage unit 21 and the negative electrode side of the second charge storage unit 22. The connection switching unit 34(1) is capable of switching between a state where the negative electrode side of the second charge storage unit 22(1) is grounded, a state where it is connected to the positive electrode side of the first charge storage unit 21, and a state where it is not connected to either.

[0140] The positive electrode side of the first charge storage unit 21 is connected to the first input terminal 35a(1) of the power multiplexer 35.

[0141] Next, we will explain the case where the variable n is any number from 2 to (N-1). A connection switching unit 34(n) is inserted between the positive electrode side of the second charge storage unit 22(n-1) and the negative electrode side of the second charge storage unit 22(n). The connection switching unit 34(n) is capable of switching between a state where the negative electrode side of the second charge storage unit 22(n) is grounded, a state where it is connected to the positive electrode side of the second charge storage unit 22(n-1), and a state where it is not connected to either.

[0142] The positive electrode side of the second charge storage unit 22(n-1) is connected to the nth input terminal 35a(n) of the power multiplexer 35. That is, the positive electrode side of the second charge storage unit 22(N-1) is connected to the nth input terminal 35a(N) of the power multiplexer 35.

[0143] The power multiplexer 35 selects one of N options, which consists of a first input terminal 35a(1) to which the output of one charge storage unit is input, and a second input terminal 35a(2) to which the outputs of any number of charge storage units connected in series are input, up to the Nth input terminal 35a(N), and outputs a voltage from the output terminal 35b corresponding to the number of charge storage units connected in series.

[0144] Next, the charge signal Sc and boost signal Sb in this embodiment will be described.

[0145] The charge signal Sc is a signal capable of distinguishing between two states, "L" and "H," similar to the first configuration example of the light-emitting drive device.

[0146] On the other hand, the boost signal Sb is a signal that can identify the number of charge storage units connected in series during the light emission period Te. For example, when the number of second charge storage units 22 is (N-1) and the power multiplexer 35 is configured to allow selection of N outputs, the number of bits k of the boost signal Sb satisfies the following equation (1). Here, Log_2() is the logarithmic function with base 2, and floor() is the floor function that finds the integer part of the numerical value.

[0147] k = floor(Log_2(N-1) + 1) ... Equation (1)

[0148] A boost signal Sb, represented by k bits, can represent 2 to the power of k different states. For example, a 3-bit boost signal Sb can represent one of the following states: "L", "H (1)", or "H (7)", for a total of eight different states.

[0149] With respect to the boost signal Sb, if we define "L(i)" (reference light emission) when i = 0 and "H(i)" (boost light emission) when 0 < i, then during the charge period Tc, charge is accumulated in (i+1) charge storage units, and during the light emission period Te, the (i+1) charge storage units are connected in series, and the (i+1) input terminal 35a(i+1) of the power multiplexer 35 is selected, thereby realizing light emission from the light-emitting unit 7 by the (i+1) charge storage units.

[0150] At this time, i of the (N-1) connection switching units 34 are switched to connect in series with the corresponding second charge storage unit 22 to another adjacent second charge storage unit 22 or first charge storage unit 21.

[0151] Furthermore, the numerical value "i" identified from the boost signal Sb can be rephrased as the number of second charge storage units 22 connected in series with the first charge storage unit 21.

[0152] In this embodiment, since the number of second charge storage units 22 is (N-1), the maximum value of i is (N-1).

[0153] For example, when i = 0, charge storage and discharge are performed using one first charge storage unit 21. In this case, there are zero connection switching units 34 that switch the second charge storage unit 22 to a series connection. That is, all connection switching units 34 switch the corresponding second charge storage unit 22 so as not to be connected in series with the first charge storage unit 21. Therefore, the only charge storage unit used for the light emission of the light-emitting unit 7 is the first charge storage unit 21. Furthermore, in the power multiplexer 35, the first input terminal 35a(1) is selected.

[0154] Furthermore, when i=1, charge storage and discharge are performed using two charge storage units, specifically one first charge storage unit 21 and one second charge storage unit 22. In this case, there is only one connection switching unit 34 (1) that switches the second charge storage unit 22 to a series connection. Therefore, the charge storage units used for light emission of the light-emitting unit 7 are the first charge storage unit 21 and the second charge storage unit 22 (1). In addition, the second input terminal 35a (2) is selected in the power multiplexer 35.

[0155] Furthermore, when i=2, charge storage and discharge are performed using three charge storage units, specifically one first charge storage unit 21 and two second charge storage units 22. In this case, the connection switching unit 34 that switches the second charge storage units 22 to a series connection consists of two connection switching units 34(1) and connection switching unit 34(2). Therefore, the charge storage units used for light emission of the light-emitting unit 7 are the first charge storage unit 21, the second charge storage unit 22(1), and the second charge storage unit 22(2). In addition, in the power multiplexer 35, the third input terminal 35a(3) is selected.

[0156] When the value of i is the maximum value in this embodiment, (N-1), charge storage and discharge are performed using N charge storage units, specifically one first charge storage unit 21 and (N-1) second charge storage units 22. At this time, the connection switching unit 34 that switches the second charge storage unit 22 to a series connection consists of all connection switching units 34(1) to 34(N-1). Therefore, the charge storage units used for light emission of the light-emitting unit 7 consist of the first charge storage unit 21 and N charge storage units from the second charge storage unit 22(1) to the second charge storage unit 22(N-1). Furthermore, in the power multiplexer 35, the Nth input terminal 35a(N) is selected.

[0157] The switching modes of each connection switching unit 34 will be explained with reference to Figure 10. In the connection switching unit 34(s) provided in correspondence with the second charge storage unit 22(s), the numerical value i and numerical value s specified from the boost signal Sb are compared, and if the value s is less than or equal to the value i, the connection of the negative electrode side of the second charge storage unit 22(s) is switched so that the corresponding second charge storage unit 22(s) is connected in series with the first charge storage unit 21 (when s is 1) or the second charge storage unit 22(s-1) (when s is 2 or more).

[0158] In other words, when "s <= i" holds true, the connection switching unit 34(s) controls the first switch 36(s) provided in the connection switching unit 34(s) to the ON state and the second switch 37(s) to the OFF state. As a result, the corresponding second charge storage unit 22(s) is connected in series with other second charge storage units 22 and the first charge storage unit 21.

[0159] On the other hand, if "s > i" is true, the connection switching unit 34(s) controls both the first switch 36(s) and the second switch 37(s) to the OFF state. As a result, the corresponding second charge storage unit 22(2) is not connected in series with other second charge storage units 22 or the first charge storage unit 21.

[0160] The processing performed by the boost signal supply unit 9 in this example is the same as that shown in Figure 2. However, in this example, the boost signal supply unit 9 not only decides to perform boost light emission in step S104 but also determines the light emission intensity. In this case, in step S105, the aforementioned boost signal Sb, which can identify not only whether or not to perform boost light emission but also the light emission intensity, is supplied to the light emission unit 2X.

[0161] <6. Example of a light-emitting section having an array configuration> A light-emitting section 7Y having an array configuration such as an LED (Light Emitting Diode) array will be described. Here, an example in which the light-emitting section 7Y has M light-emitting elements 7a such as LEDs will be described with reference to Figure 11. However, M will be a value of 2 or more.

[0162] A light-emitting unit 2 having a light-emitting section 7Y with multiple light-emitting elements 7a is referred to as the light-emitting unit 2Y.

[0163] Let the M light-emitting elements 7a be designated as light-emitting element 7a(1), light-emitting element 7a(2), ..., light-emitting element 7a(M).

[0164] The light-emitting unit 2Y comprises a light-emitting drive device 1Y, one first charge storage unit 21, and (N-1) second charge storage units 22. The (N-1) second charge storage units 22 are designated as second charge storage unit 22(1), second charge storage unit 22(2), ..., second charge storage unit 22(N-1).

[0165] The light-emitting drive device 1Y, like the light-emitting drive device 1X, includes (N-1) second charge storage selection units 32 provided for each (N-1) second charge storage unit 22, and (N-1) connection switching units 34.

[0166] The (N-1) second storage selection units 32 are designated as second storage selection unit 32(1), second storage selection unit 32(2), ..., second storage selection unit 32(N-1).

[0167] Furthermore, (N-1) of the 34s are designated as connection switching units 34(1), connection switching units 34(2), ..., connection switching unit 34(N-1).

[0168] The light-emitting drive device 1Y is equipped with M third switches 38 corresponding to M light-emitting elements 7a. M may be the same value as N or a different value from N. The M third switches 38 are designated as third switch 38(1), third switch 38(2), ..., third switch 38(M).

[0169] Each third switch 38 is supplied with the logical AND of the charge signal Sc and the selector signal Ss. The third switch 38 switches between an ON state and an OFF state based on the supplied signal.

[0170] The selector signal Ss is, for example, an M-bit signal, where each bit corresponds to the light-emitting element 7a to be illuminated. If the i-th bit of the selector signal Ss is set to selector signal Ss[i], then when only light-emitting element 7a(1) is to be illuminated, only selector signal Ss[0] is set to "H", and each of the signals from selector signal Ss[1] to selector signal Ss[M-1] is set to "L". Also, when only light-emitting element 7a(j) is to be illuminated, only selector signal Ss[j-1] is set to "H", and all other selector signals Ss are set to "L".

[0171] Figure 12 shows an example of the configuration of the third switch 38. Figure 12 is a diagram showing the configuration of the third switch 38(j).

[0172] The third switch 38(j) is composed of a p-type MOSFET 48(j), an n-type MOSFET 49(j), a resistor 50(j), and a resistor 51(j).

[0173] The connection configuration of the p-type MOSFET 48(j), the n-type MOSFET 49(j), the resistor 50(j), and the resistor 51(j) is the same as the connection configuration of the p-type MOSFET 48, the n-type MOSFET 49, and the resistors 50 and 51 shown in Figure 3.

[0174] The drain terminal of the p-type MOSFET 48(j) is connected to the anode of the light-emitting element 7a(j).

[0175] The gate terminal of the n-type MOSFET 49(j) is subjected to the logical AND of the inverted charge signal Sc and the selector signal Ss[j-1].

[0176] As a result, the third switch 38(j) is controlled to the OFF state when the charge signal Sc is set to "H". Also, the third switch 38(j) is controlled to the ON state when the charge signal Sc is set to "L" and the selector signal Ss[j-1] is set to "H", thereby emitting light from the light-emitting element 7a(j).

[0177] The light-emitting unit 2Y has the configuration shown in Figures 11 and 12, and furthermore, since the selector signal Ss is an M-bit signal, it is possible to make any of the M light-emitting elements 7a emit light. In other words, the light-emitting unit 2Y of this configuration can be applied to flexible light-emitting modes.

[0178] In this example, the boost signal supply unit 9 can realize light emission in the light-emitting unit 2Y, which is equipped with the aforementioned multiple light-emitting elements 7a, by performing a series of processes shown in Figure 2. Specifically, the boost signal supply unit 9 in this example performs the series of processes shown in Figure 2 for each light-emitting element 7a to be emitted. In addition, the boost signal supply unit 9 not only decides to perform boost light emission in step S104 but also determines the light emission intensity. Furthermore, in step S105, the boost signal supply unit 9 supplies the aforementioned boost signal Sb to the light-emitting unit 2Y, which can identify not only whether or not to perform boost light emission but also an instruction for light emission intensity.

[0179] In this example, we have described an example in which the light-emitting unit 2 is equipped with one set of light-emitting drive device 1Y and light-emitting unit 7Y. However, the light-emitting unit 2 may be equipped with two light-emitting drive devices 1Y and two light-emitting units 7Y. That is, the light-emitting unit 2 may be equipped with two sets of light-emitting drive devices 1Y and light-emitting units 7Y.

[0180] In this case, two light-emitting elements 7a can be made to emit light simultaneously during the light emission period Te.

[0181] Furthermore, by increasing the number of sets of light-emitting drive devices 1Y and light-emitting units 7Y provided in the light-emitting unit 2, the number of light-emitting elements 7a that emit light simultaneously can be increased.

[0182] <7. Modification> The vehicle system 200 may be configured as a system that includes a sensing system Sys having a light-emitting drive device 1 and a control system 100. In other words, the configuration shown in Figure 1 is merely an example.

[0183] Furthermore, the light-emitting drive device 1 (1X, 1Y) of the light-emitting unit 2 may be configured to include a first charge storage unit 21, a second charge storage unit 22, and a light-emitting unit 7.

[0184] In the examples described above, the light-emitting drive device 1 (1X, 1Y) of this technology was shown to be mounted on a sensing system Sys used by a vehicle system 200. However, the light-emitting drive device 1 (1X, 1Y) may also be mounted on AGVs (Automatic Guided Vehicles) or drones used in industrial fields, or on mobile terminal devices such as smartphones or tablet terminals.

[0185] In other words, the light-emitting drive device 1 (1X, 1Y) of this technology can be applied to various devices that emit light, detect reflected light from an object, and perform distance measurement, etc. Furthermore, the configuration of the light-emitting unit 2 is not limited to LiDAR.

[0186] The first charge storage unit 21 and one or more second charge storage units 22 described above may each have the same capacity, or at least some of them may have different capacities. If the capacities of the first charge storage unit 21 and one or more second charge storage units 22 are unified, the pulse width when the light emission intensity of the light emission unit 7 is changed will be approximately constant.

[0187] Therefore, if it is desired to intentionally change the pulse width of the light emission from the light-emitting unit 7, this can be achieved by changing the capacitance of at least a portion of the first charge storage unit 21 and the second charge storage unit 22.

[0188] <8. Summary> The light-emitting drive device 1 (1X, 1Y) according to this technology includes a first storage selection unit 31 that selects whether or not to perform charge storage in the first charge storage unit 21 by a power supply (power supply unit 8) in accordance with a charge signal Sc, a second storage selection unit 32 that selects whether or not to perform charge storage in the second charge storage unit 22 by a power supply in accordance with a charge signal Sc, and an output selection unit 33 that selects whether or not to connect the first charge storage unit 21 and the second charge storage unit 22 in series on the light-emitting current path (second light-emitting current path RD2) to the light-emitting unit 7 (7Y) in accordance with a boost signal Sb. The boost signal Sb is, for example, a signal that becomes "H (Hi)" when the light-emitting unit 7 (7Y) is made to emit light strongly (boost light emission). According to the above configuration, the first charge storage unit 21 and the second charge storage unit 22 are connected in series when the boost signal Sb is "H". As a result, for example, when the boost signal Sb is "H", a voltage based on both the charge stored in the first charge storage unit 21 and the charge stored in the second charge storage unit 22 is supplied to the light-emitting unit 7 (7Y). Therefore, when the boost signal Sb is "H", the light-emitting unit 7 (7Y) emits a stronger boost light than when it is "L (Low)". In addition, although the voltage supplied to the light-emitting unit 7 (7Y) changes and the light intensity of the light-emitting unit 7 (7Y) changes depending on whether the boost signal Sb is "H" or "L", the charge used for the light emission of the light-emitting unit 7 (7Y) is only the charge stored in the last of the multiple charge storage units connected in series, so the light emission pulse width does not become excessively wide. Therefore, safety can be improved from an eye-safe perspective. Furthermore, it is conceivable to change the light emission intensity of the light-emitting unit 7 (7Y) by changing the power supply voltage supplied to the light-emitting unit 7 (7Y). However, there is a problem in that the rate of change of the power supply voltage cannot adequately follow the light emission period of the light-emitting unit 7 (7Y). This point can also be solved by using this configuration, as the light emission intensity can be varied without changing the power supply voltage.

[0189] The output selection unit 33 in the light-emitting drive device 1 (1X, 1Y) may have a connection switching unit 34 that switches the connection configuration of the second charge storage unit 22. For example, when the boost signal Sb is "H", it is possible to switch one end of the second charge storage unit 22 to be connected to the ground voltage, and when the boost signal Sb is "L", it is possible to switch one end of the second charge storage unit 22 not to be connected to the ground voltage. In other words, it is possible to configure the circuit so that charge is stored in the second charge storage unit 22 only when charge storage in the second charge storage unit 22 is necessary. Therefore, energy efficiency can be improved.

[0190] The connection switching unit 34 in the light-emitting drive device 1 (1X, 1Y) may have a first switch 36 that switches whether or not to connect the first charge storage unit 21 and the second charge storage unit 22 in series. This makes it possible to make the light-emitting unit 7 (7Y) emit light based on both the charge stored in the first charge storage unit 21 and the charge stored in the second charge storage unit 22. In this case, the light emission intensity of the light-emitting unit 7 (7Y) can be made higher compared to the case where it is based only on the charge stored in the first charge storage unit 21. Also, when making the light-emitting unit 7 (7Y) emit light using only the charge stored in the first charge storage unit 21, it is possible to switch so that the first charge storage unit 21 and the second charge storage unit 22 are not connected in series.

[0191] The connection switching unit 34 in the light-emitting drive device 1 (1X, 1Y) may have a second switch 37 that switches whether or not to form a charging current path (second charging current path RC2) for the second charge storage unit 22. For example, when the light-emitting unit 7 (7Y) is to emit light using only the charge stored in the first charge storage unit 21, it is possible to switch so that a charging current path is not formed for the second charge storage unit 22, which is not used for light emission. This prevents unnecessary charge accumulation in the second charge storage unit 22 and prevents an increase in power consumption.

[0192] In the light-emitting drive device 1 (1X, 1Y), the charge signal Sc may be a signal that can distinguish between a charge period Tc in which charge is accumulated in at least the first charge storage unit 21, and a light emission period Te in which the light-emitting unit 7 (7Y) emits light using the charge accumulated in at least the first charge storage unit 21. For example, the charge signal Sc may be "H" during the charge period Tc in which charge is accumulated in each charge storage unit, and "L" during the light emission period Te in which the light-emitting unit 7 (7Y) emits light using the charge accumulated in each charge storage unit. This makes it possible to combine the signal indicating the charge period Tc and the signal indicating the light emission period Te into a single signal, thereby reducing the number of signal lines.

[0193] The first switch 36 in the light-emitting drive device 1 (1X, 1Y) may be controlled based on a charge signal Sc and a boost signal Sb. For example, when the charge signal Sc is "L" and the boost signal Sb is "H", the first switch 36 is controlled to the ON state, and the second charge storage unit 22 for boosting and the first charge storage unit 21 are connected in series and used to supply voltage to the light-emitting unit 7 (7Y). In other words, even if the charge signal Sc is "L" and the light emission period Te is in progress, if the boost signal Sb is "L", the second charge storage unit 22 for boosting and the first charge storage unit 21 are not connected in series. This allows the charge stored in the second charge storage unit 22 to be used for light emission only during the appropriate light emission period Te.

[0194] The second switch 37 in the light-emitting drive device 1 (1X, 1Y) may be controlled based on the charge signal Sc and the boost signal Sb. For example, the second switch 37 is a switch that switches whether or not one end of the second charge storage unit 22 is connected to ground potential. When the charge signal Sc is "H" and the boost signal Sb is "H", the second switch 37 is controlled to the ON state, switching one end of the second charge storage unit 22 to the ground voltage. As a result, for example, even if the charge signal Sc is "H", if the boost signal Sb is "L", no charge will be stored in the second charge storage unit 22. Therefore, it is prevented that the charge stored in the second charge storage unit 22 at an inappropriate timing will be used for the light emission of the light-emitting unit 7 (7Y).

[0195] The output selection unit 33 in the light-emitting drive device 1 (1X, 1Y) may include a power multiplexer 35 that can select between the output of the first charge storage unit 21 and the output of the first charge storage unit 21 and the second charge storage unit 22 connected in series. By enabling output selection with the power multiplexer 35, it becomes possible to supply an appropriate voltage to the light-emitting unit 7 (7Y), thereby enabling light emission at an appropriate intensity by the light-emitting unit 7 (7Y).

[0196] The power multiplexer 35 in the light-emitting drive device 1 (1X, 1Y) may be controlled based on a boost signal Sb. By controlling the power multiplexer 35 based on a boost signal Sb indicating whether or not to increase the light emission intensity of the light emission from the light-emitting unit 7 (7Y), the output of the series connection of the first charge storage unit 21 and the second charge storage unit 22 is selected only when it is desired to increase the light emission intensity. In other words, suitable light emission control can be performed. In particular, by controlling the power multiplexer 35 using the same boost signal Sb used for accumulating charge in the second charge storage unit 22, consistency can be ensured between the control of charge accumulation in the second charge storage unit 22 when increasing the light emission intensity and the selection control of the output of the series connection of the first charge storage unit 21 and the second charge storage unit 22.

[0197] In the light-emitting drive device 1 (1X, 1Y), when the output of the first charge storage unit 21 is selected by the power multiplexer 35, both the first switch 36 and the second switch 37 may be controlled to OFF. That is, when boost light emission is not performed, a charging current path (second charging current path RC2) for storing charge in the second charge storage unit 22 is not formed in the first place, and no charge is discharged. In other words, the second charge storage unit 22 stores charge only when necessary. This makes it possible to suppress the increase in power consumption caused by unnecessary charge storage.

[0198] The light-emitting drive device 1 (1X, 1Y) may include a third switch 38 inserted between the power multiplexer 35 and the light-emitting unit 7 (7Y). This allows the third switch 38 to be controlled to OFF during the non-light-emitting period (charge period Tc) of the light-emitting unit 7 (7Y), regardless of the output selection result of the power multiplexer 35, thereby stopping the supply of drive voltage to the light-emitting unit 7 (7Y). Therefore, control that enables light emission only at appropriate timings can be achieved.

[0199] The third switch 38 in the light-emitting drive device 1 (1X, 1Y) may be controlled according to the charge signal Sc. This ensures that the light-emitting section 7 (7Y) does not emit light during the charging period when the charge signal Sc is set to "H".

[0200] In the light-emitting drive device 1X (1Y), a plurality of second charge storage selection units 32 are provided, each corresponding to a plurality of second charge storage units 22. The output selection unit 33 may be configured to select an output by connecting the first charge storage unit 21 and any number of second charge storage units 22 in series on the light-emitting current path (second light-emitting current path RD2). That is, the number of second charge storage units 22 connected in series with the first charge storage unit 21 can be arbitrarily selected. This makes it possible to control the light emission intensity of the light-emitting unit 7 (7Y) more precisely. Furthermore, if the same number of second charge storage selection units 32 are provided as the number of second charge storage units 22, and each can select whether or not to perform charge storage in the corresponding second charge storage unit 22, it becomes possible to store charge only in the second charge storage units 22 connected in series with the first charge storage unit 21. Therefore, the light emission intensity of the light-emitting unit 7 (7Y) can be finely controlled while suppressing an increase in power consumption.

[0201] The output selection unit 33 in the light-emitting drive device 1X (1Y) has the same number of switching units as the second charge storage unit 22, a connection switching unit 34 that switches the connection configuration of the second charge storage unit 22, and a power multiplexer 35. The power multiplexer 35 is capable of selecting a first input (first input terminal 35a (1)) and the same number of second inputs as the second charge storage unit 22 (second input terminals 35a (2), ...). The first input is the output of the first charge storage unit 21, and each of the second inputs may have a different number of second charge storage units 22 connected in series with the first charge storage unit 21. In other words, the number of second charge storage units 22 connected in series with the first charge storage unit 21 can be arbitrarily selected from 0 to the total number of second charge storage units 22. This makes it possible to finely control the light emission intensity of the light-emitting unit 7 (7Y).

[0202] In the light-emitting drive device 1X (1Y), the boost signal Sb may be a signal capable of identifying any number. For example, if the number of second charge storage units 22 connected in series with the first charge storage unit 21 can be selected between 0 and 10, the boost signal Sb is a 4-bit signal capable of identifying numerical values ​​from 0 to 10 (11 types). This allows the output selection unit 33 to determine the number of second charge storage units 22 connected in series with the first charge storage unit 21 from the boost signal Sb, and to suitably adjust the light emission intensity of the light-emitting unit 7 (7Y).

[0203] In the light-emitting drive device 1 (1X, 1Y), if the number of bits in the boost signal Sb is k bits, the number of second storage selection units 32 is (N-1), the base-2 logarithmic function is Log_2(), and the floor function for finding the integer part of a numerical value is floor(), then the following equation (1) may be satisfied: k = floor(Log_2(N-1)+1) ... (1) By satisfying equation (1) in the number of bits in the boost signal Sb, it becomes possible to represent (N+1) types of numerical values ​​from 0 to N with the boost signal Sb, and it becomes possible to determine the number of second charge storage units 22 connected in series with the first charge storage unit 21 from the boost signal Sb.

[0204] In the light-emitting drive device 1 (1X, 1Y), the charge signal Sc may be a signal capable of distinguishing between a charge period Tc in which charge is accumulated in at least the first charge storage unit 21, and a light emission period Te in which light is emitted from the light-emitting unit 7 (7Y) using the charge accumulated in at least the first charge storage unit 21. For example, the charge signal Sc may be set to "H" during the charge period Tc and to "L" during the light emission period Te. This makes it possible to obtain the various operations and effects described above in a configuration in which the first charge storage unit 21 and a plurality of second charge storage units 22 can be connected in series.

[0205] The light-emitting section 7Y in the light-emitting drive device 1Y may have a plurality of light-emitting elements 7a. For example, even if the light-emitting section 7 has an array structure such as an LED array, the various functions and effects described above can be obtained.

[0206] The light-emitting drive device 1 (1X, 1Y) may include a first charge storage unit 21 and a second charge storage unit 22. Even if the light-emitting drive unit is configured to include a first charge storage unit 21 and a second charge storage unit 22, the various operations and effects described above can be obtained.

[0207] The light-emitting drive unit 1 (1X, 1Y) may also include a light-emitting section 7 (7Y). Even if the light-emitting drive unit is configured to include a light-emitting section, the various functions and effects described above can still be obtained.

[0208] Furthermore, the effects described herein are merely illustrative and not limited to those described herein, and other effects may also occur.

[0209] Furthermore, the examples described above can be combined in any way, and it is possible to obtain the various effects and benefits described above even when using various combinations.

[0210] <9. This Technology> This technology can also be configured as follows: (1) A light-emitting drive device comprising: a first storage selection unit that selects whether or not to perform charge storage in a first charge storage unit by a power supply in response to a charge signal; a second storage selection unit that selects whether or not to perform charge storage in a second charge storage unit by a power supply in response to the charge signal; and an output selection unit that selects whether or not to connect the first charge storage unit and the second charge storage unit in series on the light-emitting current path to the light-emitting unit in response to a boost signal. (2) The light-emitting drive device according to (1) above, wherein the output selection unit has a connection switching unit that switches the connection configuration of the second charge storage unit. (3) The light-emitting drive device according to (2) above, wherein the connection switching unit has a first switch that switches whether or not to connect the first charge storage unit and the second charge storage unit in series. (4) The light-emitting drive device according to (3) above, wherein the connection switching unit has a second switch that switches whether or not to form a charging current path for the second charge storage unit. (5) The light-emitting drive device according to (4), wherein the charge signal is a signal capable of distinguishing between a charge period for accumulating charge in the first charge storage unit and a light-emitting period for emitting light from the light-emitting unit using the charge accumulated in the first charge storage unit. (6) The light-emitting drive device according to (5), wherein the first switch is controlled based on the charge signal and the boost signal. (7) The light-emitting drive device according to any one of (5) to (6), wherein the second switch is controlled based on the charge signal and the boost signal. (8) The light-emitting drive device according to any one of (4) to (7), wherein the output selection unit is a power multiplexer capable of selecting between the output of the first charge storage unit and the output of the first charge storage unit and the second charge storage unit connected in series. (9) The light-emitting drive device according to (8), wherein the power multiplexer is controlled based on the boost signal. (10) The light-emitting drive device according to any one of (8) to (9) above, wherein when the output of the first charge storage unit is selected by the power multiplexer, both the first switch and the second switch are controlled to be OFF.(11) A light-emitting drive device according to any one of (8) to (10) above, further comprising a third switch inserted between the power multiplexer and the light-emitting unit. (12) A light-emitting drive device according to (11) above, wherein the third switch is controlled in accordance with the charge signal. (13) A light-emitting drive device according to any one of (1) to (12) above, further comprising a plurality of second charge storage selection units corresponding to each of the plurality of second charge storage units, wherein the output selection unit is capable of selecting an output by series connection of the first charge storage unit and any number of the second charge storage units on the light-emitting current path. (14) The light-emitting drive device according to (13) above, wherein the output selection unit has the same number of switching units as the second charge storage unit and a connection switching unit that switches the connection configuration of the second charge storage unit, and a power multiplexer, wherein the power multiplexer is selectable to have a first input and a second input the same number as the second charge storage unit, the first input is the output of the first charge storage unit, and the second input is the output of the state in which the first charge storage unit and at least one of the second charge storage units are connected in series, and each of the second inputs has a different number of second charge storage units connected in series with the first charge storage unit. (15) The light-emitting drive device according to any one of (13) to (14) above, wherein the boost signal is a signal that can identify any number. (16) The light-emitting drive device according to (15) above, wherein the number of bits in the boost signal is k bits, the number of the second storage selection units is (N-1), the base-2 logarithmic function is Log_2(), and the floor function for finding the integer part of a numerical value is floor(), and the following equation (1) is satisfied: k = floor(Log_2(N-1)+1) ... (1) (17) The light-emitting drive device according to (16) above, wherein the charge signal is a signal that can distinguish at least a charge period for storing charge in the first charge storage unit and at least a light-emitting period for emitting light from the light-emitting unit using the charge stored in the first charge storage unit. (18) The light-emitting drive device according to any one of (1) to (17) above, wherein the light-emitting unit has a plurality of light-emitting elements. (19) The light-emitting drive device according to any one of (1) to (18) above, comprising the first charge storage unit and the second charge storage unit.(20) A light-emitting drive device according to any one of (1) to (19) above, which is equipped with the light-emitting unit.

[0211] 1, 1X, 1Y Light-emitting drive unit 7, 7Y Light-emitting unit 7a Light-emitting body 8 Power supply unit (power supply) 21 First charge storage unit 22 Second charge storage unit 31 First storage selection unit 32 Second storage selection unit 33 Output selection unit 34 Connection switching unit 35 Power multiplexer 36 First switch 37 Second switch 38 Third switch RC2 Second charging current path (charging current path) RD2 Second light-emitting current path (light-emitting current path) Sb Boost signal Sc Charge signal Tc Charge period Te Light-emitting period

Claims

1. A light-emitting drive device comprising: a first storage selection unit that selects whether or not to perform charge storage in a first charge storage unit by a power supply in response to a charge signal; a second storage selection unit that selects whether or not to perform charge storage in a second charge storage unit by a power supply in response to the charge signal; and an output selection unit that selects whether or not to connect the first charge storage unit and the second charge storage unit in series on the light-emitting current path to a light-emitting unit in response to a boost signal.

2. The light-emitting drive device according to claim 1, wherein the output selection unit has a connection switching unit that switches the connection configuration of the second charge storage unit.

3. The light-emitting drive device according to claim 2, wherein the connection switching unit has a first switch that switches whether or not to connect the first charge storage unit and the second charge storage unit in series.

4. The light-emitting drive device according to claim 3, wherein the connection switching unit has a second switch that switches whether or not to form a charging current path for the second charge storage unit.

5. The light-emitting drive device according to claim 4, wherein the charge signal is a signal capable of distinguishing between a charge period for accumulating charge in the first charge storage unit and a light-emitting period for emitting light in the light-emitting unit using the charge accumulated in the first charge storage unit.

6. The light-emitting drive device according to claim 5, wherein the first switch is controlled based on the charge signal and the boost signal.

7. The light-emitting drive device according to claim 5, wherein the second switch is controlled based on the charge signal and the boost signal.

8. The light-emitting drive device according to claim 4, wherein the output selection unit is a power multiplexer capable of selecting between the output of the first charge storage unit and the output of the first charge storage unit and the second charge storage unit connected in series.

9. The light-emitting drive device according to claim 8, wherein the power multiplexer is controlled based on the boost signal.

10. The light-emitting drive device according to claim 8, wherein when the output of the first charge storage unit is selected by the power multiplexer, both the first switch and the second switch are controlled to be OFF.

11. The light-emitting drive device according to claim 8, further comprising a third switch inserted between the power multiplexer and the light-emitting unit.

12. The light-emitting drive device according to claim 11, wherein the third switch is controlled in accordance with the charge signal.

13. The light-emitting drive device according to claim 1, comprising a plurality of second charge storage selection units corresponding to each of the plurality of second charge storage units, wherein the output selection unit is capable of selecting an output by connecting the first charge storage unit and any number of second charge storage units in series on the light-emitting current path.

14. The light-emitting drive device according to claim 13, wherein the output selection unit has the same number of switching units as the second charge storage unit, which are connection switching units for switching the connection configuration of the second charge storage unit, and one power multiplexer, the power multiplexer is capable of selecting a first input and a second input the same number as the second charge storage unit, the first input is the output of the first charge storage unit, the second input is the output of the state in which the first charge storage unit and at least one of the second charge storage units are connected in series, and each of the second inputs has a different number of second charge storage units connected in series with the first charge storage unit.

15. The light-emitting drive device according to claim 13, wherein the boost signal is a signal capable of identifying any number.

16. The light-emitting drive device according to claim 15, wherein the number of bits in the boost signal is k bits, the number of the second storage selection units is (N-1), the base-2 logarithmic function is Log_2(), and the floor function for finding the integer part of the numerical value is floor(), and the following equation (1) is satisfied: k = floor(Log_2(N-1) + 1) ... (1) 17. The light-emitting drive device according to claim 16, wherein the charge signal is a signal capable of distinguishing at least a charge period for accumulating charge in the first charge storage unit and a light-emitting period for emitting light in the light-emitting unit using at least the charge accumulated in the first charge storage unit.

18. The light-emitting drive device according to claim 1, wherein the light-emitting unit has a plurality of light-emitting elements.

19. The light-emitting drive device according to claim 1, further comprising the first charge storage unit and the second charge storage unit.

20. The light-emitting drive device according to claim 1, comprising the light-emitting unit.

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