JP6980369B2 - Light source drive and distance measurement device - Google Patents

Description

The present invention relates to a light source driving device and a distance measuring device.

As a device for measuring the distance from a moving body to an object, there is a device that uses a laser pulse. Specifically, it outputs pulsed light and receives reflected light reflected by an object. Then, the distance from the device to the object is obtained based on the time from the output to the light reception. In order to repeat such measurement, it is necessary to blink the light emitting element.

Patent Document 1 describes a laser light generation circuit that charges a capacitor with magnetic energy stored in an inductor and generates laser light from a laser diode by the discharge current of the capacitor.

Japanese Unexamined Patent Publication No. 2010-139295

However, when the laser diode is driven by the discharge current of the capacitor, the interval between the light pulses cannot be made shorter than the time required for charging the capacitor. However, in a device for measuring the distance from a moving body to an object as described above, for example, it is desired to further shorten the pulse interval.

One example of the problem to be solved by the present invention is to shorten the interval between pulses output from a light source.

The invention according to claim 1 is
Multiple capacitive elements that are parallel to each other and each supply power to the light emitting element during discharge.
A power source for charging the plurality of capacitive elements and
A discharge control unit that individually controls the discharge timing of the plurality of capacitive elements is provided.
While charging at least one of the plurality of capacitive elements, the other at least one capacitive element is discharged .
Wherein a light source driving device Ru is pulse emission of the light emitting element by a discharge of the capacitor.
The invention according to claim 1 3, a light source driving device according to any one of claims 1 1 2,
With the light emitting element
It is provided with a processing unit that calculates the distance to the reflecting object that reflected the light in the emission direction of the light by using the time from the emission of the light to the reception of the reflected light of the light. It is a distance measuring device.

It is a figure which illustrates the functional structure and use environment of the light source drive device which concerns on 1st Embodiment. It is a block diagram which shows the functional structure of the distance measuring apparatus which concerns on 1st Embodiment. It is a figure which illustrates the functional structure of the distance measuring apparatus which concerns on 2nd Embodiment. It is a figure which shows the modification of the distance measuring apparatus which concerns on 2nd Embodiment. It is a figure which illustrates the circuit structure of the light source drive device and the light emitting element which concerns on Example 1. FIG. It is a figure which shows the hardware composition of an integrated circuit. It is an example of a timing chart of a trigger signal _V T1 _{~V Tn} according to the first embodiment. It is a figure which illustrates the circuit structure of the light source driving device and the light emitting element which concerns on Example 2. FIG. It is a figure which illustrates the circuit structure of the light source driving device and the light emitting element which concerns on Example 3. FIG. It is an example of a timing chart of a trigger signal _V T1 _{~V T4} according to the first example of the fourth embodiment. It is an example of a timing chart of a trigger signal _V T1 _{~V T4} according to the second example of the fourth embodiment. It is a figure which illustrates the circuit structure of the light source drive device and the light emitting element which concerns on 3rd Example of Example 4. FIG. It is a block diagram which illustrates the functional structure of the distance measuring apparatus which concerns on Example 5. It is a figure for demonstrating the 1st processing example. It is a figure which illustrates the functional structure of the light source drive device which performs the 1st processing example. It is a figure which shows the light source driving apparatus which concerns on 3rd processing example, and the use environment thereof.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by the same reference numerals, and description thereof will be omitted as appropriate.

In the following description, each component of the distance measuring device 1 and the light source driving device 20 shows a block of functional units, not a configuration of hardware units. The processing unit 80 and the control unit 70 of the distance measuring device 1, the discharge control unit 23 and the acquisition unit 24 of the light source driving device 20 are a CPU, a memory, a program loaded in the memory, a hard disk for storing the program, and the like. It is realized by any combination of hardware and software centering on the storage media and the interface for network connection. And there are various modifications in the realization method and the device.

(First Embodiment)
FIG. 1 is a diagram illustrating a functional configuration and a usage environment of the light source driving device 20 according to the first embodiment. The light source driving device 20 according to the present embodiment includes a plurality of capacitive elements 22, a power supply 21, and a discharge control unit 23. The plurality of capacitive elements 22 are in parallel with each other, and each of them supplies electric power to the light emitting element 10 at the time of discharging. The power supply 21 charges a plurality of capacitive elements 22. The discharge control unit 23 individually controls the timing at which the plurality of capacitive elements 22 are discharged. This will be described in detail below.

The light emitting element 10 is, for example, a light emitting diode, and emits light when a current flows. Further, the light emitting element 10 is a laser diode that oscillates with a laser. The light emitting element 10 emits pulse light by the discharge current of the capacitive element 22. Note that this figure shows an example in which the light source driving device 20 includes five capacitive elements 22, but the present invention is not limited to this. The light source driving device 20 may include two or more capacitive elements 22.

When using only one capacitive element and causing the light emitting element to emit light multiple times by repeating charging and discharging as in the conventional case, after discharging once, the light emitting element is again charged until a sufficient charge is charged again. Cannot emit light. Further, in order to shorten the charging time, it is necessary to set the charging time constant small and use a power source having a large current capacity, which increases the cost.

On the other hand, in the present embodiment, the plurality of capacitive elements 22 are connected in parallel with each other. Therefore, a plurality of capacitive elements 22 can be charged at the same time. Then, the discharge control unit 23 of the present embodiment controls the discharge timings of the plurality of capacitive elements 22 individually, that is, independently of each other. By doing so, for example, after discharging one capacitive element 22, the other capacitive element 22 can be discharged while charging. That is, regardless of the charging time of the capacitive element 22, the plurality of capacitive elements 22 can be continuously discharged to cause the light emitting element 10 to emit light at short pulse intervals.

Further, when only one capacitive element is used and the light emitting element is repeatedly charged and discharged to emit light multiple times as in the conventional case, in order to change the emission intensity of the light emitting element, for example, the amount of charge charged in the capacitive element is used. Needed to be controlled. Such control may be difficult to perform with high accuracy, especially when pulse emission is repeated at short intervals.

On the other hand, in the present embodiment, for example, the discharge control unit 23 discharges a plurality of capacitive elements 22 individually or simultaneously to cause the light emitting element 10 to emit light, thereby easily changing the light emitting intensity of the light emitting element 10. Can be made to.

The light source driving device 20 according to the present embodiment can be used, for example, in the distance measuring device 1.
FIG. 2 is a block diagram showing a functional configuration of the distance measuring device 1 according to the first embodiment. The distance measuring device 1 includes a light source driving device 20, a light emitting element 10, and a processing unit 80. The processing unit 80 calculates the distance to the reflecting object that reflected the light in the emission direction of the light by using the time from the emission of the light by the light emitting element 10 to the reception of the reflected light of the light. The light emitting element 10 is, for example, a light source in the distance measuring device 1.

Further, the distance measuring device 1 further includes a light receiving unit 50 that receives the reflected light. A signal indicating the discharge timing of the capacitance element 22, that is, the light emission timing of the light emitting element 10 is input from the light source driving device 20 to the processing unit 80. Then, the processing unit 80 calculates the distance based on the light emission timing and the light reception timing of the light receiving unit 50.

As described above, according to the present embodiment, the light source driving device 20 includes a plurality of capacitive elements 22, and the discharge control unit 23 individually controls the timing at which the plurality of capacitive elements 22 are discharged. Therefore, it is possible to increase the degree of freedom in controlling the interval and intensity of the pulses output from the light source.

(Second embodiment)
FIG. 3 is a diagram illustrating the functional configuration of the distance measuring device 1 according to the second embodiment. The distance measuring device 1 according to the present embodiment is the same as the distance measuring device 1 according to the first embodiment except that it includes a plurality of light emitting elements 10. The distance measuring device 1 according to the present embodiment includes a light source driving device 20, a plurality of light emitting elements 10, a light receiving unit 50, and a processing unit 80. The light source driving device 20 controls the light emission of the plurality of light emitting elements 10. The processing unit 80 calculates the distance to the reflecting object that reflected the light in the emission direction of the light by using the time from the emission of the light by the light emitting element 10 to the reception of the reflected light of the light. A signal indicating the discharge timing of the capacitive element 22, that is, the light emission timing of the light emitting element 10, is input from the discharge control unit 23 of the light source driving device 20 to the processing unit 80. This will be described in detail below.

The light source driving device 20 according to the present embodiment has the same configuration as the light source driving device 20 according to the first embodiment. However, the plurality of capacitive elements 22 supply discharge currents to light emitting elements 10 that are different from each other. The light source driving device 20 drives a plurality of light emitting elements 10. The light source driving device 20 includes a plurality of capacitive elements 22, a power supply 21, and a discharge control unit 23. Each of the plurality of capacitive elements 22 supplies electric power to any of the plurality of light emitting elements 10 at the time of discharging. For example, the first capacitive element 22a supplies electric power to the first light emitting element 10a, and the second capacitive element 22b supplies electric power to the second light emitting element 10b. Here, the second capacitive element 22b is a capacitive element 22 different from the first capacitive element 22a, and the second light emitting element 10b is a light emitting element 10 different from the first light emitting element 10a. However, the characteristics of the first capacitive element 22a and the characteristics of the second capacitive element 22b may be the same or different from each other. The characteristics of the first light emitting element 10a and the characteristics of the second light emitting element 10b may be the same or different from each other. Further, the power supply 21 charges a plurality of capacitive elements 22. The discharge control unit 23 controls the timing at which the plurality of capacitive elements 22 are discharged. The light source driving device 20 may be a physically integrated device or may be composed of a plurality of units.

FIG. 4 is a diagram showing a modified example of the distance measuring device 1 of the second embodiment. The light source driving device 20 according to this modification is the same as the light source driving device 20 of the second embodiment except that it includes a plurality of power supplies 21. The light source driving device 20 according to the present embodiment includes a plurality of capacitive elements 22, a plurality of power sources 21, and a discharge control unit 23. Each of the plurality of capacitive elements 22 supplies electric power to any of the plurality of light emitting elements 10 at the time of discharging. For example, the first capacitive element 22a supplies electric power to the first light emitting element 10a, and the second capacitive element 22b supplies electric power to the second light emitting element 10b. Further, each of the plurality of power supplies 21 charges any one of the plurality of capacitive elements 22. For example, the first power source 21a charges the first capacitive element 22a, and the second power source 21b charges the second capacitive element 22b. Here, the second power supply 21b is a power supply 21 different from the first power supply 21a. However, the characteristics of the first power supply 21a and the characteristics of the second power supply 21b may be the same or different from each other. The discharge control unit 23 controls the timing at which the plurality of capacitive elements 22 are discharged.

3 and 4 show an example in which the distance measuring device 1 includes two light emitting elements 10 and the light source driving device 20 includes two capacitive elements 22, but the present invention is not limited thereto. The distance measuring device 1 may include three or more light emitting elements 10, and the light source driving device 20 may include three or more capacitive elements 22.

The discharge control unit 23 of the present embodiment controls the discharge timings of the plurality of capacitive elements 22 independently of each other. By doing so, for example, after discharging one capacitive element 22, the other capacitive element 22 can be discharged while charging. That is, regardless of the charging time of the capacitive element 22, the plurality of capacitive elements 22 can be continuously discharged, and the plurality of light emitting elements 10 can be sequentially made to emit light at short pulse intervals.

Further, in the present embodiment, for example, the discharge control unit 23 discharges a plurality of capacitive elements 22 individually or simultaneously to cause the light emitting element 10 to emit light, thereby easily changing the light emitting intensity of the light emitting element 10. Can be done.

As described above, according to the present embodiment, the distance measuring device 1 includes a plurality of light emitting elements 10, and the discharge control unit 23 individually controls the timing at which the plurality of capacitive elements 22 are discharged. Therefore, it is possible to increase the degree of freedom in controlling the interval and intensity of the pulses output from the light source.

(Example 1)
FIG. 5 is a diagram illustrating a circuit configuration of the light source driving device 20 and the light emitting element 10 according to the first embodiment. The light source driving device 20 according to this embodiment has the configuration described in the first embodiment. The light source driving device 20 according to this embodiment is realized by using a circuit as shown in this figure and an integrated circuit 100 which will be described later.

Light source drive unit 20, n (n is a natural number) and capacitive element 22 of the (capacitive element _C chg1 _{~C chgn),} a switch _M 1 ~M _n consisting FET, a resistor _R lim1 _{to R limn,} resistor _{R chg1} It includes ~ R _chgn , a diode D _clp , a resistor R _m , a capacitive element C _p, and a power supply 21. The capacitive elements C _{chg1 to} C _chgn correspond to a plurality of capacitive elements 22, the laser diode LD corresponds to the light emitting element 10, and the voltage V _h corresponds to the output voltage of the power supply 21. The discharge control unit 23 is implemented by the switch _M 1 ~M _n and the integrated circuit 100 or the like. In this figure, an example (example of n = 5) in which the light source driving device 20 includes five capacitive elements 22 is shown, but the present invention is not limited to this.

In the light source drive device 20, the high voltage _{V h} which is output from the power source 21 is applied to the capacitor _C chg1 _{~C chgn,} the capacitor _C chg1 _{~C chgn} is charged. Then, the electric charge charged in the capacitor _C chg1 _{~C chgn,} each instantaneously discharged through the switch _M 1 ~M _n, by flowing to the laser diode LD, and outputs the pulsed laser beam. As an example, the capacitive elements C _{chg1 to} C _chgn are each charged from tens to hundreds of volts, and then discharged at tens of amperes.

Hereinafter, the discharge / charge of the capacitive element 22 will be described in detail using the capacitive element C _chgk (k is an integer of 1 or more and n or less) as an example. In the following, the first terminal and the second terminal of each element are different terminals from each other. The first terminal of the capacitor _{C Chgk} connected first terminals of the resistor _{R LIMK} is, the power supply 21 via the resistor _{R Chgk} is connected to the second terminal of the capacitor _{C chgk. Further, a switch Mk} is connected between the second terminal of the capacitive element C _{chgk and the ground terminal.} The output terminal of the control unit 230, which will be described later, is connected to the gate of the switch _{Mk. Further} , the anode of the diode D clp is connected to the second terminal of the resistor R _limk. The cathode of the diode D _clp is connected to the ground terminal.

The cathode of the laser diode LD is connected to the second terminal of the resistor R _limk. The anode of the laser diode LD is connected to the ground terminal. Further, the laser diode LD is connected in parallel to the resistor R _m and the capacitance element C _{p connected in series.}

Here, the discharge control unit 23 includes a control unit 230 and switches M _{1 to} M _n .

During charging, to apply a high voltage _{V h} to the capacitive element _{C Chgk} by the power source 21, the switch _{M k} turned off by the trigger signal _{V Tk.} Thus, the capacitor _{C Chgk} in the charging path 201 of the broken line in the figure is charged by the high voltage _{V h.} Then, at the time of discharge, the switch _Mk is turned on _{by the trigger signal VTk.} As a result, _{the electric charge stored in the capacitive element C chgk} is instantaneously discharged in the discharge path 202 shown by the broken line in this figure, and the laser diode LD emits light. Here, as the power supply 21, for example, a high-voltage generation circuit such as a charge pump can be used. By providing a trigger signal _{V Tk} for each of the capacitive elements _C chg1 _{~C chgn,} it is possible to control the charge and discharge independently.

FIG. 6 is a diagram showing a hardware configuration of the integrated circuit 100. The control unit 230 is realized by using the integrated circuit 100. Integrated circuit 100 outputs a trigger signal _V T1 _{~V Tn.} Trigger signal _V T1 _{~V Tn} output is input to the switch _M 1 ~M _n respectively. The integrated circuit 100 is, for example, a SoC (System On Chip).

The integrated circuit 100 includes a bus 102, a processor 104, a memory 106, a storage device 108, an input / output interface 110, and a network interface 112. The bus 102 is a data transmission path for the processor 104, the memory 106, the storage device 108, the input / output interface 110, and the network interface 112 to transmit and receive data to and from each other. However, the method of connecting the processors 104 and the like to each other is not limited to the bus connection. The processor 104 is an arithmetic processing unit realized by using a microprocessor or the like. The memory 106 is a memory realized by using a RAM (Random Access Memory) or the like. The storage device 108 is a storage device realized by using a ROM (Read Only Memory), a flash memory, or the like.

The input / output interface 110 is an interface for connecting the integrated circuit 100 to peripheral devices. Trigger signal _V T1 _{~V Tn} outputted from the input-output interface 110 is input to the switch _M 1 ~M _n respectively.

The network interface 112 is an interface for connecting the integrated circuit 100 to the communication network. This communication network is, for example, a CAN (Controller Area Network) communication network. The method of connecting the network interface 112 to the communication network may be a wireless connection or a wired connection.

The storage device 108 stores a program module for realizing the function of the control unit 230. The processor 104 realizes the function of the control unit 230 by reading the program module into the memory 106 and executing the program module.

The hardware configuration of the integrated circuit 100 is not limited to the configuration shown in FIG. For example, the program module may be stored in memory 106. In this case, the integrated circuit 100 may not include the storage device 108.

Figure 7 is an example of a timing chart of a trigger signal _V T1 _{~V Tn} according to the first embodiment. According to this example, the light emitting element 10 repeatedly emits light at the same interval. Information indicating the timing chart can be output, for example, by storing it in a storage device 108 or the like of the integrated circuit 100 in advance and having the discharge control unit 23 (control unit 230) read it out and execute it. Trigger signal _{V Tk} is a trigger signal for discharging the capacitor _{C chgk.} During trigger signal _{V Tk} is low (Low) level, the switch _{M k} is turned off, the capacitor _{C Chgk} is charged. Switch _{M k} at a timing at which the trigger signal _{V Tk} is changed from a low level to a high (High) level is turned on, the capacitor _{C Chgk} is discharged.

This figure is a timing chart when the _{capacitive elements C chg1 to} C _{chgn are discharged in order.} In the example of this figure, the discharge control unit 23 discharges the first capacitive element 22 (for example, the capacitive element C _{chg 1} ) at the first timing (for example, timing t 1), and the second timing different from the first timing. At (for example, timing t ₂ ), the second capacitive element 22 (for example, the capacitive element C _chg 2) different from the first capacitive element 22 is discharged. By doing so, another capacity element 22 can be discharged without waiting for the first capacity element 22 to be sufficiently charged again after discharge. As a result, the interval between pulsed light emission of the light emitting element 10 can be shortened. The interval between the first timing and the second timing is not particularly limited, but the light emitting element 10 can be made to emit light in a pulse at an interval shorter than the charging of the capacitive element 22 is completed. For example, the interval between the first timing and the second timing is the time required from the start of charging the first capacitance element 22 to the completion of charging, and the interval between the start of charging the second capacitance element 22 and the completion of charging. It takes less than at least one of the times. The time it takes from beginning to charge the capacitor _{C Chgk} until charging is complete is dependent on the resistance value or the like of the capacitance of the capacitor _{C Chgk} and resistor _{R LIMK} and resistor _{R chgk.}

Specific in the example of the figure, the timing of rising of the trigger signal V _T1, that is, from the timing has changed from low level to high level (t ₁₎ is (k-1) × t _d trigger signal V _Tk after seconds rises .. That is, the timing _{t k} the trigger signal _{V Tk} rises, based on the _{t 1 (t 1 = 0)} , is expressed by t k = (k-1) × t d (k ≧ 2). Each trigger signal V _Tk, the process returns to the low level at risen time t _pw since has elapsed timing. Then, the trigger signal _VT1 rises once and then rises again n × t _d seconds later (n is a natural number). Thus, the trigger signal _V T1 _{~V Tn} rises repeatedly in order to discharge the capacitor _C chg1 _{~C chgn} sequentially. By doing so, the light emitting element 10, either of the capacitor 22 is pulsed light at t _d seconds between each time they are discharged. In the example of this figure, the interval between the first timing and the second timing is represented by _{t d. Further, the time during which the trigger signal VTk} is at the low level between the discharge of one capacitive element 22 and the next discharge can be sufficiently long. Therefore, each capacitance element 22 can be fully charged between the time when one capacitance element 22 is discharged and the time when one capacitance element 22 is discharged next. In the example of this figure, the time that can be used for charging the capacitive element 22 is represented by _{n × t d.}

However, the timing chart of the trigger signal is not limited to the above example, and for example, the interval at which the plurality of capacitive elements 22 are discharged may not be constant.

In this embodiment, the capacitances of the capacitive elements C _{chg1 to} C _chgn may be the same as each other, or at least one may be different. The resistance values of the resistors R _{lim1 to} R _limn may be the same as each other, or at least one of them may be different. _Further, the resistance values of the resistors R _{chg1 to} R chgn may be the same as each other, or at least one of them may be different.

Further, each independent source 21 is provided with capacitive elements _C chg1 _{~C chgn,} capacitive element _C chg1 _{~C chgn} may be charged by different power 21 from each other.

As described above, also in this embodiment, as in the first embodiment, the light source driving device 20 includes a plurality of capacitive elements 22, and the discharge control unit 23 individually controls the timing at which the plurality of capacitive elements 22 are discharged. Therefore, the degree of freedom in controlling the pulse output from the light source can be increased.

In addition, the discharge control unit 23 of the present embodiment discharges the first capacitance element 22 at the first timing, and is different from the first capacitance element 22 at the second timing different from the first timing. The second capacitive element 22 is discharged. Therefore, the interval between the pulsed light emission of the light emitting element 10 can be shortened.

(Example 2)
FIG. 8 is a diagram illustrating a circuit configuration of the light source driving device 20 and the light emitting element 10 according to the second embodiment. The light source driving device 20 according to this embodiment has the configuration described in the second embodiment. That is, the light source driving device 20 drives a plurality of light emitting elements 10. The light source driving device 20 according to the present embodiment is realized by using the circuit as shown in this figure and the integrated circuit 100 as described in the first embodiment.

Light source driver 20, the capacitive element 22 of n (n is an integer) (capacitance element _C chg1 _{~C chgn),} a switch _M 1 ~M _n consisting FET, a resistor _R lim1 _{to R limn,} resistor _{R chg1} It is _provided with ~ R chgn, diodes D _{clp1 to} D _clpn , resistors R _{m1 to} R _mn , capacitive elements C _{p1 to} C _pn, and a power supply 21. Capacitive element _C chg1 _{~C chgn} correspond to a plurality of capacitive elements 22, a laser diode _LD 1 to Ld _n correspond to a plurality of light emitting elements 10, the voltage _{V h} corresponding to the output voltage of the power source 21. The discharge control unit 23 is implemented by the switch _M 1 ~M _n and the integrated circuit 100 or the like. In this figure, an example (example of n = 2) in which the light source driving device 20 includes two capacitive elements 22 is shown, but the present invention is not limited to this.

In the light source drive device 20, the high voltage _{V h} which is output from the power source 21 is applied to the capacitor _C chg1 _{~C chgn,} the capacitor _C chg1 _{~C chgn} is charged. Then, the electric charge charged in the capacitor _C chg1 _{~C chgn,} each instantaneously discharged through the switch _M 1 ~M _n, by flowing to the laser diode _LD 1 to Ld _n, and outputs a pulse laser beam. As an example, the capacitive elements C _{chg1 to} C _chgn are each charged from tens to hundreds of volts, and then discharged at tens of amperes.

Hereinafter, the discharge / charge of the capacitive element 22 will be described in detail using the capacitive element C _chgk (k is an integer of 1 or more and n or less) as an example. The first terminal of the capacitor _{C Chgk} connected first terminals of the resistor _{R LIMK} is, the power supply 21 via the resistor _{R Chgk} is connected to the second terminal of the capacitor _{C chgk. Further, a switch Mk} is connected between the second terminal of the capacitive element C _{chgk and the ground terminal.} The output terminal of the control unit 230 is connected to the gate of the switch _{Mk. Further} , the anode of the diode D clpk is connected to the second terminal of the resistor R _limk. The cathode of the diode D _clpk is connected to the ground terminal.

The cathode of the _{laser diode LD k} is connected to the second terminal of the resistor R _limk. The anode of the laser diode LD _k is connected to the ground terminal. Further, the laser diode LD _k is connected in parallel to the resistor R _mk and the capacitive element C _{pk connected in series.}

During charging, to apply a high voltage _{V h} to the capacitive element _{C Chgk} by the power source 21, the switch _{M k} turned off by the trigger signal _{V Tk.} Thus, the capacitor _{C Chgk} is charged by the high voltage _{V h.} Then, at the time of discharge, the switch _Mk is turned on _{by the trigger signal VTk.} As a result, _{the electric charge stored in the capacitive element C chg k} is instantaneously discharged, and the laser diode LD k emits light. Here, as the power supply 21, for example, a high-voltage generation circuit such as a charge pump can be used. By providing a trigger signal _{V Tk} for each of the capacitive elements _C chg1 _{~C chgn,} it is possible to control the charge and discharge independently.

An example of a timing chart of a trigger signal V _T1 ~V _Tn according to the present embodiment can be shown as in FIG 7.

In this embodiment, the capacitances of the capacitive elements C _{chg1 to} C _chgn may be the same as each other, or at least one may be different. The resistance values of the resistors R _{lim1 to} R _limn may be the same as each other, or at least one of them may be different. The resistance values of the resistors R _{chg1 to} R _chgn may be the same as each other, or at least one of them may be different. Further, the characteristics of the laser diodes LD _{1 to LD n} , the characteristics of the resistors R _{m1 to} R _mn , and the characteristics of the capacitive elements C _{p1 to} C _pn may be the same as each other, or at least one may be different. ..

As described above, also in this embodiment, as in the second embodiment, the distance measuring device 1 includes a plurality of light emitting elements 10, and the discharge control unit 23 individually controls the timing at which the plurality of capacitive elements 22 are discharged. .. Therefore, the degree of freedom in controlling the pulse output from the light source can be increased.

In addition, the discharge control unit 23 of the present embodiment discharges the first capacitance element 22 at the first timing to cause the first light emitting element 10 to emit light, and at a second timing different from the first timing. The second capacitive element 22, which is different from the first capacitive element 22, can be discharged to cause the second light emitting element 10 to emit light. Therefore, it is possible to shorten the interval between the output pulse emissions of the distance measuring device 1 as a whole.

(Example 3)
FIG. 9 is a diagram illustrating a circuit configuration of the light source driving device 20 and the light emitting element 10 according to the third embodiment. The light source driving device 20 according to the present embodiment is the same as the light source driving device 20 of the second embodiment except for the points described below. The light source driving device 20 according to the present embodiment has the configuration described in the modified example of the second embodiment. That is, a plurality of combinations of one light emitting element and its power supply circuit are configured. The light source driving device 20 according to the present embodiment is realized by using the circuit as shown in this figure and the integrated circuit 100 as described in the first embodiment.

Light source drive unit 20, n (n is a natural number) and capacitive element 22 of the (capacitive element _C chg1 _{~C chgn),} a switch _M 1 ~M _n consisting FET, a resistor _R lim1 _{to R limn,} resistor _{R chg1} It is _provided with ~ R chgn, diodes D _{clp1 to} D _clpn , resistors R _{m1 to} R _mn , capacitive elements C _{p1 to} C _pn, and a plurality of power supplies 21. Capacitive elements C _{chg1 to} C _chgn correspond to a plurality of capacitive elements 22, laser diodes LD _{1 to LD n} correspond to a plurality of light emitting elements 10, and voltages V _{h1 to} V _hn correspond to output voltages of a plurality of power supplies 21, respectively. Equivalent to. The discharge control unit 23 is implemented by the switch _M 1 ~M _n and the integrated circuit 100 or the like. In this figure, an example (example of n = 2) in which the light source driving device 20 includes two capacitive elements 22 is shown, but the present invention is not limited to this.

In the light source drive device 20, the high voltage _V h1 _{~V hn} output from the power source 21 is applied to the capacitor _C chg1 _{~C chgn,} the capacitor _C chg1 _{~C chgn} is charged. Then, the electric charge charged in the capacitor _C chg1 _{~C chgn,} each instantaneously discharged through the switch _M 1 ~M _n, by flowing to the laser diode _LD 1 to Ld _n, and outputs a pulse laser beam. As an example, the capacitive elements C _{chg1 to} C _chgn are each charged from tens to hundreds of volts, and then discharged at tens of amperes.

Hereinafter, the discharge / charge of the capacitive element 22 will be described in detail using the capacitive element C _chgk (k is an integer of 1 or more and n or less) as an example. The first terminal of the capacitor _{C Chgk} connected first terminals of the resistor _{R LIMK} is, the power supply 21 via the resistor _{R Chgk} is connected to the second terminal of the capacitor _{C chgk. Further, a switch Mk} is connected between the second terminal of the capacitive element C _{chgk and the ground terminal.} The output terminal of the control unit 230 is connected to the gate of the switch _{Mk. Further} , the anode of the diode D clpk is connected to the second terminal of the resistor R _limk. The cathode of the diode D _clpk is connected to the ground terminal.

The cathode of the _{laser diode LD k} is connected to the second terminal of the resistor R _limk. The anode of the laser diode LD _k is connected to the ground terminal. Further, the laser diode LD _k is connected in parallel to the resistor R _mk and the capacitive element C _{pk connected in series.}

During charging, to apply a high voltage _{V hk} in the capacitor _{C Chgk} by the power source 21, the switch _{M k} turned off by the trigger signal _{V Tk.} As a result, the capacitive element C _chgk is charged by the high voltage V _hk. Then, at the time of discharge, the switch _Mk is turned on _{by the trigger signal VTk.} As a result, _{the electric charge stored in the capacitive element C chg k} is instantaneously discharged, and the laser diode LD k emits light. Here, as the power supply 21, for example, a high-voltage generation circuit such as a charge pump can be used. By providing a trigger signal _{V Tk} for each of the capacitive elements _C chg1 _{~C chgn,} it is possible to control the charge and discharge independently.

An example of a timing chart of a trigger signal V _T1 ~V _Tn according to the present embodiment can be shown as in FIG 7.

In this embodiment, the voltage values of the high voltages V _{h1 to} V _hn may be the same as each other, or at least one may be different.

As described above, also in this embodiment, as in the second embodiment, the distance measuring device 1 includes a plurality of light emitting elements 10, and the discharge control unit 23 individually controls the timing at which the plurality of capacitive elements 22 are discharged. .. Therefore, the degree of freedom in controlling the pulse output from the light source can be increased.

In addition, the discharge control unit 23 of the present embodiment discharges the first capacitance element 22 at the first timing to cause the first light emitting element 10 to emit light, and at a second timing different from the first timing. The second capacitive element 22, which is different from the first capacitive element 22, can be discharged to cause the second light emitting element 10 to emit light. Therefore, it is possible to shorten the interval between the output pulse emissions of the distance measuring device 1 as a whole.

(Example 4)
The light source driving device 20 according to the present embodiment has the same configuration as the light source driving device 20 according to at least one of the first to third embodiments. Hereinafter, a case where the light source driving device 20 has the configuration described in the first embodiment will be described.

Discharge control unit 23 of this embodiment, the third timing t _S, and, in each of the fourth timing t _L which is different from the third timing t _S, at least one of a plurality of capacitive elements 22 and discharge Let me. Then, at the fourth timing t _L , a larger electric power than the third timing t _S is supplied to the light emitting element 10. This will be described in detail below.

In the fourth timing t _L , the configuration of the present embodiment in which the electric power larger than that of the third timing t _S is supplied to the light emitting element 10 includes, for example, the following first to third examples. At the fourth timing t _L , a larger power than the third timing t _S is supplied to the light emitting element 10, so that the pulsed light having a higher intensity at the fourth timing t _{L than the third timing t S.} Is output.

Figure 10 is an example of a timing chart of a trigger signal _V T1 _{~V T4} according to the first example of the fourth embodiment. In the first example, the plurality of capacitive elements 22 includes a third capacitive element 22 and a fourth capacitive element 22 having a capacitance larger than the capacitance of the third capacitive element 22. Then, the discharge control unit 23 discharges the third capacitance element at the third _{timing t S} , and discharges the fourth capacitance element 22 at the fourth _{timing t L.} In the example of this figure, for example, the light source driving device 20 includes at least four capacitive elements 22 (capacitive elements C _{chg1 to} C _chg4 ). For example, the capacitance of the capacitive element C _{chg1 and} the capacitance of C _chg2 are the same, and the capacitance of the capacitive element C _{chg3 and} the capacitance of C _chg4 are the same. Here, the capacitive element C _chg1 and the capacitive element C _chg2 are referred to as a third capacitive element 22, and the capacitive element C _chg3 and the capacitive element C _chg4 are referred to as a fourth capacitive element 22. That is, the capacitance of the capacitor _{C CHG3} is larger than the capacitance of the capacitor _{C chg1.}

The capacitive element _{C chg1} or _{C chg2} is discharged by the trigger signal _{V T1} or _{V T2} rises at the third timing _{t S.} The capacitor _{C CHG3} or _{C Chg4} is discharged by the trigger signal _{V T3} or _{V T4} rises at the fourth timing _{t L.} By discharging the capacitive element 22 having a larger capacity at the fourth timing t _L in this way, a larger current than the third timing t _{S flows through the light emitting element 10 at the fourth timing t L} , and a large current flows to the light emitting element 10. Electric power is supplied to the light emitting element 10.

Further, when the third timing is continuous, the capacitive elements C _chg1 and C _chg2 are alternately discharged, and when the fourth timing is continuous, the capacitive elements C _chg3 and _Cchg4 are alternately discharged. Therefore, the light emitting element 10 can be made to emit light at short pulse intervals. The light source driving device 20 may include three or more third capacitive elements 22 and three or more fourth capacitive elements 22. That is, when the third timing is continuous and when the fourth timing is continuous, the light source driving device 20 may discharge three or more capacitive elements 22 in order.

Figure 11 is an example of a timing chart of a trigger signal _V T1 _{~V T4} according to the second example of the fourth embodiment. In this example, the discharge control unit 23 discharges more capacitance elements 22 than the third timing t _{S at the fourth timing t L.} In the example of this figure, for example, the light source driving device 20 includes at least four capacitive elements 22 (capacitive elements C _{chg1 to} C _chg4 ). For example, capacity and capacity _{C chg2} at least the capacitive element _{C chg1} are mutually the same, capacity and capacity _{C Chg4} of the capacitor _{C CHG3} are the same as each other. Then, only the capacitance element _{C chg1} or _{C chg2} is discharged by only the third timing _{t S} trigger signal _{V T1} or _{V T2} in rises. Moreover, and a capacitive element _{C chg1} and _{C CHG3} are discharged simultaneously by a trigger signal _{V T1} and _{V T3} in fourth timing _{t L} rises at the same time. Or by a trigger signal _{V T2} and _{V T4} rises simultaneously fourth timing _{t L,} and a capacitance element _{C chg2} and _{C Chg4} are discharged simultaneously. Large Thus, by capacitive element 22 of more space than the third timing t _S in the fourth timing t _L is discharged, the fourth timing t _L, than the third timing t _S A current flows through the light emitting element 10, and a large amount of electric power is supplied to the light emitting element 10.

Further, also in this example, when the third timing is continuous and when the fourth timing is continuous, the light emitting element 10 is made to emit light at short pulse intervals by alternately discharging the plurality of capacitive elements 22. be able to. When the third timing is continuous and the fourth timing is continuous, the light source driving device 20 may discharge three or more capacitive elements 22 in order. Further, the number of capacitive elements 22 to be discharged at the same time is not particularly limited.

In the second example, the capacitances of the plurality of capacitive elements 22 that can be discharged at the same time, that is, the capacitances of the capacitive elements C _chg1 and C _chg3 may be the same as each other, or at least one may be different. When the capacities of the plurality of capacitance elements 22 are different from each other, the emission intensity of the light emitting element 10 can be changed in three stages by, for example, a combination of two types of capacitances. Specifically, in the example of this figure, when the capacitance of the capacitive element C _{chg3 and} the capacitance of C _chg4 are larger than the capacitance of the capacitive element C _{chg1 and} the capacitance of the capacitive element C _chg2 , it is desired to output weak intensity pulsed light. At the timing, only the capacitive element C _chg1 or C _chg2 is discharged, at the timing when you want to output medium intensity pulsed light, _{only the capacitive element C chg3} or _Cchg4 is discharged, and at the timing when you want to output the strong intensity pulsed light, the capacitive element C _chg1 and _{C CHG3,} or, it is sufficient to discharge simultaneously by combining capacitive element _{C chg2} and _{C chg4.}

FIG. 12 is a diagram illustrating a circuit configuration of the light source driving device 20 and the light emitting element 10 according to the third example of the fourth embodiment. The circuit configuration according to the third example is the same as the circuit configuration of the first embodiment except that a plurality of power supplies 21 are provided. An example of a timing chart of the trigger signal V _T1 and V _T2 according to the third example can be represented as in FIG 10. In the third example, the plurality of capacitive elements 22 includes a third capacitive element 22 and a fourth capacitive element 22 that is charged with a voltage larger than the voltage for charging the third capacitive element 22. Then, the discharge control unit 23 discharges the third capacitance element 22 at the third _{timing t S} , and discharges the fourth capacitance element 22 at the fourth _{timing t L.}

In FIG. 12, the light source driving device 20 includes a plurality of power supplies 21. The output voltages of the plurality of power supplies 21 are represented by _{high voltages V h1 to} V _hn. The first terminal of the capacitor _{C Chgk} resistor _{R LIMK} is connected, to the second terminal of the capacitor _{C Chgk} connected power 21 through a resistor _{R Chgk,} the high voltage _{V hk} is applied ..

In this example, the light source driving device 20 includes at least four capacitive elements 22 (capacitive elements C _{chg1 to} C _chg4 ) and four power supplies 21. For example, the high voltage V _h1 and the high voltage V _h2 are the same as each other, and the high voltage V _h3 and the high voltage V _h4 are the same as each other. Here, for example, the high voltage V _h3 is larger than the high voltage V _h1. By doing so, the capacitive element C _chg3 and the capacitive element C _chg4 are charged with a voltage larger than that of the capacitive element C _chg1 and the capacitive element C _{chg2, and more charges are accumulated.} The capacitive element _{C chg1} or capacitive element _{C chg2} is discharged by the trigger signal _{V T1} or _{V T2} rises at the third timing _{t S.} The capacitor _{C CHG3} or capacitive element _{C Chg4} is discharged by the trigger signal _{V T3} or _{V T4} rises at the fourth timing _{t L.} In this way, at the fourth timing t _L , the capacitive element 22 in which a charge larger than the third timing t _S is accumulated is discharged, so that at the fourth timing t _L , from the third timing t _S. A large current flows through the light emitting element 10, and a large power is supplied to the light emitting element 10.

Further, also in this example, when the third timing t _S is continuous and when the fourth timing t _L is continuous, the plurality of capacitive elements 22 are alternately discharged to emit light at short pulse intervals. 10 can be made to emit light. When the third timing is continuous and the fourth timing is continuous, the light source driving device 20 may discharge three or more capacitive elements 22 in order.

As described in the first to third examples, the discharge control unit 23 sets the timing at which the pulsed light of high intensity is desired to be the fourth timing t _L , and the other timings as the third timing t _S. Trigger signal is output. Specifically, for example, when the light source driving device 20 is included in the distance measuring device 1, the discharge control unit 23 _{repeatedly provides a third timing t S} as an initial state at predetermined intervals. _{Then, the fourth timing t L} is repeatedly provided at predetermined intervals from the time when the user performs the operation to improve the accuracy of the distance measurement to the distance measuring device 1 until the predetermined time elapses. By doing so, the output intensity of the light emitting element 10 can be increased and the measurement accuracy can be improved when the user desires.

In this embodiment, the discharge interval of each capacitance element 22 may be, for example, longer than the time during which each capacitance element 22 can be fully charged.

Further, in the first to third examples described above, an example is shown in which a plurality of capacitive elements 22 are alternately discharged _{when the third timing t S} is continuous and when the fourth timing t _{L is continuous.} However, it is not limited to this. The same capacitive element 22 may be continuously discharged when the third timing t _S is continuous and when the fourth timing t _{L is continuous.} Even in this case, the emission intensity can be controlled in the same manner as described above.

Further, the same method as in the first to third examples may be applied to the light source driving device 20 and the light emitting element 10 of the second embodiment.

As described above, also in this embodiment, the light source driving device 20 includes a plurality of capacitive elements 22, and the discharge control unit 23 individually controls the timing at which the plurality of capacitive elements 22 are discharged. Therefore, the degree of freedom in controlling the pulse output from the light source can be increased.

In addition, according to the present embodiment, at the fourth timing t _L , a larger electric power than the third timing t _S is supplied to the light emitting element 10. Therefore, the intensity of the pulsed light output from the light source can be controlled.

(Example 5)
FIG. 13 is a block diagram illustrating a functional configuration of the distance measuring device 1 according to the fifth embodiment. The distance measuring device 1 according to this embodiment includes a light emitting element 10, a light source driving device 20, a movable reflection unit 30, a control unit 70, a processing unit 80, and a light receiving unit 50. The distance measuring device 1 is, for example, a LIDAR (Laser Imaging Detection and Ranging) device.

The light source driving device 20 according to the present embodiment has the same configuration as the light source driving device 20 of at least one of the first embodiment, the second embodiment, and the first to fourth embodiments. Further, as described above, the light emitting element 10 is, for example, a semiconductor laser. The wavelength of the light output from the light emitting element 10 is not particularly limited, but is, for example, near-infrared light of 700 nm or more and 1050 nm or less. The movable reflection unit 30 includes, for example, a MEMS mirror and a drive circuit. The angle of the reflective surface of the MEMS mirror is controlled by the control unit 70. Then, the movable reflecting unit 30 reflects the light emitted from the light emitting element 10 on the reflecting surface, and outputs the light in a desired direction. The movable reflection unit 30 can scan the target object two-dimensionally with light, for example, by including a two-axis drive MEMS mirror. However, in the distance measuring device 1, the configuration of the distance measuring device 1 is not particularly limited as long as the light output direction is variable. For example, the light emitting element 10 may be fixed to the movable stage, and the control unit 70 may control the direction of the light emitting element 10 to control the light output direction.

When the light source driving device 20 has the configuration described in at least one of the second embodiment, the second embodiment and the third embodiment, the distance measuring device 1 includes a plurality of light emitting elements 10. In that case, for example, by using an optical system (not shown), the light from the plurality of light emitting elements 10 is configured to be output coaxially.

The hardware configuration of the control unit 70 and the processing unit 80 can be exemplified in the same manner as in FIG. The control unit 70 and the processing unit 80 are mounted by using the integrated circuit 100 described above. In the present embodiment, the switch _M 1 ~M _n of the light source drive unit 20 output interface 110, the drive circuit of the movable reflector 30, the light receiving unit 50 are connected.

The storage device 108 stores a program module for realizing the functions of the control unit 70 and the processing unit 80. The processor 104 realizes the functions of the control unit 70 and the processing unit 80 by reading the program module into the memory 106 and executing the program module.

The light receiving unit 50 includes, for example, a photodiode and a detection circuit. In the light receiving unit 50, the light incident on the light receiving surface of the photodiode is photoelectrically converted, and a light receiving signal is generated.

The processing unit 80 calculates the distance to the object that reflected the light in the emission direction of the light by using the time from when the light emitting element 10 emits the light until the light receiving unit 50 receives the reflected light of the light. do. Specifically, a trigger indicating the light output timing is input to the processing unit 80 from the discharge control unit 23 of the light source driving device 20. Further, the processing unit 80 acquires a light receiving signal from the light receiving unit 50. The processing unit 80 may perform processing such as noise removal on the received light signal, if necessary. The processing unit 80 calculates the time from when the light emitting element 10 emits light until the light receiving unit 50 receives the reflected light of the light, based on the trigger from the discharge control unit 23 and the light receiving signal from the light receiving unit 50. do. Further, the processing unit 80 may correct the calculated time as necessary. The processing unit 80 is a distance measuring device by multiplying the time from when the light emitting element 10 emits light until the light receiving unit 50 receives the reflected light by multiplying the speed of light by half. Calculate the distance from 1 to the object. Further, the processing unit 80 can generate information indicating the direction and the distance of the object by acquiring the information indicating the light emission direction from the control unit 70.

For example, when the distance measuring device 1 is attached to a moving body, the direction and distance of the surrounding objects can be detected by scanning the surroundings of the distance measuring device 1 in two dimensions while repeatedly outputting pulsed light. .. In this case, the basic timing at which the distance measuring device 1 should output a pulse is predetermined. Normally, the distance measuring device 1 outputs pulses at regular intervals. However, the pulse interval may be different depending on the region of the scanning range. The discharge control unit 23 according to the first embodiment determines, for example, one of these basic timings as the first timing and the other timing as the second timing. Further, the discharge control unit 23 according to the third embodiment determines, for example, one of such basic timings as the third timing t _S and the other one as the fourth timing t _L.

When the light source driving device 20 according to the present embodiment has the configuration of the third embodiment, the following first example of the processing for the _{discharge control unit 23 to determine the third timing t S} and the fourth timing t _{L is as follows.} There are 1 processing example to 3rd processing example.

FIG. 14 is a diagram for explaining the first processing example. Further, FIG. 15 is a diagram illustrating a functional configuration of the light source driving device 20 that performs this processing example. In the first processing example, the distance measuring device 1 is attached to the moving body 90. That is, the light emitting element 10 and the light source driving device 20 are attached to the moving body 90. The light source driving device 20 further includes an acquisition unit 24 for acquiring map information around the moving body 90. Then, the discharge control unit 23 determines _{the fourth timing t L based on the map information.} This will be described in detail below.

The mobile body 90 is, for example, a vehicle. There are cases where it is desired to specify the position of the moving body 90 with high accuracy so that the moving body 90 can move smoothly on the road. As one method for that purpose, the position of the landmark 92 that serves as a mark on the map is compared with the position of the landmark 92 that is actually specified by the distance measuring device 1 to improve the accuracy of specifying the position of the moving body 90. There is a way. Moving the case with respect to the direction d ₂ of the landmark 92 is likely to be located, and outputs the pulse light intensity higher than other directions d _1, the direction and the landmark 92 of the moving body 90 as viewed from the landmark 92 When the distance to the body 90 is measured, the S / N ratio becomes large, so that the accuracy of specifying the position of the moving body 90 can be improved. Landmark 92 is, for example, a feature such as a kilometer post, a 100 m post, a delineator, a transportation infrastructure facility (for example, a sign, a direction sign, a signal), a utility pole, a street light, etc., which are lined up on the side of a road.

In this processing example, the mobile body 90 includes an internal sensor (not shown) such as a GPS and an azimuth meter. Then, the acquisition unit 24 acquires prior information indicating the approximate position (for example, latitude and longitude) and orientation of the moving body 90 from the internal sensor. Further, the acquisition unit 24 acquires the map information around the position indicated by the prior information from, for example, the server of the map service via the communication network. Map information includes information indicating the location of landmark 92. Next, the acquisition unit 24 calculates the direction and distance in which the landmark 92 is expected to be located, based on the prior information and the map information.

The acquisition unit 24 is realized by the integrated circuit 100 as described above. The storage device 108 stores a program module for realizing the function of the acquisition unit 24. The processor 104 realizes the function of the acquisition unit 24 by reading the program module into the memory 106 and executing the program module.

In this processing example, the distance measuring device 1 scans the periphery of the moving body 90 with pulsed light. Then, the discharge control unit 23 sets the timing at which the pulsed light is output in the direction in which the landmark 92 is expected to be located as the fourth timing t _L. Then, the other timing is defined as the third timing t _S. By doing so, the direction of the landmark 92 as seen from the moving body 90 and the distance between the landmark 92 and the moving body 90 can be measured with higher accuracy. The processing unit 80 calculates the amount of deviation between the expected direction and distance of the landmark 92 and the direction and distance of the landmark 92 measured by the distance measuring device 1, and provides advance information so as to reduce the amount of deviation. It is corrected to improve the accuracy of specifying the position of the moving body 90.

Next, a second processing example will be described. In this processing example, the acquisition unit 24 acquires weather information indicating the weather. For example, the acquisition unit 24 can acquire information indicating the weather around the position indicated by the prior information from, for example, a server of the weather information providing service via a communication network. Then, the discharge control unit 23 determines _{the fourth timing t L based on the weather information.} This will be described in detail below.

The light emitted from the distance measuring device 1 is reflected by an object and can be reflected and absorbed by particles such as rain and fog before being received. In that case, the light receiving intensity may decrease, making accurate distance measurement difficult. Therefore, when the weather is rain, fog, snow, etc., it is preferable to output high-intensity pulsed light to improve the measurement accuracy.

For example, when the acquired weather information indicates rain, fog, or snow, the acquisition unit 24 sets all emission timings in scanning as the fourth timing t _L. On the other hand, the weather information is clear, or may exhibit fogging, to all emission timing in the scan and the third timing t _S. The acquisition unit 24 acquires weather information every time a predetermined predetermined time elapses, and sets a _{third timing t S} or a fourth timing t _L. The discharge control unit 23 may switch the intensity of the pulsed light in three or more stages based on the degree of rain, fog, or snow indicated by the weather information. The method of switching the strength to three or more steps is as described, for example, in the second example of the fourth embodiment. The discharge control unit 23 may discharge one or more capacitive elements 22 so as to supply a larger amount of electric power to the light emitting element 10 as the degree of rain, fog, or snow is stronger.

FIG. 16 is a diagram showing a light source driving device 20 and a usage environment thereof according to a third processing example. In this processing example, the distance measuring device 1 includes a monitor light receiving unit 12 for monitoring the light emitting intensity of the light emitting element 10. The monitor light receiving unit 12 includes, for example, a photodiode and a detection circuit. The acquisition unit 24 of this processing example acquires the detection result of the monitor light receiving unit 12 that receives at least a part of the light emitted from the light emitting element 10. Then, the discharge control unit 23 determines _{the fourth timing t L} based on the detection result of the monitor light receiving unit 12. This will be described in detail below.

The emission intensity of the light emitting element 10 may fluctuate due to deterioration of the element or other factors even if the input power is the same. Therefore, the light emitting intensity of the light emitting element 10 is monitored by the monitor light receiving unit 12, and the discharge control unit 23 determines the third timing t _S and the fourth timing t _L based on the monitored light emitting intensity, which is desired. The emission intensity of can be maintained.

In this processing example, the output light from the light emitting element 10 is branched by, for example, a half mirror or the like, and a part of the output light is incident on the detection surface of the monitor light receiving unit 12. The monitor light receiving unit 12 generates information indicating the intensity of the incident light, and the discharge control unit 23 acquires it. The light branching of the light emitting element 10 and the detection of the monitor light receiving unit 12 may be performed constantly during the normal scanning of the distance measuring device 1, or may be performed at predetermined time intervals. ..

_{For example, the discharge control unit 23 provides a fourth timing t L} when the intensity of the light received by the monitor light receiving unit 12 becomes lower than a predetermined reference. Reference discharge controller 23 specifically includes a subsequent emission timing when the detection result of the monitor light receiving portion 12 is larger than a predetermined reference as a third timing t _S, the detection result is predetermined If it is smaller than that, the subsequent emission timing is defined as the fourth timing t _L. The reference for the detection result is stored in the storage device 108 or the like in advance, and the discharge control unit 23 can read and use the reference.

In this processing example, the acquisition unit 24 may acquire the light detection result from the light receiving unit 50 instead of the monitor light receiving unit 12. Then, when the light received by the distance measuring device 1 is weak and it is difficult to measure the distance, the fourth timing t _L is provided, and a sufficient amount of light received can be secured. In that case, the distance measuring device 1 does not have to be separately provided with the monitor light receiving unit 12.

As described above, also in this embodiment, the light source driving device 20 includes a plurality of capacitive elements 22, and the discharge control unit 23 individually controls the timing at which the plurality of capacitive elements 22 are discharged. Therefore, the degree of freedom in controlling the pulse output from the light source can be increased.

Although the embodiments and examples have been described above with reference to the drawings, these are examples of the present invention, and various configurations other than the above can be adopted.
Hereinafter, an example of the reference form will be added.
1. 1. Multiple capacitive elements that are parallel to each other and each supply power to the light emitting element during discharge.
A power source for charging the plurality of capacitive elements and
A light source drive device including a discharge control unit that individually controls the timing at which the plurality of capacitive elements are discharged.
2. 2. 1. 1. In the light source driving device described in 1.
The discharge control unit discharges the first capacitance element at the first timing, and the second capacitance element different from the first capacitance element at the second timing different from the first timing. Light source drive device that discharges.
3. 3. 2. 2. In the light source driving device described in 1.
The interval between the first timing and the second timing is the time required from the start of charging the first capacitive element to the completion of charging, and the charging is completed after the second capacitive element is started to be charged. A light source drive that is shorter than at least one of the time it takes to do so.
4. 1. 1. From 3. In the light source driving device according to any one of
The discharge control unit discharges at least one of the plurality of capacitive elements at each of the third timing and the fourth timing different from the third timing.
A light source driving device that supplies electric power larger than that of the third timing to the light emitting element at the fourth timing.
5. 4. In the light source driving device described in 1.
The plurality of capacitive elements include the third capacitive element and the fourth capacitive element having a capacitance larger than the capacitance of the third capacitive element.
The discharge control unit is a light source driving device that discharges the third capacitive element at the third timing and discharges the fourth capacitive element at the fourth timing.
6. 4. In the light source driving device described in 1.
The plurality of capacitive elements include the third capacitive element and the fourth capacitive element that is charged with a voltage larger than the voltage for charging the third capacitive element.
The discharge control unit is a light source driving device that discharges the third capacitive element at the third timing and discharges the fourth capacitive element at the fourth timing.
7. 4. In the light source driving device described in 1.
The discharge control unit is a light source driving device that discharges more of the capacitive elements at the fourth timing than at the third timing.
8. 4. From 7. In the light source driving device according to any one of
The light emitting element and the light source driving device are attached to a moving body, and the light emitting element and the light source driving device are attached to the moving body.
Further equipped with an acquisition unit for acquiring map information around the moving body,
The discharge control unit is a light source driving device that determines the fourth timing based on the map information.
9. 4. From 7. In the light source driving device according to any one of
It also has an acquisition unit that acquires weather information that indicates the weather.
The discharge control unit is a light source driving device that determines the fourth timing based on the weather information.
10. 4. From 7. In the light source driving device according to any one of
Further, an acquisition unit for acquiring the detection result of the light receiving unit that receives at least a part of the light emitted from the light emitting element is provided.
The discharge control unit is a light source driving device that determines the fourth timing based on the detection result.
11. 10. In the light source driving device described in 1.
The discharge control unit is a light source driving device that provides the fourth timing when the intensity of the light received by the light receiving unit becomes lower than a predetermined reference.
12. 1. 1. From 11. The light source driving device according to any one of the above,
With the light emitting element
It is provided with a processing unit that calculates the distance to the reflecting object that reflected the light in the emission direction of the light by using the time from the emission of the light to the reception of the reflected light of the light. Distance measuring device.

1 Distance measuring device 10 Light emitting element 12 Monitor light receiving unit 20 Light source driving device 21 Power supply 22 Capacitive element 23 Discharge control unit 24 Acquisition unit 30 Movable reflection unit 50 Light receiving unit 70 Control unit 80 Processing unit 90 Mobile unit 92 Landmark 100 Integrated circuit 102 Bus 104 Processor 106 Memory 108 Storage device 110 I / O interface 112 Network interface 201 Charging path 202 Discharging path 202

Claims (13)

Multiple capacitive elements that are parallel to each other and each supply power to the light emitting element during discharge.
A power source for charging the plurality of capacitive elements and
A discharge control unit that individually controls the discharge timing of the plurality of capacitive elements is provided.
While charging at least one of the plurality of capacitive elements, the other at least one capacitive element is discharged .
Discharged by the light source driving device Ru is pulse emission of the light emitting element of the capacitive element. In the light source driving device according to claim 1,
The discharge control unit discharges the first capacitance element at the first timing, and the second capacitance element different from the first capacitance element at the second timing different from the first timing. Light source drive device that discharges. In the light source driving device according to claim 2,
The interval between the first timing and the second timing is the time required from the start of charging the first capacitive element to the completion of charging, and the charging is completed after the second capacitive element is started to be charged. A light source drive that is shorter than at least one of the time it takes to do so. The light source driving device according to any one of claims 1 to 3.
The discharge control unit discharges at least one of the plurality of capacitive elements at each of the third timing and the fourth timing different from the third timing.
A light source driving device that supplies electric power larger than that of the third timing to the light emitting element at the fourth timing. In the light source driving device according to claim 4,
The plurality of capacitive elements include the third capacitive element and the fourth capacitive element having a capacitance larger than the capacitance of the third capacitive element.
The discharge control unit is a light source driving device that discharges the third capacitive element at the third timing and discharges the fourth capacitive element at the fourth timing. In the light source driving device according to claim 4,
The plurality of capacitive elements include the third capacitive element and the fourth capacitive element that is charged with a voltage larger than the voltage for charging the third capacitive element.
The discharge control unit is a light source driving device that discharges the third capacitive element at the third timing and discharges the fourth capacitive element at the fourth timing. In the light source driving device according to claim 4,
The discharge control unit is a light source driving device that discharges more of the capacitive elements at the fourth timing than at the third timing. In the light source driving device according to any one of claims 4 to 7.
The light emitting element and the light source driving device are attached to a moving body, and the light emitting element and the light source driving device are attached to the moving body.
Further equipped with an acquisition unit for acquiring map information around the moving body,
The discharge control unit is a light source driving device that determines the fourth timing based on the map information. In the light source driving device according to any one of claims 4 to 7.
It also has an acquisition unit that acquires weather information that indicates the weather.
The discharge control unit is a light source driving device that determines the fourth timing based on the weather information. In the light source driving device according to any one of claims 4 to 7.
Further, an acquisition unit for acquiring the detection result of the light receiving unit that receives at least a part of the light emitted from the light emitting element is provided.
The discharge control unit is a light source driving device that determines the fourth timing based on the detection result. In the light source driving device according to claim 10,
The discharge control unit is a light source driving device that provides the fourth timing when the intensity of the light received by the light receiving unit becomes lower than a predetermined reference. In the light source driving device according to any one of claims 1 to 11.
The light emitting element is a light source driving device that is a laser diode. A light source driving device according to any one of claims 1 1 2,
With the light emitting element
It is provided with a processing unit that calculates the distance to the reflecting object that reflected the light in the emission direction of the light by using the time from the emission of the light to the reception of the reflected light of the light. Distance measuring device.

Images