JPH08170987A - Distance measuring apparatus and controlling method for the same apparatus - Google Patents

Abstract

PURPOSE: To transmit a desired light quantity despite characteristic change, etc., due to dirt or aging change by comparing the light quantity set by distance measuring means with the light quantity detected by light transmitting state detecting means, and controlling so that the detected quantity substantially coincides with the set quantity by control means. CONSTITUTION: A light quantity to be transmitted by light transmitting means 2 is set based on information such as a vehicle speed, weather, illuminance, etc., and its set value is supplied to light quantity control means 3. The means 3 duty-controls the closing period of a switch 201 with respect to the period of a clock pulse generated by distance measuring means 5. The means 3 regulates the switching period of the contact of the switch 201 in response to the set value. A power source 1 for transmitting a light is closed by closing the switch 201, charge is stored in a capacitor 203, and the means 5 generates a light transmission signal. A reflected light reflected on the object is received by photoreceiving means 4, input to the means 5, which measures the distance to the object according to a propagation delay time, and compares the set quantity with the detected quantity by light transmission state detecting means to be controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device for measuring a distance to an object on the basis of a propagation delay time until the transmitted light is reflected by the object and returns.

[0002]

2. Description of the Related Art Conventionally, a distance measuring device of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 49-16463. In this publication, the amount of laser light sent (irradiated) from a distance measuring device is varied according to vehicle speed, weather, and illuminance (day or night), so that the distance to the human eye is safe and reliable. It is described that a distance measuring device capable of performing measurement can be obtained.

[0003]

However, even if the light quantity of the light to be transmitted is intended to be changed, it is unclear whether the light quantity actually changes in the publication.

Further, even if the amount of light is intended to be reduced, if the actual amount of light is large, there is a possibility that the human body may be adversely affected.

Further, when the portion for transmitting light is contaminated or the characteristics of the constituent parts are changed due to aging, it has been impossible to accurately transmit the required amount of light.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to obtain a distance measuring device capable of detecting the amount of light being transmitted.

Another object of the present invention is to obtain a distance measuring device which is capable of detecting the amount of transmitted light and has a simple structure and is inexpensive.

Another object of the present invention is to provide a distance measuring device capable of accurately detecting the amount of transmitted light.

Another object of the present invention is to provide a distance measuring device capable of determining a failure when the amount of transmitted light is different from the desired amount of light.

Another object of the present invention is to provide a distance measuring device which can stop the light transmission when the device breaks down for safety.

Another object of the present invention is to provide a distance measuring device capable of transmitting a desired amount of light irrespective of contamination or characteristic changes due to aging.

Another object of the present invention is to obtain a control method of a distance measuring device which can send a desired light amount regardless of a stain or a characteristic change due to aging.

[0013]

A distance measuring device according to the present invention comprises a light-sending state detecting means for detecting the amount of light sent from the light-sending means.

Further, in the distance measuring device according to the present invention, the light-sending state detecting means is a current detecting means which is disposed in the current flow path of the light emitting means and detects a current flowing through the light emitting means. is there.

Further, in the distance measuring apparatus according to the present invention, the light transmission state detecting means is the accumulated charge detecting means for detecting the charge accumulated in the accumulating means.

Further, the distance measuring device according to the present invention comprises a failure determination means for comparing the light amount detected by the light transmission state detection means with a predetermined value and determining a failure based on the comparison result. Be prepared.

Further, the distance measuring device according to the present invention is provided with stop means for stopping the light transmission of the light transmitting means when the failure determining means determines that there is a failure.

Further, the distance measuring device according to the present invention compares the amount of light set by the distance measuring means with the amount of light detected by the sending state detecting means, and the detected amount of light is approximately the set amount of light. It is provided with a control means for controlling to match.

Further, in the control method of the distance measuring device according to the present invention, the step of setting the light quantity of the light to be sent, the step of sending the light of the set light quantity, and the light quantity to be sent are detected. And a step of comparing the set light quantity with the sent light quantity and controlling so that the sent light quantity is substantially equal to the set light quantity.

[0020]

The distance measuring device of the present invention detects the amount of light transmitted from the light transmitting means by the light transmitting state detecting means.

Further, in the distance measuring device of the present invention, the light transmitting state is detected by the current detecting means arranged in the current flowing path of the light emitting means and detecting the current flowing through the light emitting means.

Further, the distance measuring device of the present invention detects the light transmission state by the accumulated charge detecting means for detecting the charge accumulated in the accumulating means.

Further, the distance measuring device of the present invention determines a failure by comparing the light amount detected by the light transmitting state detecting means with a predetermined value.

Further, in the distance measuring device of the present invention, when the failure determination means determines that there is a failure, the stop means stops the light transmission of the light transmission means.

In the distance measuring device of the present invention, the amount of light set by the distance measuring means is compared with the amount of light detected by the light transmission state detecting means, and the detected amount of light substantially matches the set amount of light. It is controlled by the control means.

Further, according to the control method of the distance measuring apparatus of the present invention, the light amount of the light to be transmitted is set, the light of the set light amount is transmitted, the light amount of the transmitted light is detected, and the set light amount is set. And the amount of light to be transmitted are compared so that the amount of light to be transmitted substantially matches the set amount of light.

[0027]

【Example】

Example 1. FIG. 1 shows the configuration of the first embodiment. In the figure,
Reference numeral 1 is a light-sending power source that supplies power for generating light to a light-sending means to be described later. Reference numeral 3 denotes a light quantity control means for controlling the light quantity of the light sent from the light sending means 2, and 4 denotes light reflected by the light sent from the light sending means 2 reflected by an object to generate a light receiving signal. The light receiving means 5 sets a desired value for the amount of light sent by the light sending means 2 based on information such as vehicle speed, weather, illuminance (day or night), and sends a light sending signal to the light sending means 2 at a predetermined timing. The distance measuring means 5 is a distance measuring means for supplying, and the distance measuring means 5 measures the time from the output of the light transmitting signal to the generation of the light receiving signal, and this time is the propagation delay required for the light to reciprocate to the object The distance to the object is measured based on this propagation delay time as time. It should be noted that the distance measuring means 5 is provided with information from a light transmitting state detecting means which will be described later.

Next, the internal circuit configuration of the light transmitting means 2 will be described. a is a terminal for receiving power from the light-transmitting power source 1, 2
Reference numeral 01 denotes a switch as an opening / closing means in which one end of the contact is connected to the terminal a and a control terminal for controlling the opening / closing of the contact is connected to the terminal b, which is for transmitting light based on the opening / closing signal input from the terminal b. The power supply from the power supply 1 is interrupted. Two
02 is a resistor whose one end is connected to the other end of the contact of the switch 201 and which suppresses the current flowing from the switch 201;
Is a capacitor, one end of which is connected to the other end of the resistor 202 and serves as a storage means for accumulating electric charge by a current flowing through the resistor 202, and 204 is an anode of which is connected to the other end of the resistor 202 and one end of the capacitor 203. A laser diode as a light emitting means for generating light when the accumulated charges flow in, 205 is a thyristor whose anode is connected to the cathode of the laser diode 204 and whose gate is connected to the terminal c. This thyristor 205 is a capacitor. The electric charge accumulated in the capacitor 203 is discharged by being electrically connected based on the light transmission signal from the distance measuring means 5 which is arranged in the discharge path of 203 and supplied through the terminal c. Reference numeral 206 denotes a resistor which is arranged between the above-mentioned discharge circuit and the terminal e and detects a consumption current of the discharge circuit, that is, a current amount converted into light energy by the laser diode. One end of the resistance is the cathode of the thyristor 205 and the capacitor 2
The other end of 03 is connected to the terminal d, and the other end is connected to the terminal e. The terminal e is connected to the ground. It should be noted that the light-sending state detecting means for detecting the amount of light sent here is constituted by a resistor 206 which is a current detecting means.

The operation of the first embodiment will be described with reference to the drawings. FIG. 2 is a time chart showing the operation of FIG. In FIG. 2, (a) is a clock pulse generated in a fixed cycle by a clock inside the distance measuring means 5, (b) is an opening / closing signal generated from the light amount control means 3, and (c) is the distance measuring means 5.
(D) shows the voltage across the capacitor 203, and (e) shows the amount of light emitted from the laser diode 204.

The distance measuring means 5 has a pulse having a fixed cycle as shown in FIG.
z clock pulses are being generated. This clock pulse is supplied to the light quantity control means 3. Further, the distance measuring unit 5 sets the light amount of the light to be transmitted by the light transmitting unit 2 based on the information such as vehicle speed, weather, illuminance and the like obtained by sensors not shown, and supplies the set value to the light amount control unit 3. To do. The light amount control means 3 performs duty control for controlling the closed period of the switch 201 with respect to the cycle of the clock pulse generated by the distance measuring means 5. The light amount control means 3 shortens the closing period of the contact of the switch 201 when the setting value is small according to the setting value, and lengthens the closing period of the contact of the switch 201 when the setting value is large. In the figure, the case where the set value is small before the time t is shown, and the case where the set value is large after the time t is shown. A signal such as (b) generated by the light quantity control means 3 is used as a switching signal in the switch 20.
1 is supplied to the control terminal.

When the open / close signal shown in (b) becomes the "H" level, the contact of the switch 201 is closed and the power from the light-transmitting power source 1 is supplied to the capacitor 203 via the switch 201 and the resistor 202. 203 starts accumulating charges as shown in FIG. As shown in the figure, the accumulation of the charges starts earlier as the set value becomes larger, and continues until the next clock pulse is generated. When the next clock pulse is generated, the distance measuring means 5 generates a light transmission signal as shown in (c) in synchronization with this. This light-transmitting signal causes the thyristor 205 to conduct, which causes the capacitor 20 to
The electric charge accumulated in 3 is discharged through the path at the other end of the laser diode 204, the thyristor 205, and the capacitor 203. The laser diode 204 generates light according to the magnitude of the discharge current at this time. Therefore, the larger the set value is, the earlier the timing of starting the charge accumulation is, and the amount of charge accumulated in the capacitor 203 increases, and accordingly, the light generated in the laser diode 204 is generated as shown in FIG.
As shown in (e), the larger the amount of charge accumulated in the capacitor 203, the larger the amount of light. The light amount control means 3 opens the contact of the switch 201 in synchronization with the clock pulse to prepare for the next control.

Now, the consumption current that has been emitted as light energy when the laser diode 204 emits light flows through the resistor 206. Here, as the current consumption increases, the amount of light generated by the laser diode 204 increases and the voltage generated at the terminal d also increases. Therefore, by detecting the voltage of the terminal d when the laser diode 204 emits light, it is possible to detect the light amount of the light sent from the light sending means 2. The voltage generated at the terminal d is
It is taken into the distance measuring means 5 and used for various controls.

Between the terminal d and the distance measuring means 5, peak holding means for holding the highest voltage generated at the terminal d may be provided. In this case, the peak hold means may be initialized after the distance measuring means 5 reads the voltage held by the peak hold means.

A filter means for filtering the voltage generated at the terminal d may be provided between the terminal d and the distance measuring means 5. The filter means may be, for example, an averaging process or an integration process.

Although the resistor 206 is used as the current detecting means, for example, a current transformer or a Hall element may be used. Also, instead of directly detecting the current,
You may make it detect indirectly. Various types of current detecting means are known, and any means may be used.

Further, in the above embodiment, the light quantity of light is indirectly detected by detecting the current flowing through the laser diode 204. However, a well-known photoelectric conversion element such as a photocoupler or a photocell is used. Alternatively, the amount of light may be directly detected.

As described above, according to the first embodiment, when the light quantity of the light sent from the light sending means is changed, it can be confirmed whether or not the light quantity is actually changed.

Further, since the current detecting means is composed of one resistor, the structure is simple and inexpensive.

Embodiment 2 FIG. In Example 1, the amount of light was obtained by detecting the current consumed by the laser diode 204 by the current detecting means. However, since the current consumed by the laser diode 204 is weak, it is difficult to accurately detect the light amount. The second embodiment provides a distance measuring device capable of accurately detecting the amount of light sent from the light sending means.

FIG. 3 shows the configuration of the second embodiment. In the figure, the same reference numerals as those used above indicate the same or corresponding portions as those used above. In the figure, 10 is a light transmitting means, which includes a switch 1001, a resistor 1002, a capacitor 1003, a laser diode 1004, and a thyristor 1.
Reference numeral 005 corresponds to the switch 201, the resistor 202, the capacitor 203, the laser diode 204, and the thyristor 205, respectively. f is a resistor 1002 and a capacitor 1
003 and a terminal connected to the anode of the laser diode 1004 and outputting a voltage generated at the connection point, 11
Is an integrating means for integrating the voltage generated at the terminal f,
The output of the integrating means 11 is input to the distance measuring means 5. Here, the light transmission state detecting means is an accumulated charge detecting means for detecting the electric charge accumulated in the capacitor 1003 which is the accumulating means, and the integrating means 11 corresponds to this.

Since the basic operation of the apparatus shown in FIG. 3 is the same as that of the above-described first embodiment, it is omitted here, and the integrating means 11 is particularly used.
The operation of will be described. FIG. 4 shows the operation of the integrating means 11 in a time chart. In FIG. 4, (a) is a voltage generated at the terminal f and is equivalent to that shown in (d) of FIG. FIG. 4B shows the output voltage of the integrating means 11,
Almost DC voltage is output. This DC voltage has a smaller value as the accumulated charge of the capacitor 1003 is smaller, and has a larger value as the accumulated charge is larger. Therefore,
If the output voltage of the integrating means 11 is detected, the light amount of the light sent from the light sending means 10 can be detected.

As described above, in the second embodiment, the capacitor 1
Since the charge accumulated in 003 is detected by the integrating means, the detected value is not a weak value like the current value detected in the first embodiment, but a larger value. Therefore, the light amount can be detected more accurately.

Further, since the current detecting means of the first embodiment uses a resistor, if the ambient temperature changes, the resistance value changes and an error occurs in the detected value of light quantity. On the other hand, according to the second embodiment, since it does not have temperature characteristics such as resistance, the light amount can be accurately detected regardless of the ambient temperature.

Example 3. In the above-mentioned embodiment, the light amount of the light transmitted by the light transmitting means can be detected. In the third embodiment, a failure of the distance measuring device is detected by using the detected light amount.

FIG. 5 is a block diagram showing the third embodiment, and FIG. 6 is a flow chart showing the operation thereof. In the figure, the same reference numerals as those used above indicate the same or corresponding parts. In FIG. 5, reference numeral 12 is a light transmission state detecting means,
This corresponds to the resistor 206 or the integrating means 11 described above. Reference numeral 13 is a failure determination means, which inputs the set value PI of the light quantity output from the distance measuring means 5 and the actual light quantity PO detected by the light transmission state detection means 12, and determines the failure based on this. The determination result is supplied to the distance measuring means 5.

Next, the operation of the third embodiment will be described based on the flowchart of FIG. As described above, the distance measuring unit 5 sets the light amount of the light to be transmitted based on the information from the sensors (not shown), and outputs the set value PI to the light amount control unit 3. In step S61, this set value PI is fetched and the value is read. The light quantity control means 3 drives the light sending means 2 based on the set value PI to send light of a desired light quantity.
The light transmission state detection means 12 detects the light amount PO of the transmitted light. In step S62, the detected light amount P
Take in O and read its value. Step S63 is
A step of determining whether or not a failure has occurred,
It is determined whether or not the detected light amount PO is within a predetermined range. The predetermined range is centered on the set value PI and has a predetermined failure detection width ± ΔP.

For example, in the distance measuring device of the present invention, the light amount of the light transmitting means is 4 W of 10 W, 20 W, 30 W and 40 W.
Types are available. Now, if the distance measuring means 5 is used, it is 30
When the light amount of W is set, if the light amount PO detected by the light-sending state detecting means 12 is not within the range of 25W <PO <35W, it is determined that there is a failure and the process proceeds to step S64 to generate a failure signal. Then, the fact that there is a failure is transmitted to the distance measuring means 5. When the detected light amount PO is within the above range, it is determined to be normal, no processing is performed, the process returns to step S61, and the following processing is repeated. Although the failure determination width ΔP is set to 5 W in the above description, it is not limited to this and may be set freely.

Therefore, according to the third embodiment, it is possible to determine that a failure occurs when the amount of transmitted light is different from the desired amount of light.

Example 4. According to the third embodiment, a failure of the distance measuring device can be detected, but in the fourth embodiment, the light transmission of the light transmitting means 2 is stopped based on this failure signal to ensure safety.

FIG. 7 is a configuration diagram showing the configuration of the fourth embodiment, and FIG. 8 is a flow chart showing the operation of the fourth embodiment. In the figure, the same reference numerals as those used above indicate the same or corresponding parts. In FIG. 7, a switch 14, which is an opening / closing unit, is arranged in the power supply path between the light transmitting power source 1 and the light transmitting unit 2. The contacts of the switch 14 are connected to the power supply path, one end of which is connected to the light-sending power source 1 and the other end of which is connected to the light-sending means 2. A control terminal for controlling the opening / closing operation of this contact is connected to the failure determination means 13. The switch 14 constitutes stop means for stopping the light transmission.

The operation of the fourth embodiment will be described with reference to FIG. Steps S81 to S84 correspond to steps S61 to S64 described above, respectively. Now, if it is determined to be a failure in step S83, the process proceeds to step S84 to notify the distance measuring means 5 of the failure. The distance measuring unit 5 sets the light amount set value P so as to stop the light transmission of the light transmitting unit 2 when a failure signal is input.
Set I to 0. In step S85, the failure determination means 13 gives an opening signal for opening the contact to the control terminal of the switch 14, and the switch 14 receives the opening signal and opens the contact to cut off the power supply to the light transmitting means 2. Although not shown, the distance measuring device of the present invention has a control power supply in addition to the light transmission power supply 1, and this control power supply is used even when the light transmission power supply 1 is cut off. Continue to supply the power required for control. Here, it is natural that the control power supply supplies electric power to means other than the light transmitting means 2 and does not supply electric power to the light transmitting means 2. If it is determined to be normal in step S83, the process returns to step S81 to repeat the sequential processing. When no failure is determined, the control terminal of the switch 14 is supplied with a closing signal from the failure determination means 13 to close the contact.

Although the switch is used in the above embodiment, a switching element such as a relay or a semiconductor element such as a transistor may be used.

Further, the distance measuring means sets the light quantity setting value to 0 when it receives a failure signal, but the light quantity control itself may be prohibited to stop the light transmission from the light transmitting means 2.

As described above, according to the fourth embodiment, the light transmission is stopped when the device is determined to be in failure, so that an unexpectedly large amount of light is transmitted and adversely affects the human eye. There is no fear.

Further, since the power supply to the light transmitting means is cut off when the light transmission is stopped, the light transmission can be surely stopped.

Example 5. The fifth embodiment performs feedback control (negative feedback control) based on the set value PI of the transmitted light amount and the detected light amount PO. FIG. 9 is a configuration diagram showing the configuration of the fifth embodiment, and FIG. 10 is a flow chart showing the operation of the fifth embodiment. In the figure, the same reference numerals as those used above indicate the same or corresponding parts. Figure 9
In the figure, reference numeral 15 is a light quantity control means as a control means having a feedback control function, and the light quantity set value PI set by the distance measuring means 5 and the light quantity PO detected by the light sending state detection means 12 are inputted. The duty signal D is supplied to the light transmitting means 2 so that the detected light amount PO matches the set value PI.

Next, the operation of the fifth embodiment will be described with reference to the drawings. In FIG. 10, steps S1001 and S100
2 is step S61, 62 or step S8 described above.
It corresponds to 1, 82. Step S1001,
At 1002, the set value PI of the light amount and the detected light amount PO are read. In step S1003, the duty signal D is calculated such that the detected light amount PO matches the set value PI. This calculation is performed based on the deviation between the set value PI and the light amount PO, and is specifically performed by a calculation method generally called PDI control (proportional differential integration control).

That is, when the characteristics of the distance measuring device change due to aging and the like, and a light amount larger than the set value PI is transmitted, the duty ratio of the duty signal D is reduced and light is transmitted. The amount of light is reduced to match the amount of light PO to be transmitted with a desired set value PI. On the contrary, when a light amount smaller than the set value PI is transmitted,
For example, when the characteristic of the distance measuring device changes due to contamination of the light transmitting means 2 or aging, the duty signal D
The duty ratio is increased to increase the amount of light to be transmitted, and the amount of light PO to be transmitted matches the desired set value PI.

Therefore, according to the fifth embodiment, it is possible to always send a desired amount of light even if the distance measuring device is contaminated or the characteristics change due to aging.

In addition, the fifth embodiment is combined with the third embodiment to perform feedback control so as to send a desired light amount, and when the light amount PO cannot be matched with the set value PI even by the feedback control, a failure occurs. May be determined. As a result, the frequency of failure determination is reduced, and a highly reliable distance measuring device can be obtained.

[0061]

As described above, according to the distance measuring device of the present invention, since the light-transmitting state detecting means for detecting the light amount of the light transmitted from the light-transmitting means is provided, light is transmitted. The amount of light can be detected.

According to the distance measuring device of the present invention,
Since the light-sending state detecting means is composed of the current detecting means arranged in the current-flowing path of the light-emitting means and detecting the current flowing through the light-emitting means, it is possible to detect the amount of light being sent. It is possible to obtain an inexpensive distance measuring device having a simple structure.

According to the distance measuring device of the present invention,
Since the light transmitting state detecting means is constituted by the accumulated charge detecting means for detecting the electric charge accumulated in the accumulating means, it is possible to accurately detect the amount of light being transmitted.

According to the distance measuring device of the present invention,
Since the light quantity detected by the light-transmitting state detecting means is compared with a predetermined value and the failure judging means for judging a failure based on the comparison result is provided, the quantity of light being sent is the desired light quantity. Can be determined to be a failure.

According to the distance measuring device of the present invention,
Since the stop means for stopping the light transmission of the light transmitting means when the failure determination means determines that the light source has failed is provided, it is possible to stop the light transmission when the device fails, thereby achieving safety.

According to the distance measuring device of the present invention,
The light amount set by the distance measuring unit and the light amount detected by the light transmission state detecting unit are compared, and the control unit for controlling the detected light amount to substantially match the set light amount is provided. A desired amount of light can be transmitted regardless of changes in characteristics due to aging.

Further, according to the control method of the distance measuring device of the present invention, the step of setting the light quantity of the light to be sent, the step of sending the light of the set light quantity, and the light quantity to be sent are detected. And a step of comparing the set light amount with the sent light amount so that the sent light amount is substantially equal to the set light amount. It is possible to send a desired amount of light regardless of the above.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the invention.

FIG. 2 is a time chart showing the operation of the first embodiment of the invention.

FIG. 3 is a configuration diagram showing a second embodiment of the invention.

FIG. 4 is a time chart showing the operation of the integrating means.

FIG. 5 is a configuration diagram showing a third embodiment of the invention.

FIG. 6 is a flowchart showing the operation of the third embodiment of the invention.

FIG. 7 is a configuration diagram showing a fourth embodiment of the invention.

FIG. 8 is a flowchart showing the operation of the fourth embodiment of the invention.

FIG. 9 is a configuration diagram showing a fifth embodiment of the invention.

FIG. 10 is a flowchart showing the operation of the fifth embodiment of the invention.

[Explanation of symbols]

1: power supply for light transmission, 2: light transmission means, 3: light quantity control means,
4: light receiving means, 5: distance measuring means, 10: light transmitting means, 11:
Integrating means, 12: Light transmission state detecting means, 13: Failure determining means, 14: Switch, 15: Light quantity controlling means

Claims (7)

[Claims] 1. A light sending means for generating and sending light, a light quantity control means for controlling a light quantity of the light, a light receiving means for receiving reflected light of the light reflected by an object, and the light quantity control means. Distance setting means for setting a controlled light amount, measuring a propagation delay time from the sending of the light to receiving the reflected light, and measuring a distance to the object based on the propagation delay time; A distance measuring device comprising: a light sending state detecting means for detecting the amount of light sent from the means. 2. The light transmitting state detecting means is a current detecting means arranged in a current flowing path of the light emitting means of the light transmitting means and detecting a current flowing through the light emitting means. The distance measuring device according to claim 1. 3. The distance measuring device according to claim 1, wherein the light-sending state detecting means is an accumulated charge detecting means for detecting charges accumulated in the accumulating means of the light-sending means. 4. A failure determination means for comparing a light quantity detected by the light transmission state detection means with a predetermined value and determining a failure based on the comparison result. 1. The distance measuring device according to 1. 5. The distance measuring device according to claim 4, further comprising stop means for stopping the light transmission of the light transmitting means when the failure determination means determines that the failure has occurred. 6. A control means for comparing the light quantity set by the distance measuring means with the light quantity detected by the light-sending state detecting means, and controlling so that the detected light quantity substantially matches the set light quantity. The distance measuring device according to claim 6, further comprising: 7. A step of setting a light quantity of light to be sent, a step of sending a light of the set light quantity, a step of detecting the light quantity of the sent light, the set light quantity and the A method of controlling a distance measuring device, comprising the step of comparing the amount of light to be transmitted and controlling the amount of light to be transmitted so as to substantially match the set amount of light.