JP2002131051A - Distance detection device - Google Patents

Abstract

(57) [Summary] (With correction) [PROBLEMS] In a conventional distance detection circuit, a light emitting element emits pulse light having a constant output, and a distance between an object and a detector is determined by a light receiving level of a light receiving element. Therefore, the closer the object is, the larger the amount of received light is, and the farther the object is, the smaller the amount of received light is, which requires an amplifier with a wide dynamic range.
Therefore, it is necessary to reduce the influence of noise or prevent oscillation, and the circuit configuration is complicated. SOLUTION: This distance detecting device comprises a light emitting element 51 for emitting light and a light receiving element 52 for reflecting the emitted light 54a on an object and receiving the reflected light 54b, wherein the light emitting element 51 has a different light output. Is directed toward the object, and the light receiving element 52 receives the reflected light 54b from the object. When the amount of received light reaches a predetermined level, the relationship between the amount of light received by the light receiving element and the distance d of the object is set in advance using the light emitting element drive current as a parameter. Can be solved by measuring the distance of the object based on the measured value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance detecting device for detecting a distance from a detector to an object, and more particularly to a distance detecting device for optically detecting a distance using a light emitting element and a light receiving element.

[0002]

2. Description of the Related Art A conventional distance detecting apparatus will be described below with reference to FIGS. FIG. 5 is a diagram for explaining a positional relationship among a light emitting element, a light receiving element, and a target object, where 51 is a light emitting element, 52 is a light receiving element, and 53 is a target object. The detector 50 including the light emitting element 51 and the light receiving element 52
Is a distance d away from the target object 53.

The light-emitting element is driven by a drive circuit (not shown). The drive current is a pulse current having a constant peak value, and the current is supplied to the light-emitting element at a constant cycle. Is the target object 53
Are periodically emitted. The emitted light 54a reaches the object, is reflected there, becomes reflected light 54b, and enters the light receiving element. Although not shown, the output of the light receiving element is input to the detection circuit, amplified, the amount of received light is detected, and the distance d to the target object is detected based on the level.

FIG. 6 shows a waveform of a current supplied to a light emitting element. The horizontal axis is time and the vertical axis is supply current. The supply current is a pulse current having a peak value of Ip, and this pulse current is periodically supplied to the light emitting element. It is supplied first at time t1, then supplied at time t2, then supplied at time t3, and supplied at time t4. In the figure, four pulse currents are shown for simplicity.

FIG. 7 is a diagram showing how a distance from a detector including a light emitting element and a light receiving element to a target object is temporally large. The horizontal axis is time, which is the same as the time axis in FIG. The vertical axis indicates the distance d from the detector to the target object. In FIG. 7, the object is located at a distance d4 from the far distance d4.
FIG. 1 shows a state approaching over time. At time t1, the object is at a distance d4, at time t2 the object is at a distance d3, at t3 the object is at a distance d2, and at t4 the object is at a distance d1. Is shown.

FIG. 8 shows the amount of reflected light received by the light receiving element.
That is, the light receiving level is shown. The horizontal axis represents time, and the vertical axis represents the amount of received light. The horizontal axis is the same as the time axis in FIG. 6, as in FIG. At time t1, the object is at a distance d from the detector.
In this state, pulse light is emitted from the light emitting element, and the emitted light is reflected by the object and enters the light receiving element. The amount of received light at this time is at the r1 level as shown.

Next, at time t2, the target object is at a distance d3 from the detector, and in this state, pulse light is emitted from the light emitting element, and the emitted light is reflected by the object and enters the light receiving element. The amount of received light at this time is at the r2 level as shown. Similarly, at time t3, the distance between the target object and the detector is d2, the amount of light received by the light receiving element is r3 level,
In 4 hours, the distance between the target object and the detector is d1, and the amount of light received by the light receiving element is at the r4 level.

Attention is paid to the level of the amount of received light. The light emitting element is driven by a pulse current having a constant peak value, that is, a pulse light having a constant peak value is emitted, and the distance from the object to the detector is short. It can be seen that the value increases as the distance increases and decreases as the distance increases.

[0009]

However, in such a conventionally proposed distance detecting circuit, the light emitting element emits a pulse light having a constant output, and the distance between the object and the detector is determined by the amount of light received by the light receiving element. Have been. The closer the object is, the larger the amount of received light is, and the farther the object is, the smaller the amount of received light is. Therefore, the light receiving level has a wide range of values from a small value to a large value.

On the other hand, the detection circuit does not directly process the input level signal received by the light receiving element, but always amplifies and processes the signal. For this reason, the amplifier connected to the light receiving element needs to amplify a wide range of input levels from a small value to a large value. In other words, an amplifier having a wide dynamic range is required, which requires consideration for reducing the influence of noise and for preventing oscillation, and the circuit configuration is complicated.

Further, in the conventional moving object detecting device for detecting approach or speed of an object, the device is expensive because the distance detecting circuit is used. Further, since the distance detection circuit is used as a hand gesture input device for various devices, the device is expensive.

In order to solve the above problems, the present invention first proposes an inexpensive object distance detection circuit having a simple structure, a distance detection device using the circuit, and an object detection device using the detection circuit. It is an object of the present invention to provide a moving object detection device for detecting the approach or speed of a moving object, and a hand gesture input device using the detection circuit.

[0013]

The present invention is configured as follows to solve the above-mentioned conventional problems.

(1) A distance detecting device comprising a light-emitting element for emitting light and a light-receiving element for reflecting the emitted light from an object and receiving the reflected light, wherein the light-emitting element outputs different light outputs to the object. The light-receiving element receives the reflected light from the object, and when the amount of received light reaches a predetermined level, the relationship between the light-receiving element light-receiving amount and the distance to the object is measured in advance by using the light-emitting element drive current as a parameter. The distance of the object is measured based on.

(2) The distance detecting device according to item 1,
The distance data of the object is detected for a predetermined time, and the approach or speed of the object is detected based on the data.

(3) The distance detecting apparatus according to (1) or (2), wherein the object is a hand, the approach or speed of the hand is detected, and the detected information is used as input information of various devices.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. The positional relationship between the detector including the light emitting element and the light receiving element and the target object is the same as in FIG. 5, and the description will be made based on this positional relationship.

FIG. 1 shows the driving current supplied to the light emitting element over time. The horizontal axis is time and the vertical axis is drive current. The drive current supplied to the light emitting element is a pulse current, and the pulse currents are four types of currents having different peak values, and L1, L2, and L are arranged in ascending order of the peak value.
3, L4, and these four types of pulse currents are sequentially supplied to the light emitting element. Then, these four types of pulse currents correspond to the first time zone, the second time zone, the third time zone, and the fourth time zone.
It is supplied in each time zone.

First, the driving current supplied to the light emitting element in the first time period from the time t11 to the time t14 will be described. An L1 level pulse current is supplied to the light emitting element at time t11, an L2 level pulse current is supplied at time t12 after a certain time has elapsed, and an L3 level pulse current is supplied at time t13 after a certain time has elapsed. Then, at time t14 after a lapse of a certain time, a pulse current of the L4 level is supplied.

Then, the same four types of pulse currents are supplied in the second time period from the time t21 to the time t24 after a certain time has elapsed. That is, the pulse current of the L1 level is supplied at time t21, the pulse current of the L2 level is supplied at time t22 after a certain time has elapsed, and the pulse current at the L3 level is supplied at the time t23 after a certain time has elapsed. An L4 level pulse current is supplied at time t24 when the time has elapsed.

Similarly, in the third time zone and the fourth time zone, the L1 level current, the L2 level current, the L3 level current, and the L4 level current are sequentially supplied to the light emitting element.

As described above, four types of pulse currents having different levels are supplied to the light emitting element, and one pulse current is supplied once, and a total of four pulse currents are supplied at intervals. In the figure, it is four times, but for simplicity of explanation, it is four times,
In an actual detection circuit, it is repeated as necessary.

FIG. 2 is the same as FIG. 7, with the horizontal axis representing time and the vertical axis representing the distance to the target object. That is, it is a diagram that temporally shows how far the target object is from the detector. The time axis on the horizontal axis is the same as the horizontal axis in FIG. 1, that is, the time axis.

From the figure, in the first time zone (t11 to t14), the target object is at a distance d4, and in the second time zone (t21 to t14).
24), the target object is separated by a distance d3, and during the third time period (t31 to t34), the target object is separated by a distance d2.
The fourth time period (t41 to t44) indicates that the target object is at a distance d1.

In FIG. 3, the horizontal axis is the time axis, and the vertical axis is the amount of light received by the light receiving element. The horizontal axis is the same as the horizontal axis of FIG. 1, that is, the time axis. If the distance to the target object is constant, the magnitude of the amount of light received by the light receiving element increases as the amount of light emitted by the light emitting element increases. That is, the larger the driving current for driving the light emitting element, the larger the amount of light received by the light receiving element.

As shown in the figure, in the first time zone, the distance of the target object is constant at d4, so that the amount of received light changes in proportion to the drive current supplied to the light emitting element. From t11 to t14
In time, the amount of light received at time t12 is larger than the amount of light received at time t11, the amount of light received at time t13 is larger than the amount of light received at time t12, and the amount of light received at time t14 is larger than the amount of light received at time t13.

The detection circuit of the present invention focuses on whether or not the amount of received light has reached a predetermined level. That is, as shown in the drawing, attention is paid to whether or not the Rs level has been reached. Therefore, in the first time zone, only the amount of received light at the time t14 exceeds the Rs level which is the predetermined level.

Next, also in the second time zone t21 to t24, as the time from t21 to t24 elapses, the peak value of the drive current supplied to the light emitting element increases, and the amount of received light also increases accordingly. ing. In this time zone, the amount of received light exceeds the predetermined level at times t23 and t24. This means that the distance to the object is the first
Since it is closer to the time zone, it can be seen that the received light amount has reached the predetermined level even when the drive current is at a level lower than the level in the first time zone. That is, in the first time zone, the light receiving amount has not reached the predetermined level when the driving current is at the L3 level, but has reached the predetermined level in the second time zone.

Next, in the third time zone, the received light amount has reached a predetermined level when the drive current is in the range from the L2 level to the L4 level. Further, in the fourth time zone, the driving current is changed from L1 level to L level.
The received light amount has reached a predetermined level in the range of four levels.

Here, the predetermined level will be described. Prescribed level is a general amplifier (amplifier that is easily available)
When inputting and amplifying a signal to the amplifier, it is not affected by noise, it is not necessary to consider oscillation, and it means an input signal level at which a signal can be easily amplified. As a characteristic of the amplifier, when trying to amplify a small signal, a noise level becomes a problem, and a signal smaller than the noise level is buried in noise and cannot be amplified. In the case of a large input signal, the amplifier is saturated and cannot be amplified. Therefore, there is an optimum input signal level range for each amplifier. Input levels within this range,
A certain level is set as a predetermined level.

The present invention seeks to detect the distance to an object when the amount of light received by the light receiving element reaches a predetermined level. This detection method will be described with reference to FIG. In FIG. 4, the horizontal axis indicates the distance from the detector to the object, and the vertical axis indicates the amount of light received by the light receiving element. This figure shows the relationship between the distance of the object and the amount of received light when the driving current for driving the light emitting element is constant. The drive current corresponds to the drive level in FIG.
The relationship between the L1, L2, L3, and L4 levels is shown. For example, when the driving current is at the L1 level, the distance at which the light reception amount reaches the predetermined level is d1,
The light receiving level is low when the target object is farther than it, and increases when the target object is closer.

Similarly, when the drive current is at the L2 level, the distance at which the light reception amount reaches the predetermined level is d2, and when the drive current is at the L3 level, the distance at which the light reception amount reaches the predetermined level is d3. When the current is at the L4 level, the distance at which the amount of received light reaches the predetermined level is d4.

Therefore, the driving current of the light emitting element is changed, that is, the light emission amount is changed, and the driving current of the light emitting element when the light receiving amount of the light receiving element reaches a predetermined level is examined. Can be obtained from FIG. It is possible to increase the measurement accuracy by setting the drive current as a parameter to four levels or more.

In FIG. 4, the predetermined level of the amount of received light is set to the Rs level, which is an input level that can be amplified by a simple amplifier as described above.

The above-described distance detection circuit can be applied not only to the distance detection of an object but also to a wide range of applications. For example, when an object is moving, detection data is stored in chronological order, and it can be determined based on the stored data whether the object is approaching or moving away.

Further, the moving speed of the object can be detected by calculating how much the object has moved at a certain time using the distance data stored in time series.
Thus, the approach or speed of the moving object can be detected.

Various information obtained from a moving object is used in various fields. For example, there is a proposal to detect approach, speed, and the like of a hand using an object as a hand, and use the information as an input device of various devices.

For example, the present invention is applied to a volume switch of an audio device or the like. The volume switch is usually a dial type that changes the volume by turning the knob, UP switch and D
There is a push button switch type that changes the volume by pressing an OWN switch, and in each case, a mechanical switch is employed.

It is common to drive a car while listening to music. The driver must drive safely while judging the surrounding conditions.However, the surrounding conditions often change suddenly.In such a case, the volume must be reduced in a short time to determine the conditions. There must be.

In such an example, since the siren sound of the emergency vehicle is faintly heard, it is desired to reduce the volume for confirmation. Also, if you have difficulty listening in conversation with a passenger, you want to reduce the volume. Another problem is that the user may want to temporarily reduce the volume because a noise has entered the radio due to a tunnel or an obstacle, making it difficult to hear.

However, if the user tries to adjust the volume while driving, he or she must search for an operation switch with his / her gaze facing forward (in the direction of travel), which makes it difficult to operate. It is. Moving your gaze to the control panel distracts you from the front, which may result in an accident.

For this reason, there is a hand gesture input device as a method for adjusting the volume without the driver having to look at the operation panel. It detects hand movements and attempts to control the volume based on that information.

The proposed hand movement detection method uses a light-emitting element and a light-receiving element, emits light of a constant output from the light-emitting element, the emitted light reaches the hand, is reflected there, and the reflected light is reflected by the light-receiving element. The position of the hand is determined based on the level of the received light level. For example, it is determined that the hand is approaching when the received light level is increased from low to high, and conversely, the hand is moved away when the received light level is reduced from high to low. Judge. Then, these data are temporally stored, the distance between the detector and the hand, the speed at which the hand moves, and the like are determined based on the stored data, and the volume is adjusted based on the calculated data. The distance detection device of the present invention is also effective for such a hand gesture input device.

The operation principle of the present invention has been described above. However, in actual use, the reflectance changes depending on the state of the surface of the object, and the relationship between the level Rs and the distance (FIG. 4) changes. Sometimes. Or, outgoing light passing through the air, reflected light may be absorbed by the influence of rain or fog,
From this point too, accuracy may be lacking. In order to cope with such a case, it is conceivable to use a difference or a ratio of the amount of received light using a plurality of light emitting sources and receiving light sources.

[0045]

As described above, in the conventional distance detecting device, since the amount of light emitted from the light emitting element is fixed, when the light reflected from the object is received by the light receiving element, the light is received when the object is far away. The light amount is small, and conversely, the light reception amount increases when it is near.

Therefore, it was necessary to amplify a wide range of input levels from a small value to a large value at the input of the amplifier connected to the light receiving element. That is, an amplifier having a wide dynamic range is required, and therefore, it is necessary to reduce the influence of noise or prevent oscillation, and the circuit configuration is complicated.

According to the method of the present invention, the amount of light emitted from the light emitting element is changed while detecting the distance, and at the same time, the amount of light received by the light receiving element is detected. The relationship between the distance and the amount of received light is measured in advance using the amount of light emitted from the light emitting element as a parameter, and the distance is determined based on the measured value. Therefore, an inexpensive distance detection device can be provided with a simple circuit configuration. .

Further, in the conventional moving object detecting device for detecting the approach or speed of an object, the device is expensive because the conventional distance detecting circuit is used. Inexpensive moving object detection device can be provided.

Although a conventional distance detection circuit was used as a hand gesture input device for various devices, the device was expensive. However, by using the detection circuit of the present invention, an inexpensive hand gesture input device can be provided.

[Brief description of the drawings]

FIG. 1 shows a light-emitting element driving current waveform of the present invention.

FIG. 2 shows a time-series display of a distance from the detector of the present invention to an object.

FIG. 3 is a time-series display of the amount of light received by the light-receiving element of the present invention.

FIG. 4 shows a relationship between an object distance and a received light amount according to the present invention.

FIG. 5 is a positional relationship between a light emitting element, a light receiving element, and a target object.

FIG. 6 shows a conventional light emitting element driving current waveform.

FIG. 7 shows a time-series display of a distance from a conventional detector to an object.

FIG. 8 is a time-series display of the amount of light received by a conventional light receiving element.

[Explanation of symbols]

 Reference Signs List 50 detector 51 light emitting element 52 light receiving element 53 target object 54a light emitting element output light 54b reflected light from object d distance from detector to object t1 to t4 time L1 to L4 light emitting element drive current level r1 to r4 light receiving element light receiving level Rs Predetermined level of received light

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masayuki Makishima 2-9-13 Nakameguro, Meguro-ku, Tokyo F-term in Stanley Electric Co., Ltd. (reference) 2F065 AA02 AA06 FF12 FF44 FF64 GG00 GG01 JJ01 QQ28 2F112 AD03 BA01 CA12 EA03 EA07 FA19 FA41 5J050 AA49 BB17 CC00 CC09 DD01 DD03 5J084 AA05 AA07 AB07 AD03 CA03 CA07 CA23 EA06 FA03

Claims (3)

[Claims] 1. A distance detecting device comprising: a light emitting element that emits light; and a light receiving element that reflects the emitted light from an object and receives the reflected light, wherein the light emitting element outputs different light outputs to the object, The light receiving element receives the reflected light from the object, and when the amount of received light reaches a predetermined level, measures the relationship between the amount of light received by the light receiving element and the distance to the object in advance by using the light emitting element drive current as a parameter, and calculates the measured value. A distance detection device characterized by measuring the distance of an object based on the distance 2. The distance detecting apparatus according to claim 1, wherein distance data of the object is accumulated for a predetermined time, and the approach and / or speed of the object is detected based on the data. 3. The distance detecting device according to claim 1, wherein the object is a hand, the approach and / or speed of the hand is detected, and the detected information is used as input information of various devices.