JP2002214362A - Scanning photo sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily set the light beam irradiation range of a scanning photo sensor according to the size of a monitoring area. SOLUTION: A slit plate 30 having a slit width D depending upon the size of an assumed monitoring area is disposed in a designated position in front of a scanning mirror 12, and the irradiation range of the scan beam BM1 from the scanning mirror 12 is limited to the slit width D. An irradiation area limiting means is constructed to change the limited irradiation range, to be concrete, provided with a plurality of slit plates different in slit width, wherein the slit plate having a slit width corresponding to an assumed irradiation range of the monitoring area is selected, and the slit plate is capable of varying the slit width corresponding to the change of the light beam irradiation range of the monitoring area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical sensor for monitoring the presence or absence of an object in a monitoring area by scanning with a light beam, and more particularly, to easily set a scanning beam irradiation range from a light beam scanning means. And a scanning optical sensor.

[0002]

2. Description of the Related Art A scanning optical sensor of this type is disclosed in Japanese Patent Application No. 2000-1135 previously proposed by the present applicant. This device includes a pair of units including a light emitting unit, a light receiving unit, a reflector, and a scanning mirror.
A configuration in which two triangular areas are combined to monitor a quadrangular area by arranging the monitoring area of the object facing each other and scanning the light beam from each unit to another unit by a scanning mirror. is there. Then, if the light reflected from the reflector of the facing unit is received by the light receiving element across the monitoring area, it is determined that there is no object, and if it is not received, it is determined that there is an object.

In the practical use of such a scanning optical sensor, it is desired that the width and height of the monitoring area can be freely selected from at least a plurality of ways if possible. In that case, it is necessary to change the irradiation area of the scanning beam according to the width and height of the monitoring area. Conventionally, when changing the irradiation area of the scanning beam, the scanning angle of the scanning mirror is adjusted. For example, in the case of the above-described scanning optical sensor, a known electromagnetic galvano mirror is exemplified as a scanning mirror in, for example, Japanese Patent Application Laid-Open No. 8-220453. In this case, since the galvanomirror has a proportional relationship between the drive current value and the mirror scan angle, a desired mirror scan angle is obtained by adjusting the drive current value of the galvanomirror.

[0004]

However, in the method of adjusting the drive current value, the drive current value of the scanning mirror must be manually reset each time the width or height of the monitoring area is changed. If the variation in the driving current value-scanning angle characteristic for each scanning mirror cannot be ignored due to the manufacturing variation of the scanning mirror, etc., it is necessary to adjust the driving current value while confirming the actual scanning angle. As described above, the conventional method of adjusting the drive current value has a problem in that it takes time and effort to adjust the mirror scanning angle in accordance with the change of the width and height of the monitoring area, and this leads to an increase in cost.

The optical radar sensor type described in Japanese Patent Application Laid-Open No. H11-144161 and International Publication WO97 / 331
The transmission type scanning optical sensor described in 86 has the same problem. The present invention has been made in view of the above problems, and has as its object to provide a scanning optical sensor capable of easily setting a scanning beam irradiation range in accordance with a monitoring area.

[0006]

According to the present invention, a light beam scanning means for reflecting a light beam from a light beam generating means so as to scan a space, and receiving a light beam from the space. A light beam from the light beam scanning means, wherein the light beam from the light beam scanning means is monitored by the object. An irradiation range limiting means for irradiating only an area is provided.

In such a configuration, the irradiation range of the scanning beam generated from the light beam scanning means is limited so that the irradiation range limiting means irradiates only the monitoring area. In the invention of claim 2, the light beam scanning means is configured such that a light beam scanable range is larger than the monitoring area. In such a configuration,
The light beam limited by the irradiation range limiting means surely scans the entire monitoring area.

According to the third aspect of the present invention, the irradiation range limiting means can change the irradiation range to be limited. Specifically, a configuration may be adopted in which a plurality of slit plates having different slit widths are provided, and a slit plate having a slit width corresponding to an assumed irradiation range of the monitoring area is selected. As described above, a configuration in which a slit plate that can change the slit width according to the change of the light beam irradiation range of the monitoring area may be provided.

Since the slit width can be calculated geometrically according to the irradiation range of the monitoring area, the slit width corresponding to the irradiation area of each monitoring area assumed in advance is configured as in claim 4. By preparing a plurality of slit plates having the above, it is possible to change the setting of the light beam irradiation range suitable for the monitoring area only by replacing the slit plates. In the invention of claim 6, the irradiation range limiting means is configured to automatically adjust the irradiation range to be limited based on a signal indicating a monitoring area.

More specifically, a slit plate capable of changing a slit width for limiting an irradiation range of the light beam from the light beam scanning means, and the light beam based on a signal indicating the monitoring area are provided. Slit width control means for automatically controlling the slit width of the slit plate so that the light beam from the beam scanning means is not irradiated outside the boundary of the monitoring area. Further, based on the signal indicating the monitoring area, a light beam is generated from the light beam generating means based on the signal indicating the monitoring area only while the light beam scanning means is scanning the monitoring area. It may be configured to include light beam generation control means for controlling the operation of the means. According to a ninth aspect of the present invention, the apparatus further includes a light beam scanning control unit that controls an operation of the light beam scanning unit such that the light beam scanning unit scans only the monitoring region based on a signal indicating the monitoring region. Is also good.

[0011] In the configuration of the sixth to ninth aspects, since the irradiation range of the light beam is limited while checking the monitoring area, it is possible to cope with the fluctuation of the monitoring area. Claim 9
In the configuration, as in claim 10, the swing amplitude angle of the scanning mirror of the light beam scanning unit that scans a light beam by swinging a scanning mirror is symmetrical with respect to the swing center. It is preferable that a swing center position adjusting means for variably adjusting the swing center position is provided.

The signal indicating the monitoring area is generated based on a light beam irradiated near the boundary of the monitoring area. Specifically, claim 1
As in 2, the light receiving element is arranged on the direction of the light beam irradiated near the boundary of the monitoring area, and the light receiving element is generated based on the light receiving output of the light receiving element. Further, as in claim 13, a light reflecting means for generating a unique reflected light is arranged on the direction of the light beam irradiated near the boundary of the monitoring area,
It may be configured to generate the light based on the detection output of the specific reflection light generated from the light reflection unit.

In the configuration using a slit plate as in claims 4, 5 and 7, if the slit plate is configured to block or attenuate a scanning beam outside the monitoring area, as in claim 14, Good. In the invention according to claim 15, when the determination means is configured to determine that there is no object based on the output of light reception from the light reception means, the light beam scanning means determines the determination function of the determination means outside the monitoring area. Is stopped when scanning is performed.

In this configuration, when the light beam scanning unit is scanning outside the monitoring area, the determination unit erroneously reports the presence of the object based on the output of the light receiving unit without receiving light due to the limiting operation of the irradiation range limiting unit. Although there is a danger, the occurrence of the erroneous notification can be prevented by stopping the determination function of the determination unit when the light beam scanning unit is scanning outside the monitoring area.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The following is a description of Japanese Patent Application No. 2000-1135.
An embodiment of the scanning optical sensor according to the present invention will be described using the scanning optical sensor described in the above document as an example. 1 and 2
Next, a first embodiment of the scanning optical sensor according to the present invention will be described. 1 and 2, a scanning optical sensor includes first and second units 1 facing each other with a monitoring area 1 interposed therebetween.
0,20.

Each of the units 10 and 20 includes light beam generating circuits 11 and 21 as light beam generating means shown in FIG.
The light beams generated from the light beam generation circuits 11 and 21 are reflected so as to scan the monitoring area 1, and the scanning beam BM is formed.
1, BM2, and reflectors 13-1 to 13-n and 23-1 to 23-n having a large number of retroreflection characteristics and arranged in the vertical direction of the monitoring area 1. Scanning beams BM1, B incident through monitoring area 1
Reflector arrays 13 and 23 that reflect M2, and a light receiving unit that is disposed, for example, near the scanning mirrors 12 and 22 and that receives a reflected beam reflected by the reflector arrays 13 and 23 and incident through the monitoring area 1. Light receiving elements 14, 2 as
And signal loss detection circuits 15 and 25 shown in FIG. 2 as determination means for detecting the presence or absence of the output signal loss of the light receiving elements 14 and 24 and generating a notification output of the absence of an object when there is no loss. You.

The monitoring area of one unit has a substantially triangular shape having the vertexes at both end reflectors of the other unit facing the scanning mirror of one unit. The scanning mirror 12 and the light receiving element 14 of the first unit 10 and the second
By arranging the scanning mirror 22 and the light receiving element 24 of the unit 20 in a diagonal manner with the monitoring region 1 interposed therebetween as shown in FIG. 1, the monitoring region 1 has a substantially square shape as shown in FIG.

FIG. 2 shows the structure of the first unit 10 in detail. Note that the second unit 20 has the same configuration as the first unit 10, and a description thereof will be omitted. In FIG.
The light beam generating circuit 11 generates a high-frequency pulse light beam from the light emitting element 11B by the light emitting element driving circuit 11A. The light beam may be DC light.

The scanning mirror 12 includes a scanning mirror driving circuit 1
6, each of the reflectors 23-1 to 23-2 of the unit 20 facing each other.
3-n so that the scanning beam BM1 scans the rotating shaft 12
swinging in the direction of the arrow in the figure at a predetermined cycle around the light emitting element 1
The light beam from 1B is reflected so as to scan. Here, the scanning mirror 12 and the scanning mirror driving circuit 16 constitute a light beam scanning unit. In addition, the reflectors 23-1 to 23-23
−n may be a continuous reflector that is not divided.

The signal loss detection circuit 15 includes a light receiving circuit 17
, A comparator 18 and a pulse missing detection circuit 19. The light receiving circuit 17 amplifies a light receiving signal from the light receiving element 14. The comparator 18 includes a rectifier circuit 18A that performs an envelope detection of the output signal Sa of the light receiving circuit 17 and a threshold calculator 18 that calculates a threshold value of the rectified output S1 of the rectifier circuit 18A.
B, and outputs Sb = 1 (logical value 1) when the level of the rectified output S1 of the signal Sa is equal to or higher than the threshold value, and Sb = 0 (logical value 0) when the level of the rectified output S1 is lower than the threshold value.
The pulse missing detection circuit 19 includes a capacitor C, a diode D, and a threshold value operation circuit 19a, and delays the fall of the signal Sb by a predetermined off-delay time Tof, and an output S of the off-delay circuit 19A.
2 is provided with an on-delay circuit 19B for delaying the rise of the second signal by a predetermined on-delay time Ton.

The above configuration is the same as that of the scanning optical sensor described in Japanese Patent Application No. 2000-1135. In the present embodiment, in addition to the above configuration, as shown in FIG. 2, the irradiation range of the scanning beam BM1 by the scanning mirror 12 is limited so that the scanning beam BM1 is irradiated only to the triangular monitoring area. A slit plate 30 having a predetermined slit opening width as an irradiation range limiting unit is disposed at a position at a predetermined distance in front of the scanning mirror 12. The second unit 20 is also provided with a slit plate similarly to limit the irradiation range of the scanning beam BM2.

The opening width of the slit is determined as follows. The required irradiation range θ of the scanning beam BM1 in the monitoring area 1 as viewed from the scanning mirror 12 is such that the opening width of the slit is D in the light beam scanning plane (up and down direction in the figure).
The distances from the light beam reflection point (rotation center) of the scanning mirror 12 to the upper end and the lower end of the slit in the drawing are L1 and L2, respectively.
Then, θ = arccos [(L1 ² + L2 ² −D ² ) / (2 · L1 · L2)].

As described above, the opening width D of the slit can be geometrically determined according to the required irradiation range θ of the scanning beam with respect to the monitoring area 1. Since the required irradiation range θ is determined by the height and width of the monitoring area 1, a slit plate 30 having a slit having an opening width D corresponding to the area to be monitored is prepared in advance and set at a predetermined position in front of the scanning mirror 12. With only this, the scanning beam can be limited to the monitoring area 1 and irradiated. Note that the scanning mirror only needs to have a scanning angle capable of scanning a wider range than the irradiation range required in the largest monitoring area in practical use.

As described above, according to the present embodiment, the slit opening width of the slit plate 30 is simply set without changing the scanning angle of the scanning mirror 12 according to the irradiation range θ of the monitoring area to be changed. The irradiation range of the scanning beam can be set appropriately regardless of the scanning mirror. Therefore, it is not necessary to consider variations in characteristics of the scanning mirror 12 and the like, and the trouble of setting and changing the light beam irradiation range due to the change of the monitoring area is reduced.

The object detection operation of the scanning optical sensor according to the present embodiment will be briefly described below. The light beam from the light emitting element 11B is reflected by the scanning mirror 12 and is reflected by the slit plate 3
Scanning beam BM across the monitoring area 1 from the slit 0
As 1 the light enters the second unit 20 side. The light beam reflected by the scanning mirror 12 is scanned within the scanning angle range of the scanning mirror 12, but is monitored by the slit plate 30.
Is irradiated to the monitoring area limited to the required irradiation range θ. If the object 2 does not exist, the second unit 20
The scanning beam BM1 is incident on the reflectors 23-1 to 23-n, and the reflected beam BM1 'is received by the light receiving element 14. The light receiving output of the light receiving element 14 is amplified by the light receiving circuit 17, and the comparator 18 calculates the threshold value after the envelope detection.
(Logical value 1) is generated, and if less than the threshold value, Sb = 0
(Logical value 0). Output signal Sb of comparator 18
Is the off-delay circuit 1 in the pulse missing detection circuit 19
9A. The off-delay circuit 19A outputs a signal S2 = 1 when the signal Sb rises, and S2 = from the fall of the signal Sb until one off-delay time Tof elapses.
Continue with 1. Since the off-delay time Tof is set longer than the period during which the reflected beam BM1 ', which occurs during normal times, is not received, the signal S2 if the object 2 does not exist.
= 1 succeeds. This duration is on delay circuit 1
When the ON delay time Ton exceeds 9B, the signal loss detection circuit 15 generates an output Z1 = 1 to notify the absence of an object.

When the object 2 exists in the monitoring area, the scanning beam BM1 is blocked by the object 2, and the reflected beam BM1 'from the reflector located at the position where the object 2 is shadowed disappears. As a result, if the level of the signal S1 becomes lower than the threshold value of the comparator 18, and if the state of the signal Sb = 0 continues for the off-delay time Tof or more, the signal S2 = 0, and the output of the signal loss detection circuit 15 becomes Z1 = 0. Report presence. On-delay time T of on-delay circuit 19B
Since on is set to be longer than one scanning cycle of the scanning beam BM1, once Z1 = 0 generated from the pulse missing detection circuit 19 is held for at least one scanning cycle of the scanning beam BM1, and the next scanning cycle Thereafter, the above S2 =
As long as it is 0, Z1 = 0 continues.

The second unit 20 performs the same operation as described above, and the result of the logical product of the notification outputs of the two units 10 and 20 is used as the final notification output of the scanning optical sensor, so that the square unit as a whole is obtained. The presence or absence of an object in the shape monitoring region can be monitored. As a method of adjusting the slit opening width D in accordance with the change of the monitoring area, methods as shown in FIGS.

FIG. 3 shows a unit 10 (2) provided with a reflector.
A plurality of front plates 31 are prepared in advance with different opening widths D of the slits 30 as shown in FIGS.
1 is a method of replacing the whole. Note that the front plate 31 and the slit 30 may be separated from each other, and only the slit 30 may be replaced. 4A and 4B, a plurality of guide grooves 32a are provided on both side walls 32 of the slit plate 30 as shown in FIGS.
Projection 33a that can be fitted into guide groove 32a as shown in FIG.
This is a method of preparing a plurality of plates 33 which can be inserted and removed and adjusting the number of the plates 33 to adjust the slit opening width D.
(A) is a front view, and (b) is a cross-sectional view taken along the line AA of (a).

FIG. 5 shows that the movable plate 34 is slidably provided on both side walls 32 of the slit plate 30 and the movable plate 34 is moved by an actuator, for example, a motor 35 in a vertical direction indicated by an arrow in FIG. This is a method of adjusting D. (A) is a front view, and (b) is a cross-sectional view taken along line BB of (a). By the way, in the case of a scanning type optical sensor of the type that shows safety by receiving light as in the first embodiment, the light beam is cut off by the slit plate 30 outside the required irradiation range θ. This cutoff time corresponds to the off delay of the off delay circuit 19.
When the delay time Tof is exceeded, the signal S2 = 0,
There is a problem that Z1 = 0 and the presence of an object is reported even though no object exists in the monitoring area 1. Incidentally, for example, as shown in JP-A-11-144161 and the like,
Such a problem does not occur in a type of sensor that indicates danger when light is received, that is, a so-called radar sensor.

One method for avoiding the above problem is to provide a reflector or the like on the back surface of the slit plate 30 so that the light beam blocked by the slit plate 30 reaches the light receiver. that way,
While the light beam irradiates the area other than the required irradiation range θ, it can be determined that light is received. FIG. 6 shows a main part of a second embodiment of the present invention which avoids the above-described problem. In FIG.
The present embodiment has a configuration in which a counting circuit 40 is used instead of the pulse missing detection circuit 19 in the signal missing detection circuit 15 of the first embodiment. The counting circuit 40 includes the scanning mirror driving circuit 1
6 and the output Sb of the comparator 18 are input, and the signal Sb =
The number of occurrences of 1 is counted. The setting value corresponding to the number of the reflectors of the opposing unit is stored in the counting circuit 40 in advance. The other configuration is the same as that of the first embodiment.

According to the present embodiment, the counting circuit 40 outputs the signal Sb = input per scanning cycle of the scanning mirror 12.
The number of 1 is counted and compared with the set value. If no object is present, the number of occurrences of the signal Sb = 1 corresponds to the number of reflectors, and if the count value matches the set value, the counting circuit 40
Outputs Z1 = 1 to notify that there is no object. If the count value does not match the set value, Z1 = 0 and the presence of an object is notified.

According to such a configuration, the length of the interruption time of the scanning beam by the slit plate 30 is irrelevant to the determination of the presence or absence of an object by the scanning optical sensor. No problem. Next, FIG.
FIG. 9 shows a main part of a third embodiment of the present invention, which is another example for solving the above-mentioned problem.

In the third embodiment, the function of judging the presence or absence of an object is stopped during the light beam cutoff period. The same elements as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 7, the light receiving elements 51 and 52 are provided at both ends of the irradiation range θ of the scanning beam, for example, both ends of the slit of the slit plate 30.
52, the outputs Sr1 and Sr of the light receiving elements 51 and 52
2 is input to the muting circuit 53. The light receiving elements 51 and 52 are not limited to the two ends of the slit of the slit plate 30, but may be any position as long as the light beam can be received at both ends of the irradiation range θ of the scanning beam.

The muting circuit 53 outputs Sm = 1 while the light beam scans the range of the angles α1 and α2, that is, while the light beam is cut off by the slit plate 30. The generation of Sm = 1 in the range of the angle α1 is represented by S
The condition that r1 = 1 has occurred, and the generation of Sm = 1 in the range of the angle α2 must be the condition that Sr2 = 1 has occurred. The scanning angle of the scanning mirror 12 can be known from the driving signal SD1 of the scanning mirror 12 and the like.
The signal Sm may be generated by a combination process of the scanning angle and the signals Sr1 and Sr2. For example, a generation period of approximately Sm = 1 is determined by the scanning angle, and Sm = 1 is generated in a period in which it is overlapped with Sr1 = 1 or Sr2 = 1. Wired OR circuit 54 with two diodes
Inputs the output Sm of the muting circuit 53 and the output Sb of the comparator 18 of the signal loss detection circuit 15, and inputs the output Sc to the pulse loss detection circuit 19. However, each signal is shown as logical level 1> logical level 0. Other configurations are the same as those of the first embodiment.
An angle φ in the drawing indicates a scanning range of the scanning mirror 12.

The operation of the third embodiment will be described with reference to the time chart of FIG. For example, it is assumed that the scanning mirror 12 rotates counterclockwise in the drawing and the light beam is being scanned upward in the drawing. When the light beam passes the upper end of the slit of the slit plate 30, it is received by the light receiving element 51 and Sr1 = 1. Thereafter, the light beam is cut off by the slit plate 30 (Sr1 = 0), and the light beam is monitored again through the slit. Immediately before the region 1 is irradiated, the light beam is received again by the light receiving element 51, and Sr1 = 1. Sr1 = 1 before shutoff
Is generated, the muting circuit 53 generates Sm = 1 in the range of the angle α1. The same is true when the scanning mirror 12 is rotated clockwise in the drawing and the light beam is being scanned downward in the drawing. If Sr2 = 1 occurs before the interruption, the light receiving element 52 is controlled within the range of the angle α2. Sr2 = 1 in light reception
The muting circuit 53 generates Sm = 1 from the occurrence of the error to the next occurrence of Sr2 = 1.

Thus, while the light beam of Sb = 0 is cut off, Sc = 1 is output from the OR circuit 54 based on Sm = 1. The output S2 = 1 of the delay circuit 19A continues, and Z1 = 1 continues. If the on-delay time Ton of the on-delay circuit 19B is set longer than one scanning cycle, Sb = 0 as shown by the broken line in FIG.
Continues longer than the off-delay time Tof, and Z1 =
After the object presence is notified at 0, Sm = 1 and S2 =
Even if 1 is input to the ON delay circuit 19A, Sm =
Since the period of 1 does not continue for more than the on-delay time Ton, the output Z1 = 0 continues, and the output Z1 of the pulse missing detection circuit 19 is fixed to the state immediately before the light beam cutoff.

As described above, according to the present embodiment, while the light beam is in the cutoff state, the muting circuit 5
The signal presence / absence determination function is stopped by the signal Sm of No. 3, and the output Z1 of the pulse missing detection circuit 19 during that time is fixed to the state immediately before the light beam is cut off. Note that the pulse missing detection circuit 19 of the present embodiment may be replaced with the counting circuit 40 of FIG.
In this case, the set value of the counting circuit 40 needs to be determined in consideration of the influence of Sm = 1 on the number of pulses. Also,
Instead of the light receiving elements 51 and 52, a linear light receiving element may be provided at a position on the slit plate 30 corresponding to the angles α1 and α2 at which the light beam is irradiated. In this case, the angles α1 and α at which the light beam is
Since the output of the logical value 1 from each linear light receiving element continues during the period 2, the output Sm of the muting circuit 53 may be generated according to the output state of the linear light receiving element.

The configuration of the third embodiment is also applicable to the slit structures shown in FIGS. In the case of FIG. 3, the light receiving element may be arranged in the slit portion on the back side of each front plate 31. In the case of FIG. 4, the plate 33 to which the light receiving element is attached may be arranged at the upper and lower ends of the slit. In consideration of insertion / removal of the plate 33, a structure in which the light receiving element is embedded is desirable. Also in the case of FIG. 5, the light receiving element may be attached to the movable plate.

Next, FIG. 9 shows a fourth embodiment of the present invention. In FIG. 9, the present embodiment includes light receiving elements 51 and 52.
Instead of the above, for example, reflectors 61 and 62 that generate a unique reflected light pattern are arranged on the light beam projecting light beam at the end of the monitoring area as a mark recognizable by the sensor. For example, it is provided instead of the reflectors 23-1, 23-n arranged on the light beam projection light beam at the end of the monitoring area of the facing unit 20.
Further, although not shown, an envelope detection circuit for performing envelope detection on the output Sb of the comparator 18 is provided, and its output is input to the muting circuit 53 in FIG. Other configurations are the same as in the third embodiment.

As the reflectors 61 and 62, for example, the configurations shown in FIGS. 10A and 10B can be considered. FIG. 7A shows one end of a reflecting surface 61a (62a) connected to a support shaft 61b.
At (62b), the reflecting surface 61a (62a) is pivoted at a predetermined frequency by an actuator 61c (62c) such as an electrostrictive element attached to the other end, and is modulated at the predetermined frequency. This is a configuration that generates reflected light. The predetermined frequency is set to be higher than a pulse signal generated by the reflector array 23 (13). FIG. 6B shows the reflection area 61A (62A) and the non-reflection area 61.
A plurality of B (62B) are provided alternately so that the reflected light from the reflection area 61A (62A) has a predetermined frequency. When the light beam scans the reflectors 61, 62, the reflection areas 61A,
The reflected light from 62A can obtain pulse light equivalent to that shown in FIG.

The operation will be described with reference to the time chart of FIG. When reflected light modulated at a predetermined frequency, for example, f1, from the reflectors 61 and 62 is received, the light receiving circuit 17
Generates an output Sa having a frequency f1 as shown in FIG.
An output Sb as shown in FIG. 11 is generated from the comparator 18 and input to the OR circuit 54 and an envelope detection circuit (not shown). If the envelope detection circuit is configured to generate an output of a logical value 1 only when a frequency signal higher than the frequency f1 is input, the signal Sr1 (= Sr2) = 1 from the envelope detection circuit by the signal input of the frequency f1. The signal is input to the muting circuit 53. Therefore, similarly to the third embodiment, the signal Sr
After 1 = 1 (Sr2 = 1), the signal Sr1 = 1
The process of determining the presence or absence of an object can be stopped in a period until (Sr2 = 1).

Incidentally, in order to generate the signals Sr1 and Sr2 separately, the modulation frequencies of the reflectors 61 and 62 are set to different frequencies, for example, f1 and f2, and an envelope having a band-pass filter for passing only the signal of the frequency f1 is used. A line detection circuit and an envelope detection circuit having a band-pass filter that passes only the signal of the frequency f2 may be provided, and the output Sb of the comparator 18 may be input to both of the envelope detection circuits. As described above, the scanning angle and the signal Sr
If the configuration is such that the signal Sm is generated by the combination processing of the signals Sr1 and Sr2, it is not necessary to generate the signals Sr1 and Sr2 separately.

Next, FIG. 12 shows a fifth embodiment of the present invention. In the present embodiment, instead of providing a slit, emission of a light beam is stopped in a mirror scanning range other than the required irradiation range θ of the monitoring area. In FIG. 12, the reflectors 61 and 62 shown in FIG. 10 are arranged as marks that can be recognized by the sensor on the light beam projection light beam at the end of the monitoring area in the facing unit 20. Also, the envelope detection circuit 71A and the scanning mirror angle determination circuit 71B described in the fourth embodiment
And a switch element 11C between the light emitting element driving circuit 11A and the light emitting element 11B in the light beam generating circuit 11. Here, the light emission control circuit 71 and the switch element 11C constitute light beam generation control means. Other configurations are the same as the first embodiment of FIG. 2 except for the slit plate 30.

The scanning mirror angle determination circuit 71B comprises an output Sr of the envelope detection circuit 71A and the scanning mirror driving circuit 1
The irradiation direction of the light beam is determined based on the drive signal SD1 indicating the mirror scanning angle Ag from Step 6. Then, the scanning mirror 12 is positioned at a position where the light beam is irradiated in the monitoring area.
When there is, the output CNT = 1 is output as a signal indicating the monitoring area, and when the scanning mirror 12 is located at a position where the light beam is irradiated outside the monitoring area, the output CNT = 0 is output.

The switch element 11C is turned on when the output of the scanning mirror angle determination circuit 71B is CNT = 1,
Turns off when T = 0. Scanning mirror angle determination circuit 7
The operation of 1B will be described with reference to the flowchart of FIG. 13 and the time chart of FIG. Step 1 (S in the figure)
1 and the same hereinafter), the signal SD1 (angle A
g) and the signal Sr.

In step 2, it is determined whether the signal Sr has changed from Sr = 0 to Sr = 1, and if Sr = 1, the process proceeds to step 3. In step 3, it is determined that the light beam has started scanning outside the monitoring area, and the output CNT = 0 is output. As a result, the switch element 11C is turned off, the light emission of the light emitting element 11B stops, and the light beam stops.

In step 4, the angle Ag when Sr = 1 is determined in step 2 based on the signal SD1 is stored as ρ. In FIG. 14, ρ1 indicates the boundary angle when the signal Sr = 1 due to the reflected light from the reflector 61 is input, and ρ2 indicates the boundary angle when the signal Sr = 1 due to the reflected light from the reflector 62 is input. Is shown. In step 5, the signal SD1 is input again, and in step 6, the signal S1 is input.
A comparison is made between the angle Ag based on D1 and the magnitude | Ag | and | ρ | of the angle ρ stored in step 4 to determine whether | Ag | ≦ | ρ |. Until | Ag | ≦ | ρ |
The light beam continues to output CNT = 0 as outside the monitoring area,
If it is determined that | Ag | ≦ | ρ |, it is determined that the light beam is within the monitoring area, the process proceeds to step 7, and the output CNT = 1. As a result, the switch element 11C is turned on and the light emitting element 11
Light emission of B starts, and a light beam is applied to the monitoring area.

It should be noted that the signal Sr = 1 may be generated for a while after the light beam starts being irradiated on the monitoring area, and Sr =
While 1 occurs, CNT = 1/0 is repeated, but this does not cause an operational problem. In order not to cause the repetition of CNT = 1/0, for example, the signal Sr = 1 immediately after the start of irradiation by giving a delay to the transition from step 7 to step 1 or the like.
Can be ignored.

By repeating the above operation, a light beam can be emitted only when the scanning mirror 12 is at a position for scanning the monitoring area. Note that the signal Sr may be divided into the signals Sr1 and Sr2 as in the fourth embodiment. According to the fifth embodiment, since the boundary position of the monitoring area is updated frequently, even if the scanning angle of the scanning mirror 12 corresponding to the boundary position fluctuates due to environmental fluctuation, deterioration, or the like, the set monitoring area. Can be reliably scanned, and the reliability of object monitoring is improved. Further, even if the monitoring area is changed, the scanning range of the scanning beam is automatically changed, so that it is not necessary to adjust the scanning range of the scanning beam.

Once the angles ρ1 and ρ2 at which the signal Sr = 1 are set once, thereafter, the same processing as described above can be performed only by comparing ρ1 and ρ2 with the angle Ag.
It is sufficient that CNT = 0 when ρ1 or Ag <ρ2, and CNT = 1 when ρ2 ≦ Ag ≦ ρ1. However, considering the variation of the scanning angle, it is desirable to input the signal SD1 and set the angles ρ1 and ρ2 each time as shown in the flowchart of FIG.

It is not always necessary to stop the emission of the light beam outside the monitoring area, and the intensity of the light beam may be reduced to such an extent that the light reception cannot be recognized. Also in the case of the fifth embodiment, it is desirable to stop the function of determining the presence or absence of an object when the scanning mirror 12 is scanning outside the monitoring area. In that case, as in FIG.
And an OR circuit 54, and input the output CNT of the scanning mirror angle determination circuit 71B to the muting circuit 53. The muting circuit 53 has a configuration in which the output Sm = 0 when CNT = 1 and the output Sm = 1 when CNT = 0.

Instead of providing the switch element 11C, the output CNT of the scanning mirror angle determination circuit 71B is input to the light emitting element driving circuit 11A, and the output of the light emitting element driving circuit 11A is directly controlled to emit / stop the light beam. May be controlled. In this case, the light emitting element drive circuit 11 is replaced with the output CNT of the scanning mirror angle determination circuit 71B.
The output of A may be input to the muting circuit 53 (light emission / stop of the light beam is a logical value 1 /
Treated as 0).

Next, FIG. 15 shows a sixth embodiment of the present invention. This embodiment uses a mark that can be recognized by the sensor,
The slit width of the slit plate 30 is automatically controlled. In FIG. 15, reflectors 81 and 82 are arranged on the light beam projecting light beam at the end of the monitoring area of the unit 20 facing each other as marks recognizable by the sensor. The reflector 81 is shown in FIG.
As shown in an enlarged manner in FIG. 6, it is composed of two reflecting portions 81a and 81b that generate reflected light patterns having different frequencies from each other. The reflection section 81a has a reflection area / non-reflection area set at intervals such that the reflected light pulse has a frequency f1, and the reflection section 81b has an interval set such that the reflection light pulse has a frequency f2. Although not shown, the reflector 82 also includes two reflectors that generate reflected light patterns having different frequencies from each other. The frequency of the reflected light pulse of each reflector is the same as that of the reflectors 81a and 81b of the reflector 81. Is different f
3, f4.

The slit plate 83 has movable plates 83a and 83b above and below the opening, and each of the movable plates 83a and 83b
Can be moved up and down in the figure by slit driving mechanisms 84A and 84B, respectively. The slit drive mechanism 8
The slit control circuit 85 that drives and controls the 4A and 84B includes:
Output S from comparator 18 of signal loss detection circuit 15
b for detecting the reflectors 81 and 82 based on
And second detection circuits 85A and 85B, and first detection circuit 85
Output CTL based on outputs Srt1 and Srt2 from A
A first slit position adjusting circuit 85C for controlling the slit driving mechanism 84A by the first and a second slit position adjusting circuit 85D for controlling the slit driving mechanism 84B by the output CTL2 based on the outputs Srb1 and Srb2 from the second detecting circuit 85B. It is comprised including. Here, the slit control circuit 85 and the slit drive mechanisms 84A and 84B constitute a slit width control means. Output CTL
1, CTL2 corresponds to the signal indicating the monitoring area. The other configuration is the same as that of the first embodiment shown in FIG.

The first detection circuit 85A is provided, for example, in FIG.
And two band-pass filters 85a and 85b,
It is configured to include two envelope detection circuits 85c and 85d. The bandpass filter 85a is configured to pass only the signal of the frequency f1, and the bandpass filter 85b is configured to pass only the signal of the frequency f2. The second detection circuit 85B
Is a configuration similar to that of the first detection circuit 85A, except that one of the band-pass filters passes only the signal of the frequency f3 and the other band-pass filter passes only the signal of the frequency f4. .

Therefore, the first detection circuit 85A is provided with the reflector 8
1 when the reflected light is received from the reflection unit 81a, the signal Srt1 = 1 is generated from the envelope detection circuit 85c based on the output from the band-pass filter 85a, and when the reflected light from the reflection unit 81b is received. The signal Srt2 = 1 is generated from the envelope detection circuit 85d based on the output of the signal 85b. Similarly, the second detection circuit 85B generates a signal Srb1 = 1 when receiving reflected light from one reflecting portion of the reflector 82, and generates a signal Srb1 when receiving reflected light from the other reflecting portion.
Generates 2 = 1. These first and second detection circuits 85
Based on the signals from A and 85B, the first and second slit position adjusting circuits 85C and 85D control the movable plates 83a and 83 so that the light beam is irradiated only in the irradiation range θ of the monitoring area.
The position of 3b is appropriately controlled.

The operation of controlling the position of the slit plate 83 by the slit position adjusting circuit will be described with reference to the flowchart of FIG. FIG. 18 shows an example in which the scanning end of the light beam is controlled near the boundary between the two reflecting portions. Since the control operations of the first slit position adjusting circuit 85C and the second slit position adjusting circuit 85D are the same, the first slit position adjusting circuit 85C will be described below.

At step 11, it is determined whether or not the signal Srt1 = 1 is input. If so, it is determined that the reflection unit 81a is being scanned, and the process proceeds to step 12, where the movable plate 83a is lowered by a predetermined value to control the slit opening width in a direction in which the reflection unit 81a is not scanned. If not, it is determined that the reflection unit 81a is not scanned, and
Proceeding to step 13, the movable plate 83a is maintained at that position without being driven.

In step 14, the signal Srt2 = 1
It is determined whether or not is input. If no input has been made, it is determined that the reflection section 81b has not been scanned, and the process proceeds to step 15, where the movable plate 83a is raised by a predetermined value and the reflection section 81b is not scanned.
1b controls the slit opening width in the scanning direction. If so, it is determined that the reflection section 81b is being scanned, and the process proceeds to step 13, where the movable plate 83a is not driven and is maintained at that position.

The movable plate 83b is similarly controlled by the second slit position adjusting circuit 85D. Further, the seventh aspect of the present invention.
As an embodiment, each of the reflectors 81 and 82 may be configured with only one reflector, and may be controlled as shown in the flowchart of FIG. In such an embodiment, the signals Srt2 and Srb2 do not occur. FIG. 19 shows an example in which the reflector 81 is constituted by one reflector 81a.

At step 21, it is determined whether or not the signal Srt1 = 1 is input. If so, it is determined that the reflection unit 81a is being scanned, and the process proceeds to step 22, where the movable plate 83a is lowered by a predetermined value to control the slit opening width in a direction in which the reflection unit 81a is not scanned. If not, in step 23, the movable plate 83a is raised by a predetermined value, and the slit opening width is controlled in the direction in which the reflecting portion 81a is scanned.

As a result, the scanning end of the light beam is
1a is controlled near the lower end. In this case, for example, the control may be stopped when the vertical driving operation of the movable plate 83a is alternately repeated a predetermined number of times. Similarly, on the reflector 82 side, the scanning end of the light beam is controlled near the lower end of the reflecting section.
Although not explicitly shown as steps in the flowcharts of FIGS. 18 and 19, the signals Srt1,
Srt2 is input as needed. Also, in steps 11 and 14 of FIG. 18 and step 21 of FIG. 19, “Srt1 within one scanning cycle (or a predetermined period) is set.
(Srt2 in Step 14 of FIG. 18) = 1? The one scanning cycle may be determined based on the scanning angle AG by inputting the signal SD1 of the scanning mirror driving circuit 16.

Next, FIG. 20 shows an eighth embodiment of the present invention. The present embodiment has a configuration in which the scanning angle of the scanning mirror is variably controlled without using a slit plate, and the scanning beam is emitted only to the required irradiation range of the monitoring area. In FIG.
This embodiment is different from the sixth embodiment shown in FIG. 15 in that the slit plate 83, the slit driving mechanisms 84A and 84B
And a scanning mirror control circuit 90 as a light beam scanning control means and a center position control mechanism as a swing center position adjusting means for controlling the swing center position of the scanning angle of the scanning mirror 12 in place of the slit control circuit 85 91.

The scanning mirror control circuit 90 includes a first detection circuit 90A, a second detection circuit 90B, and a mirror scanning angle adjustment circuit 90C. The first and second detection circuits 90
A and 90B have the same configuration as that of FIG. The mirror scanning angle adjustment circuit 90C includes two detection circuits 90A and 90A.
On the basis of the signals Srt1 and Srb1 from 0B and the signal SD1 of the scanning mirror driving circuit 16, the scanning end of the light beam is changed to the reflector 81 by the output CSA which is a signal indicating the monitoring area.
The scanning angle of the scanning mirror 12 is adjusted by controlling the output SD1 of the scanning mirror driving circuit 16 so as to be at the position 82.
The mirror scanning angle adjusting circuit 90C outputs the signals Srt1,
Srt2, Srb1, Srb2 and scanning mirror drive circuit 1
Based on the signal SD1 of No. 6, the drive of the center position control mechanism 91 is controlled by the output CCA such that the swing amplitude angles of the scanning mirror 12 in the directions of the arrows U and L in the drawing become equal to each other.

The scanning mirror 12 of the present embodiment needs to be capable of variably controlling the scanning angle by an electric signal. As such a scanning mirror, for example, there is an electromagnetic galvanometer mirror known in Japanese Patent Application Laid-Open No. 8-220453. An example of such an electromagnetic galvanometer mirror is shown in FIG. 21 and will be described briefly. In FIG. 21, a torsion bar integrally formed on a silicon substrate and a movable plate supported by the torsion bar are provided inside a silicon substrate fixed on an insulating substrate. A plane coil is provided around the movable plate, and a mirror is provided at the center. Permanent magnets are arranged on opposite sides of the silicon substrate such that one side has an upper N pole and a lower S pole, and the other side has a lower N pole and an upper S pole on the other side.

The operation is as follows. When a current flows from the electrode terminal to the plane coil, the current flows across the static magnetic field generated by the permanent magnet.
A force acts on both ends of the movable plate according to Fleming's left-hand rule, and the movable plate rotates. The flow of the alternating current causes the movable plate to periodically rotate, and reflects and scans the light beam incident on the mirror. Since the current value flowing through the coil and the scanning angle are in a substantially proportional relationship, the scanning angle of the mirror can be controlled by controlling the current value.

In this embodiment, it is desirable that the swing amplitude angles of the scanning mirror in the directions of the arrow U and the L direction are equal, and the center position control mechanism 91 sets the swing center of the scanning angle of the scanning mirror 12 to an appropriate angle. Control. As the center position control mechanism 91, for example, a rotation mechanism such as a tilt stage shown in FIG. 22 is used. The tilt stage 100 shown in FIG.
And a tilt portion 102 having a flat upper surface supported movably in the left-right direction of the arrow in the figure along the arc-shaped upper surface of the fixed base 101. A column 103 is provided at the center of the upper surface of the tilt portion 102, and a tilt portion 10 is provided at the tip of the column 103.
2 The fixing part of the scanning mirror 12 is fixed so that the upper surface and the scanning mirror 12 are substantially horizontal. Thereby, the scanning mirror 12
The swing center of the movable plate (ie, mirror) is
The direction of the center of oscillation of the scanning mirror 12 can be changed by changing the tilt angle of the tilt portion 102 so as to be perpendicular to the upper surface.

Next, the operation of the present embodiment will be described. First, the scanning end control operation of the light beam by the mirror scanning angle adjusting circuit 90C will be described with reference to the flowchart of FIG. FIG. 23 shows an example in which the scanning end of the light beam is controlled near the lower ends of the reflecting portions of the reflectors 81 and 82 in the same manner as in the seventh embodiment shown in FIG.

At step 31, signals Srt1 and SD1 are input. Step 31 is appropriately repeated for the processing in step 32. Step 3
2, the current value of the signal SD1 is equal to the scan angle Ag (see FIG. 14).
It is determined whether or not the signal Srt1 = 1 is generated within one scanning cycle based on the signal SD1. If it is generated, the process proceeds to step 33, and the output CSA = 1 is generated. In response to the input of the output CSA = 1, the scanning mirror driving circuit 16 controls the driving current value of the signal SD1 so as to reduce the amplitude angle in the direction of arrow U in FIG. 12 is controlled. If not generated, the process proceeds to step 34, where the output CSA = 0. In response to the output CSA = 0, the scanning mirror driving circuit 16 increases the signal SD1 to increase the amplitude angle in the direction of arrow U in the figure by a predetermined value.
And the scanning mirror 12 is controlled in a direction in which the reflecting portion of the reflector 81 is scanned.

Although only the control operation of the reflector 81 is shown in FIG. 23, the control operation of the
Is replaced by the signal Srb1 and is the same as the control operation on the reflector 81 side, so the description is omitted. Next, the center control operation of the swing amplitude angle of the scanning mirror 12 will be described with reference to the flowchart of FIG. FIG. 24 shows the reflector 81,
82 has two reflecting portions as in the sixth embodiment, and the scanning end of the light beam in the U direction and the L direction is
1 and 82 show control examples when the distance is set between two reflecting portions.

In step 41, the swing amplitude angles in the U and L directions are set to maximum values a _m and b _m (shown in FIG. 22) so that the reflectors 81 and 82 can be reliably scanned. In step 42, the signals Srt1 and Srt2 and the signal SD1 are input. Mirror scan angle Ag from signal SD1
Is obtained. In step 43, Srt = 1 to Srt
It is determined whether there is a signal change to 2 = 1 or from Srt2 = 1 to Srt1 = 1. When a change has to have determination, the light beam is determined that the irradiated boundary of the reflective portion 81a and 81b, and stores the scan angle Ag at that time as [rho _a in step 44.

Steps 45 to 47 correspond to steps 42 to 4
In the same manner as in No. 4, the scanning angle Ag on the reflector 82 side (however, it is set to 0 degree at the center of oscillation) is detected. That is, step 4
In step 5, the signals Srb1 and Srb2 and the signal SD1 are input. In step 46, Srb = 1 to Srb2 = 1,
Alternatively, it is determined whether or not there has been a signal change from Srb2 = 1 to Srb1 = 1, and when it is determined that there has been a change, the scan angle Ag at that time is stored as ρ _b in step 47.

[0073] At step 48, the magnitude of ρ _a | ρ _a | and [rho _b magnitude | [rho _b | Compare. If | ρ _a | <| ρ _b |, it is determined that the swing center is deviated in the U direction, and the process proceeds to step 49, in which the tilt unit 102 is turned to change the swing center in the L direction by a predetermined value. It is turned to the left in FIG. Conversely, if | ρ _a |> | ρ _b |, it is determined that the swing center is deviated in the L direction, and the flow advances to step 50 to tilt the swing center by a predetermined value in the U direction. The part 102 is rotated rightward in FIG.

The operations of steps 42 to 50 are repeated, and if it is determined in step 48 that | ρ _a | = | ρ _b |, the control for adjusting the center position of the swing amplitude angle is terminated. The operation shifts to scanning end control of the light beam. In the case of another embodiment except the above-described eighth embodiment, the scanning mirror only needs to have a scanning angle capable of scanning a wider range than the maximum irradiation range of the monitoring area required in practical use. Not only mirrors but also commercially available galvanometer mirrors and polygon mirrors can be applied. In addition, the light beam blocking performance of the slit plate is not necessarily limited to 100%, and it is sufficient that the light beam can be attenuated to such an extent that light reception cannot be recognized.
Further, a galvanomirror having a displacement detection function capable of detecting the displacement of a movable plate, such as an electromagnetic galvanomirror described in Japanese Patent Application Laid-Open No. 7-218857, is used for scanning in the fifth and eighth embodiments. When applied to a mirror, a signal of a displacement detection coil may be used as the angle signal Ag.

As described above, according to the irradiation range limiting means of the present invention, the light beam irradiation range corresponding to the monitoring area can be adjusted without manually adjusting the scanning angle of the light beam scanning means, and This can be set more easily than by manual adjustment of the scanning angle. Further, since the irradiation limitation by the irradiation range limiting unit is determined geometrically according to the monitoring area, it is not affected by the variation or fluctuation of the scanning angle of the light beam scanning unit. In particular, in the methods of the first to seventh embodiments, if the scanning range of the scanning mirror is set to be larger than the required irradiation range in advance, the scanning can be performed independently of the scanning range.

Each embodiment is described in Japanese Patent Application No. 2000-113.
Although illustrated as an application to the reflection type scanning optical sensor described in No. 5, etc., the present invention can be applied to a scanning optical sensor other than this type. For example, in the transmission type scanning optical sensor described in International Publication WO97 / 33186 or the like, the light receiving elements 14 and 24 are omitted in the configuration of FIGS. Is provided with a light receiving array, and the output of the light receiving array is input to signal loss detection circuits 15 and 25 to determine the presence or absence of an object. The point that the area is irradiated with a scanning light beam and the presence or absence of an object is determined based on the light beam received through the monitoring area is the same as the reflection type scanning optical sensor described in Japanese Patent Application No. 2000-1135. Each embodiment of the present invention is similarly applicable. Also, Japanese Patent Application Laid-Open No. 11-144161
The scanning optical sensor of the optical radar sensor type described in Japanese Patent Application Laid-Open Publication No. H10-15095 has only the configuration of the unit 10 in which the reflector array is omitted in the configuration of FIGS. 1 and 2 described above. The only difference is that the presence / absence determination is in the opposite relationship, and the point that the light beam scanning means irradiates the monitoring area with a scanning light beam to determine the presence / absence of an object based on the light beam received through the monitoring area is disclosed in Japanese Patent Application Laid-Open (JP-A) no. This is the same as the reflection-type scanning optical sensor described in, for example, 2000-1135, and each embodiment of the present invention is similarly applicable. Further, Japanese Patent Application Laid-Open No. 11-306485 and Japanese Patent Application No. 2000-30276
The present invention is similarly applicable to a two-dimensional scanning type scanning optical sensor described in No. 0 or the like.

In a two-dimensional scanning type scanning optical sensor,
The light beam is scanned in two directions (hereinafter referred to as a vertical direction and a horizontal direction). When a slit plate is used as the irradiation range limiting means as shown in FIGS. 3 to 5, the slit opening width may be changed not only in the vertical direction but also in the horizontal direction. Specifically, in FIG. 3, different combinations of the vertical width and the horizontal width may be prepared, and in FIGS. 4 and 5, for example, a slit plate in which the vertical width can be adjusted and a slit plate in which the horizontal width can be adjusted are overlapped with each other. What is necessary is just to comprise a board. If the reflector shown in FIG. 10 is arranged on the light beam passing through the slit edge of the slit plate, the configuration shown in FIG. 9 is realized. The configuration in FIG. 12 is realized by disposing the light receiving element or the reflector in FIG. 10 on the light beam passing through the slit edge. FIG. 1 shows the vertical and horizontal scanning directions.
Step 3 can be used in a similar manner. 7 and 9
When the configuration of FIG. 13 and the processing of FIG. 13 are applied, it is necessary to arrange the light receiving element or the reflector on the light beam passing through the slit edge, that is, at the edge of the monitoring area. What is necessary is just to arrange so that the area | region edge part may be bordered.
By the way, if the monitoring area is a quadrangular pyramid having the light beam scanning means (light beam reflecting point) as a vertex, for example, the light receiving element or the reflector may be arranged on at least two diagonal sides of the quadrangular pyramid. The arrangement of the element or the reflector becomes easy. Then, the angle in the vertical direction is ρ1, ρ2, and the angle in the horizontal direction is ρ3, based on the light receiving output Sr = 1 by the light receiving element or the reflector.
ρ4 (ρ3, ρ4 is ρ1, ρ1,
ρ2), and | Ag | ≦ | in FIG.
ρ | determination processing (CNT =
The process returns to step 5 as 0, and if YES in step 6, the process of returning to step 5 is performed after step 7). Also in the case of the automatic slit width adjustment method of FIG. 15, the processing of FIG. 18 or 19 may be performed in the vertical direction and the horizontal direction. It is needless to say that the reflector in FIG. 10 is configured such that the blinking frequency of the reflected light beam is different for each reflector. The slit plate with the slit drive mechanism is provided for the vertical direction and the horizontal direction. In the processing of FIGS. 18 and 19, it is determined whether or not the light to be detected has been received (Srt1 = 1 or Srt2 = 1 has occurred) even once, for example, in one scanning cycle. It is not always necessary to arrange the reflector so as to border the edge. What is necessary is just to provide in the position which becomes the maximum scanning angle in each of the up / down direction and the left / right direction among the light beams projected to the monitoring area.
For example, if the monitoring area is a quadrangular pyramid having the light beam scanning means (light beam reflection point) at the apex, the light receiving element or the reflector may be arranged on at least two diagonal sides. The adjustment of the light beam scanning means in FIG. 20 can be similarly applied.

In the scanning optical sensor of the two-dimensional scanning type, the muting circuit 53 shown in FIG. 7 is provided for the vertical direction and the horizontal direction, and the OR output of the output signals of both circuits is used as the signal Sm. The scanning mirror angle determination circuit 71 in FIG. 12 is provided for the vertical direction and the horizontal direction, and the vertical direction circuit outputs a scanning mirror vertical driving signal including the vertical scanning angle information and a signal Sr related to the vertical direction. The circuit for the left and right direction is extracted from Sb and processed, and the scanning mirror left and right driving signal including the left and right scanning angle information and the signal Sr related to the left and right direction are obtained.
Is extracted from the signal Sb and processed. Even in the case of FIG.
A slit control circuit 85 for the vertical direction and a slit control circuit 85 for the horizontal direction are provided, and processing is performed by signals related to each. The same applies to the scanning mirror control circuit 90 in FIG.

JP-A-11-306485 and Japanese Patent Application No.
In a two-dimensional scanning type scanning optical sensor described in, for example, 000-302760, a semiconductor galvanometer mirror known in Japanese Patent Application Laid-Open No. 7-175005 is cited as an example of a two-dimensional scanning mirror. This mirror is provided with a mirror (movable plate) that is supported on two axes orthogonal to each other and swings two-dimensionally around both axes, and can be driven to swing independently around both axes. Can be set independently of each other. There is a proportional relationship between the drive current around each axis and the swing angle (that is, the scan angle). In addition, Japanese Patent Application Laid-Open
As disclosed in Japanese Patent No. 218857, if a detection coil for detecting the displacement of a mirror (movable plate) is provided, the mirror displacement angle can be detected by this detection coil.

[0080]

As described above, according to the present invention, since the irradiation range limiting means for limiting the light beam from the light beam scanning means to a predetermined range is provided, the light beam irradiation range corresponding to the monitoring area is provided. Setting work becomes easy. According to the configuration in which the irradiation range can be automatically set as in claims 6 to 9, since the boundary position of the monitoring area is updated frequently, the scanning angle of the light beam scanning means fluctuates due to environmental fluctuation or deterioration. Even so, you can reliably scan the set monitoring area,
The reliability of object monitoring is improved. Also, even if the monitoring area changes, the scanning range of the scanning beam is automatically changed,
The trouble of adjusting the scanning range of the scanning beam can be eliminated.

According to the fifteenth aspect of the present invention, in the case of a scanning type optical sensor of a type in which the absence of an object is notified by the output of light reception from the light receiving means, the light beam scanning means scans outside the monitoring area. In addition, it is possible to prevent erroneous notification of the presence of an object based on the output without light reception.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of the embodiment;

FIG. 3 is a diagram showing a configuration example of a slit section.

FIG. 4 is a diagram showing a configuration example of another slit portion.

FIG. 5 is a diagram showing a configuration example of still another slit portion.

FIG. 6 is a configuration diagram of a main part of a second embodiment of the present invention.

FIG. 7 is a configuration diagram of a main part of a third embodiment of the present invention.

FIG. 8 is an operation time chart of the embodiment.

FIG. 9 is a configuration diagram of a main part of a fourth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration example of a reflector according to the embodiment.

FIG. 11 is an operation time chart of the embodiment.

FIG. 12 is a configuration diagram of a main part of a fifth embodiment of the present invention.

FIG. 13 is an operation flowchart of the embodiment.

FIG. 14 is a diagram showing the relationship between the presence or absence of light beam reception and the mirror scanning angle according to the embodiment.

FIG. 15 is a configuration diagram of a main part of a sixth embodiment of the present invention.

FIG. 16 is a configuration diagram of a reflector according to the embodiment.

FIG. 17 is a configuration diagram of a first detection circuit of the embodiment.

FIG. 18 is an operation flowchart of slit section control of the embodiment.

FIG. 19 is an operation flowchart of a slit section control according to the seventh embodiment of the present invention.

FIG. 20 is a configuration diagram of a main part of an eighth embodiment of the present invention.

FIG. 21 is a configuration diagram of a scanning mirror applied to the embodiment.

FIG. 22 is a configuration diagram of a tilt stage applied to the embodiment.

FIG. 23 is an operation flowchart of scanning mirror control of the embodiment.

FIG. 24 is an operation flowchart of swing amplitude angle control of the embodiment.

[Explanation of symbols]

 Reference Signs List 1 monitoring area 11 light beam generating circuit 11C switch element 12 scanning mirror 13 reflector array 14 light receiving element 15 signal loss detecting circuit 16 scanning mirror driving circuit 30, 83 slit plate 51, 52 light receiving element 53 muting circuit 54 wired OR circuit 61 , 62, 81, 82 Reflector 71 Emission control circuit 84A, 84B Slit drive mechanism 85 Slit control circuit 90 Scanning mirror control circuit 92 Center position control mechanism

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA02 AA06 BB25 FF09 FF24 GG01 GG12 HH04 HH12 JJ01 LL12 LL28 LL30 LL62 MM16 PP22 QQ06 QQ25 QQ28 QQ51 2H045 AB53 BA02 DA02

Claims (15)

[Claims] 1. A light beam scanning means for reflecting a light beam from a light beam generating means so as to scan a space, a light receiving means for receiving a light beam from the space, and a light receiving means for receiving light from the light receiving means. A scanning type optical sensor comprising: a determination unit configured to determine the presence / absence of an object by irradiating the light beam from the light beam scanning unit only to a monitoring area of the object. A scanning optical sensor, characterized in that: 2. The scanning optical sensor according to claim 1, wherein said light beam scanning means has a configuration in which a light beam scanable range is larger than said monitoring area. 3. The scanning optical sensor according to claim 1, wherein said irradiation range limiting means is configured to change an irradiation range to be limited. 4. The irradiation range limiting means according to claim 3, wherein a plurality of slit plates having different slit widths are provided, and a slit plate having a slit width corresponding to an assumed irradiation range of the monitoring area is selected. Scanning optical sensor 5. The scanning optical sensor according to claim 3, wherein said irradiation range limiting means includes a slit plate capable of changing a slit width in accordance with a change in a light beam irradiation range of a monitoring area. 6. A scanning optical sensor according to claim 3, wherein said irradiation range limiting means is configured to automatically adjust the irradiation range to be limited based on a signal indicating a monitoring area. 7. The irradiation range limiting means includes a slit plate capable of changing a slit width for limiting an irradiation range of the light beam from the light beam scanning means, and the light beam scanning means based on a signal indicating the monitoring area. 7. The scanning optical sensor according to claim 6, further comprising: slit width control means for automatically controlling a slit width of the slit plate so that a light beam from the light source does not irradiate outside a monitoring area boundary. 8. An irradiation range limiting means for generating a light beam from the light beam generating means based on a signal indicating the monitoring area only during a period when the light beam scanning means is scanning the monitoring area. 7. A configuration comprising light beam generation control means for controlling the operation of the light beam generation means.
3. The scanning optical sensor according to claim 1. 9. The light beam scanning control means for controlling the operation of the light beam scanning means so that the light beam scanning means scans only the monitoring area based on a signal indicating the monitoring area. The scanning optical sensor according to claim 6, wherein the scanning optical sensor is provided. 10. The swing center position of the light beam scanning means for scanning a light beam by swinging a scanning mirror so that the swing amplitude angle of the scanning mirror is symmetrical with respect to the swing center. The scanning optical sensor according to claim 9, further comprising a swing center position adjusting means for variably adjusting. 11. The scanning optical sensor according to claim 6, wherein the signal indicating the monitoring area is generated based on a light beam irradiated near the boundary of the monitoring area. . 12. A signal indicative of the monitoring area, wherein a light receiving element is arranged on the direction of a light beam irradiated near a boundary of the monitoring area, and is generated based on a light receiving output of the light receiving element. 12. The scanning optical sensor according to item 11. 13. A signal indicating the monitored area is generated from the light reflecting means, wherein a light reflecting means for generating a unique reflected light is arranged in the direction of the light beam irradiated near the boundary of the monitored area. The scanning optical sensor according to claim 11, wherein the scanning optical sensor is configured to generate the light based on a detection output of the intrinsic reflected light. 14. The scanning optical sensor according to claim 4, wherein the slit plate is configured to block or attenuate a scanning beam outside the monitoring area. 15. When the judging means judges that there is no object based on the output of light reception from the light receiving means, the light beam scanning means scans outside the monitoring area by the light beam scanning means. The scanning optical sensor according to claim 1, wherein the scanning type optical sensor is configured to stop when the scanning is performed.