JP2004233250A - Distance measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distance measuring device capable of measuring the distance surely even if the reflectivity of a detection object is low, in a constitution for measuring the distance to the detection object based on the ratio of the total receiving quantity of light irradiated onto a detection region. <P>SOLUTION: A first floodlighting means 1 irradiates focusing light toward the detection region, and a second floodlighting means 2 irradiates diffuse light. In this case, since the focusing light on one side and the diffuse light on the other side are changed differently according to the distance to the detection object, a control means 3 can determine the distance to the detection object based on the ratio of the light receiving quantity corresponding to each floodlighting means 1, 2 from a sampling means 5. When the light receiving quantity is below a prescribed level, since the sampling time of the sampling means 5 is adjusted in the state where the primary ratio is maintained in the state where the detection object is positioned on the farthest position on the detection region, a signal can be amplified without being influenced by a noise, and the distance to the detection object can be surely measured. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a distance measuring device that measures a distance to an object located in a detection area using light projection or light reception having different properties.
[0002]
[Prior art]
Japanese Patent Application Laid-Open No. 2000-46516 discloses a distance measuring device for measuring a distance to an object. This device irradiates diffused light and substantially parallel light from two light projecting means having different beams of light toward a detection area, receives each reflected light reflected by an object to be detected by one light receiving means, and receives the amount of received light. By measuring the ratio, the distance is measured while preventing the influence of the reflectance of the object.
[0003]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-46516
[0004]
[Problems to be solved by the invention]
However, when the reflectance of the detected object is low, the amount of diffused light illuminated and reflected on the detected object is smaller than the amount of substantially parallel light received. Therefore, there is a problem that the accuracy of determination of the ratio between the two light receiving amounts is reduced.
[0005]
As a countermeasure against such a problem, it is conceivable to increase the amount of diffused light. However, the deterioration of the light emitting element constituting the light emitting means is accelerated, and there is a limit to increasing the amount of light emitted. In fact, it is actually difficult to increase the accuracy of distance measurement.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to measure a distance to a detected object based on a ratio of a total received light amount of light applied to a detection area. It is an object of the present invention to provide a distance measuring device that can surely measure a distance even if the rate is low.
[0007]
[Means for Solving the Problems]
The present invention is directed to a first light projecting means and a second light projecting means for alternately irradiating different beams of light toward a detection area at different timings, and a detected object irradiated from these light projecting means and positioned in the detection area. A light receiving means for receiving the light reflected by the light emitting means; a sampling means for sampling a light receiving signal output from the light receiving means in accordance with a light emitting timing of each of the light emitting means for a predetermined period; Means for calculating the ratio of the total amount of received light sampled in accordance with the light emission timings of the first light emitting means and the second light emitting means, and an object to be detected based on the ratio calculated by the calculating means. Measuring means for measuring a distance between the light receiving means and the sampling means, and when the total amount of received light sampled according to the light emitting timing of each of the light emitting means is lower than a predetermined level, In which the total amount of received light while maintaining the ratio of the amount is composed of the control means for adjusting the sampling time by the sampling means to above the predetermined level (claim 1).
[0008]
According to such a configuration, since the beams of light from the first light emitting means and the second light emitting means are different, the light receiving signal level from the light receiving means is different depending on the detection distance of the detected object. Therefore, the total amount of received light obtained by the sampling means sampling the light receiving signal from the light receiving means for a predetermined period according to the light emitting timings of the first light emitting means and the second light emitting means is equal to the distance to the detected object. Since the calculation means calculates the ratio of the total amount of received light, the measuring means can measure the distance to the detected object without being affected by the reflectance of the detected object.
[0009]
When the reflectance of the detected object is low, the total amount of received light is insufficient, and the accuracy of measuring the detection distance is reduced.
Therefore, when the total amount of received light is lower than the predetermined level, the control unit adjusts the sampling time by the sampling unit until the total amount of received light exceeds the predetermined level while maintaining the ratio of the total amount of received light. Thus, the total received light amount can be increased while maintaining the ratio of the total received light amount, so that the distance to the detected object can be reliably measured without being affected by noise.
[0010]
The present invention is directed to a first light projecting means and a second light projecting means for alternately irradiating different beams of light toward a detection area at different timings, and a detected object irradiated from these light projecting means and positioned in the detection area. A light receiving means for receiving the light reflected by the light emitting means; a sampling means for sampling a light receiving signal output from the light receiving means in accordance with a light emitting timing of each of the light emitting means for a predetermined period; Means for calculating the ratio of the total amount of received light sampled in accordance with the light emission timings of the first light emitting means and the second light emitting means, and an object to be detected based on the ratio calculated by the calculating means. Measuring means for measuring the distance of the sampler, setting means provided to be operable externally, and setting the sampling time of the sampling means, and a sampler set in the setting means. And control means for adjusting the sampling time of the sampling means so as to be a time.If the total received light amount sampled by the sampling means in accordance with the light emission timing of each of the light emitting means is lower than a predetermined level, The setting means is externally operated until the total received light quantity by the sampling means exceeds a predetermined level while maintaining the ratio of the total received light quantity (claim 2).
[0011]
According to such a configuration, when the total amount of received light obtained by the sampling unit is low, the sampling time of the sampling unit is set long by an external operation on the setting unit. Then, since the control means adjusts the sampling time of the sampling means, the setting means is externally operated while maintaining the ratio of the total received light amount until the total received light amount by the sampling means exceeds a predetermined level. Therefore, the sampling time is not erroneously changed due to the influence of noise or the like, and the distance to the detected object can be reliably measured.
[0012]
In each of the above configurations, it is desirable to adjust the sampling time while maintaining the ratio of the total amount of received light corresponding to the farthest position in a state where the detected object is located at the farthest position in the detection area. .
According to such a configuration, the total amount of received light can be set to a predetermined level or more while maintaining the ratio of the total amount of received light over the entire detection area.
[0013]
Further, the first light projecting means is configured to irradiate a converging light in which a light beam converges toward a detection area, and the second light projecting means irradiates a diffuse light in which a light beam diffuses toward a detection area. (Claim 4).
According to such a configuration, since one beam is a convergent beam and the other beam is a diffuse beam, the ratio of the total amount of received light can be set to the maximum, and the resolution of the detection distance can be increased.
[0014]
Further, in the light emitting area of the first light emitting means and the second light emitting means and the light receiving area of the light receiving means, respective optical axes may be set substantially coaxially.
According to such a configuration, since the light projecting area and the light receiving area are set substantially coaxially, it is possible to set a wide detection area where each area overlaps.
[0015]
Further, the light projecting area of the first light projecting means and the light receiving area of the light receiving means are set to be substantially the same area, and the second light projecting means is provided with a light projecting area of the first light projecting means. The optical axes may be set to intersect so as to form an intersecting light projecting area (claim 6).
According to such a configuration, since there are no structural restrictions and the degree of freedom of design can be increased, it is possible to manufacture the device inexpensively and easily.
[0016]
The present invention provides a light projecting means for irradiating a light of a predetermined beam of light toward a detection area, and a different light receiving area set in the detection area, and a light irradiated from the light projecting means and reflected by a detected object located in the detection area. A first light receiving means and a second light receiving means for receiving light; a sampling means for sampling a light receiving signal output from these light receiving means for a predetermined period to obtain a total amount of received light; A calculating means for calculating a ratio of the total amount of light received by the light receiving means and the second light receiving means; a measuring means for measuring a distance to an object to be detected based on the ratio calculated by the calculating means; If the total received light amount sampled according to the light emission timing of the means is lower than the predetermined level, the total received light amount exceeds the predetermined level while maintaining the ratio of the total received light amount. Are those composed of a control means for adjusting the sampling time by the sampling means to (claim 7).
[0017]
According to such a configuration, the light receiving signals from the two light receiving means for receiving the light emitted from the light emitting means in the different light receiving areas in the detection area are sampled by the sampling means, and the ratio of the total amount of received light is calculated by the calculating means. , The measuring means can measure the distance to the detected object.
[0018]
Here, when the total received light amount by the sampling means is lower than the predetermined level, the sampling time by the sampling means is adjusted until the total received light amount exceeds the predetermined level while maintaining the ratio of the total received light amount. Can be reliably detected.
[0019]
The present invention provides a light projecting means for irradiating a light of a predetermined beam of light toward a detection area, and a different light receiving area set in the detection area, and a light irradiated from the light projecting means and reflected by a detected object located in the detection area. A first light receiving means and a second light receiving means for receiving light; a sampling means for sampling a light receiving signal output from these light receiving means for a predetermined period to obtain a total amount of received light; Calculating means for calculating the ratio of the total amount of light received by the light receiving means and the second light receiving means; measuring means for measuring the distance to the detected object based on the ratio calculated by the calculating means; and Setting means for setting a sampling time of the sampling means; and a sampling means of the sampling means for setting the sampling time set in the setting means. Control means for adjusting the time, wherein when the total received light amount sampled by the sampling means in accordance with the light emitting timing of the light emitting means is lower than a predetermined level, the ratio of the total received light amount is maintained. The setting means is externally operated until the total amount of light received by the sampling means exceeds a predetermined level.
According to such a configuration, the total amount of received light can be adjusted by an external operation.
[0020]
In each of the above configurations, it is desirable to adjust the sampling time while maintaining the ratio of the total amount of received light corresponding to the farthest position in a state where the detected object is located at the farthest position in the detection area. .
According to such a configuration, the total amount of received light can be equal to or higher than a predetermined level while maintaining the ratio of the total amount of received light over the entire detection region.
[0021]
The first light receiving means may be configured such that the light receiving area converges toward the detection area, and the second light emitting means may be configured such that the light receiving area is diffused toward the detection area. Item 10).
According to such a configuration, since one light receiving region converges and the other light receiving region diffuses, the ratio of the total amount of received light can be set to the maximum, and the resolution of the detection distance can be increased.
[0022]
Further, the light projecting area of the light projecting means and the light receiving areas of the first light receiving means and the second light receiving means may be set so that their optical axes are substantially coaxial.
According to such a configuration, since the light projecting area and the light receiving area are set substantially coaxially, it is possible to set a wide detection area where each area overlaps.
[0023]
Further, each optical axis is set coaxially so that the light emitting area of the light emitting means and the light receiving area of the first light receiving means are substantially the same area. Each optical axis may be set to intersect so as to form a light receiving area that intersects the light projecting area.
According to such a configuration, there is no restriction on the structure, and the degree of freedom in design can be increased.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram schematically showing the configuration of the distance measuring device. In FIG. 1, a first light projecting means 1 and a second light projecting means 2 make a predetermined beam of light differently forward when a drive signal is given from a control means (which also serves as a calculating means and a measuring means) 3. Irradiation is performed at the timing. The light receiving means 4 converts the received light into a light receiving signal and outputs the signal to the sampling means 5. The sampling means 5 obtains a total light receiving amount (hereinafter simply referred to as a light receiving amount) by integrating the light receiving signal from the light receiving means 4 for a predetermined period according to the sampling signal from the control means 3 and also determines the end timing of the sampling signal. Is output to the control means 3 in a state where the received light amount is held for a predetermined period from.
[0025]
FIG. 2 is a block diagram showing an electrical configuration of the distance measuring device. In FIG. 2, the first light projecting means 1 includes a light projecting element 6 and a converging lens 7, and irradiates a converging light obtained by converging the light from the light projecting element 6 with the converging lens 7 to a detection area. .
[0026]
The second light projecting means 2 is composed of a light projecting element 8, and irradiates the detection area with diffused light from the light projecting element 8. In this case, the optical axis of the first light projecting means 1 and the second light projecting means The second optical axis 2 intersects with the optical axis 2 so that light from the second light projecting means 2 is not irradiated on the converging lens 7. In the present embodiment, the above-mentioned convergent light and diffused light correspond to “light having different light beams” in the present invention. In short, different beams of light have different irradiation widths of light, so that the degree of change in the amount of received light with respect to the distance differs, and the ratio of the amount of received light changes in accordance with the distance. Such “different beams of light” is not limited to convergent light and diffused light, but may be a combination of convergent light and parallel light, or parallel light and diffused light.
[0027]
The light receiving means 4 includes a light receiving element 9, and the light receiving element 9 is disposed adjacent to the light emitting element 6 constituting the first light emitting means 1. Accordingly, light is received in a condensed state via the converging lens 7 constituting the first light projecting means 1, and the light receiving area of the light receiving means 4 is substantially coaxial with the first light projecting means 1. It is set so as to substantially overlap the light projection area.
[0028]
The sampling means 5 includes a gate circuit 10, an integration circuit 11, and a sample and hold circuit 12. The gate circuit 10 passes the light receiving signal from the light receiving element 9 only during the command period from the control means 3. The integrating circuit 11 integrates the light receiving signal that has passed through the gate circuit 10. The sample hold circuit 12 holds the light receiving integration level integrated by the integration circuit 11 for a predetermined time according to a command from the control means 3. The predetermined time is a time sufficient for an A / D conversion circuit described later to convert an analog signal into a digital signal.
[0029]
The control means 3 mainly includes a CPU 13 and includes an A / D conversion circuit 14, a ROM 15, a mode changeover switch 16, and a monitor LED 17. The CPU 13 drives the first and second light emitting means 1 and 2 alternately to emit light, and causes the sampling means 5 to perform a sampling operation in accordance with each light emitting timing. The A / D conversion circuit 14 converts the amount of received light, which is an analog value, into a digital value according to a command from the CPU 13 and outputs the digital value to the CPU 13. Then, the CPU 13 takes in the received light amount digitized by the A / D conversion circuit 14, calculates the ratio of each received light amount, and calculates the ratio of the received light amount to the detected object based on a preset table. To determine the distance.
[0030]
The sampling time of the sampling means 5 is adjusted to a predetermined time when the distance measuring device is shipped from the factory. That is, the first and second light projecting means 1 and 2 are alternately driven in a state where the reference detection object (for example, matte white paper) is sequentially positioned as the detection object from the shortest position to the farthest position in the detection area. Sampling times S1 and S2 are set in advance so that each received light amount detected by the sampling means 5 according to the drive timing is equal to or more than a predetermined level sufficient for distance measurement, and a change in the ratio of received light amounts becomes an ideal ratio change. Is set.
[0031]
In the ROM 15, in addition to the operation program of the CPU 13, a table indicating the relationship between the ratio of the amount of received light and the distance obtained as described above is stored in advance.
The mode switch 16 switches between a detection mode and a setting mode. The detection mode is a mode for executing a normal detection operation, and the setting mode is a mode for adjusting a sampling time.
[0032]
Next, the operation of the above configuration will be described.
To measure the distance to the detected object, the distance measuring device is driven with the mode changeover switch 16 switched to the detection mode. Then, the CPU 13 executes the detection mode in a state where the mode changeover switch 16 is switched to the detection mode.
[0033]
FIG. 3 shows a detection mode of the CPU 13. 3, the CPU 13 drives the light emitting element 6 of the first light emitting means 1 (S101, see FIG. 5A). As a result, the first light (convergent light) is emitted from the light projecting element 6 toward the detection area. Therefore, in a state where the detected object is present in the detection area, the light reflected by the light receiving unit 4 is reflected by the detected object. (See FIG. 5C).
[0034]
The CPU 13 reads the amount of received light according to the drive timing of the first light emitting means 1 (S102). That is, the gate circuit 10 of the sampling means 5 is turned on for a predetermined period. The ON time of the gate circuit 10 is the sampling time S1 preset at the time of factory shipment as described above (see FIG. 5D). As a result, the integration circuit 11 integrates the light reception signal that has passed through the gate circuit 10, so that the light reception signal rises with time and is finally converted into the light reception amount D1 (see FIG. 5E). The received light amount D1 is converted into a digital value in the A / D conversion circuit 14, and the CPU 13 reads the digital value.
[0035]
Subsequently, the CPU 13 drives the second light projecting means 2 (S103, see FIG. 5A), reads the received light amount D2 (S104, see FIG. 5E), and sets the received light amount D2 to the predetermined level Dm. Is exceeded (S105: YES), and the ratio of the received light amount is calculated from the received light amounts D1 and D2 (S106).
[0036]
Here, the first light emitted from the first light emitting means 1 is a converged light, and the light emitting area of the first light emitting means 1 and the light receiving area of the light receiving means 4 are substantially overlapped. The light receiving amount D1 corresponding to the light has a smaller attenuation with respect to an increase in the distance to the detected object (indicated by a broken line in FIG. 7), whereas the second light emitting from the second light emitting means 2 is diffused. Since the light is light, the received light amount D2 corresponding to the second light emission is greatly attenuated (shown by a solid line in FIG. 7). Therefore, since the ratio between the light receiving amounts D1 and D2 changes according to the distance to the detected object, the distance to the detected object can be obtained from the ratio based on the table (S107). In this case, the distance to the object to be detected is uniquely determined by the ratio D1 / D2 of the amount of received light corresponding to the first light emission and the second light emission, and thus is not affected by the reflectance of the object to be detected. Is the feature.
[0037]
When the received light amounts D1 and D2 are equal to or higher than a predetermined level, the distance to the detected object can be accurately detected at all positions in the detection area as described above, but the reflectance of the detected object is high. If the value is low, the amount of received light becomes excessively small and is likely to be affected by noise, so that the distance measurement based on the ratio of the amount of received light may become uncertain. Therefore, when the amount of received light corresponding to the second light emission falls below a predetermined level, the CPU 13 notifies an error using the monitor LED 17 (S108).
[0038]
When the reflectance of the detected object is extremely low, the light receiving amount D1 corresponding to the first light emission in addition to the second light emission may fall below a predetermined level Dm. When the received light amount D1 is lower than the predetermined level Dm, the received light amount D2 corresponding to the second light projection is also always lower than the predetermined level Dm. Therefore, the received light amount is determined only by the light received amount D2 corresponding to the second light projection. Is fine.
[0039]
When an error is notified by the monitor LED 17 of the distance measuring device as described above, the user sets the mode changeover switch 16 to the setting mode with the detected object positioned at the farthest position in the detection area. Switch. Then, the CPU 13 executes the setting mode with the mode changeover switch 16 switched to the setting mode.
[0040]
FIG. 4 shows a setting mode of the CPU 13. In FIG. 4, the CPU 13 drives the second light projecting means 2 (S201), and reads the amount of received light with a sampling time S2 in accordance with the light projecting timing of the second light projecting (S202). As a result, the second light projecting means 2 irradiates the detection area with the second light (diffused light), and the second light is reflected by the object to be detected. The received light amount D2 corresponding to the light is input. At this time, the light reception amount D2 becomes lower than the predetermined level Dm (see FIG. 6E). Note that, depending on the reflectance of the detected object, the received light amount D1 corresponding to the first light projection may be lower than the predetermined level Dm.
[0041]
Here, the CPU 13 extends the sampling time S2 of the second light projecting means 2 by the predetermined time α since the received light amount D2 corresponding to the second light projection is below the predetermined level Dm (S203: NO) ( S209) When the amount of received light reaches or exceeds the predetermined level Dm (see FIG. 6 (E ')), the sampling time is set as the sampling time S2 of the second light emission (see FIG. 4 (D')).
[0042]
At this time, since only the received light amount D2 corresponding to the second light projection is increased, the ratio of the received light amount corresponding to each light projection changes from the original value (the ratio of the received light amount corresponding to the farthest position). ing.
Therefore, when the light reception amount corresponding to the second light emission is increased by extending the sampling time S2 as described above, the CPU 13 reads the ratio X of the light reception amount at the farthest position from the table (S204), and performs the first light emission. While driving the light means 1 (S205), the light reception is read for a sampling time S1 according to the light emission timing of the first light emission means 1 (S206), and it is determined whether the ratio D1 / D2 of the light reception amount is X or more. (S207).
[0043]
At this time, since the ratio D1 / D2 of the light reception amount is smaller than X (S207: NO), the light reception amount D1 corresponding to the first light emission is extended by extending the sampling time S1 of the first light emission by a predetermined time α. It increases (S210), and when the ratio D1 / D2 of the amount of received light becomes X or more (S207: YES, see FIG. 6 (E ')), the monitor LED 17 notifies that the setting has been completed (S208). Then, the setting mode ends.
[0044]
In addition, even if the light reception amount D1 corresponding to the first light projection is equal to or less than the predetermined level Dm, the first light reception amount D2 corresponding to the second light emission is adjusted to be equal to or higher than the predetermined level Dm. Since the light reception amount D1 corresponding to the light projection is always equal to or higher than the predetermined level Dm, it is not necessary to determine whether the light reception amount D1 corresponding to the first light emission is equal to or higher than the predetermined level Dm.
The adjustment of the sampling times S1 and S2 as described above is, of course, within a period in which the light receiving signal corresponding to each light projection is valid.
[0045]
When the end of the setting is notified by the monitor LED 17, the user operates the mode changeover switch 16 to set the detection mode.
When the detection mode is set, the CPU 13 detects the light reception amounts D1 and D2 corresponding to the first and second light projections based on the sampling times S1 and S2 set in the setting mode, and calculates a ratio between the light reception amounts. The distance to the detected object is obtained based on the table. Therefore, when the detected object is located in the detection area, not only the light reception amount D1 corresponding to the first light emission but also the light reception amount D2 corresponding to the second light emission is equal to or more than the predetermined level Dm. The distance to the object to be detected can be accurately measured based on the ratio of the two received light amounts.
[0046]
In the case where an object to be detected having a high reflectance is detected in a state where the sampling time is set to be longer than the reference sampling time as described above, in particular, the amount of light received corresponding to the first light emission is excessively large. In such a case, the sampling time is returned to the reference time because the distance becomes high and the distance measurement becomes uncertain.
[0047]
According to such an embodiment, in a configuration in which the amount of received light corresponding to the first light emission and the second light emission of different beams of light is obtained, and the distance to the detected object is obtained based on the ratio of the amounts of received light, When the received light amount is equal to or less than the predetermined level, the setting mode is executed so that the ratio of the received light amounts D1 and D2 corresponding to the respective light projections exceeds the predetermined level while maintaining the initial ratio. Since the sampling times S1 and S2 of the received light signal are adjusted, the signal can be amplified without being affected by noise, and the distance to the detected object can be reliably measured.
[0048]
In addition, since the resolution of distance measurement can be increased as the ratio of the light receiving level greatly changes depending on the distance, one of the two is focused light and the other is focused so that the ratio of the light receiving level greatly changes as in the present embodiment. It is desirable that both beams of light greatly differ by making the light a diffused light.
[0049]
Further, since the optical axis of the second light projecting means 2 is provided so as to intersect the optical axis of the first light projecting means 1, the first light projecting means 1 and the second light projecting means 2 are arranged in parallel. Compared to the first embodiment, although the light is converged by the converging lens 7 as the first light projecting means 1, the diffused light from the second light projecting means 2 is efficiently transmitted to the detection area without being affected by the converging lens 7. Since irradiation can be performed, the degree of freedom in design can be increased and the device can be easily manufactured at low cost.
[0050]
(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. 8, and the same parts as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted. The second embodiment is characterized in that one light beam is substantially parallel light.
[0051]
In FIG. 8 showing the configuration of the first light projecting means 1 and the second light projecting means 2, the first light projecting means 1 comprises a light projecting element 6 and a collimator lens 21. The light is converted by the collimator lens 21 into parallel light. That is, one is a parallel light and the other is a diffused light. In addition, the light receiving area of the light receiving means 4 substantially matches the light emitting area of the first light emitting means 1.
[0052]
According to such an embodiment, since one of the light from the light projecting means 1 is a parallel light and the other is a diffused light, the change in the ratio of the received light amount corresponding to the distance is small, and the detection accuracy is accordingly small. It is possible to detect an object to be detected which has a low reflectance, though it is low.
[0053]
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is characterized in that an optical fiber is used.
In FIG. 9 showing the first light projecting means, the second light projecting means, and the light receiving means, each light projecting optical fiber 31, 32 and light receiving optical fiber 33 constituting each means are arranged adjacent to each other. The optical axes of the optical fibers 31 to 33 are set substantially coaxially. In this case, the light projecting area of each of the light projecting optical fibers 31 and 32 and the light receiving area of the light receiving optical fiber 33 depend on the opening angle of the optical fiber, and the characteristics can be set according to the type of the optical fiber. it can.
[0054]
According to such an embodiment, the optical axes of the light projecting optical fibers 31 and 32 and the light receiving optical fiber 33 can be set substantially coaxially, so that the region where the light projecting region and the light receiving region overlap each other is reduced. It can be set to the maximum, and the detection area can be set to the maximum.
By mounting a lens at the end of the optical fiber, the light emitting area of each light emitting means and the light receiving area of the light receiving means may be set.
[0055]
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is characterized in that one light projecting means is provided and two light receiving means are provided.
[0056]
In FIG. 10 showing the configuration of the light projecting means and the light receiving means, a convergent light is emitted from the light projecting means 1 and a first light receiving means 41 and a second light receiving means 42 are provided. 1 is received. In this case, the first light receiving means 41 has a light receiving area substantially the same as the light emitting area of the light emitting means 1. Further, the optical axis of the second light receiving means 42 is set so as to intersect with the optical axis of the first light receiving means 41, so that the second light receiving means 42 has a high degree of freedom in arrangement.
[0057]
According to such an embodiment, the light emitted from the light emitting means 1 and received by the two light receiving means 41 and 42 having different light receiving characteristics depending on the distance with respect to the light reflected by the detected object is received. Therefore, as in the first embodiment, when the amount of received light is equal to or less than the predetermined level, the sampling time is extended until the amount of received light exceeds the predetermined level, so that the distance to the detected object can be accurately determined. Can be measured.
[0058]
The present invention is not limited to the above embodiments, and can be modified or expanded as follows.
As the first and second light projecting means, means for irradiating any two rays of diffused light, focused light, and parallel light may be combined.
Regarding the adjustment of the sampling time, in each of the above embodiments, the adjustment of the sampling time was an automatic operation of the CPU in the setting mode. The sampling time may be set while observing the quantity waveform, and the control means may adjust the sampling time to be the set sampling time.
[0059]
When an error is notified, the setting mode may be executed in a state where the detected object is located at the position where the error has been notified. In this case, it is necessary to provide the distance measuring device with the distance to the detected object.
When the sampling time S2 corresponding to the second light emission is adjusted, the sampling time S1 corresponding to the first light emission may be adjusted so as to have a ratio of the initial sampling time. In this case, there is no need to provide the distance measuring device with the distance to the detected object, so that the setting mode may be executed with the detected object positioned at the position where the error has been reported, and the usability is excellent.
[0060]
【The invention's effect】
As is clear from the above description, according to the distance measuring device of the present invention, when the sampled total received light amount is lower than the predetermined level, the total received light amount exceeds the predetermined level while maintaining the ratio of the total received light amount. Since the sampling time is adjusted up to, in the configuration that measures the distance to the detected object based on the ratio of the total amount of light received on the detection area, even if the reflectance of the detected object is low, It has an excellent effect that the distance can be measured.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing an overall configuration according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing an electrical configuration.
FIG. 3 is a flowchart showing the operation of a CPU in a detection mode.
FIG. 4 is a flowchart showing an operation of a CPU in a setting mode.
FIG. 5 is a diagram showing an output state of each signal.
FIG. 6 is a diagram corresponding to FIG. 5, showing a sampling time adjustment state.
FIG. 7 is a diagram showing a relationship between a detection distance and a received light amount corresponding to each light projection.
FIG. 8 is an arrangement diagram of an optical system according to a second embodiment of the present invention.
FIG. 9 is a view corresponding to FIG. 8, showing a third embodiment of the present invention;
FIG. 10 is a view corresponding to FIG. 8, showing a fourth embodiment of the present invention;
[Explanation of symbols]
1 is a first light projecting means, 2 is a second light projecting means, 3 is a control means (computing means, measuring means), 4 is a light receiving means, 5 is a sampling means, 31 and 32 are light projecting optical fibers (light projecting means). Means), 33 is a light receiving optical fiber (light receiving means), 41 is a first light receiving means, and 42 is a second light receiving means.

Claims (12)

A first light projecting means and a second light projecting means for alternately irradiating different beams of light toward the detection region at different timings;
Light receiving means for receiving light emitted from these light emitting means and reflected by the detected object located in the detection area;
Sampling means for obtaining a total amount of received light by sampling a light receiving signal output from the light receiving means in accordance with a light emitting timing of each of the light emitting means for a predetermined period;
Calculating means for calculating the ratio of the total amount of received light sampled by the sampling means in accordance with the light emitting timings of the first light emitting means and the second light emitting means;
Measuring means for measuring the distance to the detected object based on the ratio calculated by the calculating means,
If the total received light amount sampled by the sampling means according to the light emitting timing of each of the light emitting means is lower than a predetermined level, the total received light amount exceeds the predetermined level while maintaining the ratio of the total received light amount. A distance measuring device, comprising: a control unit for adjusting a sampling time by the sampling unit. A first light projecting means and a second light projecting means for alternately irradiating different beams of light toward the detection region at different timings;
Light receiving means for receiving light emitted from these light emitting means and reflected by the detected object located in the detection area;
Sampling means for obtaining a total amount of received light by sampling a light receiving signal output from the light receiving means in accordance with a light emitting timing of each of the light emitting means for a predetermined period;
Calculating means for calculating the ratio of the total amount of received light sampled by the sampling means in accordance with the light emitting timings of the first light emitting means and the second light emitting means;
Measuring means for measuring the distance to the detected object based on the ratio calculated by the calculating means,
Setting means provided so as to be able to be operated externally, and setting a sampling time of the sampling means;
Control means for adjusting the sampling time of the sampling means so as to be the sampling time set in the setting means,
If the total received light amount sampled by the sampling means in accordance with the light emission timing of each of the light projecting means is lower than a predetermined level, the total received light amount by the sampling means is reduced to a predetermined level while maintaining the ratio of the total received light amount. A distance measuring device, wherein the setting means is operated externally until the distance exceeds a predetermined value. 3. The distance according to claim 1, wherein the sampling time is adjusted while maintaining the ratio of the total amount of received light corresponding to the farthest position in a state where the detected object is located at the farthest position in the detection area. measuring device. The first light projecting means is configured to irradiate a converging light in which a beam of light converges toward a detection area,
The distance measuring device according to claim 1, wherein the second light projecting unit is configured to irradiate a diffused light in which a beam of light is diffused toward a detection area. 5. The light emitting area of the first light emitting means, the light emitting area of the second light emitting means, and the light receiving means, each optical axis of which is set substantially coaxially. Distance measuring device. The light emitting area of the first light emitting means and the light receiving area of the light receiving means are set to be substantially the same area,
5. The optical system according to claim 1, wherein the second light projecting means is set so that respective optical axes intersect so as to form a light projecting area intersecting with the light projecting area of the first light projecting means. 6. The distance measuring device according to any one of the above. Light emitting means for irradiating a predetermined beam of light toward the detection area,
A different light receiving area is set in the detection area, a first light receiving means and a second light receiving means for receiving light emitted from the light projecting means and reflected by a detected object located in the detection area,
Sampling means for obtaining the total amount of received light by sampling light receiving signals output from these light receiving means for a predetermined period;
Calculating means for calculating the ratio of the total amount of received light of the first light receiving means and the second light receiving means sampled by the sampling means;
Measuring means for measuring the distance to the detected object based on the ratio calculated by the calculating means,
If the total received light amount sampled by the sampling means in accordance with the light emitting timing of the light emitting means is lower than a predetermined level, the sampling is performed until the total received light amount exceeds a predetermined level while maintaining the ratio of the total received light amount. And a control unit for adjusting a sampling time by the unit. Light emitting means for irradiating a predetermined beam of light toward the detection area,
A different light receiving area is set in the detection area, a first light receiving means and a second light receiving means for receiving light emitted from the light projecting means and reflected by a detected object located in the detection area,
Sampling means for obtaining the total amount of received light by sampling light receiving signals output from these light receiving means for a predetermined period;
Calculating means for calculating the ratio of the total amount of received light of the first light receiving means and the second light receiving means sampled by the sampling means;
Measuring means for measuring the distance to the detected object based on the ratio calculated by the calculating means,
Setting means provided so as to be able to be operated externally, and setting a sampling time of the sampling means;
Control means for adjusting the sampling time of the sampling means so as to be the sampling time set in the setting means,
If the total received light amount sampled by the sampling means according to the light emission timing of the light emitting means is lower than a predetermined level, the total received light amount by the sampling means exceeds a predetermined level while maintaining the ratio of the total received light amount. A distance measuring device, wherein the setting means is externally operated until the setting is completed. 9. The distance according to claim 7, wherein the sampling time is adjusted while maintaining the ratio of the total amount of received light corresponding to the farthest position in a state where the detected object is located at the farthest position in the detection area. measuring device. The first light receiving unit is configured such that the light receiving region converges toward the detection region,
The distance measuring device according to any one of claims 7 to 9, wherein the second light projecting means is configured so that a light receiving region is diffused toward a detection region. 11. The light-emitting area of the light-emitting means and the light-receiving areas of the first light-receiving means and the second light-receiving means, wherein respective optical axes are set substantially coaxially. The distance measuring device as described. Each optical axis is set coaxially so that the light emitting area of the light emitting means and the light receiving area of the first light receiving means are substantially the same area,
11. The optical system according to claim 7, wherein the second light receiving unit is set so that the respective optical axes intersect so as to form a light receiving region that intersects with a light projecting region of the light projecting unit. Distance measuring device.

Images