Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1997-03-18
2001-04-03
Tong, Nina (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S436000, C340S903000, C340S815530
Reexamination Certificate
active
06211784
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an object detector, an object detector system, a display device for object detectors, and a setting device for object detectors.
Object detectors such as photoelectric switches, proximity switches, ultrasonic switches have heretofore been used for detecting the presence or absence of a moving object along production lines in plants (or factories). For example, a photoelectric switch determines the presence or absence of an object by projecting light onto the conveying path of an object and detecting the presence or absence of reflected light or transmitted light from the object.
In a photoelectric switch of a transmitting type, in the case where there is no object to be detected in a sensing region, light emitted from the light-emitting section is received by the light-receiving section. In this case, when the level of light received is equal to or smaller than a predetermined threshold, it is judged that the object is present. On the other hand, in a photoelectric switch of a reflecting type, in the case where there is an object to be detected in the sensing region, light emitted from the emitting section is reflected by the object, and the reflected light is received by the light-receiving section. In this case, when the level of light received exceeds a predetermined threshold, it is judged that the object is present. The sensitivity of the photoelectric switch is adjusted by changing the aforementioned threshold (operative level).
The thus operating photoelectric switches may, in some cases, face the problem that the level of light received is reduced due to such causes as displaced optical axis, stained light-emitting or light-receiving surfaces, or deteriorated performance of the light-emitting element of the light-emitting section. In these cases, it is necessary to re-set the sensitivity by changing the threshold of the photoelectric switch.
To overcome this problem, photoelectric switches of an automatic sensitivity setting type which can set the sensitivity automatically are being developed. Automatic sensitivity setting photoelectric switches sample received light quantities by a control input from an external device and set a threshold based on groups of data obtained by causing a microcomputer or the like to calculate the sampled data.
In the aforementioned automatic sensitivity setting type photoelectric switch, a threshold is automatically set within the photoelectric switch so that the sensitivity of the photoelectric switch becomes proper. However, the operator is not informed of a set threshold, nor can he finely adjust the set threshold so as to match a measuring environment.
On the other hand, some conventional photoelectric switches display the level of light received by using a plurality of light-emitting diodes (LED). However, the operator is not informed of a correct quantity of light received, nor can he be informed of a currently set threshold. Thus, a margin of the quantity of light received with respect to the currently set threshold cannot be recognized. As a result, the operator cannot know the timing at which to re-set the sensitivity, either.
Moreover, in a photoelectric switch system having a plurality of photoelectric switches, a respective threshold must be set for each photoelectric switch. In an automatic sensitivity setting type photoelectric switch system in particular, each photoelectric switch has a threshold automatically set. In this case, the operator is not informed of a threshold set for each photoelectric switch, nor can he be informed of the level of light received of each photoelectric switch correctly, either. Further, he cannot make a fine adjustment of the threshold set for each photoelectric switch so as to match a measuring environment, either.
An object of the present invention is to provide an object detector system including an object detector that allows the operator to be informed of a set threshold or a detected quantity correctly.
Another object of the present invention is to provide an object detector system including an object detector that allows the operator to finely adjust a set threshold.
Still another object of the present invention is to provide a display device for object detectors that can display the threshold or detected quantity of an object detector correctly.
Still another object of the present invention is to provide a setting device for object detectors that can finely adjust the threshold of an object detector.
SUMMARY OF THE INVENTION
An object detector according to a first aspect of the invention includes: detecting means for outputting a detected quantity based on the presence or absence of an object to be detected; setting means for setting a threshold; a comparing means for comparing the detected quantity obtained by the detecting means with the threshold set by the setting means and outputting a detected result; and display means for numerically displaying either the detected quantity obtained by the detecting means or the threshold set by the setting means.
An object detector according to a second aspect of the invention further includes adjusting means for adjusting the threshold set by the setting means in the construction of the object detector according to the first aspect of the invention.
According to a third aspect of the invention, in the object detector according to the first and the second aspects of the invention, the setting means further includes automatic setting means for determining, at a setting operation, the threshold based on a detected quantity of the presence of the object and a detected quantity of the absence of the object.
In the object detectors according to the first, the second, and the third aspects of the invention, not only the detected result is outputted by comparing the detected quantity obtained by the detecting means with the threshold set by the setting means, but also the detected quantity obtained by the detecting means or the threshold set by the setting means is numerically displayed. Therefore, the operator is informed of the detected quantity or the set threshold correctly.
In the object detector according to the second aspect, of the invention in particular, the threshold set by the setting means can be adjusted by the adjusting means. Therefore, the operator can finely adjust the preset threshold so as to match a measuring environment.
Further, in the object detector according to the third aspect of the invention, the setting means includes the automatically setting means. Therefore, the threshold is automatically set based on detected quantities to be obtained by the detecting means at the time a setting operation is performed, the detected quantities being obtained at the time a detecting operation is performed and at the time a detecting operation is not performed. In this case, the automatically set threshold is numerically displayed. Hence, the operator is informed of the automatically set threshold correctly.
An object detector according to a fourth aspect of the invention includes: detecting means for outputting a detected quantity based on the presence or absence of an object to be detected; setting means for setting a threshold; comparing means for comparing the detected quantity obtained by the detecting means with the threshold set by the setting means and outputting a detected result; and display means for numerically displaying a detection ratio of the detected quantity obtained by the detecting means with respect to the threshold set by the setting means.
In the object detector according to the fourth aspect of the invention, not only the detected result is outputted by comparing the detected quantity obtained by the detecting means with the threshold set by the setting means, but also the detection ratio of the detected quantity obtained by the detecting means with respect to the threshold set by the setting means is numerically displayed. Therefore, the operator can recognize a margin of the detected quantity with respect to the set threshold. As a result, the operator c
Keyence Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
Tong Nina
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