Apparatus and method for detecting transparent substances

Abstract

A semiconductor light-emitting device which emits first light of a wavelength absorbed by a substance containing an OH group is sent toward a detection object. A semiconductor light-emitting device emits second visible light toward the detection object. A photoreceptor receives light from the detection object and acquires first and second received light-quantities derived from the respective ones of the first and second light. A processing system corrects the first photoreceiving quantity on the basis of the second photoreceiving quantity. The processing system determines the color of the detection object by the second photoreceiving quantity, and corrects the first photoreceiving quantity on the basis of this determination result. Further, it compares the corrected first photoreceiving quantity with a prescribed threshold value, detects whether or not water, which is the subject containing the OH group, is contained in the detection object, and outputs the same as an output signal.

We claim:  
     
       1. A device which determines whether a substance contains an OH groups  group, said device comprising: 
       a semiconductor light emitting device  laser which generates light having a wavelength between 1.40 μm to 1.50 μm, said light being applied to a substance;  
       a photoreceptor responsive to light which originated from said semiconductor light emitting device  laser and is received from said substance, said photoreceptor generating an output as a function thereof; and  
       a comparator which compares said output with a threshold value and generates a detection signal in response to the comparison, said detection signal indicating whether said substance contains an OH group.  
     
     
       2. The device in accordance with  claim 1 , further comprising: 
       a first optical guide which guides light from said semiconductor light emitting device  laser to said substance, and  
       a second optical guide which guides light from said substance to said photoreceptor.  
     
     
       3. The switching  device in accordance with  claim 1 , further comprising: 
       a controller which is effective to change said prescribed  threshold value.  
     
     
       4. A device which determines whether a substance contains a CH 2  or CH 3  group, said device comprising: 
       a semiconductor light emitting device  laser which generates light having a wavelength between 1.60 μm to 1.80 μm, said light being applied to a substance;  
       a photoreceptor responsive to light which originated from said semiconductor light emitting device  laser and is received from said substance, said photoreceptor generating an output as a function thereof; and  
       a comparator which compares said output with a threshold value and generates a detection signal in response to the comparison said detection signal indicating whether said substance contains a CH 2  group or a CH 3  group.  
     
     
       5. The device in accordance with  claim 4 , further comprising: 
       a first optical guide which guides light from said semiconductor light emitting device  laser to said substance, and  
       a second optical guide which guides light from said substance to said photoreceptor.  
     
     
       6. The photoelectric switching  device in accordance with  claim 4 , further comprising: 
       a controller which is effective to chance  change said threshold value.  
     
     
       7. A device which detects the existence of a substance, disposed within or upon an object, said substance containing an OH group, a CH 2  group, or a CH 3  group and producing a detection signal in response thereto, said device comprising: 
       a first light source in the form of a semiconductor light emitting element which generates a first light having a first wavelength between 1.40 μm to 1.50 μm or between 1.60 μm to 1.80 μm, said first light being applied to said substance  an object;  
       a second light source which generates a second light of a second wavelength different from said first wavelength, said second light being applied to said substance;  
       a photoreceptor responsive to light which originated from said first and second light sources and is received from said substance, said photoreceptor generating first and second outputs in response to receiving said light from said first and second light sources; and  
       a signal generator which generates said detection signal in response to said first and second outputs, said signal generator having a first comparator which compares said second output with a conditional threshold value and produces a comparison result in response to the comparison of said first comparator, a first amplifier which modifies said first output in response to said comparison result thereby producing a modified first output, and a second comparator which compares said modified first output with a detection threshold value and generates said detection signal in response to the comparison of said second comparator,  
       
         wherein said first light and second light are affected by a surface state of said object, said first wavelength is included in an absorption band of said substance, and said second wavelength is excluded from said absorption band.  
       
     
     
       8. The photoelectric switching device in accordance with  claim 7 , wherein said signal generator further comprises: 
       a third comparator which compares said second output with a second conditional threshold value which is adjustable and produces, in response to the comparison of said third comparator, another comparison result; and  
       a second amplifier which modifies said first output in response to said another comparison result.  
     
     
       9. The device in accordance with  claim 7 , wherein said first and second lights of different wavelengths are visible light and invisible light, respectively. 
     
     
       10. The device in accordance with  claim 7 , wherein said signal generator further comprises: 
       a controller which is effective to change said detection threshold value.  
     
     
       11. The device in accordance with  claim 7 , further comprising: 
       a fiber unit which guides said first and second lights of different wavelengths on a single optical path.  
     
     
       12. The device in accordance with  claim 7 , wherein said signal generator further comprises: 
       a controller which is effective to change said conditional threshold value.  
     
     
       13. The device in accordance with  claim 7 , further comprising: 
       a light control  controller which controls a turning-on and turning-off said light sources independently.  
     
     
       14. The device in accordance with  claim 9 , further comprising: 
       a third comparator which compares said second output with a gate threshold value and generates a gate signal in response to the comparison of said third comparator, said gate signal indicating a presence of said detection object;  
       a fourth comparator which compares said first output with a detection threshold value and generates another detection signal in response to the comparison of said fourth comparator; and  
       a gate which combines said another detection signal with said gate signal thereby generating said detection signal.  
     
     
       15. A method of detecting the presence of  a substance containing an OH group, said method comprising: 
       applying light having a wavelength between 1.40 μm to 1.50 μm from a semiconductor light emitting device  laser toward a substance;  
       generating an output responsive to light originating from said semiconductor light emitting device  laser and received from said substance; and  
       comparing said output with a prescribed threshold value and generating a detection signal indicating whether said substance contains an OH group.  
     
     
       16. A method of detecting a substance containing a CH 2  group or a CH 3  group, said method comprising: 
       applying light of a wavelength between 1.60 μm to 1.80 μm from a semiconductor light emitting device  laser toward a substance;  
       generating an output responsive to light originating from said semiconductor light emitting device  laser and received from said substance; and  
       comparing said output with a prescribed threshold value and generating a detection signal indicating whether said substance contains a CH 2  group or a CH 3  group.  
     
     
       17. A method of detecting the existence of a substance, disposed within or upon an object, said substance containing one of  an OH group, a CH 2  group, or a CH 3  group, said method comprising: 
       applying first light having a first wavelength between 1.40 μm to 1.50 μm or between 1.60 μm to 1.80 μm toward a substance, said first light being generated by a semiconductor light emitting device;  
       applying second light of a second wavelength different from said first wavelength toward said substance, said second light being generated by a second light source;  
       generating first and second outputs responsive to light originating from said light sources and received from said substance;  
       first comparing said second output with a conditional threshold value and producing a comparison result in response to said first comparing;  
       modifying said first output in response to said comparison result, thereby producing a modified first output; and  
       second comparing said modified first output with a detection threshold value and generating, in response to said second comparing, said detection signal which indicates the existence of a substance containing one of an OH group, a CH 2  group, or a CH 3  group,  
       
         wherein said first light and second light are affected by a surface state of said object, said first wavelength is included in an absorption band of said substance, and a second wavelength is excluded from said absorption band.  
       
     
     
       18. The method in accordance with  claim 17 , further comprising: 
       pre-applying said first and second light upon an adjusting object and  
       adjusting said detection threshold value and said conditional threshold value on the basis of light received from said adjusting object before performing said applying first light and applying second light.  
     
     
       19. The switching  method in accordance with  claim 17 , wherein said step of modifying comprises: 
       multiplying said first output by a prescribed value in response to said second output and said detection signal  comparison result.  
     
     
       20. The method in accordance with  claim 17 , further comprising: 
       third comparing said second output with a gate threshold value and generating a gate signal in response to said third comparing, said gate signal indicating a presence of an object having said substance disposed within or upon said object; and  
       deciding whether or not said detection signal is to be outputted in response to said gate signal.  
     
     
       21. A device which detects the existence of a substance, disposed within or upon an object, containing one of an OH group, a CH 2  group, or a CH 3  group, said device comprising: 
       a first light source in the form of a semiconductor light emitting element which generates a first light having a wavelength between 1.40 μm to 1.50 μm or between 1.60 μm to 1.80 μm, said first light being applied to a region of said object;  
       a second light source which generates visible light being applied to said object, wherein said visible light [indicates] points out said region of said object; 
       a second light source which generates visible light being applied to said object, wherein said visible light points out said region of said object;  
       a photoreceptor responsive to said first light originating from said first light source and received from said substance, said photoreceptor generating an output which is a function of said first light; and  
       a signal generator which generates a detection signal in response to said output, indicating whether said substance contains one of an OH group, a CH 2  group, or a CH 3  group.  
     
     
       22. A device which detects the existence of a substance, disposed within or upon an object, said substance having one of  an OH group, a CH 2  group, or a CH 3  group, said device comprising: 
       at least a first light source in the form of a semiconductor light emitting device  laser and which emanates a first light toward said substance  object, said first light having a first wavelength, said first wavelength being selected so that one of a reflection and an  absorption of said first light is affected by whether said substance contains one of  an OH group, a CH 2  group, or a CH 3  group;  
       a photoreceptor disposed so as to receive received light which originated from said first light source, said received light being received from said substance  object; and  
       a controller which analyzes characteristics of said received light which was received by said photoreceptor and determines said existence of a substance having one of  an OH group, a CH 2  group, or a CH 3  group.  
     
     
       23. The device as claimed in  claim 22  further comprising: 
       an object having said substance disposed within or upon said object; and 
       at least a second light source which emanates a second light toward said substance, said second light having a second wavelength, said second wavelength being selected so that one of a  reflection and an absorption  of said second light is affected by a surface state of said object;  
       wherein said photoreceptor is responsive to light which originated from said second light source and is received from said substance  object.  
     
     
       24. A method of detecting the existence of a substance, disposed within or upon an object, said substance having containing one of  an OH group, a CH 2  group, or a CH 3  group, said method comprising: 
       applying to said substance  object a first light having a first wavelength and originating from a semiconductor light emitting device  laser, said first wavelength being selected so that one of a reflection and an  absorption of said first light is affected by whether said substance contains one of  an OH group, a CH 2  group and a Ch 3  group;  
       receiving received light which originated from said first light and which has been received from said substance  object; and  
       analyzing characteristics of said received light to determine whether said substance contains one of  an OH group, a CH 2  group or a CH 3  group.  
     
     
       25. The method as claimed in  claim 24  further comprising: 
       applying to an  said object a second light having a second wavelength, said second wavelength being selected so that one of a  reflection and an absorption  of said second light is affected by a surface state of an  said object, said object having said substance disposed within or upon said object .