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CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This application is a Continuation of U.S. application Ser. No. 12/612,292, filed Nov. 4, 2009, which claims priority to China P.R. Priority Application 200810202228.3, filed Nov. 5, 2008. Both U.S. Ser. No. 12/612,292 and China P.R. Priority Application 200810202228.3 are incorporated by reference in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a distance detecting sensor applicable in the technical field of sanitary automation (e.g., automatic sensing faucets, automatic flushing urinals, etc.) and a close range detecting method of the distance detecting sensor. 
       BACKGROUND ART 
       [0003]    Infrared sensors have been widely used in sanitary wares, such as automatic faucets, automatic flushing urinals, toilet flushing devices, hot water spraying toilet seats, hand driers, and toilets provided with hot air fan. 
         [0004]    Most conventional infrared sensors adopt an active infrared detection manner, in which an infrared emitter emits an infrared light at a specific wavelength, the infrared light is reflected from human body and the signal strength of the reflected signal is judged after being received by an infrared receiver, thereby to achieve automatic sensing and judgment. However, it is difficult to achieve the automatic sensing and judgment for substances with low infrared reflectivity (e.g., black clothing, hair, etc.). After the infrared light from the infrared emitter is reflected by such substances, only a small amount of infrared light is received by the infrared receiver. Since the intensity of reflected signal is not high enough, the sensor is unable to judge whether there exists an object, and therefore the sensing fails. 
         [0005]    In order to solve the sensing failure problem of conventional infrared sensing sanitary ware, a distance detecting sensor is introduced into the field of sanitary automation. As shown in  FIG. 1 , a position detecting sensor, or called as position sensitive detector (PSD) is a photoelectric device that is sensitive to the position of incident light. That is to say, when the incident light irradiates at different positions on the photosensitive surface of the device, different electric signals can be outputted. The PSD achieves automatic detection and judgment by utilizing the triangular measurement principle with which distance can be measured accurately. As shown in  FIG. 1 , the light emitted from the light emitting source S.sub.1 is focused by a lens L 1  and then projected onto the surface of an object O 1  to be detected. The reflected light is focused by a lens L 2  onto a one dimensional PSD (i.e., a receiving unit P 1 ), and forms a light spot. Suppose the center distance between lens L 1  and L 2  is b, the distance from lens L 2  to the surface of the PSD (i.e., focal length of lens L 2 ) is f, and the distance from the light spot focused on the surface of the PSD to the center of lens L 2  is x, it can be obtained based on the nature of similar triangles PAB and BCD that the distance DIS to be measured will be DIS=bf/x. Therefore, the distance of the object to be detected can be measured as long as the position coordinate x of the light spot on the PSD is obtained. 
         [0006]    If it is detected that the distance of the object O 1  falls within a preset range, the distance detecting sensor will control the operation states, including for example water output, flushing and etc, of the sanitary ware. Since the distance detecting sensor achieve the object of automatic detection by judging the distance between the object and the distance detecting sensor, it can effectively overcome the drawback of sensing failure of conventional infrared sensors. 
         [0007]    However, there are some requirements for detection distance when such a distance detecting sensor is used. If the distance from the object to be detected to the distance detecting sensor is too close, the infrared light emitted from the light emitting source of the distance detecting sensor can&#39;t be focused onto the surface of the PSD, and therefore the detection will fail. For example, when such a distance detecting sensor is mounted on a faucet, if the hands of the user are too close to the distance detecting sensor, sensing failures happen easily. 
         [0008]    Therefore, it is necessary to invent a distance detecting sensor and a method that can effectively overcome the drawback in the prior art. 
       SUMMARY OF THE INVENTION 
       [0009]    The object of the present invention is to provide a distance detecting sensor that can detect more reliably. 
         [0010]    The object of the present invention is attained with the following technical solution: 
         [0011]    a distance detecting sensor mounted in sanitary ware, comprising: an infrared light emitting source, an infrared light receiving unit, and an emitting lens and an receiving lens, arranged in front of the light emitting source and the receiving unit respectively to focus infrared light. The receiving unit is a photo-electric device that is sensitive to the position of infrared light. At least a close range light emitting source is arranged near the light emitting source. The light emitting source and the close range light emitting source are light emitting diodes (LEDs). 
         [0012]    Furthermore, the emission power of the infrared light emitting source is higher than that of the close range light emitting source. 
         [0013]    Furthermore, the emission frequency of the infrared light emitting source and the close range light emitting source is lower when there is no object to be detected than when there is an object to be detected. 
         [0014]    Another object of the present invention is to provide a close range detection method, which makes the distance detecting sensor operates more reliably. 
         [0015]    The above object of the present invention can be attained with the following technical solution: 
         [0016]    A close range detection method of a distance detecting sensor, comprising the following steps: 
         [0017]    Step 1: activating a light emitting source to emit an infrared light, and proceeding to step 2; 
         [0018]    Step 2: judging whether a receiving unit receives a reflected infrared light signal; if the receiving unit receives a reflected infrared light signal, going to step 5; otherwise proceeding to step 3; 
         [0019]    Step 3: activating a close range light emitting source to emit an infrared light, and proceeding to step 4; 
         [0020]    Step 4: judging whether the receiving unit receives a reflected infrared light signal; if the receiving unit receives a reflected infrared light signal, proceeding to step 5; otherwise returning to step 1; 
         [0021]    step 5: calculating the distance value of an object to be detected based on the received infrared light reflected from the object; 
         [0022]    Step 6: judging whether the distance value of the object is within a preset range; if the distance is within the preset range, proceeding to step 7; otherwise returning to step 1; 
         [0023]    Step 7: controlling the action of the sanitary ware. 
         [0024]    Furthermore, the emission power of the light emitting source is higher than that of the close range light emitting source. 
         [0025]    Furthermore, the emission frequency of the light emitting source and the close range light emitting source is lower when there is no object to be detected than when there is an object to be detected. 
         [0026]    Alternatively, the objects of the present invention can be attained with the following technical solution: 
         [0027]    A close range detection method of a distance detecting sensor, comprising the following steps: 
         [0028]    Step 1: activating a light emitting source and a close range light emitting source synchronously to emit an infrared light respectively, and proceeding to step 2; 
         [0029]    Step 2: judging whether a receiving unit receives an reflected infrared light signal; if the receiving unit receives an infrared light signal, proceeding to step 3; otherwise returning to step 1; 
         [0030]    Step 3: calculating the distance value of an object to be detected based on the received infrared light reflected from the object, and proceeding to step 4; 
         [0031]    Step 4: judging whether the distance value of the object is within a preset range; if the distance is within the preset range, proceeding to step 5; otherwise returning to step 1; 
         [0032]    Step 5: controlling the action of the sanitary ware. 
         [0033]    Furthermore, the emission power of the light emitting source is higher than that of the close range light emitting source. 
         [0034]    Furthermore, the emission frequency of the light emitting source and the close range light emitting source is lower when there is no object to be detected than when there is an object to be detected. 
         [0035]    Alternatively, the object of the present invention can be attained with the following technical solution: 
         [0036]    A close range detection method of a distance detecting sensor, comprising the following steps: 
         [0037]    Step 1: activating a close range light emitting source to emit an infrared light, and proceeding to step 2; 
         [0038]    Step 2: judging whether a receiving unit receives an infrared light signal reflected from an object to be detected; if the receiving unit receives a reflected infrared light signal, proceeding to step 3; otherwise returning to step 1; 
         [0039]    Step 3: calculating the distance value of the object to be detected based on the received infrared light reflected from the object, and proceeding to step 4; 
         [0040]    Step 4: judging whether the distance value of the object is within a preset close range; if the distance is within the preset close range, going to step 8; otherwise proceeding to step 5; 
         [0041]    Step 5: activating a light emitting source to emit an infrared light, and proceeding to step 6; 
         [0042]    Step 6: judging whether the receiving unit receives an infrared light signal reflected from the object to be detected; if the receiving unit receives an infrared light signal reflected from the object, proceeding to step 7; otherwise returning to step 1; 
         [0043]    step 7: judging whether the distance value of the object is within a normal range; if the distance value is within the preset normal range, proceeding to step 8; otherwise returning to step 1; 
         [0044]    Step 8: controlling the action of the sanitary ware. 
         [0045]    Furthermore, the emission power of the light emitting source is higher than that of the close range light emitting source. 
         [0046]    Furthermore, the emission frequency of the light emitting source and the close range light emitting source is lower when there is no object to be detected than when there is an object to be detected. 
         [0047]    Compared with the prior art, the close range detection method of the distance detecting sensor provided in the present invention can effectively prevent incorrect operation resulted from mirror interference, make the distance detecting sensor operates more reliably, and thereby improve the overall detection performance of the distance detecting sensor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0048]      FIG. 1  is an operational principal diagram of a distance detecting sensor of the prior art. 
           [0049]      FIG. 2  is a structural schematic diagram of a distance detecting sensor in accordance with the present invention. 
           [0050]      FIG. 3  is a flow chart of a close range detection method of a distance detecting sensor in accordance with an embodiment of the present invention. 
           [0051]      FIG. 4  is a flow chart of a close range detection method of a distance detecting sensor in accordance with another embodiment of the present invention. 
           [0052]      FIG. 5  is a flow chart of a close range detection method of a distance detecting sensor in accordance with still another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0053]    Various embodiments of the present invention will be detailed with reference to the accompanying drawings, in which identical structures or functionalities are designated with the same reference numbers. It is noted that the accompanying drawings are provided only for convenience of explanations of the embodiments, and are not superfluous description or any limitation to the present invention. In addition, the accompanying drawings may not be drawn to scale. 
         [0054]    As shown in  FIG. 2 , the distance detecting sensor  100  in accordance with the present invention includes a light emitting source S 1 , a receiving unit P 1 , an emitting lens L 1  and a receiving lens L 2  arranged in front of the light emitting source S 1  and the receiving unit P 1  respectively. The light emitting source S 1  is an infrared light emitting source, generally an LED. The receiving unit P 1  is a photo-electric device, i.e. a PSD module that is sensitive to the position of incident infrared light on its surface. Specially, a close range light emitting source S 2  is further arranged beside the light emitting source S 1  of the distance detecting sensor  100 . The close range light emitting source S 2  is also an infrared light emitting source, generally an LED. 
         [0055]    As shown in  FIG. 1 , if an object O 1  to be detected is in a normal detection area, the infrared light emitted from the light emitting source S 1  is focused by the emitting lens L 1  and then irradiated onto the object O 1 . The infrared light is reflected from the object O 1 , and the reflected infrared light can be focused by the receiving lens L 2  and then irradiated onto the receiving unit P 1 . Furthermore, the distance from the object O 1  to be detected to the distance detecting sensor  100  of the present invention is calculated on the basis of the PSD triangle principle. If the calculated distance is within the preset range, the distance detecting sensor  100  will control valve-open, valve-close and etc. of the sanitary ware through its main controller and further control actions of the sanitary ware such as water output and flushing. However, if the object O 1  to be detected is too close to the distance detecting sensor  100 , the case is different, specifically described as follows: 
         [0056]    The distance detecting sensor  100  of the present invention is mounted on sanitary ware, such as a faucet or urinal, etc. The object to be detected (e.g., hands or body of the user) is often too close to the distance detecting sensor  100  of the present invention, especially in the situation where the distance detecting sensor  100  is mounted on a faucet, in which the hands of the user tend to stretch out towards the position of the detector (i.e., the distance detecting sensor  100 ). In such a case, the emitted infrared light, after irradiated onto the object to be detected, can not be normally reflected onto or can not be reflected onto the receiving unit and therefore can not be sensed. Thus, the distance detecting sensor  100  can&#39;t detect the object O 1 . This eventually results in non-operation of the corresponding sanitary ware such as faucet and urinal. 
         [0057]    Further, as shown in  FIG. 2 , the infrared light emitted from the light emitting source S 1  reaches the object O 1  to be detected and is reflected from the object O 1 . Since the object O 1  is too close to the distance detecting sensor  100 , the infrared light MB reflected from the object O 1  can&#39;t be focused by the receiving lens L 2  onto the receiving unit  2 . Therefore, the distance detecting sensor  100  of the present invention can&#39;t detect existence of the object O 1 , with the result that the sanitary wares such as faucet and urinal do not operate. 
         [0058]    In view of the above, a close range light emitting source S 2  is arranged beside the light emitting source S 1  of the distance detecting sensor  100 , to specially detect whether any object O 1  exists within a range that is less than the normal detection range (i.e., close range). When the light emitting source S 1  can&#39;t detect the object O 1 , the close range light emitting source S 2  is activated to emit an infrared light. Because the infrared light emission angle of the close range light emitting source S 2  is designed specially for close range detection, if the object O 1  exists within the range that is less than the normal detection range, the light emitted from the close range light emitting source S 2  will irradiate on the object O 1  and will be reflected, and the reflected infrared light NA can be focused by the receiving lens L 2  onto the receiving unit P 1 . Thereby, the distance detecting sensor  100  of the present invention can detect existence of the object O 1  and calculate the distance value, on the basis of triangular principle. If the distance value is within a preset range, the distance detecting sensor  100  of the present invention can control the sanitary wares (faucet, urinal, etc.) by means of its main controller to act (e.g., open the valve, and etc.). The preset distance range described above needs to be configured in advance according to actual application environments, specifically, whenever it is judged that an object to be detected is within the preset distance range, it is believed that some user wants to use or is using a corresponding sanitary ware; and then, the sanitary ware controls the on-off valve before, during and after the use according to actual situations, thereby achieving automatic control of sanitary ware. 
         [0059]    As shown in  FIG. 3 , a close range detection method of the distance detecting sensor  100  in accordance with the present invention mainly comprises the following steps: 
         [0060]    Step 1: activating the light emitting source S 1  to emit an infrared light, and proceeding to step 2; 
         [0061]    Step 2: judging whether the receiving unit P 1  (i.e., the PSD module) receives a reflected infrared light signal; if the receiving unit P 1  receives a reflected infrared light signal, going to step 5; otherwise proceeding to step 3; 
         [0062]    Step 3: activating the close range light emitting source S 2  to emit an infrared light, and proceeding to step 4; 
         [0063]    Step 4: judging whether the receiving unit P 1  receives a reflected infrared light signal; if the receiving unit P 1  receives a reflected infrared light signal, going to step 5; otherwise returning to step 1; 
         [0064]    Step 5: calculating the distance value of an object O 1  to be detected based on the received infrared light reflected from the object O 1 , and proceeding to step 6; 
         [0065]    Step 6: judging whether the distance value of the object O 1  is within the preset range; if the distance value of the object O 1  is within the preset range, proceeding to step 7; otherwise returning to step 1; 
         [0066]    Step 7: determining that some user wants to use or is using the sanitary ware, and controlling the corresponding sanitary ware by means of a main controller to perform operations such as opening or closing valve). 
         [0067]    In accordance with the above preferred embodiment, if it is detected that an object is within the normal distance range, it is not necessary to activate the close range light emitting source, so that the power consumption can be saved more effectively. Of course, in accordance with another embodiment of the present invention, the close range light detection method of distance detecting sensor  100  in the present invention can be that: the light emitting source S 1  and the close range light emitting source S 2  emit an infrared light synchronously; then, it is judged whether the receiving unit P 1  receives an infrared light, and whether the position of the object O 1  to be detected is within a preset range; and finally, the operations (opening/closing the valve, and etc.) of the sanitary ware (faucet, urinal and etc.) is controlled according to the result of judgment. The specific steps of the method are as follows: 
         [0068]    Step 1: activating a light emitting source S 1  and a close range light emitting source S 2  synchronously, and proceeding to step 2; 
         [0069]    Step 2: judging whether a receiving unit P 1  receives a reflected infrared light signal; if the receiving unit P 1  receives a reflected infrared light signal, proceeding to step 3; otherwise returning to step 1; 
         [0070]    Step 3: calculating the distance value of an object O 1  to be detected based on the received infrared light reflected from the object O 1 , and proceeding to step 4; 
         [0071]    Step 4: judging whether the distance value of the object O 1  is within the preset range; if the distance value of the object O 1  is within the preset range, proceeding to step 5; otherwise returning to step 1; wherein, the preset range includes a preset normal range and a preset close range. 
         [0072]    Step 5: controlling the corresponding sanitary ware to perform operations such as opening or closing valve). 
         [0073]    Furthermore, the emission frequency of infrared light when an object is detected is different from when no object is detected. The emission frequency is lower when no object is detected than when an object is detected. In a preferred embodiment of the present invention, the emission frequency of infrared light is once per 0.3 s when no object O 1  is detected, and is once per 0.15 s when an object O 1  is detected. Such an arrangement is favorable for saving of power consumption. 
         [0074]    Furthermore, in actual applications, since the close range light emitting source S 2  is used for close range detection, the power for activating the close range light emitting source S 2  to emit infrared light is higher than the power for activating the light emitting source S 1  to emit infrared light. In a preferred embodiment of the present invention, the current for activating the light emitting source S 1  to emit infrared light is about 70 mA, while the current for activating the close range light emitting source S 2  to emit infrared light is about 20 mA. 
         [0075]    Since the power for activating the close range light emitting source S 2  to emit infrared light is lower, the close range light emitting source S 2  is normally open in another embodiment of the present invention. When an object is detected within the close range detection area, the sanitary ware will be controlled to profound actions such as opening valve. 
         [0076]    The close range light emitting source S 2  can also faintly detect whether an object O 1  enters into the normal detection area. As a consequence, after the close range light emitting source S 2  emits an infrared light and detects that an object O 1  enters into the normal detection area, the light emitting source S 1  is activated to emit an infrared light, to detect the object accurately. When an object is detected accurately in the normal detection area, it can be judged that the distance value of the object is within the preset range, and the corresponding sanitary ware is controlled to perform actions such as opening valve. This is helpful for saving of power consumption. The specific steps of the method are as follows: 
         [0077]    Step 1: activating the close range light emitting source S 2  to emit an infrared light, and proceeding to step 2; 
         [0078]    Step 2: judging whether the receiving unit P 1  receives an infrared light signal reflected from object O 1  to be detected; if the receiving unit P 1  receives a reflected infrared light signal, proceeding to step 3; otherwise returning to step 1; 
         [0079]    Step 3: calculating the distance value of the object O 1  based on the received infrared light signal reflected from the object O 1 , and proceeding to step 4; 
         [0080]    Step 4: judging whether the distance value of the object O 1  is within a preset close range; if the distance value is within the preset close range, going to step 8; otherwise proceeding to step 5; 
         [0081]    Step 5: activating the light emitting source S 1  to emitting an infrared light, and proceeding to step 6; 
         [0082]    Step 6: judging whether the receiving unit P 1  receives an infrared light signal reflected from the object O 1 ; if the receiving unit P 1  receives a reflected infrared light signal, proceeding to step 7; otherwise returning to step 1; 
         [0083]    Step 7: judging whether the distance value of the object O 1  is within a preset normal range; if the distance value is within the preset normal range, proceeding to step 8; otherwise returning to step 1; 
         [0084]    Step 8: controlling the corresponding sanitary ware to perform actions (e.g. opening/closing valve, and etc.). 
         [0085]    In addition, in the embodiments of the present invention, two or more close range light emitting sources S 2  can be arranged to attain better close range detection effect. 
         [0086]    Although some embodiments of the present invention have been disclosed above, the present invention is not limited to them. Those skilled in the prior art can make various modifications or variations to the embodiments described above without departing from the scope of the present invention.

Summary:
The present invention discloses a distance detecting sensor. The distance detecting sensor includes a casing, a focusing lenses, a circuit board mounted with several electronic elements, an emitting device for emitting infrared light, and a receiving device for receiving and sensing a reflected infrared light. The distance detecting sensor is configured to have a high detection accuracy and improved detection performance.