Abstract:
A sensing multi-stage control system for hand dryers aims to be installed in a lavatory and energized by electric power to generate heat and airflow to dry human hands to improve shortcomings of conventional hand dryers that cannot control airflow amount and temperature level. The hand dryer according to the invention includes a heater, a fan motor and a detection unit. The detection unit has at least two sets of sensors located at an air outlet of the hand dryer and is electrically connected to a control circuit which starts, stops and controls the heater and fan motor at a desired temperature level and rotation speed to form the sensing multi-stage control system. The control circuit, incorporating with the sensors and a comparison and logic processor to process signals, can provide multi-stage control of the temperature level of the heater and rotation speed of the fan motor.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a wet article drying apparatus and particularly to a hand dryer control system installed in a lavatory and energized by electric power to generate heat and airflow to dry human hands. 
       BACKGROUND OF THE INVENTION 
       [0002]    People after washing hands in lavatories usually try to dry their hands with paper towels or handkerchiefs they carry with them, or the paper towels provided in public environments such as vehicle stations, office buildings, companies, plants, hotels, restaurants or malls. In many occasions, people could forget to carry the paper towels or handkerchiefs, or the paper towels are exhausted and not available in the public environments, then they have to let their hands dry naturally. The wet hands easily breed bacteria and are not hygienic. To remedy these problems, hand dryers have been developed to allow users quickly drying hands after washing in the lavatories. 
         [0003]    In the past, the hand dryers mostly are started by pushing a touch switch to generate hot air. Such an approach requires the wet hand to push the touch switch to start the hand dryer and create a number of problems, notably: 
         [0004]    1. Unsafe operation: as user&#39;s hands are wet before drying, they are electrically conductive and could result in electric shock. 
         [0005]    2. Not hygienic: to start the hand dryer operation by pushing the touch switch with wet hands creates a higher possibility of virus contagion through physical contact of the touch switch. 
         [0006]    These days, consumers have a higher demand, and technology has a greater progress; as a result, hand dryers activated by infrared sensors have been developed. Such a hand dryer usually has a fan driven by a motor and a heater, and an infrared emitter and an infrared receiver located at an air outlet of the hand dryer. When user&#39;s hands move within the detection range of the infrared emitter, an infrared signal generated by the infrared emitter is blocked, and the infrared receiver generates another signal to activate the motor to drive the fan to generate airflow, and the heater also is activated at the same time to generate heat so that the airflow passing through is heated to a higher temperature and channeled through an air outlet to be discharged to dry the user&#39;s hands. 
         [0007]    However, such type of hand dryer that starts or stops the heater and motor through the infrared sensor delivers or stops delivering a fixed amount of airflow at a constant temperature. It still has drawbacks in practice, notably: 
         [0008]    1. The amount and temperature level of the airflow cannot be controlled: the site where the hand dryer is installed varies and users&#39; requirements could be different, especially in terms of airflow amount and temperature level. For instance, climate conditions could change greatly in winter and summer, and temperature level requirements could alter significantly. The hand dryer that cannot control airflow amount and temperature level cannot fully meet user&#39;s requirements. 
         [0009]    2. As the conventional hand dryer does not provide control function of the airflow amount and temperature level, ancillary function such as indicating the airflow amount and temperature reading also is not available. 
       SUMMARY OF THE INVENTION 
       [0010]    The primary object of the present invention is to provide two or more non-touch sensing sensors incorporating with a comparison and logic processor to process signals to enable a control circuit to provide multi-stage control of a heater to reach a selected temperature and a fan motor to rotate at a desired speed, so that the amount of airflow and temperature thereof of a hand dryer can be easily and quickly controlled by users to meet safety and hygienic requirements. 
         [0011]    To achieve the foregoing object, the present invention provides a sensing multi-stage control system for hand dryers. The hand dryer according to the invention includes: 
         [0012]    a heater close to an air outlet of the hand dryer to raise the temperature of airflow; 
         [0013]    a fan motor located in the hand dryer to generate and deliver the airflow; and 
         [0014]    a sensing multi-stage control system located at the air outlet that has a detection unit and a control circuit. The detection unit has at least two sets of sensors electrically connected to the control circuit. The control circuit starts and stops the heater and fan motor; and controls the temperature of the heater at a selected level and the rotation speed of the fan motor. 
         [0015]    By means of the technique of the invention, the invention provides many benefits over the conventional techniques, notably: 
         [0016]    1. The invention provides functions of controlling airflow amount and temperature level of the hand dryer, thus can better meet user&#39;s requirements regardless the installation environment. It especially adaptable to suit climate change in winter and summer in which user&#39;s requirement of temperature level differs significantly. By providing the functions of controlling airflow amount and temperature level, the practicality improves. 
         [0017]    2. The invention provides a fast and simple control means: alteration of airflow amount and temperature level can be controlled by placing a targeted object (user&#39;s hands) within the detection range of the hand dryer. Thus it can be done quickly and easily by the users after finishing hand washing by simply extending the wet hands in a selected direction. 
         [0018]    3. Safer operation and control: Although the targeted object (user&#39;s hands) is wet before drying and is electrical conductive that might incur electric shock, the invention provides a non-touch sensing means to start and stop control of alteration of the airflow amount and temperature level, thus is much safer. 
         [0019]    4. The control method of the invention can better meet the hygienic requirement of modern people: Due to the sensors are non-touch sensing types, user&#39;s hands are not in contact with the control panel. Hence virus contagion that might otherwise occur due to direct contact can be avoided. 
         [0020]    5. An ancillary function of indicating the airflow amount and temperature level can be added in the invention: The invention may include a signal converter, a display device and a loudspeaker, thus can convert a control signal to a video signal to be displayed on the display device, or be transformed to an audio signal to be broadcast through the loudspeaker so that users can be instantly informed regarding the temperature and airflow amount of the hand dryer. 
         [0021]    The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a block diagram of an embodiment of the sensing multi-stage control system for hand dryers of the invention. 
           [0023]      FIG. 2A  is a schematic view of a detection unit of the invention in a first condition. 
           [0024]      FIG. 2B  is a control status table of the detection unit of the invention in the first condition. 
           [0025]      FIG. 3A  is a schematic view of the detection unit of the invention in a second condition. 
           [0026]      FIG. 3B  is a control status table of the detection unit of the invention in the second condition. 
           [0027]      FIG. 4A  is a schematic view of the detection unit of the invention in a third condition. 
           [0028]      FIG. 4B  is a control status table of the detection unit of the invention in the third condition. 
           [0029]      FIG. 5  is a block diagram of another embodiment of the sensing multi-stage control system for hand dryers of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    Please refer to  FIGS. 1 and 2A  for a block diagram of a first embodiment of the sensing multi-stage control system for hand dryers of the invention, and a first condition of the detection unit. The hand dryer  10  according to the invention includes a heater  20  located inside close to an air outlet thereof (it is known in the art, thus is not shown in the drawings), a fan motor  30  located inside to generate and deliver airflow and a detection unit  50  electrically connected to a control circuit  60  to start and stop the heater  20  and the fan motor  30 . This embodiment provides features as follows: the detection unit  50  is located at the air outlet of the hand dryer  10 , and includes four sets of sensors  51   a ,  52   a ,  53   a  and  54   a . These sensors are electrically connected to the control circuit  60  which starts and stops the heater  20  and fan motor  30  and controls the temperature level and rotation speed thereof to form a sensing multi-stage control system  40 . The sensing multi-stage control system  40  receives electric power from a power source  70 . Each of the sensors  51   a ,  52   a ,  53   a  and  54   a  has an emission end and a receiving end (not shown in the drawings). These four sensors  51   a ,  52   a ,  53   a  and  54   a  may be infrared sensors or CCDs (Charge Coupled Devices). In addition, the control circuit  60  has a comparison and logic processor  61  electrically connected to the detection unit  50 . The comparison and logic processor  61  has a comparator (not shown in the drawings) to compare detection sequence of the sensors  51   a ,  52   a ,  53   a  and  54   a , and a logic processor (also not shown in the drawings) to perform logical judgment. Refer to  FIG. 2B  for a control status table of the detection unit in the first condition. As there are four sensors  51   a ,  52   a ,  53   a  and  54   a  in the detection unit  50  (referring to  FIG. 2A ), when a targeted object  80  moves from the front side into a detection range of the detection unit  50 , the comparison and logic processor  61  senses that one of the sensors  51   a  and  52   a  detects first; next, one of other sensors  53   a  and  54   a  also detects; then a signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to a preset condition (H→Hi, M→Hi). When the targeted object  80  moves away from the detection range of the detection unit  50 , the control circuit  60  stops operation of the heater  20  and fan motor  30 . When the targeted object  80  moves from the left side towards the right side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensor  53   a  detects first; next, another sensor  52   a  detects; then the signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to another preset condition (H→Hi, M→Lo). Similarly, when the targeted object  80  moves away from the detection range of the detection unit  50 , the control circuit  60  stops operation of the heater  20  and fan motor  30 . By the same token, when the targeted object  80  moves from the right side towards the left side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensor  54   a  detects first; next, another sensor  51   a  detects; then the signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to yet another preset condition (H→Lo, M→Hi). Finally, when the targeted object  80  moves away from the detection range of the detection unit  50 , the control circuit  60  stops operation of the heater  20  and fan motor  30 . In the event that one targeted object  80  moves from the left side towards the right side into the detection range of the detection unit  50 , and another targeted object  80  moves almost at the same time from the right side towards the left side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensor  53   a  detects first; next, another sensor  51   a  detects, and the sensor  54   a  also detects first; and the other sensor  52   a  detects later; then the signal process is executed, and the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to yet another preset condition (H→Lo, M→Lo). The comparison and logic processor  61  compares and judges various different detection conditions of the detection unit  50  to adjust the temperature of the heater  20  and rotation speed of the fan motor  30  according to preset conditions in response to varying requirements. 
         [0031]    Refer to  FIGS. 3A and 3B  for the detection unit in a second condition and the sensing multi-stage control system in such a condition. In  FIG. 3A , the detection unit  50  has three sets of sensors  51   b ,  52   b  and  53   b  which have respectively an emission end and a receiving end (not shown in the drawings). These three sensors  51   b ,  52   b  and  53   b  may be infrared sensors or CCDs. When the targeted object  80  moves from the front side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensor  53   b  detects first; then one of other sensors  51   b  and  52   b  detects; then a signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to a preset condition (H→Hi, M→Hi). When the targeted object  80  moves away from the detection range of the detection unit  50 , the control circuit  60  stops operation of the heater  20  and fan motor  30 . When the targeted object  80  moves from the left side towards the right side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensor  51   b  detects first; next, another sensor  53   b  detects; then the signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to another preset condition (H→Hi, M→Lo). Similarly, when the targeted object  80  moves away from the detection range of the detection unit  50 , the control circuit  60  stops operation of the heater  20  and fan motor  30 . When the targeted object  80  moves from the right side towards the left side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensor  52   b  detects first; next, another sensor  53   b  detects; then the signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to yet another preset condition (H→Lo, M→Hi). Finally, when the targeted object  80  moves away from the detection range of the detection unit  50 , the control circuit  60  stops operation of the heater  20  and fan motor  30 . In the event that one targeted object  80  moves from the left side towards the right side into the detection range of the detection unit  50 , and another targeted object  80  moves almost at the same time from the right side towards the left side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensor  51   b  detects first; next, another sensor  52   b  detects, and finally yet another sensor  53   b  detects; then the signal process is executed. Or the sensor  52   b  detects first; next, another sensor  51   b  detects, and finally yet another sensor  53   b  detects; then the signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to another preset condition (H→Lo, M→Lo). Similarly, the comparison and logic processor  61  compares and judges various different detection conditions of the detection unit  50  to adjust the temperature of the heater  20  and rotation speed of the fan motor  30  according to preset conditions in response to varying requirements. 
         [0032]    Refer to  FIGS. 4A and 4B  for the detection unit in a third condition and the sensing multi-stage control system in such a condition. In  FIG. 4A , the detection unit  50  has two sets of sensors  51   c  and  52   c  which have respectively an emission end and a receiving end (not shown in the drawings). These two sensors  51   c  and  52   c  may be infrared sensors or CCDs. When the targeted object  80  moves from the front side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensors  51   c  and  52   c  detect almost at the same time, then a signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to a preset condition (H→Hi, M→Hi). When the targeted object  80  moves away from the detection range of the detection unit  50 , the control circuit  60  stops operation of the heater  20  and fan motor  30 . When the targeted object  80  moves from the left side towards the right side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensor  51   c  detects first; next, another sensor  52   c  detects; then the signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to another preset condition (H→Hi, M→Lo). When the targeted object  80  moves away from the detection range of the detection unit  50 , the control circuit  60  stops operation of the heater  20  and fan motor  30 . Finally, when the targeted object  80  moves from the right side towards the left side into the detection range of the detection unit  50 , the comparison and logic processor  61  senses that the sensor  52   c  detects first; next, another sensor  51   c  detects; then the signal process is executed. And the control circuit  60  starts the heater  20  and fan motor  30 , and alters the temperature of the heater  20  and rotation speed of the fan motor  30  to yet another preset condition (H→Lo, M→Hi, or H→Lo, M→Lo). Similarly, the comparison and logic processor  61  compares and judges various different detection conditions of the detection unit  50  to adjust the temperature of the heater  20  and rotation speed of the fan motor  30  according to preset conditions in response to varying requirements. 
         [0033]    Based on the various conditions previously discussed, in  FIG. 1  the detection unit  50  has two or more sensors (not shown in the drawing), by incorporating with signal process of the comparison and logic processor  61 , the control circuit  60  can control the temperature of the heater  20  and rotation speed of the fan motor  30  in a multi-stage fashion. 
         [0034]    Refer to  FIG. 5  for another embodiment of the sensing multi-stage control system for hand dryers of the invention. In this embodiment, the hand dryer  10  includes the heater  20  located inside close to the air outlet thereof (it is known in the art, thus is not shown in the drawings), the fan motor  30  located inside to generate and deliver airflow and the detection unit  50  electrically connected to the control circuit  60  to start and stop the heater  20  and the fan motor  30 . This embodiment provides features as follows: the detection unit  50  includes at least two sets of sensors (not shown in the drawing) located at the air outlet and is electrically connected to the control circuit  60  which starts and stops the heater  20  and fan motor  30  and controls the temperature level and rotation speed thereof to form the sensing multi-stage control system  40 . The sensing multi-stage control system  40  receives electric power from a power source  70 . The control circuit  60  has the comparison and logic processor  61  electrically connected to the detection unit  50 . The control circuit  60  also has a signal converter  62 , and the hand dryer  10  has a display device  91  and a loudspeaker  92 . The signal converter  62  aims to transform signals of preset conditions corresponding to the temperature of the heater  20  and rotation speed of the fan motor  30  in response to various detection conditions of the detection unit  50  to video signals to be displayed on the display device  91 , or audio signals to be broadcast through the loudspeaker  92 . Thereby users can be instantly informed of the temperature of the hand dryer  10  and airflow amount of the fan motor  30 . 
         [0035]    While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.