Patent Publication Number: US-6032950-A

Title: Detecting device for detecting a transfer object

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a detecting device for detecting a transfer object, such as a document sheet or recording paper, in a facsimile machine, a printer, a copying machine or an image scanner for example. 
     2. Description of the Related Art 
     In a facsimile machine for example, it is necessary to detect the movement or presence of a transfer object, such as a document sheet or a recording paper sheet, in a transfer path for controlling the operation of the facsimile machine. For this purpose, a detecting device is provided which comprises an actuator and a sensor. 
     More specifically, as shown in FIG. 8, a prior detecting device comprises an actuator 100 and a sensor 101. The actuator 100 includes a horizontal shaft 100a, a first arm 100b extending upwardly from the shaft 100a, and a second arm 100c extending downwardly from one end of the shaft 100a. The sensor 101 is mounted on a circuit board 102. 
     In the absence of a transfer object (not shown) in the transfer path, the first arm 100b of the actuator 100 projects into the transfer path. On the other hand, when a transfer object is present in the transfer path, the first arm 100b comes into engagement with the transfer object and is thereby pressed downwardly. In this way, the actuator 100 pivots up and down about the horizontal shaft 100a in response to the presence and absence of a transfer object. 
     The second arm 100c of the actuator 100 is bent to extend first obliquely and then substantially vertically. Since the second arm 100c is thus bent, the actual orientation of the second arm may be represented by an effective length line EL which passes through the center of the actuator shaft 100a and the lower end of the second arm 100c. In the absence of a transfer object in the transfer path, the angle θ between the effective length line EL of the second arm 100c and a vertical line VL passing through the center of the shaft 100a is less than 45°. 
     The lower end of the second arm 100c is provided with a reflector 103 which faces the sensor 101 when the second arm 100c is pivoted down due to the absence of a transfer object. Further, the reflector 103 has a rounded stopper projection 104 which comes into resting contact with the circuit board 102, thereby maintaining a predetermined clearance H 1  between the reflector 103 and the circuit board 102. 
     The sensor 101 is a reflection type sensor which has a light emitting portion and a light receiving portion. When the actuator 100 is pivoted to bring the stopper projection 104 into contact with the circuit board 102, the light emitted from the light emitting portion of the sensor 101 is reflected on the reflector 103 for incidence into the light receiving portion of the sensor 101, so that the sensor 101 notifies the absence of a transfer object. On the other hand, when the second arm 100c of the actuator 100 is pivoted up due to the presence of a transfer object, the reflector 103 becomes far from the sensor 101 to come completely out of the light reflecting position (see the phantom line in the center of FIG. 8), so that the sensor 101 notifies the presence of a transfer object. 
     Normally, the circuit board 102 is mounted at a standard distance H 0  from the actuator shaft 100a to make the reflector 103 substantially parallel to the upper surface of the sensor 101 in facing relation thereto (see the center representation in FIG. 8) when the stopper projection 104 of the reflector 104 comes into contact with the circuit board 102. However, it is possible, due to some production or assembly error, that the circuit board 102 may positionally deviate from the standard distance position H 0  relative to the actuator shaft 100a. If the circuit board 102 is erroneously positioned at a distance (H 0  -ΔH) or (H 0  ΔH) from the actuator shaft 100a (see the left and right representations in FIG. 8), the orientation of the reflector 103 becomes improper relative to the upper surface of the sensor 101. As a result, the sensor 101 may fail to provide a reliable detection of a transfer object. Such a disadvantage will become particularly remarkable as the angle θ between the effective length line EL of the actuator second arm 100c and the vertical line VL is small. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention is to provide a detecting device which is capable of reliably detecting a transfer object, particularly a paper sheet for use in e.g. a facsimile machine, even if a circuit board or support member for a sensor positionally deviates from a standard mounting position 
     According to one aspect of the present invention, there is provided a detecting device for detecting a transfer object which is transferred along a predetermined transfer path, the detecting device comprising: a non-contact sensor mounted on a support member; an actuator including a contact portion for contact with the transfer object in the transfer path, and a pivotal portion which is pivotable about a pivotal axis between a first position adjacent to the sensor and a second position away from the sensor, the pivotal portion having a free end; a cooperative element provided at the free end of the pivotal portion of the actuator for detection by the sensor; and a stopper projection provided on the cooperative element for contact with the support member when the pivotal portion of the actuator is pivoted to the first position; wherein the cooperative element includes a first surface and a second surface inclined relative to the first surface. 
     The technical advantages obtainable with the above-described detecting device will be specifically described hereinafter on the basis of the preferred embodiments of the present invention. 
     The cooperative element may further include a third surface inclined relative to the first surface and the second surface. In this case, the first surface may be provided at a central portion of the cooperative element, whereas the second and third surfaces may be located at a respective side portion of the cooperative element and inclined in mutually opposite directions 
     Typically, the sensor may be a reflection type sensor for optical detection, whereas the cooperative element may be a reflector with each of the first and second surfaces (or the first to third surfaces) acting as a reflecting surface. 
     According to a preferred embodiment, the actuator comprises a first arm as the contact portion and a second arm as the pivotal portion, and the first arm projects into the transfer path when the second arm is in the first position. Further, the second arm of the actuator extends downwardly from the pivotal axis in a bent manner. Preferably in this case, an angle formed between a vertical line passing through the pivotal axis and an effective length line of the second arm passing through the pivotal axis and the free end of the second arm should be less than 45°. 
     According to another aspect of the present invention, there is provided a detecting device for detecting a transfer object which is transferred along a predetermined transfer path, the detecting device comprising: a non-contact sensor mounted on a support member; an actuator including a contact portion for contact with the transfer object in the transfer path, and a pivotal portion which is pivotable about a pivotal axis between a first position adjacent to the sensor and a second position away from the sensor, the pivotal portion having a free end; a cooperative element provided at the free end of the pivotal portion of the actuator for detection by the sensor; and a stopper projection provided on the cooperative element for contact with the support member when the pivotal portion of the actuator is pivoted to the first position; wherein the cooperative element includes a round surface which is convex toward the sensor in facing relation thereto when the pivotal portion is pivoted to the first position. 
     Preferably, the round surface of the cooperative element may be arcuately curved. In this case, it is advantageous if the arcuately curved round surface of the cooperative element is generally centered about the pivotal axis. 
     Again, in the second aspect of the present invention, the sensor may typically be a reflection type sensor for optical detection, whereas the cooperative element may be a reflector with the round surface acting as a reflecting surface. 
     According to a further aspect of the present invention, there is provided a detecting device for detecting a transfer object which is transferred along a predetermined transfer path, the detecting device comprising: a reflection type sensor mounted on a support member; an actuator including a contact portion for contact with the transfer object in the transfer path, and a pivotal portion which is pivotable about a pivotal axis between a first position adjacent to the sensor and a second position away from the sensor, the pivotal portion having a free end; a reflector provided at the free end of the pivotal portion of the actuator for detection by the sensor; and a stopper projection provided on the reflector for contact with the support member when the pivotal portion of the actuator is pivoted to the first position; wherein wall thickness of the reflector is maximum at a central portion of the reflector but progressively reduces toward at least one side of the reflector. 
     Preferably, the wall thickness of the reflector progressively reduces toward both sides of the reflector. 
     Other objects, features and advantages of the present invention will be apparent from the detailed description of a preferred embodiment given below with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a sectional view showing a facsimile machine which incorporates a detecting device embodying the present invention; 
     FIG. 2 is a front view showing the same detecting device; 
     FIG. 3 is a side view showing the same detecting device with a circuit board mounted at a standard position; 
     FIG. 4 is a side view similar to FIG. 3 but showing the same detecting device with a circuit board mounted slightly upward from the standard position; 
     FIG. 5 is a schematic side view showing another detecting device embodying the present invention, with a circuit board mounted at the standard position; 
     FIG. 6 is a side view showing the detecting device of FIG. 5 with a circuit board mounted slightly downward from the standard position; 
     FIG. 7 is a schematic side view showing a further detecting device embodying the present invention, with a circuit board mounted at the standard position; and 
     FIG. 8 is a side view showing a prior art detecting device in three different positions. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. 
     FIG. 1 of the accompanying drawings represents an overall view of a facsimile machine which incorporates a detecting device embodying the present invention. The facsimile machine generally represented by reference numeral 1 comprises a housing 2 which includes a front operation/display panel 3 provided with key switches (not shown) and liquid crystal display devices (not shown). Immediately under the front panel 3 is formed a document transfer path 4. 
     A document sheet DS is transferred along the document transfer path 4 by a feed roller 5, a platen roller 6a and a pair of discharge rollers 7. These rollers are driven by a drive motor (not shown) through a transmission gear mechanism (not shown). In the course of such transfer, the images (including characters, letters, numerals and etc.) carried on the document sheet DS is optically read by an image reader (e.g. CCD image scanner) 6 arranged in facing relation to the platen roller 6a. 
     The housing 2 supports a recording paper receiver 20 for receiving a stack of recording paper sheets RS. Each of the recording paper sheets RS is transferred by a feed roller 21, a platen roller 22 and a pair of discharge rollers 23. These rollers are driven by a drive motor (not shown) through a transmission gear mechanism (not shown). In the course of such transfer, the recording paper sheet RS is subjected to printing by means of a printhead 24 held in facing relation to the platen roller 22 with an ink ribbon held therebetween. 
     The present invention may be applied for detecting either one or both of the document sheet DS and the recording paper sheet RS. For the convenience of illustration and description, however, the present invention is applied only for detecting the document sheet DS alone in the illustrated embodiment. 
     More specifically, for detecting the presence of the document sheet DS in the document transfer path 4, a detecting device 8 is provided under a guide wall 9 which defines a part of the document transfer path 4. The detecting device 8 is arranged behind the feed roller 5. The guide wall 9 is provided with a slit 9a. 
     As shown in FIG. 2, the detecting device 8 comprises an actuator 10 and a sensor 11. The actuator 10 includes a horizontal shaft 10a, a first or upper arm 10b extending upwardly from an intermediate portion of the shaft 10a, and a second or lower arm 10c extending downwardly from one end of the shaft 10a. The shaft 10a is rotatably supported by a first support bracket 12a adjacent to the second arm 10c, and by a second support bracket 12b at the remote end of the shaft 10d. 
     The first support bracket 12a has a U-shaped groove (see FIG. 3) for rotatably fitting the shaft 10a from above, whereas the second support bracket 12b has a circular hole (not shown) for rotatably receiving the remote end of the shaft 10a. Further, the remote end of the shaft 10a is formed with an elastically expandable flange 10d for preventing unexpected removal of the shaft 10a from the second support bracket 12b. 
     If no document sheet is present at the inlet of the document transfer path 4 the first arm 10b of the actuator 10 projects into the document transfer path 4 through the slit 9a of the guide wall 9, as indicated by phantom lines in FIG. 1. On the other hand, when a document sheet DS is present at the inlet of the document transfer path 4, the first arm 10b comes into engagement with the document sheet DS and is thereby depressed into the slit 9a, as indicated by solid lines in FIG. 1. In this way, the actuator 10 pivots up and down about the horizontal shaft 10a in response to the presence and absence of a document sheet DS. 
     As shown in FIGS. 2 and 3, the second arm 10c of the actuator 10 is bent to extend first obliquely and then substantially vertically. Since the second arm 10c is thus bent, the actual orientation of the second arm may be represented by an effective length line EL (FIG. 3) which passes through the center of the actuator shaft 10a and the lower end of the second arm 10c. When the actuator 10 assumes the paper-out position (the phantom line position in FIG. 1), the angle θ between the effective length line EL of the second arm 10c and a vertical line VL passing through the center of the shaft 10a is less than 45° according to the illustrated embodiment. 
     The lower end of the second arm 10c is provided with a reflector 13 which faces the sensor 11 when the second arm 10c is pivoted down due to the absence of a document sheet DS (see the phantom line position in FIG. 1). The sensor 11 is mounted on a circuit board CB which is, in turn, supported substantially horizontally at the bottom of the housing 2 (FIG. 1). Further, the reflector 13 has a rounded stopper projection 14 which comes into resting contact with the circuit board CB, thereby maintaining a predetermined clearance H 1  between the reflector 13 and the circuit board CB. 
     The sensor 11 is a reflection type sensor which has a light emitting portion and a light receiving portion. When the actuator 10 assumes the paper-out position (the phantom line position in FIG. 1), the light emitted from the light emitting portion of the sensor 11 is reflected on the reflector 13 for incidence into the light receiving portion of the sensor 11, so that the sensor 11 generates a paper-out signal. On the other hand, when the actuator 10 assumes the paper-in position (the solid line position in FIG. 1), the reflector 13 becomes far from the sensor 11 to come completely out of the light reflecting position, so that the sensor 11 generates a paper-in signal. 
     As previously described, the angle θ between the effective length line EL of the actuator second arm 10c and the vertical line VL is less than 45° when the actuator 10 assumes the paper-out position. Thus, even if the pivotal angle of the actuator 10 caused by the presence of the document sheet DS is relatively small, the reflector 13 at the lower end of the second arm 10c may be brought sufficiently far from the sensor 11 for reliable detection of the sheet presence. 
     As shown in FIG. 3, the reflector 13 according to a first embodiment of the present invention has a first reflecting surface 13a and a second reflecting surface 13b. The reflector 13 may be entirely formed of a white resin to make the first and second reflecting surfaces 13a, 13b sufficiently reflective to light. Alternatively, a white coating or film may be applied to the bottom surface of the reflector 13 for making the first and second reflecting surfaces 13a, 13b sufficiently reflective. 
     If the circuit board CB is positioned at a standard distance H 0  from the actuator shaft 10a, the first surface 13a of the reflector 13 becomes substantially parallel to the circuit board CB (i.e., the upper surface of the sensor 11) in facing relation to the sensor 11 when the actuator 10 assumes the paper-out position. As a result, the light from the light emitting portion of the sensor 11 is reflected on the first reflecting surface 13a of the reflector 13 for reentry into the light receiving portion of the sensor, whereby the sensor 11 generates a paper-out signal. The second reflecting surface 13b is inclined relative to the first reflecting surface 13a to be progressively farther from the circuit board CB as it extends away from the first reflecting surface 13a. If the circuit board CB is positioned at the standard distance H 0  from the actuator shaft 10a, the second reflecting surface 13b is oriented away from the sensor 11 when the actuator 10 assumes the paper-out position. 
     On the other hand, it is possible, due to some production or assembly error, that the circuit board CB may positionally deviate from the standard distance or position H 0  relative to the actuator shaft 10a. It is now assumed that the circuit board CB is erroneously positioned at a distance (H 0  -ΔH) from the actuator shaft 10a, as shown in FIG. 4. In this case, when the stopper projection 14 comes into contact with the circuit board CB in the paper-out pivotal position of the actuator 10, the second reflecting surface 13b becomes substantially parallel to the circuit board CB (i.e., the upper surface of the sensor 11) in facing relation to the sensor 11. As a result, the light from the light emitting portion of the sensor 11 is reflected on the second reflecting surface 13b of the reflector 13 for reentry into the light receiving portion of the sensor, whereby the sensor 11 generates a paper-out signal. 
     In this way, either one of the first and second reflecting surfaces 13a, 13b of the reflector 13 may be held substantially parallel to the upper surface of the sensor 11 in facing relation thereto in the paper-out pivotal position of the actuator 10. Thus, even if the circuit board CB positionally deviates from the standard distance position H 0  relative to the actuator shaft 10a, the sensor 11 can reliably generate a paper-out signal when no document sheet is present at the inlet of the document transfer path 4. 
     FIG. 5 represents a second embodiment of reflector according to the present invention. Specifically, the reflector in the second embodiment, designated by reference numeral 13&#39;, has a first reflecting surface 13a&#39; at a central portion of the reflector, a second reflecting surface 13b&#39; at one side portion of the reflector, and a third reflecting surface 13c&#39; at the opposite side portion of the reflector. The second and third reflecting surfaces 13b, 13c&#39; are inclined relative to the first reflecting surface 13a&#39; to become progressively farther from the circuit board CB as they extend away from the first reflecting surface 13a&#39;. Thus, the second and third reflecting surfaces 13b&#39;, 13c&#39; are oppositely inclined. 
     According to the second embodiment, if the circuit board CB is positioned at the standard distance H 0  from the actuator shaft 10a, the first surface 13a&#39; of the reflector 13&#39; becomes substantially parallel to the upper surface of the sensor 11 in facing relation thereto when the actuator 10 assumes the paperout position (see FIGS. 3 and 5). If the circuit board CB is erroneously positioned at a distance (H 0  -ΔH) from the actuator shaft 10a, the second reflecting surface 13b&#39; becomes substantially parallel to the upper surface of the sensor 11 in facing relation thereto (see FIG. 4). 
     Further, if the circuit board CB is erroneously positioned at a distance (H 0  -ΔH) from the actuator shaft 10a, the third reflecting surface 13c&#39; becomes substantially parallel to the upper surface of the sensor 11 in facing relation thereto when the actuator 10 assumes the paper-out position, as shown in FIG. 6 As a result, the light from the light emitting portion of the sensor 11 is reflected on the third reflecting surface 13c&#39; of the reflector 13&#39; for reentry into the light receiving portion of the sensor, whereby the sensor 11 generates a paper-out signal. Thus, the second embodiment is advantageous in that the circuit board CB may positionally deviate either upward or downward. 
     FIG. 7 represents a third embodiment of reflector according to the present invention. Specifically, the reflector in the third embodiment, designated by reference numeral 13&#34;, has a single reflecting surface 13a&#34; which is arcuately curved. The arcuate reflecting surfaces 13a&#34; may be generally centered about the actuator shaft 10a. 
     According to the third embodiment, even if the circuit board CB positionally deviates upward or downward from the standard distance position Ho from the actuator shaft 10a, some portion of the arcuate reflecting surface 13&#34; faces the upper surface of the sensor 11 substantially in parallel thereto when the actuator 10 assumes the paper-out position with the stopper projection 14 resting on the circuit board CB. As a result, the light from the light emitting portion of the sensor 11 is reflected on the facing portion of the arcuate reflecting surface 13a&#34; of the reflector 13&#39; for reentry into the light receiving portion of the sensor, whereby the sensor 11 generates a paper-out signal. Thus, the third embodiment is advantageous in that the sensor 11 can always provide a reliable paper-out detection regardless of the degree and direction of positional deviation of the circuit board CB. 
     The preferred embodiments of the present invention being thus described, it is obvious that the same may be varied in many other ways. For instance, the reflector 13&#39; shown in FIG. 5 may include four or more reflecting surfaces which inclined relative to each other. Further, the configuration of the first and second arms 10a, 10b of the actuator 10 may be modified, provided that the actuator can perform the intended detecting function. Such variations should not be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to those skilled in the art are intended to be included within the scope of the following claims