Patent Publication Number: US-8115790-B2

Title: Medium detecting apparatus and image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a medium detecting technology in an image forming apparatus to execute medium detection and execute print. 
     2. Related Background Art 
     Generally, a paper detecting sensor in a printer with former skew adjustment function is constructed as shown by  FIG. 13A . Then, for example, when executing a print of manually supplying paper, an operator puts the paper  1  on a table  4  and sets the paper so as to make its front edge or its whichever corner of left and right touch a contact point position of a upper feed roller  2  and a lower feed roller  3 , through a detection of the paper  1  executed by a table sensor  5 , according to a command of a controlling section (not shown), a print operation is started. 
     The table sensor  5  generally is constructed by two of sensor substrate A ( 6 ) and sensor substrate B ( 7 ), on the sensor substrate A ( 6 ), a light emitting element  8  is installed; and on the sensor substrate B ( 7 ), a light receiving element  9 . The table sensor  5  detects the paper  1  as a light penetrating type sensor. The table sensor  5  plurally arranged in a breadth direction in order to realize a free location function that not only can perform skew adjustment, but also can detect position of the paper  1  for printing, at which position soever the paper  1  is set on the table  4  in left direction or right direction. 
     When detected the paper  1  by the above-stated structure, as shown by  FIG. 13B , firstly, a cam  11  coupled by a drive of a motor  10  turns, and a linked piece  12  drops the upper skew adjusting roller  13  to press and contact with the lower skew adjusting roller  14  so as to enter a skew adjustment mode. 
     Then, a skew adjusting motor  15  start to drive, the drive is transmitted to the lower skew adjusting roller  14  and a skew adjusting roller pulley  16  on the same shaft via a belt  17 . Through the rotations of the upper skew adjusting roller  13  and the lower skew adjusting roller  14 , the paper  1  is conveyed, and all of front edge of the paper  1  hits the contact points of the feed rollers  2  and  3  that are stopping. Because the feed force of the skew adjusting rollers  13  and  14  is very little, after the paper  1  hit, the skew adjusting rollers  13  and  14  only slip until they stop rotating. 
     Because the shaft direction of the feed rollers  2  and  3  is set to be parallel with the operation direction (toward the inner from the surface of the paper) of a carriage  18  which loads a head, through the above stated operations, the skew of the paper  1  is adjusted. Then, while the feed rollers  2  and  3  convey the paper  1 , the skew adjusting rollers  13  and  14  open to move to positions making a movement load of the paper  1  lose, thus a paper conveyance mode is carried out, and the paper  1  is conveyed to a print position. 
     In the apparatus with the above stated structure, because a sensor substrate A ( 6 ) and a sensor substrate B ( 7 ) are mounted up and down, a problem occurs, that is, the number of parts such as connection cord (not shown) to connect them and the like increases, and cost become high. In order to solve such problem, as shown by  FIG. 14 , a sensor lever manner to mount sensor only on one direction side is used (for example, see patent document 1). 
     In the sensor lever manner, a sensor lever  20  having a turning pivot  19  is pressed by the passage of the paper  1  so that a shading section  21  turns with respect to the turning pivot  19 . Thus, a light penetrating sensor  23  is opened from a shaded state that it is shaded by the shading section  21  when the paper  1  does not exist, and receives penetrating light. Thereby, it is detected that the paper  1  has passed. 
     Patent document 1: Japan patent publication H7-89643. 
     However, regarding the detection of the paper  1  performed by the sensor lever  20 , it is performed not only while the conveyance of the paper  1 , but also while the skew adjustment. Further, in the case to detect the paper  1  by the conventional sensor lever  20 , such problem exists, that is, as shown by  FIG. 15 , when to adjust the skew, because the paper  1  turns as shown by an arrow on a-part in drawing, the paper  1  hit the side surface of the sensor lever  20 , and a skew adjustment can not be executed. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the invention to provide a medium detecting apparatus and an image forming apparatus capable of solving the above problem. 
     According to the present invention, there is provided a medium detecting apparatus, comprising a medium hit portion having a medium hit surface holding inclinations at least in a conveyance direction of medium and in a width direction of the medium, wherein a medium detection is performed through detecting that the medium hit portion is pressed downward by a hit of the medium toward the medium hit surface. 
     Moreover, the medium detecting apparatus may further comprise a guider furnished near the medium hit surface to limit the medium. 
     Moreover, the medium detecting apparatus may further comprise a shading section which turns through the pressing downward; and a sensor which detects the turn of the shading section, wherein the medium is detected according to an output of the sensor. 
     Moreover, in the medium detecting apparatus, an outside diameter above a position in which the medium hits the medium hit portion may be smaller than that under the position. 
     Moreover, in the medium detecting apparatus, an outside diameter may gradually decrease near a position in which the medium hits the medium hit portion. 
     Moreover, in the medium detecting apparatus, the medium hit portion may approximately indicate either of a conic shape and a truncated cone shape. 
     Further, according to the present invention, there is provided an image forming apparatus, comprising a medium detecting apparatus, wherein the medium detecting apparatus includes a medium hit portion having a medium hit surface holding inclinations at least in a conveyance direction of medium and in a width direction of the medium, wherein a medium detection is performed through detecting that the medium hit portion is pressed downward by a hit of the medium toward the medium hit surface. 
     Moreover, in the image forming apparatus, the medium detecting apparatus may further include a guider furnished near the medium hit surface to limit the medium. 
     Moreover, in the image forming apparatus, the medium detecting apparatus may further include a shading section which turns through the pressing downward; and a sensor which detects the turn of the shading section, wherein the medium is detected according to an output of the sensor. 
     Moreover, in the image forming apparatus, an outside diameter above a position in which the medium hits the medium hit portion may be smaller than that under the position. 
     Moreover, in the image forming apparatus, an outside diameter may gradually decrease near a position in which the medium hits the medium hit portion. 
     Moreover, in the image forming apparatus, the medium hit portion may approximately indicate either of a conic shape and a truncated cone shape. 
     Moreover, in the image forming apparatus, the medium detecting apparatus may be used to serve as a detecting sensor for executing a skew adjustment. 
     Moreover, in the image forming apparatus, the medium detecting apparatus may be used to serve as sensors to detect a movement of a carriage and to detect the medium. 
     Moreover, the image forming apparatus may further comprise a sheet guider, wherein the medium detecting apparatus may be used to serve as sensor to detect a setting of the medium. 
     Moreover, the image forming apparatus may further comprise a hand-operated adjustment print function, wherein the medium detecting apparatus may be used to serve as sensor to detect a setting of the medium. 
     THE EFFECT OF THE PRESENT INVENTION 
     According to the present invention, because the sensor lever comprises is a medium hit portion which has a medium hit surface holding inclination at least along medium conveyance direction and width direction, and detects that the medium hit portion is pressed downward by a hit of the medium toward the medium hit surface, it is possible to certainly detect out the paper and to execute an skew adjustment without that the paper un-moves after hit the sensor lever. 
     The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing a structure of a sensor lever in embodiment 1 of the present invention; 
         FIG. 2  is a diagram to explain function of a sensor lever in embodiment 1; 
         FIG. 3A  is a diagram showing a shape transformation example of a medium hit portion of a sensor lever in embodiment 1; 
         FIG. 3B  is a diagram showing a shape transformation example of a medium hit portion of a sensor lever in embodiment 1; 
         FIG. 3C  is a diagram showing a shape transformation example of a medium hit portion of a sensor lever in embodiment 1; 
         FIG. 3D  is a diagram showing a shape transformation example of a medium hit portion of a sensor lever in embodiment 1; 
         FIG. 4  is a diagram to explain operations of a sensor lever in embodiment 1; 
         FIG. 5  is a diagram to explain operations of a skew adjustment in embodiment 1; 
         FIG. 6  is a diagram showing a structure of an image forming apparatus in embodiment 2; 
         FIG. 7  is a diagram showing a structure of a ribbon protector in embodiment 2; 
         FIG. 8  is a diagram to explain operations of an image forming apparatus in embodiment 2; 
         FIG. 9  is a diagram showing a structure of an image forming apparatus in embodiment 3; 
         FIG. 10A  is a diagram to explain operations of a conventional image forming apparatus; 
         FIG. 10B  is a diagram to explain operations of an image forming apparatus in embodiment 3; 
         FIG. 11A  is a diagram showing a structure of an image forming apparatus in embodiment 4; 
         FIG. 11B  is a diagram showing a structure of an image forming apparatus in embodiment 4; 
         FIG. 11C  is a diagram showing a structure of an image forming apparatus in embodiment 4; 
         FIG. 12  is a diagram to explain operations of an image forming apparatus in embodiment 4; 
         FIG. 13A  is a diagram showing a structure of a former image forming apparatus; 
         FIG. 13B  is a diagram showing a structure of a former image forming apparatus; 
         FIG. 14  is a diagram showing a structure of a former sensor lever; and 
         FIG. 15  is a diagram to explain operations of a former skew adjustment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the invention will be described in detail hereinbelow with reference to the drawings. Moreover, in the following embodiments, a general serial impact type printer is explained as an example, but the present invention is not limited by the example. 
     Embodiment 1 
     An image forming apparatus of embodiment 1 makes a paper hit surface of a sensor lever for detecting skew hold inclinations in plural directions and be pressed down through a hit of medium. 
       FIG. 1  is a diagram showing a structure of a sensor lever in embodiment 1 of the present invention. A sensor lever  32  with a turning pivot  31  holds inclinations in all directions of 360 degrees, paper guiders  36  and  37  are used to limit the paper to move up or down in order to make an edge of the paper always flatly touch an inclined surface. Then, a shading section  33  of the sensor lever  32  which turns because of a down pressure of the limited paper  1  opens a light penetrating sensor  35  furnished on a substrate  34  so that the paper  1  is detected. 
       FIG. 2  is a diagram to explain the function of a sensor lever in embodiment 1, also is a diagram showing a relation between inclination and turning direction of the sensor lever  32 . As shown by the diagram, when the paper  1  begins moving along a direction shown on the left side or the right side and hits the sensor lever  32  on the inclined surface, a pressure F of the paper  1  is resolved into a force F 1  in the turning direction of the sensor lever  32  and a friction force F 2  between the paper  1  and the inclined surface. Then, because the inclined surface of the sensor lever  32  is made from a material of plastic or metal, does not produce friction force, so the paper  1  will not move due to the limitation of the paper guider  36 . Thus, the force F 2  is counteracted by a rebound force of the paper guider  36 . 
     When the force F 1  acts on the sensor lever  32 , with respect to the turning pivot  31 , a turning torque is produced in the direction of an arrow Fr 1 . The inclination of the sensor lever  32  is set to be able to get enough force F 1  so as to make the sensor lever  32  turn by the paper  1 , at the same time, also is set to be able to produce enough turning torque with respect to the turning pivot  31  even though the paper  1  presses towards the sensor lever  32  from other directions. 
     Moreover, the medium hit portion of the sensor lever  32  may be any other shape instead of trapezoid so long as the sensor lever can be turned by the paper  1 . For example, a lune shape as shown by  FIG. 3A ; a triangle pyramid shape as shown by  FIG. 3B ; a shape with a trapezoid added on the underside as shown by  FIG. 3C . 
     Or, the medium hit portion of the sensor lever  32  also may just hold inclination in directions of a predetermined range instead of in all directions, and it also may has such shape as a hollowed structure shown by  FIG. 3D . Furthermore, if setting the inclinations to be different in respective directions, it is possible to obtain all kinds of forces F 1  and all kinds of turning torques respectively corresponding to the forces F 1 . 
     &lt;Operations&gt; 
       FIG. 4  is a diagram to explain operations of a sensor lever in embodiment 1; and  FIG. 5  is a diagram to explain operations of a skew adjustment in embodiment 1. 
     Firstly, when the paper  1  moves as shown by the arrow and hits the inclined surface of the sensor lever  32  so as to produce a turning torque with respect to the turning pivot  31 , as shown by  FIG. 4 , the sensor lever  32  turns from the position with broken line to the position with solid line. Then, because the shading section  33  that is shading the light penetrating sensor  35  leaves from the light penetrating sensor  35 , so the penetrating light is able to penetrate. Thereby, the sensor lever  32  is detected that it has begun to turn. 
     The following is to explain operation of skew adjustment by using the sensor lever  32 . 
     Firstly, as shown by  FIG. 5 , as soon as the paper  1  passes any position of the sensor lever  32 , the paper  1  is judged having be set, then, a upper skew adjusting roller  13  goes down to press and contact with a lower skew adjusting roller  14 , so as to enter a skew adjustment mode. 
     And then, the paper  1  is conveyed through rotation the skew adjusting rollers  13  and  14 , as shown by the part b, the front edge of the paper  1  hits the contact points of feed rollers  2  and  3  that are stopping. Then, until the whole front edge of the paper  1  hits the contact points of the feed rollers  2  and  3 , the skewing paper  1  turns along the arrow direction, here, as shown by the part a, the paper  1  hits the sensor lever  32  at a slant from lateral side. 
     Because the paper-feeding force of the skew adjusting rollers  13  and  14  is puny, after the whole front edge of the paper  1  hits the contact points of the feed rollers  2  and  3 , until the skew adjusting rollers  13  and  14  stop slipping, the whole front edge of the paper  1  is placed being parallel with the axis direction of the feed rollers  2  and  3 , thus, the skew adjustment ends. 
     &lt;Effect of the Embodiment 1&gt; 
     According to the image forming apparatus of the embodiment 1 stated above, because the paper hit surface of the sensor lever is made to hold inclination in plural directions and is pressed down by the hit of the mediums, it is possible to certainly detect out the paper and to execute an skew adjustment without that the paper un-moves after hit the sensor lever. 
     Embodiment 2 
     An image forming apparatus of embodiment 2 makes a paper hit surface of a sensor lever for detecting skew hold inclinations in plural directions, and uses one sensor to perform position detections of paper in a movement direction of carriage and in a conveyance direction of paper. 
       FIG. 6  is a diagram showing a structure of an image forming apparatus in embodiment 2; and  FIG. 7  is a diagram showing a structure of a ribbon protector in embodiment 2. That is, the  FIG. 6  showed the circumference of a carriage in the image forming apparatus of the embodiment 2, and the  FIG. 7  showed a protector bracket  41  and a sensor lever  32 . 
     In the image forming apparatus of the embodiment 2, as shown by  FIG. 8  which will be stated below, when a carriage  18  moved to a beginning position, the protector bracket  41  loaded on the carriage  18  goes across the sensor lever  32 . 
     The sensor lever  32 , when being pressed downward by the protector bracket  41  as the structure in embodiment 1, through that the shading section  33  turns to open the light penetrating sensor  35  on the substrate  34 , detects the position of the protector bracket  41 . 
     The protector bracket  41  is constructed as shown by the  FIG. 7 . On its center portion  42 , a hole is furnished, when the center portion  42  comes to the upside of the sensor lever  32  in a state that the paper  1  does not exist, the sensor lever  32  which is pressed downward for a time by the protector bracket  41  returns to original position. 
     In general, because the movement of the carriage  18  is executed by an open control, a sensor  44  is mounted in the movement direction of the carriage  18  as shown by a broken line used for deciding the beginning position. However, in the image forming apparatus of the embodiment 2, because the sensor lever  32  also fulfills the function of the sensor  44 , and when the protector bracket  41  presses downward the sensor lever  32  for a time by the movement of the carriage  18 , and the sensor lever  32  returns again a position by the center portion  42  of the protector bracket  41 , the return position can be judged being the beginning position, so it is unnecessary to furnish the sensor  44 . 
     &lt;Operations&gt; 
       FIG. 8  is a diagram to explain operations of an image forming apparatus in embodiment 2. On the right side in the same drawing, a flow is shown. 
     Firstly, when the power source of the image forming apparatus is supplied (Step S 01 ), according to a command of a controlling section (not shown), the carriage  18 , as shown by an arrow A in the drawing, starts to move toward a left direction which serves as a standard in order to decide a beginning position. When the sensor lever  32  is pressed downward by the protector bracket  41 , the movement speed of the carriage  18  is reduced slowly so as to enter a beginning position deciding mode (Step S 02 ). 
     Then, the center portion  42  of the protector bracket  41  locates above the sensor lever  32 , and a position in which the sensor lever  32  returns is judged being the beginning position so as to enter a standing-by state. Continuously, an operator sets the paper  1  on the table  4  as shown by an arrow B in the drawing, and makes the front edge of the paper  1  hit the contact point position of the feed rollers  2  and  3  (Step S 03 ). 
     Further, when the setting of the paper  1  is detected by the table sensor  5 , according to a command of the controlling section (not shown), the feed rollers  2  and  3  rotates to convey the paper  1  as shown by an arrow C. Then, through the paper  1  passes over the sensor lever  32 , because the sensor lever  32  is pressed downward again, and the light penetrating sensor  35  which is shaded by the shading section  33  is opened, so the front edge position of the paper  1  is detected, that is, the head position of the paper  1  is detected (Step S 04 ). 
     As stated above, because the paper hit surface of the sensor lever  32  is made to hold inclinations in all directions, so it is possible to use the sensor lever  32  not only serving as a position detecting sensor while the movement of the carriage  18 , but also serving as a position detecting sensor in the conveyance direction of the paper  1 . 
     &lt;Effect of the Embodiment 2&gt; 
     According to the image forming apparatus of the embodiment 2 stated above, because the paper hit surface of the sensor lever is made to hold inclination in plural directions, and the position detections in the movement direction of the carriage  18  and the conveyance direction of the paper  1  is performed by one sensor, it is possible to certainly detect the medium and to decrease the number of parts for detection use. As a result, space can be saved and cost can be reduced. 
     Embodiment 3 
     An image forming apparatus of embodiment 3 is an image forming apparatus which comprises a sheet guider. In the image forming apparatus, a sensor lever whose paper hit surface holds inclinations in plural directions is furnished as a sensor to detect paper setting. 
       FIG. 9  is a diagram showing a structure of an image forming apparatus in embodiment 3. 
     In general, in an image forming apparatus which has not skew adjustment function, in order to prevent the skew, a sheet guider  54  is furnished as shown by  FIG. 9 , and the paper  1  is set by making the paper  1  hit the sheet guider  54 . In the image forming apparatus of the embodiment 3, a sensor lever  32  having inclinations in all directions of 360 degrees and a turning pivot  31  is furnished as a table sensor  51  for detecting the setting of the paper  1 , and the sensor lever  32  is pressed downward by setting the paper  1 , then the shading section  33  turns to open the light penetrating sensor  35  on the substrate  34 , thus, a detection is performed. 
     In order to certainly detect the setting of the paper  1 , the position of the table sensor  51  is set at the right side than the sheet guider  54  on the table  4  which is hit as a left edge standard, but at the front side than the contact points of feed rollers  52  and  53  that are hit as a front edge standard of the paper  1 , the position best is such position which does not leave the intersecting position of the front edge and the left edge as much as possible. 
     Further, in the image forming apparatus of the embodiment 3, the feed rollers  52  and  53  that are hit while setting the paper  1  are formed into a long roller shape with a shaft, its surface is made of material such as plastic, metal or the like so as to the paper  1  slips easily. 
     &lt;Operations&gt; 
       FIG. 10A  is a diagram to explain operations of a conventional image forming apparatus; and  FIG. 10B  is a diagram to explain operations of an image forming apparatus in embodiment 3. 
     In conventional image forming apparatus, when setting the paper  1 , as shown by  FIG. 10A , two operations must be performed. That is, first is to make the left edge of the paper  1  hit (arrow Dx direction) the sheet guider  54  on the table  4 , next is to make the front edge of the paper  1  hit (arrow Dy direction) the contact points of the feed rollers  2  and  3 . If doing the operations according to contrary order, that is, first is to hit along the arrow Dy direction and next is to hit along the arrow Dx direction, because the paper  1  would be scratched by gap of the plural rollers or by the sensor lever  20 , so a correct setting can not be performed. 
     In the image forming apparatus of the embodiment 3, because the sensor lever whose paper hit surface holds inclinations in all directions of 360 degrees is used to serve as a table sensor  51 , so it is possible to set the paper  1  without that the paper  1  hits the sensor lever, even if only using one operation to set the paper  1  along a slant direction such as the arrow D direction. 
     &lt;Effect of the Embodiment 3&gt; 
     According to the image forming apparatus of the embodiment 3 stated above, in the image forming apparatus comprising a sheet guider, because a sensor lever whose paper hit surface holds inclinations in plural directions is furnished as a sensor to detect paper setting, and the feed rollers are made of material making the paper  1  slip easily, it is possible to set the paper  1  only by using one operation. As a result, the operation performance can be improved. 
     Embodiment 4 
     An image forming apparatus of embodiment 3 is an image forming apparatus which has a function capable of executing a hand-operated adjustment print. In the image forming apparatus, a sensor lever whose paper hit surface holds inclinations in plural directions is furnished as a sensor to detect paper setting. 
       FIG. 11A  is a diagram showing a structure of an image forming apparatus in embodiment 4;  FIG. 11B  is a diagram showing a structure of an image forming apparatus in embodiment 4; and  FIG. 11C  is a diagram showing a structure of an image forming apparatus in embodiment 4. 
     The  FIG. 11A  showed a whole structure of an image forming apparatus in embodiment 4. The image forming apparatus of the embodiment 4 has a hand-operated adjustment print function capable of executing a print in a desired position of the paper  1  desired by operator. In order to execute the hand-operated adjustment print, a table sensor  51  to perform a detection of the paper  1 , a single bill (i.e. single paper, also i.e. separated type paper) head detecting sensor  61  and a continuous bill (i.e. continuously arranged type paper) head detecting sensor  62  serve as a sensor lever whose paper hit surface holds inclinations in all directions of 360 degrees. 
     Then, as a retreating function of a continuous bill  65  having been performed print, a mechanism is furnished which opens feed rollers  2  and  3 , and feed rollers  63  and  64  according to a command of a controlling section (not shown). When operator pressed a retreating switch (not shown), a mode motor  66  drives according to a command from the controlling section, then as shown by  FIG. 11B , an opening bar  67  coupling with the mode motor  66 , while being monitored by a mode sensor  68 , moves to a bill retreat position as shown by an arrow Ex. 
     Then, through the movement, slope portions (c 1 , c 2  portions) of the opening bar  67  lift up the upper feed roller  2  on front side and the upper feed roller  63  on rear side along an arrow Ey direction. Thus, the feed rollers  2  and  3  and the feed rollers  63  and  64  are opened. 
     Further, a protector bracket  69  carried by the carriage  18  is made of a transparent resinous material, as shown by  FIG. 11C , a marker  70  whose size is the same as character is printed. 
     &lt;Operations&gt; 
       FIG. 12  is a diagram to explain operations of an image forming apparatus in embodiment 4. 
     Firstly, when operator pressed a hand-operated adjustment print switch (not shown), according to a command of the controlling section (not shown), the opening bar  67  moves while being monitored by the mode sensor  68  so as to open the feed rollers  2  and  3 , and the feed rollers  63  and  64 . 
     As shown on the left side in the same drawing, in the case of single bill print, because the carriage  18  stops in a position that the marker  70  of the protector bracket  69  corresponds to the print position of first character in the single bill, the operator moves the paper  1  to a desired position by hand through the transparent protector bracket  69 . That is, the operator moves and adjusts the paper  1  to the position corresponding to the first character of the paper  1  forward, backward, leftward and rightward as shown by an arrow symbol F. 
     Further, as shown on the right side in the same drawing, in the case of continuous bill print, because the carriage  18  also stops in a position that the marker  70  of the protector bracket  69  corresponds to the print position of first character in the continuous bill, the operator adjusts the continuous bill  65  into a breadth direction (an arrow Gx direction) of a desired position by hand together with a tractor  71  through the transparent protector bracket  69 , then makes the tractor  71  and a platen knob (not shown) coupling with driving system turn forcibly, further puts the continuous bill  65  along a direction of the front and the rear as shown by an arrow Gy. Thus, the continuous bill  65  is adjusted into a breadth direction of a desired position. 
     As stated above, in the hand-operated adjustment print mode, even if moving the paper  1  or the continuous bill  65  forward, backward, leftward and rightward, because a sensor lever holding inclinations in all directions of 360 degrees is furnished as a paper sensor, it is possible to freely move the paper  1  or the continuous bill  65  without hitting these sensors. 
     Then, through press again the hand-operated adjustment print switch (not shown), the opening feed rollers  2  and  3 , and the feed rollers  63  and  64  return the original positions, thus, a normal printable state is returned, and the paper setting for the hand-operated adjustment print ends. 
     &lt;Effect of the Embodiment 4&gt; 
     According to the image forming apparatus of the embodiment 4 stated above, in the image forming apparatus having hand-operated adjustment print function of single paper or continuous paper, because a sensor lever whose paper hit surface holds inclinations in plural directions is furnished as sensors to detect positions of paper, in which one of directions soever the paper is moved, it is possible to set the paper in simple operation without hitting. 
     &lt;Transformation Example&gt; 
     In the embodiments stated above, the paper hit surface of the sensor lever is provided on the upside. However, it is possible to use a structure to turn the sensor lever upside down so that the paper hit surface is provided on the underside. Further, in the case that the paper moves along a vertical direction, it is possible to furnish the sensor lever toward left or right so that the paper hit surface is provided on the left side or on the right side. 
     The utilization possibility on industry: 
     As stated above, an example regarding a paper detecting sensor in serial impact type printer is explained. However, the present invention also can be widely applied to other medium processing apparatus which conveys medium and performs predetermined process such as laser beam printer, copying apparatus, ticket issuing machine and the like. 
     The present invention is not limited to the foregoing embodiments but many modifications and variations are possible within the spirit and scope of the appended claims of the invention.