Abstract:
A cover opening/closing mechanism, including a housing having an opening; a flexible cover movable between a closed position and an opened position; a first locking mechanism; and a second locking mechanism, wherein a first distance by which a pair of members of the first locking mechanism slide and move with respect to each other in order to bring the first locking mechanism to a locked state is longer than a second distance by which a pair of members of the second locking mechanism slide with respect to each other in order to bring the second locking mechanism to a locked state. An external force for causing the pair of the members of the first locking mechanism to slide and move with respect to each other is weaker than an external force for causing the pair of members of the second locking mechanism to slide with respect to each other.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2010-103811, filed on Apr. 28, 2010. The entire subject matter of the application is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     Aspects of the present invention relate to a cover opening and closing mechanism configured to open and close a cover for covering an opening formed in a housing, and to an image processing device provided with such a cover opening and closing mechanism. 
     2. Related Art 
     Conventionally, an image forming device having a cover opening and closing mechanism capable of opening and closing a cover for covering an opening formed in a housing of the image forming device has been used. One of such image forming devices is provided with a pair of auxiliary locking mechanisms in addition to a pair of main locking mechanisms so that the cover is prevented from being closed in a one-sided closed state (i.e., a state where one of right and left sides of the cover is locked). 
     SUMMARY 
     However, there is a possibility that, if the degree of rigidity of the cover is low and the cover could be deformed when receiving an external force, a drawing force for drawing the cover toward a closed position is weakened and thereby the cover may be closed in a one-sided closed state. 
     If a sensor for detecting whether the cover is closed is located at a position shifted closer to one of the pair of locking mechanism with respect to the center of the pair of locking mechanisms, the sensor may erroneously detect the state of the cover. 
     Aspects of the present invention are advantageous in that they provide at least one a cover opening and closing mechanism and an image processing device configured to prevent a cover from being closed in a one-sided closed state, and to properly detect whether the cover is closed or opened even when a sensor for detecting the state of the cover is located as a position shifted closer to one of a pair of locking mechanisms. 
     According to an aspect of the invention, there is provided a cover opening and closing mechanism, comprising: a housing having an opening; a cover that is attached to the housing to be rotatable about a predetermined rotation axis so that the cover is movable between a closed position and an opened position, the cover being formed to have flexibility and to be deformed when receiving an external force; a first locking mechanism having a pair of members respectively provided at a first position on the cover and at a corresponding position on the housing, the pair of members of the first locking mechanism being brought to a locked state when the cover is in the closed position; and a second locking mechanism having a pair of members respectively provided at a second position on the cover and at a corresponding position on the housing, the pair of members of the second locking mechanism being brought to a locked state when the cover is in the closed position. In this configuration, a first distance by which the pair of members of the first locking mechanism slide and move with respect to each other in order to bring the first locking mechanism to the locked state is longer than a second distance by which the pair of members of the second locking mechanism slide and move with respect to each other in order to bring the second locking mechanism to the locked state. An external force for causing the pair of the members of the first locking mechanism to slide and move with respect to each other is weaker than an external force for causing the pair of members of the second locking mechanism to slide and move with respect to each other. 
     According to another aspect of the invention, there is provided an image processing device, comprising: an image processing unit; and the above described cover opening and closing mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         FIG. 1  is a perspective view illustrating an outer appearance of an image forming device according to an embodiment. 
         FIG. 2  is a vertical cross section illustrating an inner structure of the image forming device. 
         FIG. 3A  is a perspective view illustrating a state where a cover is in a closed position, and  FIG. 3B  is a perspective view illustrating a state where the cover is in an opened position. 
         FIG. 4A  is a plan view illustrating a state where the cover is in the closed position, and 
         FIG. 4B  is a plan view illustrating a state where the cover is slightly moved from the closed position toward the opened position. 
         FIG. 5A  is a cross section illustrating a state where a hook engages with a receiving portion, and  FIG. 5B  is a cross section illustrating a state where the hook is released from the receiving portion. 
         FIG. 6A  is a left side view illustrating a state where the cover is slightly moved from the closed position toward the opened position, and  FIG. 6B  is a left side view illustrating a state where the cover is in the closed position. 
         FIG. 7A  is a right side view illustrating a state where the cover is moved slightly from the closed position toward the opened position, and  FIG. 7B  is a right side view illustrating a state where the cover is in the closed position. 
         FIG. 8A  is a left side view illustrating a state where a stopper portion and a receiving portion of a first locking mechanism contact with each other,  FIG. 8B  is a left side view illustrating a state where the stopper portion and the receiving portion engage with each other,  FIG. 8C  is a right side view illustrating a state where an stopper portion and a receiving portion of a second locking mechanism contact with each other, and  FIG. 8D  is a right side view illustrating a state where the stopper portion and the receiving portion of the second locking mechanism engage with each other. 
         FIG. 9  is an explanatory illustration for explaining deformation of a cover caused when a left edge part of the cover is pressed. 
         FIG. 10A  is a plan view illustrating a state where the stopper portion properly engages with the receiving portion,  FIG. 10B  is a left side view illustrating a state where the stopper portion properly engages with the receiving portion,  FIG. 10C  is a plan view illustrating a state where the stopper portion is not able to engage with the receiving portion, and  FIG. 10D  is a left side view illustrating a state where the stopper portion is not able to engage with the receiving portion. 
     
    
    
     DETAILED DESCRIPTION 
     Hereafter, an embodiment according to the invention will be described with reference to the accompanying drawings. In the following, positional relationships between components are explained while referring to upward, downward, leftward and rightward directions indicated in the drawings. 
     As shown in  FIG. 1 , an image forming device  1  includes a pullout paper cassette  5  at a lower front part of a housing  3 . On the front side of the housing  3 , a cover  7  is provided above the paper cassette  5 . The cover  7  is attached to the housing  3  to be rotatable about an axis situated at a lower side of the cover  7  so that an upper side of the cover  7  can be inclined frontward with respect to the axis. On the top surface of the housing  3 , an output tray  9  to which a recording medium on which an image has been formed is ejected is provided. 
     As shown in  FIG. 2 , the image forming device  1  is formed as a device having a tandem type image formation unit capable of forming an image through an electrophotographic process. The image forming device  1  includes a paper supply unit  11 , a belt unit  12 , process cartridges  13 , a scanning unit  14 , a fixing unit  15 , an ejection unit  16  and a drawer  17 . 
     The paper supply unit  11  sends out a sheet-like recording medium (e.g., a sheet of paper) accommodated in the paper cassette  5  toward the downstream side along a paper carrying path (indicated by a double chain line in  FIG. 2 ). 
     The belt unit  12  carries the recording medium sent out by the paper supply unit  11  from the front side to the rear side while sandwiching the recording medium between the belt unit  12  and the process cartridges  13 . The four process cartridges  13  are arranged in equal intervals above the belt unit  12 . Each process cartridge  13  includes a photosensitive body and a developing mechanism which develops an electrostatic latent image formed on the photosensitive body. 
     The scanning unit  14  emits a laser beam toward the photosensitive body of each process cartridge  13  so as to form an electrostatic latent image on the photosensitive body. Then, the electrostatic latent image formed on the photosensitive body by the scanning unit  14  is developed as a toner image by the developing mechanism provided in the process cartridge  13 . Next, the toner image is transferred to the recording medium being carried on the belt unit  13 . 
     The fixing unit  15  fixes the toner image on the recording medium by heating and pressing the recoding medium on which the toner image has been transferred, while sandwiching the recording medium between rollers. The recording medium which has passed the fixing unit  15  is then ejected to the output tray  9  through the ejection unit  16 . 
     The drawer  17  is configured such that the drawer  17  can be pulled out toward the front side in a state where the cover  7  is opened. On the drawer  17 , the process cartridges  13  are mounted so that the process cartridges  13  can be changed by pulling out the drawer  17 . 
     The image forming device  1  includes upper frames  21 L and  21 R and lower frames  23 L and  23 R which serve as a framework for supporting the above described various components in the image forming device  1  (see  FIGS. 3A and 3B ). Each of the upper frames  21 L and  21 R is a member made of sheet metal. The upper frames  21 L and  21 R are arranged to have a certain interval in the left and right direction so that the upper frames  21 L and  21 R are located above the lower frames  23 L and  23 R, respectively. Each of the lower frames  23 L and  23 R is a member made of resin of which rigidity is lower than the upper frames  21 L and  21 R. 
     The paper supply unit  11 , the belt unit  12 , the process cartridges  13 , the scanning unit  14 , the fixing unit  15 , the ejection unit  16  and the drawer  17  are accommodated in the inside between the upper frames  21 L and  21 R. The paper cassette  5  is accommodated in the inside between the lower frames  23 L and  23 R. 
     At the front edge parts of the lower frames  23 L and  23 R, the cover  7  is attached. The cover  7  is arranged such that the cover  7  can be inclined between a closed position (see  FIG. 3A ) and an opened position (see  FIG. 3B ) by rotating about a rotation shaft  25  which is parallel with the upper edge or the lower edge of an opening  24  formed on the front side of the housing  3 . By rotating the cover  7  to the opened position, it becomes possible to pull out the drawer  17  through the opening  24 . It should be noted that the rotation shaft  25  may not be completely parallel with the upper edge or the lower edge of the opening  24 . For example, the rotation shaft  25  may be slightly inclined with respect to the upper edge or the lower edge of the opening  24 . That is, the rotation shaft  25  may be arranged to be substantially parallel with the upper edge or the lower edge of the opening  24 . 
     As shown in  FIGS. 4A and 4B , a push button  27  is provided at the upper edge portion of the cover  7 . The push button  27  is pressed by a user to open the cover  7 . 
     More specifically, as shown in  FIGS. 4B and 5A , in a main body of the image forming device  1 , receiving portions  31 L and  31 R are provided. On the cover  7 , hooks  33 L and  33 R are provided at positions respectively corresponding to the positions of the receiving portions  31 L and  31 R (In  FIG. 5A , the hook  33 R is shown). 
     In a state where the cover  7  is closed, the hooks  33 L and  33 R engage with the receiving portions  31 L and  31 R, respectively, so that the cover  7  is prevented from moving toward the opened position. When the press button  27  is pressed, the hooks  33 L and  33 R rotate in accordance with movement of the press button  27 . 
     Therefore, when the hooks  33 L and  33 R are rotated together with the movement of the press button  27 , engagement between the hooks  33 L and  33 R and the receiving portions  31 L and  31 R are released as shown in  FIG. 5B . By pulling the cover  7  frontward in a sate where the engagement between the hooks  33 L and  33 R and the receiving portions  31 L and  31 R is released, the cover  7  can be opened. 
     As shown in  FIG. 6A , a first locking mechanism  40  is provided on a left side of the front surface of the image forming device  1 . The first locking mechanism  40  includes a stopper portion  41  provided on the cover  7 , and a receiving portion  43  provided on a left surface of the upper frame  21 L. The receiving portion  43  is in a state of being pressed upward by an elastic force from a compression spring  45 . 
     As shown in  FIG. 6B , in a state where the cover  7  is in the closed position, the stopper portion  41  and the receiving portion  43  lock with respect to each other, so that the cover  7  is prevented from moving toward the opened position. 
     In the vicinity of the first locking mechanism  40 , a limit switch  47  is provided. When the cover  7  moves from the opened position to the closed position, a projection  49  which is formed on the cover  7  to protrude from the cover  7  contacts a lever  47 A, and thereby the limit switch  47  switches from ON to OFF. 
     On the other hand, when the cover  7  moves from the closed position to the opened position, the projection  49  moves away from the lever  47 A, and thereby the limit switch  47  switches from OFF to ON. Therefore, it is possible to detect whether the cover  7  is in the closed position in accordance with whether the limit switch  47  is ON or OFF. 
     As shown in  FIG. 7A , a second locking mechanism  50  is provided on a right side of the front surface of the image forming device  1 . The second locking mechanism  50  is similar to the configuration of the first locking mechanism  40 . The second locking mechanism  50  includes a stopper portion  51  provided on the cover  7 , and a receiving portion  53  provided on a left surface of the upper frame  21 R. The receiving portion  53  is in a state of being pressed upward by an elastic force from a compression spring  55 . 
     As shown in  FIG. 7B , in a state where the cover  7  is in the closed position, the stopper portion  51  and the receiving portion  53  lock with respect to each other, so that the cover  7  is prevented from moving toward the opened position. 
     However, the stopper portion  51  of the second locking mechanism  50  is formed to be slightly different from the stopper portion  41  of the first locking mechanism  40 . Due to such a difference in shape between the stopper portion  51  and the stopper portion  41 , the second locking mechanism  50  requires a stronger force for bringing the stopper portion  51  to the state of being locked with the receiving portion  53  than a force for bringing the stopper portion  41  to the state of being locked with the receiving portion  43 . 
     More specifically, as shown in  FIG. 8A , when the cover  7  moves from the opened position to the closed position, the stopper portion  41  of the first locking mechanism  40  first moves in a traveling direction D 1  (which is substantially horizontal when the stopper portion  41  contacts the receiving portion  43 ), and contacts the receiving portion  43  at a contact start point  41 A. 
     Then, as the stopper portion  41  moves further in the traveling direction D 1 , the stopper portion  41  and the receiving portion  43  slide with respect to each other while keeping the state of contacting with each other. As a result, a contacting point defined on the receiving portion  43  between the stopper portion  41  and the receiving portion  43  moves along a first guide surface  41 B from the contact start point  41 A to a peak point  41 C. 
     Next, as the stopper portion  41  moves further in the traveling direction D 1 , the stopper portion  41  and the receiving portion  43  slide with respect to each other while keeping the state of contacting with each other. As a result, the contacting point defined on the receiving portion  43  between the stopper portion  41  and the receiving portion  43  passes over the peak point  41 C, and further moves along a second guide surface  41 D from the peak point  41 C to an engagement completion point  41 E. When the contacting point between the stopper portion  41  and the receiving portion  43  reaches the engagement completion point  41 E, the stopper portion  41  and the receiving portion  43  are brought to the locked state. 
     Regarding the stopper portion  41 , the first guide surface  41 B is formed such that an angle θ 1  formed between the first guide surface  41 B and the traveling direction D 1  (which is substantially horizontal when the stopper portion  41  contacts the receiving portion  43 ) is relatively small. Therefore, when a force for moving the stopper portion  41  in the traveling direction D 1  is divided into an component force which is horizontal with respect to the first guide surface  41 B and a component force which is perpendicular to the first guide surface  41 B, almost all of the force acts as the component force which is horizontal with the first guide surface  41 B, and therefore the component force which is horizontal with the first guide surface  41 B causes the stopper portion  41  to slide along the first guide surface  41 B. 
     On the other hand, as shown in  FIG. 8C , when the cover  7  moves from the opened position to the closed position, the stopper portion  51  of the second locking mechanism  50  first moves in the traveling direction D 1  (which is substantially horizontal when the stopper portion  51  contacts the receiving portion  53 ), and contacts the receiving portion  53  at a contact start point  51 A. 
     Then, as the stopper portion  51  moves further in the traveling direction D 1 , the stopper portion  51  and the receiving portion  53  slide with respect to each other while keeping the state of contacting with each other. As a result, a contacting point defined on the receiving portion  53  between the stopper portion  51  and the receiving portion  53  moves along a first guide surface  51 B from the contact start point  51 A to a peak point  51 C. 
     Next, as the stopper portion  51  moves further in the traveling direction D 1 , the stopper portion  51  and the receiving portion  53  slide with respect to each other while keeping the state of contacting with each other. As a result, the contacting point defined on the receiving portion  53  between the stopper portion  51  and the receiving portion  53  passes over the peak point  51 C, and further moves along a second guide surface  51 D from the peak point  51 C to an engagement completion point  51 E. When the contacting point between the stopper portion  51  and the receiving portion  53  reaches the engagement completion point  51 E, the stopper portion  51  and the receiving portion  53  are brought to the locked state. 
     Regarding the stopper portion  51 , the first guide surface  51 B is formed such that an angle θ 2  formed between the first guide surface  51 B and the traveling direction D 1  (which is substantially horizontal when the stopper portion  51  contacts the receiving portion  53 ) is larger than the angle θ 1 . 
     Therefore, when a force for moving the stopper portion  51  in the traveling direction D 1  is divided into a component force which is parallel with the first guide surface  51 B and a component force which is perpendicular to the first guide surface  5   r   1 B, the component force which is parallel with the first guide surface  51 B becomes smaller than the component force acting in parallel with the first guide surface  41 B in the case of the stopper portion  41 . 
     Therefore, the force for causing the stopper portion  51  to slide along the first guide surface  51 B is weaker than the force for causing the stopper portion  41  to slide along the first guide surface  41 B. In addition, since the component force which is perpendicular to the first guide surface  51 B becomes larger than the component force which is perpendicular to the first guide surface  41 B in the case of the stopper portion  41 , the stopper portion  51  is pressed against the first guide surface  51 B more strongly in comparison with the case where the stopper portion  41  is pressed against the first guide surface  41 B. That is, a frictional resistance acting between the stopper portion  51  and the first guide surface  51 B becomes larger than a frictional resistance acting between the stopper portion  41  and the first guide surface  41 B. 
     Therefore, in the state where the stopper portions  41  and  51  respectively contact the receiving portions  43  and  53 , the stopper portion  41  can be pushed toward the closed position with a force which is weaker than that for pushing the stopper portion  51  toward the closed position. In other words, in order to bring the second locking mechanism  50  into a locked state, it is necessary to apply, to the first locking mechanism  50 , a stronger external force than an external force for bringing the first locking mechanism  40  into a locked state. 
     The stopper portion  51  is formed such that a distance between the contact start point  51 A and the peak pint  51 C is shorter than a distance between the contact start point  41 A and the peak point  41 C in the case of the stopper portion  41 . Therefore, the stopper portion  51  can be moved such that the contacting point defined on the receiving portion  53  passes over the peak point  51 C and reaches the second guide surface  51 D without the need for pressing the stopper portion  51  to a relatively deep position, although, in order to bring the second locking mechanism  50  to the locked state, it is necessary to apply, to the second locking mechanism  50 , a stronger force than a force for bringing the first locking mechanism  40  to the locked state. 
     Regarding the stopper portion  51 , the inclination of the second guide surface  51 D is defined such that a pressing force acting on the stopper portion  51  when the stopper portion  51  is pressed upward from the receiving portion  53  also acts as a drawing force for drawing the stopper portion  51  toward the closed position. Therefore, when the stopper portion  51  is pressed toward the closed position, the cover  7  can be drawn to the closed position without applying a strong force to the stopper portion  51  after the contacting point between the stopper portion  51  and the receiving portion  53  passes over the peak point  51 C. 
     In this point of view, regarding the stopper portion  41 , the distance between the contact start point  41 A and the peak point  41 C is longer than the distance between the contact start point  51 A to the peak point  51 C. Therefore, it is necessary to press the stopper portion  41  to a relatively deep point in order to cause the receiving portion  43  to pass over the peak point  41 C. In other words, if the stopper portion  41  is not pressed to a relatively deep point, the first locking mechanism  40  cannot be brought to the locked state. 
     Furthermore, after the contacting point between the stopper portion  41  and the receiving portion  43  passes over the peak point  41 C, the contacting point between the stopper portion  41  and the receiving portion  43  reaches the engagement completion point  41 E by slightly pressing the stopper portion  41 . For this reason, the drawing force for drawing the stopper portion  41  toward the closed position is not so strong as that for drawing the stopper portion  51  toward the closed position. 
     That is, although initially the stopper portion  41  can be pushed easily in comparison with the stopper portion  51 , the stopper portion  41  is not drawn strongly toward the closed position in comparison with the case of the stopper portion  51 . On the other hand, initially the stopper portion  51  is hard to push toward the closed position, but afterward the stopper portion  51  becomes easier to be drawn to the closed position in comparison with case of the stopper portion  41 . 
     In addition, the cover  7  is configured such that the flexural rigidity in the left and right direction is relatively low. Therefore, in a state where the stopper portion  41  is easily to push and the stopper portion  51  is hard to push, the cover  7  deforms, for example, when the cover  7  is moved to the closed position by pressing the left edge portion of the cover  7 . In this case, the cover  7  deforms as indicated by a dashed line in  FIG. 9 . 
     If the cover  7  deforms as described above, an elastic restoring force is caused in the cover  7  depending on the elastic deformation of the cover  7 . The elastic restoring force acts in a direction of drawing back the stopper portion  41  from the closed position side. Therefore, through the elastic restoring force, it becomes possible to prevent the cover  7  from being closed in the one-sided closed state (i.e., a state where one side of the cover  7  is closed). 
     Furthermore, as shown in  FIGS. 10A and 10B , regarding the stopper portion  41  and the receiving portion  43 , when the stopper portion  41  moves straight in the proper traveling direction D 1 , a peak part  41 P of the stopper portion  41  and a peak part  43 P of the receiving portion  43  become parallel with each other, and in this case the stopper portion  41  and the receiving portion  43  engage with each other after the peak parts  41 P and  43 P clime over with respect to each other. 
     By contrast, as shown in  FIGS. 10C and 10D , when the stopper portion  41  moves in an inclined direction D 2  (improper direction) with respect to the proper traveling direction D 1 , the peak parts  41 P and  43 P become to a state where the peak parts  41 P and  43 P are not parallel with each other. In this case, the peak parts  41 P and  43 P become unable to pass over with respect to each other. As a result, the stopper portion  41  and the receiving portion  43  cannot be moved to the position where the stopper portion  41  and the receiving portion  43  engage with each other. Such a configuration of the stopper portion  41  also contributes to preventing the cover  7  from being closed in the one-sided closed state in the first locking mechanism  40 . 
     Hereafter, advantages achieved by the above described embodiment will be explained. As described above, the cover  7  is configured such that the cover  7  is deformed when receiving an external force. Therefore, there may be a case where an upper right part of the cover  7  cannot reach the closed position regardless of the fact that an upper left part of the cover  7  reaches a position near to the closed position. However, even when such a condition occurs, by the elastic restoring force of the cover  7 , the first locking mechanism  40  can be prevented from being brought to the locked state. 
     Therefore, by employing such a configuration which utilizes the elastic restoring force for preventing occurrence of the state where the cover  7  is closed in the one-sided closed state, it becomes possible to prevent occurrence of a situation where only the first locking mechanism  40  is in the closed state, thereby ensuring that both of the first locking mechanism  40  and the second locking mechanism  50  are in the locked state. 
     Therefore, for the limit switch  47 , it is not necessary to detect whether the cover  7  is at a position where both of the first locking mechanism  40  and the second locking mechanism  50  are in the locked state. Such a configuration makes it possible to simplify the configuration of a detecting unit which is not required to detect whether the cover  7  is at a position where both of the first locking mechanism  40  and the second locking mechanism  50  are in the locked state, in comparison with the case where a detecting unit is required to detect whether the cover  7  is at a position where both of the first locking mechanism  40  and the second locking mechanism  50 . 
     That is, even if the detecting unit is formed by a single limit switch  47 , it becomes possible to prevent the detecting unit from erroneously detecting that the cover  7  is in the closed state in the situation where only the first locking mechanism  40  is in the locked state while the second locking mechanism  50  is not in the locked state. 
     Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. 
     Hereafter, variations of the above described embodiment will described. 
     In the image forming device according to the above described embodiment, when the cover  7  is opened by pressing the push button  27 , the force for releasing the locked state of the first locking mechanism and the force for releasing the locked state of the second locking mechanism are different from each other. Therefore, the first locking mechanism  40  tends to be released from the locked state more easily relative to the second locking mechanism  50 . If the cover  7  is opened in an inclined state, the user may have uncomfortable feel. 
     Therefore, in order to suppress such uncomfortable feeling, the push button  27  may be located at a rightward position in accordance with the difference of the force for locking the first locking mechanism  50  and the force for locking the second locking mechanism  50 . Such a configuration makes it possible to prevent the cover  7  from being opened in an inclined state. In other words, the push button  27  may be located at a position shifted in some degree from the center in the left and right direction between the first and second locking mechanisms  40  and  50 . 
     In the above described embodiment, the image forming device  1  is described as an example of an image forming device configured to form an image through an electrophotographic process and to have a housing in which an opening is formed. However, the feature of the above described embodiment may be applied to various types of image processing devices, such as an image reading device provided with, in a housing, a reading unit configured to read an image from a document, and a multifunction-type image processing device provided with both of a reading unit and an image formation unit in a housing.