JP7643259B2 - Head lock device and image forming apparatus - Google Patents

Description

The present invention relates to a head lock device and an image forming device.

Conventionally, image forming devices such as printers, copiers, facsimile machines, and multifunction machines, for example electrophotographic printers, are provided with an image forming unit, in which the surface of a photosensitive drum that has been uniformly charged by a charging roller is exposed to light by an LED head as an exposure device to form an electrostatic latent image, which is then developed with toner to form a toner image, which is then transferred to paper by a transfer roller.

The toner image is then fixed to the paper in a fixing unit installed in the printer, forming an image and printing the paper (see, for example, Patent Document 1).

JP 2018-159801 A

However, in the above-mentioned conventional printers, when it becomes necessary to perform maintenance on the printer with the LED head moved to a specified position, it is necessary to improve the operability of the head locking device for locking and unlocking the LED head.

The present invention aims to provide a head lock device and an image forming device that can solve the problems of the conventional printers and improve the operability of the head lock device when performing maintenance on the image forming device.

To this end, the head lock device of the present invention has a holding member that is movably arranged within the device body, is linked to the exposure device, and places the exposure device in a number of positions as it moves, and a locking member that is arranged between the holding member and the frame of the device body and places the exposure device in a locking position where the exposure device is locked.

The locking member is then biased by a biasing member in a direction that unlocks the exposure device, and is engaged with the frame when the exposure device is placed in the locked position.

According to the present invention, the head lock device has a holding member that is movably arranged within the device body, is linked to the exposure device, and places the exposure device in a number of positions as it moves, and a locking member that is arranged between the holding member and the frame of the device body and places the exposure device in a locking position where the exposure device is locked.

The locking member is then biased by a biasing member in a direction that unlocks the exposure device, and is engaged with the frame when the exposure device is placed in the locked position.

In this case, when the exposure device is placed in the locked position, the locking member is biased by the biasing member in a direction that unlocks the exposure device, thereby improving the operability of the head locking device for locking and unlocking the exposure device when performing maintenance on the image forming device.

5 is a diagram for explaining a dynamic model of the headlock device according to the embodiment of the present invention. FIG. 1 is a first perspective view of a printer according to an embodiment of the present invention; FIG. 2 is a second perspective view of the printer according to the embodiment of the present invention. 1 is a conceptual diagram of a printer according to an embodiment of the present invention. FIG. 1 is a first perspective view showing a state of a printer when a front cover is open according to an embodiment of the present invention. 1 is a perspective view showing a state of a printer when an image forming unit is removed from an apparatus main body according to an embodiment of the present invention. FIG. 2 is a second perspective view showing a state of the printer when the front cover is open in the embodiment of the present invention. 13A and 13B are diagrams illustrating a state of the linking mechanism on the left side wall side when the front cover is opened in the embodiment of the present invention. 13A and 13B are diagrams illustrating a state of the linking mechanism on the left side wall side when the front cover is closed in the embodiment of the present invention. FIG. 4 is a perspective view of a main portion of a linking mechanism on the left side wall side in the embodiment of the present invention. 11 is an exploded view of a main portion for illustrating a state in which a linking mechanism on a left side wall side is attached to an inner panel in the embodiment of the present invention. FIG. 2 is a perspective view showing an arrangement of a head holder in a device main body according to the embodiment of the present invention; FIG. 1 is a perspective view showing a state of a printer when an LED head according to an embodiment of the present invention is placed at an exposure position. FIG. 2 is a perspective view showing a state of the printer when the LED head is placed at a retracted position in the embodiment of the present invention. FIG. 2 is a perspective view of a head holder according to the embodiment of the present invention. 2 is a front view showing a state in which the LED head is held by a head holder in the embodiment of the present invention; FIG. 2 is a cross-sectional view showing a state in which the LED head is held by a head holder in the embodiment of the present invention. FIG. 2 is a front view of the cam according to the embodiment of the present invention. FIG. 2 is a plan view of a cam according to an embodiment of the present invention. FIG. 2 is a front view of a lock lever according to the embodiment of the present invention. FIG. 2 is a plan view of a lock lever according to the embodiment of the present invention. 4 is a front view showing a state of a head lock device when an LED head is placed at an exposure position in the embodiment of the present invention. FIG. This is a cross-sectional view taken along the line XX in Figure 22. 4 is a front view showing a state of the head lock device when the LED head is placed in a locked position in the embodiment of the present invention. FIG. This is a cross-sectional view taken along the line YY in FIG. 24. 4 is a front view showing a state of the head lock device when the lock of the LED head is released in the embodiment of the present invention. FIG. This is a cross-sectional view taken along the line ZZ in Figure 26.

The following describes in detail an embodiment of the present invention with reference to the drawings. In this case, a printer will be described as an image forming device.

Figure 2 is a first perspective view of a printer according to an embodiment of the present invention, Figure 3 is a second perspective view of a printer according to an embodiment of the present invention, and Figure 4 is a conceptual diagram of a printer according to an embodiment of the present invention. Note that in Figures 2 and 3, the positive X-axis direction is the rear direction of the printer 10, the negative X-axis direction is the front direction of the printer 10, the positive Y-axis direction is the left direction of the printer 10, the negative Y-axis direction is the right direction of the printer 10, the positive Z-axis direction is the upward direction of the printer 10, and the negative Z-axis direction is the downward direction of the printer 10.

In the figure, 10 is the printer, Bd is the main body of the printer 10, i.e., the device main body, and Cs is the housing that surrounds the device main body Bd as the device exterior of the printer 10.

The housing Cs has a front wall Wf, a back wall Wr, a left side wall Ws1 serving as a first wall member arranged on the left side of the front wall Wf when viewed from the front and as a first side wall, a right side wall Ws2 serving as a second wall member arranged on the right side of the front wall Wf when viewed from the front and as a second side wall, and a top wall Wt.

A front cover Pf is arranged so as to be freely opened and closed from the upper half Wfa of the front wall Wf to the front half Wtb of the top wall Wt. By opening the front cover Pf, a printer operator as the first operator of the printer 10 can access the device body Bd and install or remove the image forming unit (developing device) 20 to or from the device body Bd, or remove the paper P as a jammed medium, or a maintenance/manager as the second operator of the printer 10 can perform maintenance such as maintenance of each part in the device body Bd. In addition, a front panel 22f of a paper cassette 22 as a medium storage unit is arranged so as to be freely opened and closed in the lower half of the front wall Wf. In this embodiment, cut paper is used as the paper P, but roll paper, fan-folded paper, etc. can be used instead of cut paper.

An operation panel 65 is disposed in the portion of the top wall Wt adjacent to the front wall Wf and the right side wall Ws2. The operation panel 65 includes a display unit 66 consisting of an LED screen or the like for displaying the status of the printer 10, and an operation unit 67 consisting of switches, keys, etc. for the printer operator to input instructions to the printer 10. When the operation panel 65 is formed of a touch panel, the operation panel 65 functions as both the display unit and the operation unit. In addition, a stacker sk is formed as a medium stacking unit from the center of the top wall Wt to the back wall Wr, and a discharge port Hh1 is formed facing the stacker sk for discharging paper P on which an image has been formed outside the device body Bd, and a pair of discharge rollers 26 as a discharge member is rotatably disposed in the discharge port Hh1.

In addition, a top cover Pt is disposed adjacent to the left side wall Ws1 on the top wall Wt so that it can be opened and closed freely, and the printer operator can access the inside of the left side wall Ws1 by opening the top cover Pt.

In the housing Cs, the image forming unit 20 and the paper cassette 22 are detachably mounted to the device main body Bd, an LED head 21 serving as an exposure device is detachably mounted and movable in the vertical direction, a transfer roller 24 serving as a transfer member is rotatably mounted below the image forming unit 20, and a fixing device 25 serving as a fixing device is disposed adjacent to the image forming unit 20.

The image forming unit 20 includes a main body 20a and a toner storage section 17 as a developer storage section that stores toner as a developer. A toner storage section 18 as a developer storage section is formed below the toner storage section 17 within the main body 20a, and the toner supplied from the toner storage section 17 is stored in the toner storage section 18.

The image forming unit 20 includes a photosensitive drum 11 as an image carrier, a developing roller 12 as a developer carrier that is rotatably arranged opposite the photosensitive drum 11 and adheres toner to the photosensitive drum 11 to form a toner image as a developer image, a supply roller 13 as a developer supply member that supplies toner to the developing roller 12, a charging roller 14 as a charging device that is rotatably arranged opposite the photosensitive drum 11 and uniformly charges the surface of the photosensitive drum 11, a developing blade 19 as a developer regulating member that is arranged with its tip pressed against the developing roller 12 and thins the toner supplied to the developing roller 12 to form a toner layer, a cleaning blade 15 as a cleaning member that scrapes off and removes residual toner as transfer residual developer on the photosensitive drum 11, and a waste toner transport path 16 as a waste developer transport path that transports the residual toner scraped off and removed by the cleaning blade 15 as waste toner, which is waste developer.

The LED head 21 is disposed above the main body 20a facing the photosensitive drum 11, and exposes the photosensitive drum 11, which is charged by the charging roller 14, based on image data, forming an electrostatic latent image on the surface of the photosensitive drum 11. The developing roller 12 exposes the photosensitive drum 11 by attaching toner to the electrostatic latent image, forming a toner image on the photosensitive drum 11.

The transfer roller 24 is disposed below the main body portion 20a facing the photosensitive drum 11 and transfers the toner image on the photosensitive drum 11 onto paper P supplied from the paper cassette 22.

The fixing device 25 includes a heating roller R1 as a first fixing member and a pressure roller R2 as a second fixing member, and a heating element such as a halogen lamp (not shown) is disposed inside the heating roller R1. In the fixing device 25, the toner image transferred to the paper P is heated by the heating roller R1 and pressed by the pressure roller R2, so that the toner image is fixed to the paper P.

In FIG. 4, 27 is a sealing member made of a film or the like, and is arranged with its tip pressed against the developing roller 12. The sealing member 27 prevents the toner in the toner storage section 18 from leaking out of the main body section 20a.

The photosensitive drum 11, developing roller 12, supply roller 13, charging roller 14 and transfer roller 24 are each rotated in the direction of the arrow.

The paper P in the paper cassette 22 is fed in the direction of arrow A by the feed roller 23 to the media transport path Rt1, transported by the transport roller m1 as a transport member, and transported in the direction of arrow B between the photosensitive drum 11 and the transfer roller 24 (nip portion), where the toner image is transferred, and the toner image is fixed in the fixing device 25 to form an image. The paper P is then transported in the direction of arrow C, and discharged in the direction of arrow D (outside the device body Bd) by the discharge roller pair 26 through the discharge port Hh1, and loaded onto the stacker sk.

However, for example, if a printer operator accidentally touches or impacts the LED head 21 when opening the front cover Pf and installing or removing the image forming unit 20 from the device body Bd, the LED head 21 may be damaged. Therefore, in this embodiment, when the front cover Pf is opened, the LED head 21 is moved to a retracted position by a linking mechanism 33 (Figure 8) described later.

FIG. 5 is a first oblique view showing the state of the printer when the front cover is open in an embodiment of the present invention; FIG. 6 is an oblique view showing the state of the printer when the image forming unit is removed from the device main body in an embodiment of the present invention; FIG. 7 is a second oblique view showing the state of the printer when the front cover is open in an embodiment of the present invention; FIG. 8 is a diagram showing the state of the linking mechanism on the left side wall side when the front cover is open in an embodiment of the present invention; FIG. 9 is a diagram showing the state of the linking mechanism on the left side wall side when the front cover is closed in an embodiment of the present invention; FIG. 10 is an oblique view of the main parts of the linking mechanism on the left side wall side in an embodiment of the present invention; and FIG. 11 is a diagram showing the linking mechanism on the left side wall side in an embodiment of the present invention. 12 is a perspective view showing the arrangement of the head holder in the device body in an embodiment of the present invention, FIG. 13 is a perspective view showing the state of the printer when the LED head in an embodiment of the present invention is placed in the exposure position, FIG. 14 is a perspective view showing the state of the printer when the LED head in an embodiment of the present invention is placed in the retracted position, FIG. 15 is a perspective view of the head holder in an embodiment of the present invention, FIG. 16 is a front view showing the state of the LED head in an embodiment of the present invention held by the head holder, and FIG. 17 is a cross-sectional view showing the state of the LED head in an embodiment of the present invention held by the head holder. In addition, in FIGS. 5 to 9, the positive X-axis direction is the rear direction in the printer 10, the negative X-axis direction is the front direction in the printer 10, the positive Y-axis direction is the left direction in the printer 10, the negative Y-axis direction is the right direction in the printer 10, the positive Z-axis direction is the upward direction in the printer 10, and the negative Z-axis direction is the downward direction in the printer 10.

In the figure, 10 is the printer, Wf is the front wall, Wr is the back wall, Ws1 is the left side wall, Ws2 is the right side wall, Wt is the top wall, Pf is the front cover, Wfa is the upper half of the front wall Wf, Wtb is the front half of the top wall Wt, Bd is the device body, 21 is the LED head, 30 is a cover metal plate as a protective member, 31 is a predetermined part of the front cover Pf, in this embodiment, a protrusion as an engagement part formed by protruding from the left and right side edges of the upper half Wfa, 33 is a linkage mechanism disposed on the left side wall Ws1 and the right side wall Ws2, respectively, that moves the LED head 21 in response to the operation of the front cover Pf by the printer operator.

The blind metal plate 30 extends in the left-right direction and is arranged so as not to move relative to the device body Bd. It covers the exposure unit consisting of the head holder 45 (described later) as a third linking member and the flexible printed cable (FFC) 53 as a cable, and protects the LED head 21 and flexible printed cable 53 held by the head holder 45.

The left side wall Ws1 and the right side wall Ws2 have a double structure and respectively include inner panels In1, In2 as the first frame of the device body Bd, and outer panels Ou1, Ou2 as the second frame of the device body Bd that cover the inner panels In1, In2, and the linking mechanism 33 is attached to the inner panels In1, In2 between the inner panels In1, In2 and the outer panels Ou1, Ou2.

Next, we will explain the linkage mechanism 33.

The linking mechanism 33 arranged on the left side wall Ws1 and the linking mechanism 33 arranged on the right side wall Ws2 have almost the same structure, with the only difference being the shape of the cam 41 (described below) which serves as a holding member and a guided member. Therefore, in Figures 8 to 11, only the linking mechanism 33 arranged on the left side wall Ws1 is shown and described, and the linking mechanism 33 arranged on the right side wall Ws2 is not shown or described.

In this embodiment, when the printer operator opens the front cover Pf, the head holder 45 is moved upward by each linking mechanism 33, and the LED head 21 is placed in a predetermined position behind the concealing metal plate 30 and is protected by the concealing metal plate 30.

To this end, each linking mechanism 33 includes a cam member 35 as a first linking member arranged to be movable in the front-rear direction (X-axis direction) as the front cover Pf is opened and closed, a lever member 36 as a second linking member arranged to be swingable relative to the device body Bd as the cam member 35 moves, and the head holder 45 arranged to extend between the left side wall Ws1 and the right side wall Ws2 of the device body Bd and to be movable in the up-down direction (Z-axis direction) as the lever member 36 swings.

The cam member 35 includes a cam 41, and a contact surface s1 that contacts the protrusion 31 is formed at the front end of the cam 41. A shaft groove dt1 is formed as an engaged portion from the front end to the rear end of the cam 41. A long hole h1 is formed as a guide portion extending in the vertical direction at the rear end side of the shaft groove dt1. A pair of guide shafts ps1 and ps2 are formed as engaging members and guide members by protruding toward the outer panels Ou1 and Ou2 at a predetermined interval in the front-rear direction at positions corresponding to the shaft groove dt1 in the inner panels In1 and In2 of the left side wall Ws1 and the right side wall Ws2. The cam 41 is arranged movably along the guide shafts ps1 and ps2, and the guide shafts ps1 and ps2 are accommodated in the shaft groove dt1 while the cam 41 moves.

As the guide shafts ps1 and ps2 move within the shaft groove dt1, the cam 41 is guided and the cam member 35 is moved in the front-rear direction. To prevent the guide shafts ps1 and ps2 from coming off the shaft groove dt1, an E-ring eg as a fixing member is engaged with the tip of the guide shafts ps1 and ps2 via a washer ws as a spacer.

The lever member 36 includes a lever 43 having a "L"-shaped configuration, and a guide shaft ps3 as a locking member that is moved along the long hole h1 is formed at the end of the lever 43 on the cam member 35 side, protruding toward the cam 41. A sleeve SL1 having a cylindrical shape is formed at the center of the lever 43, protruding toward the inner panels In1, In2 and the outer panels Ou1, Ou2. At the end of the lever 43 on the head holder 45 side, a long hole h2 is formed as a guide portion extending radially outward from the sleeve SL1. Then, at a position corresponding to the sleeve SL1 in the inner panels In1, In2, a swing shaft sh1 supporting the lever member 36 is disposed protruding toward the outer panels Ou1, Ou2, respectively, and penetrating the sleeve SL1. Additionally, a torsion spring sp1 as a first biasing member is fitted onto the portion of the sleeve SL1 that protrudes toward the inner panels In1 and In2, with one end of the torsion spring sp1 engaging with a predetermined location on the lever member 36 and the other end engaging with a predetermined location on the inner panels In1 and In2. As a result, the lever member 36 is biased in the direction of arrow E (clockwise in Figures 8 and 9), and the cam member 35 is biased forward accordingly.

When each of the cam members 35 is moved in the forward and backward directions, the guide shaft ps3 is moved along the long hole h1, and the lever member 36 is swung relative to the device body Bd.

As shown in Figures 15 to 17, the head holder 45 includes a main body portion 75 extending in the left-right direction, and holding portions 45a, 45b that are formed to hang down from the main body portion 75 at both ends of the main body portion 75, i.e., at the ends on the left side wall Ws1 and right side wall Ws2 sides, and the LED head 21 is housed and held in the area Ar1 between the holding portions 45a, 45b.

To achieve this, the holding portions 45a, 45b have locking pieces am1, am2 that are formed to hang down from the main body portion 75, and the LED head 21 has lockable portions 21a, 21b that are formed to rise up at both ends. The LED head 21 is held by the head holder 45 by locking the claws ne1, ne2 of the locking pieces am1, am2 to the lockable portions 21a, 21b.

Spring seats sph1 and sph2 as biasing member holders are formed hanging down at locations adjacent to the holding parts 45a and 45b of the head holder 45, which are closer to the center than the holding parts 45a and 45b, and a head grounding spring 55 as a second biasing member and a grounding member is disposed on the spring seats sph1 and sph2. The head grounding spring 55 grounds the LED head 21 and biases the LED head 21 toward the photosensitive drum 11 (Figure 4) with a predetermined biasing force.

A pair of holder bosses bs1, bs2 are formed on the end faces of the retaining portions 45a, 45b at a predetermined interval and protrude toward the inner panels In1, In2, and a guide groove dt2 is formed in the inner panels In1, In2, extending in the vertical direction (Z-axis direction).

The head holder 45 is therefore moved in the vertical direction while each of the holder bosses bs1 and bs2 slides along the guide groove dt2, and while one of the holder bosses bs1 and bs2, in this embodiment the lower holder boss bs1, slides along the long hole h2.

When the lever member 36 is swung relative to the device body Bd, the holder bosses bs1 are moved along the long holes h2, the head holder 45 is moved vertically along the guide grooves dt2 behind the blind sheet metal 30, and the LED head 21 is moved vertically together with the head holder 45.

In this embodiment, print data is sent to the printer 10 from a host computer (not shown) as a higher-level device, the print data is edited in a control unit (not shown) to generate image data, and the image data is sent to the LED head 21 to drive the LED head 21. For this purpose, a control board 51 as a board constituting the control unit is disposed within the device body Bd of the printer 10, and the control board 51 and the LED head 21 are electrically connected via the flexible print cable 53. The flexible print cable 53 curves and extends backward from the LED head 21, then curves forward and extends upward, then extends further backward, and is connected to the control board 51.

Next, the operation of the linkage mechanism 33 will be described.

When the printer operator opens the front cover Pf as shown in FIG. 8, the biasing force of the torsion spring sp1 moves the cam member 35 forward, causing the lever member 36 to rotate in the direction of the arrow E. This causes the head holder 45 to move upward, and the LED head 21 is retracted from the exposure position and placed in the retracted position, where it is covered by the blind metal plate 30 as shown in FIG. 14.

Therefore, for example, when a printer operator installs or removes the image forming unit 20 from the device body Bd, the printer operator will not accidentally touch the LED head 21 or apply an impact to the LED head 21, thereby preventing damage to the LED head 21.

When the front cover Pf is closed, the protrusion 31 moves the cam member 35 rearward against the biasing force of the torsion spring sp1, and the lever member 36 is rotated counterclockwise in Figures 8 and 9. This causes the head holder 45 to move downward, and the LED head 21 is placed in the exposure position where it exposes the surface of the photosensitive drum 11 (Figure 4), as shown in Figure 13.

However, for example, a maintenance/administrator of the printer 10 may perform maintenance on the printer 10 by removing and inspecting the exposure unit, which is made up of the head holder 45, flexible print cable 53, etc., and then reinstalling or replacing it. In such cases, the maintenance work is complicated, and the exposure unit may be damaged if the maintenance work procedure is not performed correctly.

Therefore, a lock position is set at a predetermined position in the movement direction of the LED head 21, which in this embodiment is slightly below the exposure position, and a head lock device is disposed between each of the linking mechanisms 33 and a predetermined location of the housing Cs, which in this embodiment is between the inner panels In1 and In2, so that a maintenance/manager can place the LED head 21 in the lock position and lock it by operating the head lock device when performing maintenance on the printer 10. Therefore, when the LED head 21 is placed in the lock position and locked, it becomes immovable and is kept in a stable state without moving to an upper retracted position, etc., which simplifies maintenance work for the exposure unit.

Next, we will explain the headlock device formed in the linkage mechanism 33 on the left side wall Ws1 side.

Figure 1 is a diagram for explaining a mechanical model of a head lock device in an embodiment of the present invention, Figure 18 is a front view of a cam in an embodiment of the present invention, Figure 19 is a plan view of the cam in an embodiment of the present invention, Figure 20 is a front view of a lock lever in an embodiment of the present invention, Figure 21 is a plan view of the lock lever in an embodiment of the present invention, Figure 22 is a front view showing the state of the head lock device when the LED head in an embodiment of the present invention is placed in the exposure position, Figure 23 is an X-X cross-sectional view of Figure 22, Figure 24 is a front view showing the state of the head lock device when the LED head in an embodiment of the present invention is placed in the locked position, Figure 25 is a Y-Y cross-sectional view of Figure 24, Figure 26 is a front view showing the state of the head lock device when the LED head in an embodiment of the present invention is released from the lock, and Figure 27 is a Z-Z cross-sectional view of Figure 26. 18 to 27, the positive X-axis direction is the rear direction of the printer 10, the negative X-axis direction is the front direction of the printer 10, the positive Y-axis direction is the left direction of the printer 10, the negative Y-axis direction is the right direction of the printer 10, the positive Z-axis direction is the upward direction of the printer 10, and the negative Z-axis direction is the downward direction of the printer 10.

In the figure, 33 is a linkage mechanism, 41 is a cam, 43 is a lever, 45 is a head holder, dt1 is a shaft groove, h1 is an oblong hole, 45 is a head holder, In1 is an inner panel, ps1 to ps3 are guide shafts, bs1 and bs2 are holder bosses, and 71 is a lock lever disposed between the cam and inner panel In1 and serving as a locking member for placing the LED head 21 (Figure 8) in the locked position. The cam 41 and lock lever 71 form a head lock device for locking the LED head 21.

The cam 41 is arranged to extend from the front end where the abutment surface s1 is formed to the rear end where the long hole h1 is formed, and includes a first cam portion 41a whose width in the height direction is narrowed from the front end to the center, a second cam portion 41b whose width in the height direction is widened from the center to the rear end, and a third cam portion 41c whose width changes and connects the first and second cam portions 41a and 41b at the center, and the shaft groove dt1 extends over almost the entire cam 41 from the front end of the cam 41 to the long hole h1.

The cam 41 is thickened at the first and third cam portions 41a and 41c, and supports the lock lever 71 on the upper surfaces Sa of the first and third cam portions 41a and 41c so that the lock lever 71 can swing freely. For this purpose, a support shaft sh2 for supporting the lock lever 71 is formed to protrude upward at a predetermined location on the upper surface Sa, in this embodiment, at the rear end portion of the first cam portion 41a. A semicircular protruding edge eg1 is formed to protrude forward at the front half of the upper end of the support shaft sh2 to prevent the lock lever 71 from falling off the cam 41.

A restriction protrusion 73 is formed as a first restriction portion for restricting the rotation range of the lock lever 71 in the clockwise direction in FIG. 23 at a predetermined location on the upper surface Sa, which in this embodiment is the edge portion on the outer panel Ou1 side (positive Y-axis side) of the front end portion of the first cam portion 41a, and a restriction protrusion 74 is formed as a second restriction portion for restricting the rotation range of the lock lever 71 in the counterclockwise direction in FIG. 23 at a predetermined location on the upper surface Sa, which in this embodiment is the rear end portion of the third cam portion 41c.

The regulating protrusion 73 has a flat shape with a predetermined length and height in the front-rear direction, and the regulating protrusion 74 has an "L" shape and includes a protrusion portion 74a with a flat shape with a predetermined length and height in the front-rear direction, and a rib 74b formed from the protrusion portion 74a toward the inner panel In1 side of the third cam portion 41c.

The lock lever 71 is made of a resin material and includes a bearing portion 76 that houses the support shaft sh2 and is fitted onto the support shaft sh2, a first arm portion Ap1 that extends forward from the bearing portion 76 along the first cam portion 41a, and a second arm portion Ap2 that extends rearward from the bearing portion 76 along the third cam portion 41c.

The bearing portion 76 includes a support shaft housing hole h3 that houses the support shaft sh2. The support shaft housing hole h3 includes a support portion ha that is formed on the front half of the support shaft housing hole h3 and has an inner diameter slightly larger than the outer diameter of the support shaft sh2, and supports the support shaft sh2 so that it can swing freely, and a large diameter portion hb that is formed on the rear half of the support shaft housing hole h3 and has an inner diameter sufficiently larger than the outer diameter of the support shaft sh2, and is used to remove the lock lever 71 from the support shaft sh2. When the support shaft sh2 is positioned within the support portion ha, the protruding edge eg1 of the support shaft sh2 and the inner peripheral edge of the support portion ha are engaged, so that the lock lever 71 does not fall off the cam 41.

In addition, an engagement protrusion 78 is formed at a predetermined location in the length direction of the first arm portion Ap1, in this embodiment near the front end feg, protruding toward the inner panel In1. The engagement protrusion 78 has a mountain shape, and when the LED head 21 is placed in the locked position, it enters a frame hole h4 formed at a predetermined position of the inner panel In1 and engages with the inner panel In1.

For this purpose, the front inclined surface of the engagement projection 78 is cut into an "L" shape to form a notch 81. The notch 81 is formed by extending diagonally to the right and forward at a predetermined angle relative to the inner panel In1, and is made up of an engagement surface Sb that engages with the inner periphery of the frame hole h4, and an abutment surface Sc that is formed approximately perpendicular to the engagement surface Sb and abuts against the inner panel In1.

Furthermore, a restricted portion p1 is formed on the surface of the first arm portion Ap1 facing the outer panel Ou1, which abuts against the restricting protrusion 73 when the lock lever 71 is rotated in the clockwise direction in FIG. 23 and restricts the rotation range of the lock lever 71. In addition, a restricted portion p2 is formed at the rear end of the second arm portion Ap2, which is made of a protrusion formed by protruding rearward along the inner panel In1 and is pressed against the restricting protrusion 74 when the lock lever 71 is rotated in the counterclockwise direction in the figure and restricts the rotation range of the lock lever 71, and an elastic portion p3 is formed as a third biasing member that protrudes rearward parallel to the restricted portion P2, is deformed when the restricted portion p2 is pressed against the restricting protrusion 74, and is pressed against the restricted portion P2.

When the front cover Pf is closed as shown in FIG. 9 and the LED head 21 is placed in the exposure position as shown in FIG. 13, the engagement protrusion 78 comes into contact with the inner panel In1 at a position forward of the frame hole h4 as shown in FIG. 23.

In addition, when a maintenance/administrator of the printer 10 (Figure 2) opens the front cover Pf to perform maintenance on the printer 10, such as maintaining the exposure unit, the LED head 21 is placed in the retracted position as shown in Figure 8.

Then, when the maintenance/manager presses the front end feg of the lock lever 71 to move the lock lever 71 and the cam 41 backward and place the LED head 21 in the locked position, the engagement protrusion 78 faces the frame hole h4, and then, when the maintenance/manager applies an external force to the lock lever 71 and rotates the lock lever 71 counterclockwise in FIG. 25 against the biasing force of the elastic part p3, the engagement protrusion 78 enters the frame hole h4. When the maintenance/manager releases the lock lever 71 with the contact surface Sc in contact with the inner panel In1, the torsion spring sp1 (FIG. 10) moves the cam 41 and the lock lever 71 forward, the inner periphery of the frame hole h4 is pressed against the engagement surface Sb, and the engagement protrusion 78 engages with the inner panel In1.

At this time, the elastic portion p3 of the second arm portion Ap2 of the lock lever 71 is deformed and pressed against the regulated portion p2, and the lock lever 71 is urged in the clockwise direction in FIG. 25. However, since the inner peripheral edge of the frame hole h4 is pressed against the engagement surface Sb, a frictional force is generated, so that the engagement protrusion 78 remains engaged with the inner panel In1.

The mechanical model of the headlock device when the engagement protrusion 78 is engaged with the inner panel In1 is shown in Figure 1.

That is, if the frictional force generated on the engagement surface Sb is Fd, the axis of the support shaft sh2, i.e., the rotation center of the lock lever 71 is E, the intersection point between the engagement surface Sb and the abutment surface Sc of the cutout portion 81 is D, and the angle between the direction perpendicular to the straight line ED connecting the rotation center E and the intersection point D and the engagement surface Sb is θ, then the component force Fa of the frictional force Fd generated in the direction perpendicular to the straight line ED is given by
Fa = Fd × cosθ
become.

If the length of the straight line ED is Led, then the torque Tr1 that tends to rotate the lock lever 71 counterclockwise at the rotation center E is
Tr1 = Fa × Led
is generated.

In addition, if the contact point between the elastic portion p3 and the regulating protrusion 74 is G, the force generated by the urging force of the elastic portion p3 at the contact point G in a direction perpendicular to the straight line EG connecting the rotation center E and the contact point G is Fg, and the length of the straight line EG is Leg, then the torque Tr2 that tends to rotate the lock lever 71 clockwise about the rotation center E is
Tr2 = Fg x Leg
is generated.

Therefore, by setting the positions of the rotation center E, the intersection point D and the contact point G, the angle θ, the shape of the elastic part p3, etc. so that the torque Tr1 is greater than the torque Tr2, the state in which the engagement protrusion 78 is engaged with the inner panel In1 is maintained, and the state in which the LED head 21 is locked in the locked position is maintained.

When the maintenance/administrator finishes maintenance of the printer 10 and further presses the front end feg of the lock lever 71, moving the lock lever 71 and cam 41 slightly backward, the engagement surface Sb moves away from the inner peripheral edge of the frame hole h4, frictional force Fd is no longer generated, and torque Tr1 is no longer generated, so that the lock lever 71 is rotated clockwise by the biasing force of the elastic portion p3 as shown in FIG. 27. As a result, the engagement protrusion 78 is no longer engaged with the inner panel In1, and the LED head 21 is unlocked.

In this manner, in this embodiment, when the LED head 21 is placed in the locked position, the lock lever 71 is biased by the elastic portion p3 in a direction that unlocks the LED head 21, thereby improving the operability of the head lock device for locking and unlocking the LED head 21 when performing maintenance on the printer 10.

In this embodiment, a printer 10 having one image forming unit 20 has been described, but the present invention can also be applied to a printer having multiple image forming units.

In addition, the printer 10 in this embodiment is a direct transfer type printer that transfers a toner image directly to paper P, but the present invention can also be applied to an intermediate transfer type printer that transfers a toner image to a belt as an intermediate transfer member and transfers the toner image on the belt to paper P.

Furthermore, in this embodiment, the LED head 21 is designed to be movable in the vertical direction, but the LED head 21 can also be arranged to be rotatable or swingable.

The present invention can also be applied to image forming devices such as copiers, facsimile machines, and multifunction devices.

The present invention is not limited to the above-described embodiment, and various modifications are possible based on the spirit of the present invention, and are not excluded from the scope of the present invention.

21 LED head 41 Cam 71 Lock lever Bd Device body In1, In2 Inner panel p3 Elastic portion

Claims (5)

(a) a holding member that is movably disposed within the apparatus body, that is associated with the exposure device, and that positions the exposure device at a plurality of positions as it moves;
(b) a locking member disposed between the holding member and a frame of an apparatus main body, for placing the exposure device in a locking position where the exposure device is locked;
(c) a head lock device, wherein the lock member is biased by a biasing member in a direction in which the exposure device is unlocked, and is engaged with the frame when the exposure device is placed at a locked position . 2. The head lock device according to claim 1 , wherein the lock member includes an engagement protrusion adapted to be engaged with an inner peripheral edge of a frame hole formed in the frame. (a) the locking member is disposed rotatably about a support shaft formed on the holding member,
3. The head lock device according to claim 2 , wherein the biasing member is an elastic member that is deformed as the lock member rotates. (a) the engagement projection is formed with an engagement surface adapted to engage with an inner peripheral edge of the frame hole,
4. A headlock device as claimed in claim 3, wherein the torque generated in the locking member by the frictional force between the engagement surface and the inner peripheral edge of the frame hole is greater than the torque generated in the locking member by the biasing force of the biasing member. An image forming apparatus having a head lock device according to any one of claims 1 to 4.

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