JP2024075172A - Image forming device - Google Patents

Abstract

[Problem] To prevent damage caused by interference between an image forming unit and an exposure unit when an opening/closing member is closed. [Solution] The apparatus includes an opening/closing member, an image forming unit 20 that is movably arranged relative to the device body Bd and that is placed in an image forming position when the opening/closing member is closed, an exposure unit 30 that is movably arranged relative to the device body Bd and that is placed in a retracted position when the opening/closing member is opened and that is placed in an exposure position when the opening/closing member is closed, and a link mechanism M1 that places the exposure unit 30 in the exposure position after the image forming unit 20 is placed in the image forming position when the opening/closing member is closed. Even if an operator closes the opening/closing device when the image forming unit 20 is in a half-set state, there is no interference between the image forming unit 20 and the exposure unit 30. [Selected Figure] Figure 1

Description

The present invention relates to 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, which has been uniformly charged by a charging roller, is exposed to light by an LED head of an exposure unit 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 by a fixing device provided in the printer, forming an image and printing.

By the way, there is a printer provided in which, for example, when an operator opens a front cover as an opening/closing member provided on the printer, replaces an image forming unit, and then closes the front cover, the exposure unit is moved to a predetermined exposure position (see, for example, Patent Document 1).

JP 2014-56152 A

However, in the conventional printers described above, if the operator closes the front cover while the image forming unit is in a half-set state, i.e., not fully attached to the image forming position, the image forming unit and the exposure unit may interfere with each other and be damaged.

The present invention aims to provide an image forming device that solves the problems of the conventional printers and prevents the image forming unit and the exposure unit from interfering with each other and being damaged when the opening and closing member is closed.

To this end, the image forming apparatus of the present invention has an opening/closing member that is arranged so as to be freely opened and closed relative to the housing, an image forming unit that is arranged so as to be freely attached/detached and movable relative to the device body and is placed in an image forming position where an image is formed when the opening/closing member is closed, an exposure unit that is arranged so as to be freely movable relative to the device body and is placed in a retracted position when the opening/closing member is opened and is placed in an exposure position where an image carrier is exposed when the opening/closing member is closed, and a link mechanism that places the exposure unit in the exposure position after the image forming unit is placed in the image forming position when the opening/closing member is closed.

According to the present invention, the image forming device has an opening/closing member arranged so as to be freely opened and closed relative to the housing, an image forming unit arranged so as to be freely attached/detached and movable relative to the device body and placed in an image forming position where an image is formed when the opening/closing member is closed, an exposure unit arranged so as to be freely movable relative to the device body and placed in a retracted position when the opening/closing member is opened and placed in an exposure position where an image carrier is exposed when the opening/closing member is closed, and a link mechanism that places the exposure unit in the exposure position after the image forming unit is placed in the image forming position when the opening/closing member is closed.

In this case, when the opening/closing member is closed, the link mechanism places the exposure unit in the exposure position after the image forming unit is placed in the image forming position. Therefore, even if the operator closes the opening/closing device in a half-set state where the image forming unit is not completely attached to the image forming position, there is no interference between the image forming unit and the exposure unit, and damage to the image forming unit and exposure unit can be prevented.

5A to 5C are diagrams illustrating an interlocking mechanism between the front cover and the image forming unit and the exposure unit in the first embodiment of the present invention. 1 is a first perspective view of a printer according to a first embodiment of the present invention; FIG. 2 is a second perspective view of the printer according to the first embodiment of the present invention. 1 is a conceptual diagram of a printer according to a first embodiment of the present invention. FIG. 2 is a perspective view of an exposure unit according to the first embodiment of the present invention. FIG. 4 is a first diagram for explaining the operation of the image forming unit and the exposure unit when the front cover is closed in the first embodiment of the present invention. FIG. 11 is a second diagram for explaining the operations of the image forming unit and the exposure unit when the front cover is closed in the first embodiment of the present invention. FIG. 11 is a third diagram for explaining the operations of the image forming unit and the exposure unit when the front cover is closed in the first embodiment of the present invention. FIG. 4 is a fourth diagram for explaining the operation of the image forming unit and the exposure unit when the front cover is closed in the first embodiment of the present invention. FIG. 11 is a schematic diagram showing a state in which the front cover of a printer according to a second embodiment of the present invention is closed. FIG. 11 is a schematic diagram showing a state in which the front cover of a printer according to a second embodiment of the present invention is open. FIG. 11 is a conceptual diagram showing a link mechanism according to a second embodiment of the present invention.

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 the printer in the first embodiment of the present invention, Figure 3 is a second perspective view of the printer in the first embodiment of the present invention, Figure 4 is a conceptual diagram of the printer in the first embodiment of the present invention, and Figure 5 is a perspective view of the exposure unit in the first embodiment of the present invention. In the figures, 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, Cs is the housing that is the exterior of the printer 10, and Bd is the main body of the printer 10, i.e., the main body of the device.

The housing Cs has a front wall Wf, a back wall Wr, a side wall Ws1 on the left side as viewed from the front wall Wf, a side wall Ws2 on the right side as viewed from the front wall Wf, and a top wall Wt, and an inner plate Pin that constitutes a frame within the device body Bd is formed inside the side walls Ws1 and Ws2. In addition, a front cover Pf as an opening/closing member is disposed so as to be freely opened and closed relative to the housing Cs from the upper half Wfa of the front wall Wf to the front half Wtb of the top wall Wt.

An operation panel 65 is disposed in the portion of the top wall Wt adjacent to the front wall Wf and the side wall Ws2. The operation panel 65 includes a display section 66 consisting of an LED screen or the like for displaying the status of the printer 10, and an operation section 67 consisting of switches, keys, etc. for the operator to input instructions to the printer 10. In addition, a stacker (discharge tray) sk as a medium stacking section is formed from the center of the top wall Wt to the back wall Wr, and a discharge outlet Hh1 is formed facing the stacker sk for discharging paper P as a medium on which an image has been formed.

A paper cassette 22 serving as a medium storage section is disposed at the bottom of the device body Bd so as to be freely attached and detached to the device body Bd, and paper P is disposed in the paper cassette 22. In this embodiment, cut paper is used as the paper P, but roll paper, fan-folded paper, etc. can also be used. The paper cassette 22 has a front panel 22f at its front end, and an operator can attach and detach the paper cassette 22 to and from the device body Bd via the front panel 22f, and set or replace paper P in the paper cassette 22.

At the front end of the paper cassette 22, a separation section is provided, which is made up of a pickup roller 12 as a feeding member, a paper feed roller 13 as a paper feed member, and a separation roller 14 as a separation member. When the pickup roller 12 is rotated, paper P is fed out of the paper cassette 22, and as the paper feed roller 13 and separation roller 14 are rotated, the paper P is separated one sheet at a time and fed to the paper transport path Rt1 as the media transport path.

At the top of the device body Bd, an image forming unit (developing unit) 20, which serves as a first unit and a consumable unit, is disposed so as to be detachable from the device body Bd and movable in the horizontal direction.

The image forming unit 20 includes a main body 16 and a toner container 17 that is adjacent to the main body 16 and is detachably attached to the main body 16, and serves as a developer container that contains toner as a developer.

A toner storage section (not shown) is formed as a developer storage section below the toner storage section 17 within the main body section 16, and the toner supplied from the toner storage section 17 is stored in the toner storage section.

The main body 16 also includes a photosensitive drum 11 as an image carrier, a developing roller (not shown) 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 (not shown) as a developer supply member that supplies toner to the developing roller, a charging roller (not shown) 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 (not shown) as a developer regulating member that is arranged with its tip pressed against the developing roller and thins out the toner supplied to the developing roller to form a toner layer, and a cleaning blade (not shown) as a cleaning member that scrapes off and removes residual toner from the photosensitive drum 11.

Above the main body 16 in the device main body Bd, an exposure unit 30 as a second unit is disposed opposite the photosensitive drum 11 and is movable in the vertical direction (Z-axis direction) relative to the device main body Bd.

As shown in FIG. 5, the exposure unit 30 includes a head holder HR arranged to extend in the Y-axis direction within the device body Bd, and an LED head Hd as an exposure device held by the head holder HR. The head holder HR includes posts Up, Lp formed to protrude in the Y-axis direction at the upper and lower edges of both ends in the longitudinal direction, and the posts Up, Lp are guided by guides (not shown) formed on the inner plate Pin on the inside of the side walls Ws1, Ws2, and are moved in the height direction (Z-axis direction).

In the device body Bd, when the image forming unit 20 is placed in a preset image forming position and the exposure unit 30 is placed in a preset exposure position, the LED head Hd exposes the photosensitive drum 11, which has been charged by the charging roller, according to image data, and an electrostatic latent image is formed on the surface of the photosensitive drum 11.

The developing roller forms a toner image on the photoreceptor drum 11 by adhering toner to the electrostatic latent image.

In addition, below the image forming unit 20 in the device body Bd, a transfer roller 24 serving as a transfer member is rotatably disposed opposite the photosensitive drum 11.

The paper P is fed from the paper cassette 22 and fed to the paper transport path Rt1. It is transported by the transport roller pair m1 as the first transport member, and the skew is corrected by the registration roller pair m2 as the second transport member to improve the printing position accuracy. The paper P is then supplied to the transfer section between the photosensitive drum 11 and the transfer roller 24, where the toner image on the photosensitive drum 11 is transferred.

A fixing device, 25, is disposed downstream of the transfer section on the paper transport path Rt1.

The fixing device 25 includes a heating roller R1 as a first fixing member and a backup roller (pressure roller) R2 as a second fixing member, and a halogen lamp Ht as a heating element is disposed within 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 backup roller R2, so that the toner image is fixed to the paper P.

Next, the paper P is transported by the transport roller pair m3 as the third transport member, and is discharged outside the device body Bd through the discharge port Hh1 by the discharge roller pair m4 as the fourth transport member, and is loaded onto the stacker sk.

In the printer 10, the image forming unit 20 is arranged so as to be freely attached and detached to the device body Bd, and the front cover Pf is arranged so as to be freely opened and closed. Therefore, an operator can open the front cover Pf to replace the image forming unit 20, remove the image forming unit 20 from the device body Bd to remove jammed paper P, and perform maintenance and management of each part within the device body Bd.

However, if the operator closes the front cover Pf after replacing the image forming unit 20, removing the paper P, and completing maintenance and inspection, etc., and the image forming unit 20 is in a half-set state where it is not completely attached to the image forming position, the image forming unit 20 and the exposure unit 30 may interfere with each other, causing damage to the image forming unit 20, exposure unit 30, etc.

Therefore, in this embodiment, when the front cover Pf is closed after it has been opened, the image forming unit 20 and the exposure unit 30 are moved in conjunction with each other, so that even if the operator closes the front cover Pf when the image forming unit 20 is in the half-set state, there is no interference between the image forming unit 20 and the exposure unit 30.

Next, we will explain the operation of the image forming unit 20 and the exposure unit 30 when the front cover Pf is opened and closed.

1 is a diagram for explaining the interlocking mechanism between the front cover and the image forming unit and exposure unit in the first embodiment of the present invention, FIG. 6 is a first diagram for explaining the operation of the image forming unit and exposure unit when the front cover is closed in the first embodiment of the present invention, FIG. 7 is a second diagram for explaining the operation of the image forming unit and exposure unit when the front cover is closed in the first embodiment of the present invention, FIG. 8 is a third diagram for explaining the operation of the image forming unit and exposure unit when the front cover is closed in the first embodiment of the present invention, and FIG. 9 is a fourth diagram for explaining the operation of the image forming unit and exposure unit when the front cover is closed in the first embodiment of the present invention. In the diagrams, 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, Cs is the housing, Bd is the device body, and Pf is the front cover that is arranged so that it can swing freely around a hinge Hg as a swing support part arranged at a specified part below the housing Cs and can be opened and closed freely relative to the device body Bd.

In addition, 11 is a photosensitive drum, 20 is an image forming unit, 16 is a main body, 17 is a toner cartridge, and 30 is an exposure unit.

The exposure unit 30 includes an LED head Hd and a head holder HR that holds the LED head Hd.

In this embodiment, when the front cover Pf is opened, the exposure unit 30 is placed in a retracted position as shown in FIG. 1, and when the front cover Pf is closed, the image forming unit 20 is placed in an image forming position where it forms an image on the photoconductor drum 11, and the exposure unit 30 is placed in an exposure position where it exposes the photoconductor drum 11, as shown in FIG. 9.

To this end, the image forming unit 20 is arranged to be freely movable in the forward and backward directions (X-axis directions), which are the directions of the arrow A.

The exposure unit 30 is arranged so as to be freely movable in the vertical direction (Z-axis direction), which is the direction of arrow B, and is biased upward (positive Z-axis direction) by the biasing force of a first spring (not shown) that serves as a first biasing member disposed between the exposure unit 30 and the inner plate Pin.

A push-in protrusion 35 is formed protruding into the device body Bd near the end of the inner wall surface Sb of the front cover Pf on the top wall Wt side as a first pushing member for pushing the slider 31 described below into the device body Bd and placing the exposure unit 30 in the exposure position when the front cover Pf is closed, and a push-in protrusion 37 is formed protruding into the device body Bd on the hinge Hg side as a second pushing member for pushing the image forming unit 20 into the device body Bd and placing it in the image forming position when the front cover Pf is closed.

In this embodiment, the height w1 of the pushing protrusion 35 is set lower than the height w2 of the pushing protrusion 37 (the height w2 of the pushing protrusion 37 is set higher than the height w1 of the pushing protrusion 35) so that the image forming unit 20 and the exposure unit 30 move appropriately when the front cover Pf is closed.

When the front cover Pf is opened, the exposure unit 30 is placed in the retracted position as shown in FIG. 1 by the biasing force of the first spring, and when the front cover Pf is closed, it is moved downward (in the negative Z-axis direction) against the biasing force of the first spring and placed in the exposure position as shown in FIG. 9.

Furthermore, a link mechanism M1 is provided in the device body Bd to place the exposure unit 30 in the exposure position after the image forming unit 20 is placed in the image forming position when the front cover Pf is closed.

The link mechanism M1 includes a slider 31 as a first link member that is moved in a first direction, the front-to-back direction (X-axis direction) indicated by an arrow A, as the front cover Pf is closed, and the head holder HR as a second link member that is moved in a second direction, the up-down direction (Z-axis direction) indicated by an arrow B, as the slider 31 is moved in the front-to-back direction (X-axis direction).

The link mechanism M1 constitutes a cam mechanism, the slider 31 constitutes the driver, and the head holder HR constitutes the follower.

The slider 31 is biased backward (negative direction of the X-axis) by the biasing force of a second spring (not shown) that serves as a second biasing member disposed between the slider 31 and the inner plate Pin.

When the front cover Pf is opened, the slider 31 is placed in the rearmost position as shown in FIG. 1 by the force of the second spring, and when the front cover Pf is closed, the slider 31 is placed in the forwardmost position as shown in FIG. 9 against the force of the second spring.

In this case, the image forming unit 20 is designed to be detachable from the device body Bd. Therefore, if the exposure unit 30 is located on the attachment/detachment path when the operator removes or attaches the image forming unit 20 in the direction of arrow C, the image forming unit 20 and the exposure unit 30 will interfere with each other.

In this embodiment, when the front cover Pf is opened, the exposure unit 30 is synchronously retracted from the attachment/detachment trajectory and placed in the retracted position, and when the front cover Pf is closed, the image forming unit 20 is placed in the image forming position, and then the exposure unit 30 is placed in the exposure position.

To this end, the slider 31 is made of a plate-shaped member, and a cam surface Sa is formed at the front end, extending diagonally downward toward the rear.

In addition, a cylindrical contact 33 is disposed rotatably along the cam surface Sa at the portion of the exposure unit 30 that faces the cam surface Sa, which in this embodiment is the rear corner of the upper end surface of the head holder HR.

Therefore, when the slider 31 is moved in the front-back direction (X-axis direction), the contact 33 moves while rotating along the cam surface Sa, and the exposure unit 30 is moved in the up-down direction (Z-axis direction).

The angle θ between the upper edge Eg of the slider 31 and the cam surface Sa is set to 45° or less. If the distance by which the slider 31 is moved is La and the distance by which the exposure unit 30 is moved is Lb, then the distances La and Lb are such that La>Lb.
to be.

Next, we will explain the operation of the image forming unit 20 and the exposure unit 30 when the front cover Pf is closed.

First, when the operator rotates the front cover Pf counterclockwise from the state shown in FIG. 1, the pushing protrusion 37 comes into contact with the rear end surface Ur of the image forming unit 20, as shown in FIG. 6.

Next, when the operator further rotates the front cover Pf counterclockwise, as shown in FIG. 7, the image forming unit 20 is moved forward (positive direction of the X-axis) as indicated by the arrow, and the image forming unit 20 is placed in the image forming position. At this time, the movement of the image forming unit 20 is restricted by a restricting device (not shown) at the image forming position, and the image forming unit 20 does not move further forward (positive direction of the X-axis). Also, at this time, the pushing protrusion 35 is brought into contact with the rear end surface Sr of the slider 31.

Next, when the operator further rotates the front cover Pf counterclockwise, as shown in FIG. 8, the slider 31 is moved forward (positive direction of the X-axis) as indicated by the arrow, and accordingly, the exposure unit 30 is moved downward (negative direction of the Z-axis) as indicated by the arrow, and the LED head Hd is positioned facing the exposure window h1 formed in the main body 16.

When the front cover Pf is completely closed, as shown in FIG. 9, the LED head Hd is placed in the exposure position where it exposes the surface of the photosensitive drum 11. At this time, the movement of the LED head Hd is restricted by the main body 16 at the exposure position, and it does not move further downward (negative Z-axis direction).

In this manner, in this embodiment, when the front cover Pf is closed, the link mechanism M1 places the exposure unit 30 in the exposure position after the image forming unit 20 is placed in the image forming position, so that when the operator closes the front cover Pf in a half-set state in which the image forming unit 20 is not fully attached to the image forming position, interference between the image forming unit 20 and the exposure unit 30 can be prevented, which would cause damage to the image forming unit 20 and the exposure unit 30.

In the first embodiment, the exposure unit 30 is moved up and down (Z-axis direction) by moving the slider 31 in the front-rear direction (X-axis direction). In this case, however, in order to bring the contact 33 into contact with the cam surface Sa, it is necessary to bias the exposure unit 30 upward (positive Z-axis direction) using the biasing force of the second spring, which complicates the interlocking mechanism between the front cover Pf and the exposure unit 30.

Therefore, a second embodiment of the present invention will be described in which a link mechanism M2 (FIG. 10) is arranged inside the device body Bd in order to place the exposure unit 30 in the exposure position after the image forming unit 20 is placed in the image forming position when the front cover Pf is closed. Note that the same reference numerals are used for components having the same structure as in the first embodiment, and the effects of the invention resulting from having the same structure are taken from the effects of the first embodiment.

Figure 10 is a schematic diagram showing the state in which the front cover of the printer in the second embodiment of the present invention is closed, Figure 11 is a schematic diagram showing the state in which the front cover of the printer in the second embodiment of the present invention is open, and Figure 12 is a conceptual diagram showing the link mechanism in the second embodiment of the present invention.

In the figure, 10 is the printer, Wt is the top wall, Pf is the front cover as the opening and closing member, 35 is the pushing protrusion as the first pushing member, 30 is the exposure unit as the second unit, HR is the head holder, Hd is the LED head as the exposure device, Pin is the inner plate, and M2 is the link mechanism.

The link mechanism M2 moves the exposure unit 30 downward (Z-axis negative direction) when the front cover Pf is closed. To achieve this, the link mechanism M2 includes a cam member 51 as a first link member that is moved in a first direction, the front-rear direction (X-axis direction), as the front cover Pf is closed, the head holder HR as a second link member that is moved in a second direction, the up-down direction (Z-axis direction), as the cam member 51 is moved in the front-rear direction (X-axis direction), and a lever member 53 as a third link member that is connected to the cam member 51 and the head holder HR so as to be able to swing freely.

The cam member 51 is supported so as to be movable in the front-rear direction (Y-axis direction) by support pins p1 and p2 formed to protrude from the inner plate Pin.

The head holder HR is moved in the height direction (Z-axis direction) as the posts Up and Lp formed at both ends in the longitudinal direction (Y-axis direction) are guided by the guides Gd formed on the inner plate Pin.

The lever member 53 is supported on the inner plate Pin so that it can swing freely (in the direction of arrow D in FIG. 12) around axis sh1 as the swing center. The cam member 51 and the lever member 53 are connected so that they can swing freely via axis sh2, and the exposure unit 30 and the lever member 53 are connected so that they can swing freely via axis sh3 consisting of the post Lp.

When the distance that the lever member 53 can be moved in the front-back direction (X-axis direction) is L1 and the distance that the exposure unit 30 can be moved in the up-down direction (Z-axis direction) is L2, the distances L1 and L2 are expressed as follows: L1 ≧ L2
to be.

In this embodiment, the cam member 51 and the exposure unit 30 are connected by the lever member 53, so the exposure unit 30 cannot be moved independently of the cam member 51.

Therefore, when the operator closes the front cover Pf in a half-set state in which the image forming unit 20 is not completely attached to the image forming position, not only can it be prevented that the image forming unit 20 and the exposure unit 30 will interfere with each other and be damaged, but it can also reliably prevent damage to the LED head Hd.

Although the above embodiments have been described with reference to a printer 10, the present invention can also be applied to image forming devices such as copiers, facsimile machines, and multifunction machines.

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

10 Printer 20 Image forming unit 30 Exposure unit Bd Apparatus main body Cs Housings M1, M2 Link mechanism Pf Front cover

Claims (7)

(a) an opening/closing member disposed so as to be openable and closable relative to a housing;
(b) an image forming unit that is detachably and movably disposed in the apparatus body and that is placed in an image forming position where an image is formed when the opening and closing member is closed;
(c) an exposure unit that is movably disposed with respect to the main body of the apparatus, that is placed at a retracted position when the opening/closing member is opened, and that is placed at an exposure position for exposing an image carrier to light when the opening/closing member is closed;
(d) a link mechanism for placing said exposure unit at an exposure position after said image forming unit is placed at an image forming position when said opening/closing member is closed. The image forming apparatus according to claim 1, wherein the link mechanism includes a first link member that is moved in a first direction as the opening/closing member is closed, and a second link member that is moved in a second direction as the first link member is moved in the first direction. The image forming apparatus according to claim 2, wherein when the opening/closing member is closed, the second link member is moved in a second direction after the image forming unit is placed in the image forming position, and the exposure unit is placed in the exposure position. (a) the opening/closing member includes a first pushing member that pushes the first link member into the apparatus body when the opening/closing member is closed, and a second pushing member that pushes the image forming unit into the apparatus body,
4. The image forming apparatus according to claim 3, wherein the height of the second pushing member is made higher than the height of the first pushing member. The image forming position according to claim 4, wherein the distance by which the first link member is moved when the opening/closing member is closed is greater than the distance by which the second link member is moved. (a) a cam surface is provided on the first link member, and a contact that moves along the cam surface is provided on the second link member;
6. The image forming position according to claim 5, wherein the angle between the first link member and the cam surface is set to 45[deg.] or less. The image forming apparatus according to claim 5, wherein the first link member, the second link member and the third link member are connected to each other so as to be freely pivotable.