# Patent

## Title
Liquid ejection apparatus

## Abstract

A liquid ejection apparatus is provided. The liquid ejection apparatus includes a first housing, a second housing, covers and a moving mechanism. The first housing is rotatable relative to the second housing about a rotational shaft between a close position and a separate position. The covers are movable relative to heads provided to the first housing between a protection position of covering the heads and a retraction position. When the first housing is moved from the close position toward the separate position, the moving mechanism moves the covers such that an angle formed between the first housing and the second housing when a cover corresponding to the head away from the rotational shaft reaches the protection position is smaller than an angle formed between the first housing and the second housing when a cover corresponding to the head close to the rotational shaft reaches the protection position.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority from Japanese Patent Application No. 2011-188249, filed on Aug. 31, 2011, the entire subject matter of which is incorporated herein by reference.
TECHNICAL FIELD
Aspects of the present invention relate to a liquid ejection apparatus which ejects liquid such as ink.
BACKGROUND
There has been know a liquid ejection apparatus in which an ejection surface of a head is covered with a cover so as to protect the ejection surface from a user's hand or foreign matters (refer to JP Hei.9-109403A). In the liquid ejection apparatus described in JP Hei.9-109403A, a plurality of heads (head units 34Y, 34M, 34C, 34B) are provided with covers (caps 37Y, 37M, 37C, 37B), respectively. The covers are synchronously moved from a retraction position where the covers do not cover ejection surfaces of the corresponding heads toward a protection position where the covers cover the ejection surfaces of the corresponding heads.
In the meantime, in a liquid ejection apparatus, a user manually performs a jam resolving operation of a recording medium on a conveyance path. In this case, in order to secure an operation space, the liquid ejection apparatus may be configured by a first housing accommodating a plurality of heads and a second housing. And, the first housing is configured to be rotatable relative to the second housing about a rotational shaft. Accordingly, compared to a configuration in which the first housing is moved upward and downward with respect to the second housing so as to perform the jam solving operation, it is possible to simplify a configuration of a mechanism moving the first housing. The plurality of heads are arranged in a direction orthogonal to the rotational shaft in the first housing.
SUMMARY
However, according to the inventors' analysis, when the covers described in JP Hei.9-109403A are adopted in the above configuration and the covers are synchronously moved according to the rotation of the first housing, following problems might occur.
For example, if the covers reach the protection position at an early stage of rotation, a recording medium jammed on the conveyance path is caught in the covers (particularly, a cover corresponding to the head close to the rotational shaft). In order to suppress the problem, it is necessary to delay a timing at which the covers reach the protection position to some extent.
On the other hand, if the covers reach the protection position at a later stage of rotation, the user's hand may be brought into contact with an ejection surface of the head (particularly, a head distant from the rotational shaft). In order to suppress the problem, it is necessary to make the timing earlier to some extent, at which the covers reach the protection position. According to the technique of JP Hei.9-109403A, since the covers are synchronously moved, it is difficult to suppress all the above two problems.
Accordingly, it is an aspect of the present invention to provide a liquid ejection apparatus capable of suppressing the above two problems.
According to an illustrative embodiment of the present invention, there is provided a liquid ejection apparatus including a first housing, a second housing, a plurality of covers, and a moving mechanism. The first housing is rotatable relative to the second housing about a rotational shaft to be moved between a close position where the first housing comes close to the second housing and a separate position where the first housing is separated from the second housing than the close position, the first housing accommodates a plurality of heads arranged in a direction orthogonal to the rotational shaft, and each of the heads includes an ejection surface having a plurality of ejection ports for ejecting liquid to a recording medium. The plurality of covers are provided for the plurality of heads, respectively, and include a far-side cover corresponding to one of the heads away from the rotational shaft and a near-side cover corresponding to one of the heads close to the rotational shaft. Each of the covers are movable relative to the corresponding head between a protection position where the cover covers the ejection surface of the corresponding head and a retraction position where the cover does not cover the ejection surface of the corresponding head. The moving mechanism is configured to move each of the covers according to the rotation of the first housing so as to take the retraction position when the first housing is located at the close position and take the protection position when the first housing is located at the separate position. When the first housing is moved from the close position toward the separate position, the moving mechanism is configured to move the covers such that an angle formed between the first housing and the second housing when the far-side cover reaches the protection position is smaller than an angle formed between the first housing and the second housing when the near-side cover reaches the protection position.
According to the above configuration, the moving of the covers is made to be different between the head away from the rotational shaft and the head close to the rotational shaft. Thereby, it is possible to suppress the problem where the recording medium jammed on the conveyance path is caught in the covers and the problem where the user's hand is brought into contact with the ejection surfaces of the heads.



BRIEF DESCRIPTION OF THE DRAWINGS
The above and other aspects of the present invention will become more apparent and more readily appreciated from the following description of illustrative embodiments of the present invention taken in conjunction with the attached drawings, in which:
FIG. 1 is a perspective view showing an outer appearance of an inkjet printer according to an illustrative embodiment of the present invention;
FIG. 2 is a schematic side view showing an interior of the printer;
FIGS. 3A and 3B are front views showing a lock mechanism, wherein FIG. 3A shows a state where a first housing is regulated from moving by the lock mechanism and FIG. 3B shows a state where the moving regulation of the first housing by the lock mechanism is released;
FIGS. 4A to 4D are schematic side views of the printer showing operations of covers when the first housing is moved from a close position to a separate position, and specifically, FIGS. 4A to 4D show states when an angle formed between the first housing and a second housing is 0°, 10°, 13° and 29°, respectively;
FIGS. 5A to 5D are schematic side views of the printer showing operations of the covers when the first housing is moved from the close position to the separate position, in which intermediate members are not shown, and specifically, FIGS. 5A to 5D show states when the angle formed between the first housing and the second housing is 0°, 10°, 13° and 29°, respectively; and
FIG. 6 is a graph showing a relation between the angle formed between the first housing and the second housing and a rotating angle of each cover.



DETAILED DESCRIPTION
Hereinafter, illustrative embodiments of the present invention will be described with reference to the drawings.
First, an overall configuration of an inkjet printer 1 according to an illustrative embodiment is described with reference to FIGS. 1 and 2.
The printer 1 includes a first housing 1a and a second housing 1b, both of which have a rectangular parallelepiped shape and the same size. The first housing 1a has an opened lower surface and the second housing 1b has an opened upper surface. When the first housing 1a overlaps with the second housing 1b and the opened surfaces thereof are covered, an interior space of the printer 1 is defined (refer to FIG. 2).
An upper part of a top plate of the first housing 1a is provided with a sheet discharge part 31. A space defined by the first and second housings 1a, 1b is formed with a conveyance path along which a sheet P is conveyed from a feeder unit 1c toward the sheet discharge part 31 along thick arrows of FIG. 2.
The first housing 1a is rotatable relative to the second housing 1b about a hinge part 1h located a lower end of one side of the first housing 1a. According to the rotation, the first housing 1a can take a close position (a position shown in FIG. 2) where the first housing comes close to the second housing 1b and a separate position (a position shown in FIG. 1) where the first housing is separated from the second housing 1b than the close position. When the first housing 1a is located at the separate position, a part of the conveyance path is exposed, so that an operation space of a user is secured between the first housing 1a and the second housing 1b. The user can use the operation space to manually perform a jam resolving operations of the sheet P on the conveyance path.
The first housing 1a is urged from the close position toward the separate position by a spring, for example. The first housing 1a can be opened up to a predetermined angle with respect to a horizontal plane and is regulated from being further opened by a stopper and the like. The predetermined angle of the first housing 1a with respect to the horizontal plane refers to a state where an angle between the first housing 1a and the second housing 1b becomes the predetermined angle. The predetermined angle is an angle capable of securing an operation space in which the user can put a hand and perform the jam resolving operations between the first housing 1a and the second housing 1b. In this illustrative embodiment, the predetermined angle is 29°.
In this illustrative embodiment, the close position is a position along the horizontal plane and the separate position is a position which is inclined to the horizontal plane by about 29°.
A front face of the first housing 1a (a left front side in FIG. 1) is provided with a lock mechanism 70 which regulates (prohibits) the first housing 1a located as the close position from moving. A front face of the second housing 1b is provided with an openable and closable lid 1d which covers the front face of the first housing 1a. When the lid 1d is opened, the lock mechanism 70 is exposed. A configuration of the lock mechanism 70 will be specifically described later.
The first housing 1a accommodates therein two heads, two cartridges (not shown) corresponding to the two heads, a controller 1p (refer to FIG. 2) configured to control operations of respective units of the printer 1, a part of a conveyance unit 20 (refer to FIG. 2), and the like. The two heads include a pre-coat head 10a which ejects pre-processing liquid and an inkjet head 10b which ejects black ink, in order from an upstream side of a sheet conveyance direction shown with the thick arrows in FIG. 2.
The heads 10a, 10b have the same configuration and are arranged in a direction (sub-scanning direction) orthogonal to an extending direction (main scanning direction) of the hinge part 1h of the first housing 1a. 
The second housing 1b accommodates therein flat plate-shaped platens 9a, 9b which are provided below the respective heads 10a, 10b, respectively, the feeder unit lc, a part of the conveyance unit 20, and the like.
The first housing 1a is provided with covers 11a, 11b which are configured to cover ejection surfaces 10x of the respective heads 10a, 10b and a support member 1a1 which rotatably supports the covers 11a, 11b (refer to FIG. 4). In FIGS. 1 and 2, the covers 11a, 11b and the like are not shown. A configuration of the covers 11a, 11b and the like will be described later in more detail.
The respective cartridges store the pre-processing liquid and black ink (hereinafter, collectively referred to as ‘liquid’) which are supplied to the corresponding heads 10a, 10b, respectively. The pre-processing liquid is liquid having a function of preventing the ink from bleeding or exuding back, a function of improving color expression property or quick-drying of the ink and the like. The liquids in the cartridges are supplied to the corresponding heads 10a, 10b by driving of a pump and the like.
Each of the heads 10a, 10b is a line type which is long in the main scanning direction and have a substantially rectangular parallelepiped shape. The heads 10a, 10b are spaced from each other in the sub-scanning direction and are supported to the first housing 1a via a frame 3. The respective heads 10a, 10b are provided on upper surfaces thereof with joints to which flexible tubes are attached and the ejection surfaces 10x, which are the lower surfaces of the respective heads 10a, 10b, are formed with a plurality of opened ejection ports. The respective heads 10a, 10b are formed therein with flow paths along which the liquids supplied from the corresponding cartridges via the tubes and joints reach the ejection ports.
The controller 1p controls a preparation operation relating to recording, feeding, conveyance and discharge operations of the sheet P, a liquid ejection operation synchronous with the conveyance of the sheet P and the like such that an image is recorded on the sheet P, based on a recording command transmitted from an external apparatus (PC connected to the printer 1, for example).
The controller 1p has a ROM (Read Only Memory), a RAM (Random Access Memory: including a non-volatile RAM), an I/F (Interface) and the like, in addition to a CPU (Central Processing Unit) which is a calculation processing device. The ROM stores therein programs which are executed by the CPU, a variety of fixed data and the like. The RAM temporarily stores data (image data and the like) which is necessary when executing the programs. The controller 1p transmits and receives data to and from the external apparatus via the I/F.
The feeder unit 1c has a sheet feeding tray 1c1 and a sheet feeding roller 1c2. The sheet feeding tray 1c1 is detachably mounted to the lower housing 1b in the sub-scanning direction. The sheet feeding tray 1c1 is a box which is opened upward and can accommodate therein a plurality of types of sheets P having various sizes. The sheet feeding roller 1c2 is rotated under control of the controller 1p and feeds the uppermost sheet P in the sheet feeding tray 1c1.
The platens 9a, 9b are arranged to face the ejection surfaces 10x of the corresponding heads 10a, 10b in a vertical direction. Surfaces of the platens 9a, 9b are support surfaces 9x which support the sheet P from a backside thereof while facing the ejection surfaces 10x of the corresponding heads 10a, 10b. The respective heads 10a, 10b are supported to the frame 3 such that a predetermined gap appropriate for recording is formed between the ejection surfaces 10x and the support surfaces 9x when performing a recording operation.
The conveyance unit 20 has roller pairs 22, 23, 24, 25, 26, 27, guides 29a, 29b, 29c, 29d, 29e and an intermediate roller 21.
Among the constitutional elements of the conveyance unit 20, the intermediate roller 21, an upper roller 24a of the roller pair 24, the roller pairs 26, 27 and the guides 29d, 29e are provided (supported) to the first housing 1a. The roller pairs 22, 23, 25, a lower roller 24b of the roller pair 24 and the guides 29a, 29b, 29c are provided (supported) to the second housing 1b. 
The roller pairs 22 to 27 are arranged in the order from an upstream side of the conveyance direction so as to form the conveyance path from the feeder unit 1c to the sheet discharge part 31. The lower rollers 23b, 24b, 25b of the roller pairs 23 to 25 are driving rollers which are connected to a conveyance motor (not shown) and are rotated under driving control of the conveyance motor by the controller 1p. The upper rollers 23a, 24a, 25a of the roller pairs 23 to 25 are driven rollers. Also, in the respective roller pairs 26, 27, one roller is a driving roller and the other roller is a driven roller. Also, while the lower rollers 23b to 25b of the roller pairs 23 to 25 are rubber rollers having a rubber layer on an outer periphery thereof, the upper rollers 23a to 25a of the roller pairs 23 to 25 and the intermediate roller 21 are spur rollers having a metal layer formed with a plurality of protrusions on an outer periphery thereof.
The guides 29a to 29e are arranged in the order from an upstream side of the conveyance direction between the feeder unit 1c and the roller pair 22 and between the respective roller pairs so as to form the conveyance path. Each of the guides 29a to 29e is configured by a pair of plates which are spaced from each other in a plane direction.
The intermediate roller 21 is arranged at an upper position of the conveyance path between the head 10a and the roller pair 24. In other words, the intermediate roller 21 is arranged at a position which faces a surface (a recording surface on which an image is formed) of the sheet P between the head 10a and the roller pair 24.
The sheet P fed from the feeder unit 1c passes between the plates of the guides 29a to 29e and is conveyed in the conveyance direction while it is put between the roller pairs 22 to 27.
When the sheet P sequentially passes below the heads 10a, 10b with being supported on the support surfaces 9x, the respective heads 10a, 10b are driven under control of the controller 1p, so that the liquid is ejected from the ejection ports of the respective ejection surfaces 10x toward the surface of the sheet P. As the liquid is ejected from the ejection ports of the respective ejection surfaces 10x toward the surface of the sheet P, an image is formed on the sheet P. The liquid ejection operation from the ejection ports is performed under control of the controller 1p, based on a detection signal from a sheet sensor 32. After that, the sheet P is conveyed upward and discharged to the sheet discharge part 31 through an opening 30 which is formed at the upper part of the first housing 1a. 
In the below, the configuration of the lock mechanism 70 is described with reference to FIGS. 3A and 3B.
The lock mechanism 70 includes a cylindrical rotary member 71, two interlocking members 73a, 73b, two swing members 74a, 74b, two springs 76a, 76b and two fixed members 75a, 75b. One longitudinal ends of the interlocking members 73a, 73b are respectively connected to a peripheral surface of the rotary member 71. The swing members 74a, 74b are respectively formed with recess portions 74c, 74d which are opened in a direction separating away from the rotary member 71a. The fixed member 75a, 75b are provided with shaft members 75c, 75d which can be respectively received in (engaged with) the recess portions 74c, 74d. In the meantime, swing shafts of the swing members 74a, 74b are fixed to the first housing 1a. One ends of the springs 76a, 76b, which are close to the rotary member 71a, are respectively fixed to the first housing 1a. Also, the fixed members 75a, 75b are respectively fixed to the second housing 1b. 
A rod-shaped knob 72 is fixed on a front face of the rotary member 71. The knob 72 is integrally rotated with the rotary member 71. The springs 76a, 76b urge upper ends of the swing members 74a, 74b in a direction coming close to the rotary member 71. Thereby, under a state where external force is not applied, the respective parts of the lock mechanism 70 are stationary with the knob 72 extending in a vertical direction, as shown in FIG. 3A.
At a state shown in FIG. 3A, the recess portions 74c, 74d are respectively engaged to the shaft members 75c, 75d. By this engagement, the moving of the first housing 1a is regulated such that the first housing 1a at the close position is not rotated toward the separate position. When a user rotates the knob 72 in a clockwise direction against the urging force of the springs 76a, 76b, the recess portions 74c, 74d are separated from the shaft members 75c, 75d. Thereby, the moving regulation of the first housing 1a is released.
When the first housing 1a is returned to the close position from the separate position, the engagement between the recess portions 74c, 74d and the shaft members 75c, 75d is restored. Thereby, the moving of the first housing 1a is again regulated by the lock mechanism 70.
In the below, the configuration and operation of the covers 11a, 11b are described with reference to FIGS. 4A to 4D, 5A to 5D and 6.
As shown in FIGS. 4A to 4D, the covers 11a, 11b are supported to the support member 1a1 via side plates 12a, 12b. The support member 1a1 supports the frame 3 in addition to the side plates 12a, 12b and intermediate members 13a, 13b. The frame 3 supports the heads 10a, 10b. 
The covers 11a, 11b have a substantially rectangular plate-shaped member which is long in the main scanning direction, respectively. Lengths of the covers 11a, 11b in the main scanning direction are longer than those of the ejection surfaces 10x of the heads 10a, 10b, respectively. Lengths of the covers 11a, 11b in the sub-scanning direction are a little shorter than those of the heads 10a, 10b, respectively. The covers 11a, 11b can be moved relative to the heads 10a, 10b, respectively, between a protection position (a position shown in FIG. 4D) where the covers cover the ejection surfaces 10x of the corresponding heads 10a, 10b and a retraction position (a position shown in FIG. 4A) where the covers do not cover the ejection surfaces 10x. As shown in FIG. 4A, the retraction position of the cover 11a is provided at a left side of the head 10a and the retraction position of the cover 11b is provided at a right side of the head 10b. 
At the protection position (refer to FIG. 4D), the covers 11a, 11b face the ejection surfaces 10x in the direction orthogonal to the ejection surfaces 10x, and at the retraction position (refer to FIG. 4D), the covers do not face the ejection surfaces 10x in the direction orthogonal to the ejection surfaces 10x. 
The covers 11a, 11b are moved according to the rotation of the first housing 1a such that the covers take the retraction position (refer to FIG. 4A) when the first housing 1a is located at the close position and take the protection position (refer to FIG. 4D) when the first housing 1a is located at the separate position. The side plates 12a, 12b, the intermediate members 13a, 13b, torsion coil springs 13a4, 13b4 and guide parts 14a, 14b formed at the second housing 1b function as a moving mechanism for realizing the above movement.
The side plates 12a, 12b are fixed to both ends of the covers 11b, 11b in the main scanning directions and are rotatably supported to the support member 1a1 via shafts 12a1, 12b1. That is, the covers 11a, 11b can be rotated relative to the support member 1a1 about the shafts 12a1, 12b1.
The side plates 12a, 12b have pins 12a2, 12b2 which protrude outward in the main scanning direction. The pins 12a2, 12b2 are inserted into long holes 13a2, 13b2 which are formed at the intermediate members 13a, 13b. Tip ends of the pins 12a2, 12b2 are arranged outside the long holes 13a2, 13b2 and have diameters larger than widths of the long holes 13a2, 13b2. That is, the tip ends of the pins 12a2, 12b2 are enlarged, so that the pins 12a2, 12b2 are prevented from being separated from the long holes 13a2, 13b2 and the engagement of the intermediate members 13a, 13b and the side plates 12a, 12b is kept.
The intermediate members 13a, 13b are engaged with the side plates 12a, 12b via the pins 12a2, 12b2 and are rotatably supported to the support member 1a1 via shafts 13a1, 13b1. The intermediate members 13a, 13b are located at more outward positions than the side plates 12a, 12b (except for the pins 12a2, 12b2) in the main scanning direction. The shafts 13a1, 13b1 of the intermediate members 13a, 13b are located at positions closer to a center of the support member 1a1 than the shafts 12a1, 12b1 of the corresponding side plates 12a, 12b in the sub-scanning direction, and rotating radii of the intermediate members 13a, 13b are larger than those of the side plates 12a, 12b, respectively.
The intermediate members 13a, 13b are long members having one ends to which the shafts 13a1, 13b1 are provided and the other ends 13a3, 13b3 spaced from the shafts 13a1, 13b1, and are rotated about the shafts 13a1, 13b1 according to respective contact states of the other ends 13a3, 13b3 with the guide parts 14a, 14b. It is noted that a distance between the one end having the shaft 13a1 and the other end 13a3 of the intermediate member 13a is longer than a distance between the one end having the shaft 13b1 and the other end 13b3 of the intermediate member 13b. 
The torsion coil springs 13a4, 13b4 are provided to the shafts 13a1, 13b1 of the intermediate members 13a, 13b. More specifically, the torsion coil springs 13a4, 13b4 are provided to the shafts 13a1, 13b1 of the intermediate members 13a, 13b serving as guide rods. One ends of the torsion coil springs 13a4, 13b4 are fixed to the support member 1a1 and the other ends of the torsion coil springs 13a4, 13b4 are fixed to the intermediate members 13a, 13b. Thereby, the intermediate members 13a, 13b are applied with urging forces of counterclockwise and clockwise directions, respectively. That is, the covers 11a, 11b are respectively urged from the retraction position toward the protection position by the urging forces of the torsion coil springs 13a4, 13b4.
The guide parts 14a, 14b are plate-shaped protrusions which are provided on an upper end surface of the second housing 1b. The guide parts 14a, 14b have a substantially rectangular shape, respectively, when seen from the main scanning direction. While an upper end surface of the guide part 14a extends horizontally, an upper end surface of the guide part 14b has a mountain shape having two inclined portions which are inclined with respect to a horizontal plane in an opposite direction to each other from an apex.
In the meantime, the side plates 12a, 12b, the intermediate members 13a, 13b and the guide parts 14a, 14b are provided at both ends of the covers 11a, 11b in the main scanning direction. That is, although only the configuration of the covers 11a, 11b at one end side in the main scanning direction is shown in FIGS. 4A to 4D and 5A to 5D, the configuration of the covers 11a, 11b at the other end side in the main scanning direction is also the same.
Subsequently, the operations of the intermediate members 13a, 13b, the side plates 12a, 12b and the covers 11a, 11b are specifically described when the first housing 1a is moved from the close position to the separate position. When a user lifts up the first housing 1a, the first housing is moved from the close position (refer to FIG. 2) to the separate position (refer to FIG. 1). At this time, the support member 1a1 is moved together with the first housing 1a. 
When the first housing 1a is located at the close position, an angle θ formed between the first housing 1a and the second housing 1b is 0(zero)° (refer to FIGS. 4A and 5A). At this time, the intermediate members 13a, 13b are stationary with the other ends 13a3, 13b3 contacting the upper end surfaces of the guide parts 14a, 14b, respectively. The side plates 12a, 12b are stationary with being engaged to the intermediate members 13a, 13b via the pins 12a2, 12b2.
When the first housing 1a is moved from the close position toward the separate position, a distance between the support member 1a1 and the guide parts 14a, 14b is increased. At this time, since the urging forces of the torsion coil springs 13a4, 13b4 are applied to the shafts 13a1, 13b1, the intermediate members 13a, 13b are rotated with the other ends 13a3, 13b3 contacting the guide parts 14a, 14b, respectively. That is, the intermediate members 13a, 13b are rotated about the shafts 13a1, 13b1 in the clockwise and counterclockwise directions in FIG. 4, respectively, according to the contact states of the other ends 13a3, 13b3 with the upper end surfaces of the guide parts 14a, 14b. As the intermediate members 13a, 13b are rotated, the pins 12a2, 12b2 are moved in the long holes 13a2, 13b2, so that the side plates 12a, 12b are rotated about the shafts 12a1, 12b1 in the counterclockwise and clockwise directions in FIG. 5B, respectively.
In the course of the angle θ reaching 10° from 0°, the other end 13b3 of the intermediate member 13b is moved along the right inclined part toward the apex while contacting the right inclined part of the upper end surface of the guide part 14b shown in FIGS. 4A and 5A.
When the angle θ is 10° (refer to FIG. 4B), the cover 11a has reached the protection position but the cover 11b has not reached the protection position yet.
In the course of the angle θ reaching 13° from 10°, the other end 13a3 of the intermediate member 13a is separated from the guide part 14a. The other end 13b3 of the intermediate member 13b is moved along the left inclined part in a direction separating away from the apex while contacting the left inclined part of the upper end surface of the guide part 14b shown in FIGS. 4B and 5B.
When the angle θ is 13° (refer to FIG. 4C), the cover 11a has reached the protection position but the cover 11b has not yet reached the protection position.
In the course of the angle θ reaching 29° from 13°, the other end 13b3 of the intermediate member 13b is separated from the guide part 14b. 
When the angle θ is 29° (refer to FIGS. 4D and 5D), i.e., when the first housing 1a is at the separate position, both the covers 11a, 11b have reached the protection position. That is, in the course of the angle θ reaching 29° from 0°, the covers 11a, 11b are moved from the retraction position to the protection, as shown in FIGS. 5A to 5D.
As shown in FIG. 6, in this illustrative embodiment, rotating angles of the covers 11a, 11b from the retraction position to the protection position are 100°. The rotating angle of the cover 11a from the retraction position to the protection position refers to an angle A shown in FIG. 5D and the rotating angle of the cover 11b from the retraction position to the protection position refers to an angle B shown in FIG. 5D. That is, in this illustrative embodiment, both the angles A and B are 100°. Here, the angle A is an angle between an imaginary line L1 and an imaginary line L3 and the angle B is an angle between an imaginary line L2 and an imaginary line L4. The imaginary line L1 is a line connecting the shaft 12a1 of the side plate 12a and the pin 12a2 of the side plate 12a when the angle θ is 0°. The imaginary line L3 is a line connecting the shaft 12a1 of the side plate 12a and the pin 12a2 of the side plate 12a when the angle θ is 29°. The imaginary line L2 is a line connecting the shaft 12b1 of the side plate 12b and the pin 12b2 of the side plate 12b when the angle θ is 0°. The imaginary line L4 is a line connecting the shaft 12b1 of the side plate 12b and the pin 12b2 of the side plate 12b when the angle θ is 29°.
While the cover 11a reaches the protection position when the angle θ is 10°, the cover 11b reaches the protection position when the angle θ is 15°.
FIG. 6 shows an amount of change of the rotating angles of the covers 11a, 11b with respect to the angle θ. In the cover 11b, the amount of change is V1 when the angle θ is 0° to 13°, V2 (>V1) when the angle θ is 13° to 15°, and zero when the angle θ is larger than 15°. In the cover 11a, the amount of change is V3 (>V1) when the angle θ is 0° to 10° and zero when the angle θ is larger than 10°.
In the course of the angle θ reaching 29° from 0°, after the covers 11a, 11b reach the protection position, the covers 11a, 11b and the intermediate members 13a, 13b and side plates 12a, 12b corresponding to the covers 11a, 11b are not moved relative to the support member 1a1 and the first housing 1a and are moved together with the support member 1a1 and the first housing 1a with being held to the support member 1a1 and the first housing 1a. In other words, in the course of the angle θ reaching 29° from 0°, after the angle θ exceeds the 10° in the cover 11a and the angle θ exceeds the 15° in the cover 11b, the covers 11a, 11b and the intermediate members 13a, 13b and side plates 12a, 12b corresponding to the covers 11a, 11b are not moved relative to the support member 1a1 and the first housing 1a and are moved together with the support member 1a1 and the first housing 1a with being held to the support member 1a1 and the first housing 1a. 
When the first housing 1a is moved from the separate position to the close position, the operations of the intermediate members 13a, 13b, the side plates 12a, 12b and the covers 11a, 11b are opposite operations to the operations which are made when the first housing 1a is moved from the close position to the separate position.
As described above, according to the printer 1 of this illustrative embodiment, when the first housing 1a is rotated about the hinge part 1h serving as a rotational shaft from the close position to the separate position, the angle θ (10)° formed when the cover 11a corresponding to the head 10a away from the hinge part 1h reaches the protection position is smaller than the angle θ (15)° formed when the cover 11b corresponding to the head 10b close to the hinge part 1h reaches the protection position (refer to FIG. 6).
That is, the moving of the covers 11a, 11b is made to be different between the head 10a away from the hinge part 1h and the head 10b close to the hinge part 1h. Thereby, it is possible to suppress both the problem where the sheet P jammed on the conveyance path P is caught in the covers 11a, 11b (particularly, the cover 11b corresponding to the head 10b close to the hinge part 1h) and the problem where the user's hand is brought into contact with the ejection surfaces 10x of the heads 10a, 10b (particularly, the head 10a away from the hinge part 1h).
As the moving mechanism of the covers 11a, 11b, the side plates 12a, 12b, the intermediate members 13a, 13b, the torsion coil springs 13a4, 13b4 and the guide parts 14a, 14b provided to the second housing 1b are used. When an electrical mechanism is used as the moving mechanism, a configuration of the moving mechanism may be complicated or the moving mechanism may not be operated unless it is powered. However, when the mechanical mechanism like the above illustrative embodiment is used as the moving mechanism, a configuration of the moving mechanism is simplified and the moving mechanism is operated without electric power.
Also, the intermediate members 13a, 13b having the larger rotating radii than those of the covers 11a, 11b are provided as the moving mechanism. Accordingly, it is possible to increase the rotating angles of the covers 11a, 11b, compared to a configuration in which the intermediate members 13a, 13b are not provided.
As shown in FIGS. 4A and 5A, the retraction position of the cover 11a is at a side of the head 10a which is away from the hinge part 1h. In this case, it is possible to suppress the user's hand from contacting the ejection surface 10x of the head 10a by the cover 11a. 
When the first housing 1a is rotated about the hinge part 1h from the close position toward the separate position, the moving amount (the amount of change of the rotating angle: slope of the graph in FIG. 6) of the cover 11b would be V1 and then V2 (>V1) sequentially with respect to the angle θ. That is, just after the first housing 1a starts to move from the close position to the separate position, the problem where the sheet P jammed on the conveyance path P is caught in the cover 11b can be securely suppressed by moving the cover 11b with the relatively small moving amount V1. Then, the cover 11b is quickly moved with the relatively large moving amount V2 (>V1) and is thus enabled to reach the protection position. Thereby, it is possible to suppress the problem where the user's hand is brought into contact with the ejection surface 10x of the head 10b close to the hinge part 1h, more securely.
When the first housing 1a is rotated about the hinge part 1h from the close position toward the separate position, the moving amount (the amount of change of the rotating angle: slope of the graph in FIG. 6) of the cover 11a with respect to the angle θ is V3 (>V1). That is, when the first housing 1a is moved from the close position to the separate position, the cover 11a is moved with the moving amount larger than that of the cover 11b, so that the space between the first housing 1a and the second housing 1b is rapidly blocked by the cover 11a. Thereby, it is possible to suppress the user's hand from contacting the ejection surfaces 10x of the heads 10a, 10b by the cover 11a. Then, the cover 11a is enabled to reach the protection position, so that it is possible to suppress the problem where the user's hand is brought into contact with the ejection surface 10x of the head 10a distant from the hinge part 1h, more securely.
The printer 1 has the two heads 10a, 10b, and the retraction position of the cover 11a is located at the left side (a side away from the head 10b other than the head 10a) of the corresponding head 10a and the retraction position of the cover 11b is located at the right side (a side away from the head 10a other than the head 10b) of the corresponding head 10b, as shown in FIGS. 4A and 5A.
Thereby, it is possible to reduce a distance between the heads 10a, 10b. If the distance between the heads 10a, 10b is long, positions on the sheet P, which the liquids ejected from the head 10b located at a downstream side of the conveyance direction of the sheet P reach, are deviated, so that a quality of an image may be deteriorated. However, according to this illustrative embodiment, since it is possible to reduce the distance between the heads 10a, 10b, it is possible to suppress that problem.
More specifically, since it is not necessary to secure a space between the heads 10a, 10b as the retraction position of the covers 11a, 11b, it is possible to arrange the roller pair 24 in the space and to thus improve the conveyance accuracy. If the roller pair 24 is omitted, the sheet P passes the position (recording position) facing the ejection surfaces 10x of the heads 10a, 10b while it is conveyed by the roller pair 23 arranged at the more upstream side than the heads 10a, 10b in the conveyance direction and/or the roller pair 25 arranged at the more downstream side than the heads 10a, 10b in the conveyance direction. When there is no roller pair 24 between the heads 10a, 10b, a distance between the roller pair 23 and the roller pair 25 is increased. Thus, a length of a part of the sheet P held and cantilevered only by the roller pair 23, which is at the more downstream side than the roller pair 23 in the conveyance direction, becomes longer. As a result, a problem where the corresponding part is floated upward and a problem where the corresponding part is floated upward and is thus brought into contact with the ejection surfaces 10x of the heads 10a, 10b may be caused. Also, the same problems may occur in a part of the sheet P held and cantilevered only by the roller pair 25, which is at the more upstream side than the roller pair 25 in the conveyance direction.
However, in this illustrative embodiment, the roller pair 24 is arranged between the heads 10a, 10b. Therefore, the part of the sheet P held by the roller pair 23, which is at the more downstream side than the roller pair 23 in the conveyance direction, is also held by the roller pair 24. Also, the part of the sheet P held by the roller pair 25, which is at the more upstream side than the roller pair 25 in the conveyance direction, is also held by the roller pair 24. Thereby, since it is possible to reduce the distance between the roller pairs with which the sheet P can be held, the above problems are suppressed and the conveyance accuracy is enhanced. In the meantime, in the roller conveyance configuration as this illustrative embodiment, the above problems may be remarkable when a plurality of line-type heads having the ejection surfaces 10x, which have the long lengths in the conveyance direction, are arranged in parallel in the conveyance direction. The lengths of the ejection surfaces 10x in the conveyance direction are preferably short so as to make the heads smaller. However, when the number of ejection ports is increased so as to improve the quality of an image, the lengths of the ejection surfaces tend to be longer.
Also, the upper roller 24a of the roller pair 24 is provided to the first housing 1a. Therefore, when the first housing 1a is moved from the close position to the separate position, the upper roller 24a is also moved together with the first housing 1a. Thereby, the conveyance path is exposed, so that it is possible to easily perform the jam resolving operation.
While the present invention has been shown and described with reference to certain illustrative embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
[Cover]

    
    
        A sponge absorbing the liquid and the like may be provided to a part of the cover facing the ejection surface. In this case, it is possible to suppress the liquid leaked from the ejection ports from scattering into the liquid ejection apparatus.
        The cover may cover the entirety or a part of the ejection surface.
        The retraction position of the cover may be located at any direction with respect to the corresponding head.
    
    


[Moving Mechanism of Over]

    
    
        In the above illustrative embodiment, the side plates 12a, 12b, the intermediate members 13a, 13b, the torsion coil springs 13a4, 13b4 and the guide parts 14a, 14b are exemplified as the moving mechanism. However, the other mechanisms may be also employed. It may be possible to arbitrarily change the shapes and the like of the side plates 12a, 12b, the intermediate members 13a, 13b, the torsion coil springs 13a4, 13b4 and the guide parts 14a, 14b. For example, the intermediate members 13a, 13b may be omitted and the side plates 12a, 12b may be enabled to function as the intermediate members (that is, a configuration may be possible in which the side plates 12a, 12b directly contact the guide parts 14a, 14b and the covers 11a, 11b are moved according to the contact states therebetween.). Also, the moving mechanism is not limited to the mechanical mechanism and may be an electrical mechanism.
        In the above illustrative embodiment, the rotating angle of the cover is 100°. However, the rotating angle is not particularly limited. Also, the rotating angles of the two covers may be different from each other.
        The angle formed between the first housing and the second housing when the covers reach the protection may be different or same for each of the covers.
        When the first housing is rotated from the close position toward the separate position, the moving amounts of the covers with respect to the angle between the first housing and the second housing may be constant without stepwise changing.
        The moving mechanism is not limited to the configuration of rotating the covers and may move the covers along one direction (for example, vertical or horizontal direction (not rotating manner)).
    
    


[Housing]

    
    
        The first housing may be moved between the close position and the separate position as the controller controls a mechanical mechanism, not by the user's manual operation.
    
    


[Conveyance Mechanism]

    
    
        Both rollers of the roller pair arranged between the heads may be provided to the second housing.
        The roller pair which is arranged between the heads may be omitted.
        The intermediate roller 21 may be omitted.
        The roller which can contact the recording surface of the recording medium just after the recording may not be the spur roller.
        The present invention is not limited to the roller conveyance manner as the above illustrative embodiment and may adopt a belt conveyance manner.
    
    


[Head]

    
    
        The head may eject any liquid, other than the pre-processing liquid or ink.
        The head is not limited to the line type (for example, the head may be a serial type).
        The liquid ejection apparatus may have three or more heads. In this case, three or more heads may be respectively provided with covers.
    
    


[Others]

    
    
        The recording medium is not limited to the sheet P and may be any recordable medium.
        The present invention is not limited to the printer and can be applied to a facsimile, a copier and the like.

## Claims

1. A liquid ejection apparatus comprising:
a first housing;
a second housing, wherein the first housing is rotatable relative to the second housing about a rotational shaft to be moved between a close position where the first housing comes close to the second housing and a separate position where the first housing is separated from the second housing than the close position, the first housing accommodates a plurality of heads arranged in a direction orthogonal to the rotational shaft, and each of the heads includes an ejection surface having a plurality of ejection ports for ejecting liquid to a recording medium;
a plurality of covers provided for the plurality of heads, respectively, and including a far-side cover corresponding to one of the heads away from the rotational shaft and a near-side cover corresponding to one of the heads close to the rotational shaft, wherein each of the covers are movable relative to the corresponding head between a protection position where the cover covers the ejection surface of the corresponding head and a retraction position where the cover does not cover the ejection surface of the corresponding head; and
a moving mechanism configured to move each of the covers according to the rotation of the first housing so as to take the retraction position when the first housing is located at the close position and take the protection position when the first housing is located at the separate position,
wherein when the first housing is moved from the close position toward the separate position, the moving mechanism is configured to move the covers such that an angle formed between the first housing and the second housing when the far-side cover reaches the protection position is smaller than an angle formed between the first housing and the second housing when the near-side cover reaches the protection position,
wherein the head corresponding to the far-side cover includes a first side close to the rotational shaft and a second side away from the rotational shaft, and
wherein the retraction position of the far-side cover is located at the second side of the head corresponding to the far-side cover.

2. The liquid ejection apparatus according to claim 1,
wherein the moving mechanism includes:
a plurality of guide parts provided to the second housing for the plurality of heads, respectively;
a plurality of intermediate members engaged with the covers and configured to contact the guide parts, respectively; and
an urging part configured to urge each of the covers from the retraction position toward the protection position,

wherein when the first housing is located at the close position, each of the intermediate members is brought into contact with the corresponding guide part to cause the covers to be located at the retraction position, and when the first housing is located at the separate position, each of the intermediate members is separated from the corresponding guide part to cause the covers to be located at the protection position, and
wherein when the first housing is moved from the close position toward the separate position, the moving mechanism is configured to move each of the covers such that an angle formed between the first housing and the second housing when one of the intermediate members, which is engaged with the far-side cover, is separated from the corresponding guide part is smaller than an angle formed between the first housing and the second housing when one of the intermediate members, which is engaged with the near-side cover, is separated from the corresponding guide part.

3. The liquid ejection apparatus according to claim 1,
wherein the plurality of heads include two heads,
wherein each of the two heads includes a first side close to a head other than the corresponding head and a second side away from the head other than the corresponding head, and
wherein the retraction position of each of the covers is located at the second side of the corresponding head.

4. The liquid ejection apparatus according to claim 1,
wherein when the first housing is moved from the close position toward the separate position, the moving mechanism is configured to move the near-side cover by a first moving amount with respect to the angle between the first housing and the second housing in a first stage and configured to move the near-side cover by a second moving amount larger than the first moving amount with respect to the angle between the first housing and the second housing in a second stage after the first stage.

5. The liquid ejection apparatus according to claim 4,
wherein when the first housing is moved from the close position toward the separate position, the moving mechanism is configured to move the far-side cover by a third moving amount larger than the first moving amount with respect to the angle between the first housing and the second housing.

6. A liquid ejection apparatus comprising:
a first housing;
a second housing, wherein the first housing is rotatable relative to the second housing about a rotational shaft to be moved between a close position where the first housing comes close to the second housing and a separate position where the first housing is separated from the second housing than the close position, the first housing accommodates a plurality of heads arranged in a direction orthogonal to the rotational shaft, and each of the heads includes an ejection surface having a plurality of ejection ports for ejecting liquid to a recording medium;
a plurality of covers provided for the plurality of heads, respectively, and including a far-side cover corresponding to one of the heads away from the rotational shaft and a near-side cover corresponding to one of the heads close to the rotational shaft, wherein each of the covers are movable relative to the corresponding head between a protection position where the cover covers the ejection surface of the corresponding head and a retraction position where the cover does not cover the ejection surface of the corresponding head; and
a moving mechanism configured to move each of the covers according to the rotation of the first housing so as to take the retraction position when the first housing is located at the close position and take the protection position when the first housing is located at the separate position,
wherein the moving mechanism includes:
a plurality of guide parts provided to the second housing for the plurality of heads, respectively; and
a plurality of intermediate members provided to be rotatable and engaged with the covers, respectively, each intermediate member including:
a first end portion provided with a shaft about which the intermediate member is rotatable; and
a second end portion configured to contact a corresponding guide part,


wherein a distance between the first end portion and the second end portion of the intermediate member corresponding to the far-side cover is longer than that of the intermediate member corresponding to the near-side cover,
wherein the head corresponding to the far-side cover includes a first side close to the rotational shaft and a second side away from the rotational shaft, and
wherein the retraction position of the far-side cover is located at the second side of the head corresponding to the far-side cover.