JP2001191610A - Positioning mechanism of recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanism for positioning a recording head highly accurately. SOLUTION: An ink jet printer comprises a drum 3 for carrying a sheet while sucking onto the outer circumferential surface 3a thereof, and a nozzle unit 5 disposed above the drum 3 through a constant gap. Sections 21C, 21M, 21Y, 21B for containing four nozzle heads 5C, 5M, 5Y, 5B juxtaposed radially along the carrying direction of sheet are provided in the nozzle unit 5. When the nozzle head 5C is inserted into the containing section 21, a shaft 25 disposed at the upper end part of the nozzle head 5C is supported rotatably and a leaf spring fixed to one side at the lower end part of the nozzle head 5C acts on a regulation member. Consequently, movement of the lower end part of the nozzle head 5C to one side is regulated by the regulation member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head positioning mechanism for positioning a recording head of an ink jet printer at a predetermined position.

[0002]

2. Description of the Related Art An ink jet printer has at least one recording head facing a conveyance surface for conveying a recording medium. At the tip where the recording head faces the transport surface,
A large number of ink ejection ports are formed in a direction transverse to the transport direction of the recording medium. To form high-definition images,
Each ink ejection port is formed to have a very small diameter and is arranged at a high density.

For this reason, in particular, in a color printer of a type in which a plurality of recording heads of different ink colors are juxtaposed in the direction of conveyance of a recording medium, a large number of ink ejection ports provided in the recording heads of each color are used. In order to superimpose the ejected inks of the respective colors on the recording medium with high precision, extremely advanced technology is required. For this reason, in the conventional color printer, it is necessary to position the recording heads of each color relatively and with respect to the transport surface with high accuracy.

[0004]

However, in the conventional ink jet printer, there is no effective means for positioning the recording heads of each color with high accuracy. For example, vibration due to paper jam or vibration at the time of transportation is caused. There has been a problem that the recording head is displaced.

The present invention has been made in view of the above points, and an object of the present invention is to provide a recording head positioning mechanism capable of positioning a recording head with high accuracy.

[0006]

In order to achieve the above object, a recording head positioning mechanism according to the present invention provides a recording medium for conveying a sheet-like recording medium in a first direction.
A positioning section for positioning a recording head having a tip portion provided with a plurality of ink ejection ports in a second direction orthogonal to the first direction, wherein one end of the recording head along the second direction; A reference surface disposed opposite to the recording head, and provided at the other end of the recording head along the second direction, and pressing the other end so as to press the one end against the reference surface; A first for urging the recording head toward one end thereof
Adjusting the position of the recording head along the second direction by pressing the one end in a direction away from the reference surface against the urging force of the first urging member. Means, holding means for holding a rear end portion of the recording head separated from the transport surface, and the first means near the front end portion.
A regulating member that is disposed to face one side along the direction, and regulates movement of the distal end to the one side; and a second biasing member that biases the distal end toward the regulating member. , Is provided.

According to the invention, the recording head is pressed at one end in the second direction by the first biasing member against the reference surface, and the position in the second direction is adjusted by the adjusting means. Further, the rear end of the recording head is held by the holding means, and the front end is pressed against the regulating member by the second biasing member, so that the movement in the first direction is regulated. That is, by the positioning mechanism of the present invention, the position of the recording head along the second direction can be adjusted and positioned with high precision, and the position along the first direction can be positioned with high precision.

According to the above-mentioned invention, the rear end of the recording head has a shaft extending in parallel with the second direction, and the holding means supports the shaft rotatably. It is characterized by having a member.

Thus, the recording head is supported so as to be swingable about the rear end and the front end is regulated by the regulating member, so that the play at the rear end can be eliminated, and the front end can be eliminated. The movement in the first direction can be regulated with higher accuracy.

Further, according to the invention described above, the second biasing member has a leaf spring attached to the recording head acting on the regulating member.

As described above, the structure of the positioning mechanism can be simplified by attaching the leaf spring to the recording head.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of an ink jet printer (hereinafter simply referred to as a printer) 1 to which the present invention is applied.

The printer 1 has a housing 2 and a substantially cylindrical drum 3 which rotates at a constant peripheral speed in a counterclockwise direction in the figure at a substantially central predetermined position in the housing 2. The rotating shaft of the drum 3 extends horizontally from the front side to the rear side of the printer 1, and is rotatably attached to a frame (not shown) fixed to the housing 2.

Around the drum 3, the outer peripheral surface 3 of the drum 3
a (conveying surface) to charge the sheet to a predetermined potential, and a color image by spraying ink onto a sheet of recording medium electrostatically attracted onto the outer peripheral surface 3a by the action of the charger 4. And a separating claw (not shown) for separating the sheet on which the image is formed by being attracted onto the outer peripheral surface 3 a from the outer peripheral surface 3 a of the drum 3 are sequentially arranged along the rotation direction of the drum 3. I have.

The nozzle unit 5 is moved by an elevating mechanism 6
The printing position shown in the figure is opposed to the upper part of the drum 3, the maintenance position is separated from the printing position by a predetermined distance, and the fixed position is separated from the maintenance position. ing.

The nozzle unit 5 is arranged at the printing position shown in FIG.
For example, four nozzle heads 5C, 5M, 5Y, and 5B (recording heads) each having a tip portion facing each other with an interval of 1 mm are provided. Each nozzle head 5C, 5M, 5
Y and 5B are held by the nozzle unit 5 so as to extend radially from the central axis 3c of the drum 3 (see FIG. 2), and extend in the rotation direction of the drum 3, that is, in the sub-scanning direction (first direction). At a predetermined distance from each other.
At the tip of each of the nozzle heads 5C, 5M, 5Y, and 5B, a large number of unillustrated ink jets arranged at equal intervals in the axial direction of the drum 3, that is, in the main scanning direction (second direction). An exit is provided.

A nozzle unit 5 is provided on the rotating shaft of the drum 3.
A maintenance mechanism 10 for cleaning a large number of ink ejection ports provided at the tip of each of the nozzle heads 5C, 5M, 5Y, and 5B is swingably mounted.
The maintenance mechanism 10 is disposed between the drum 3 and the nozzle unit 5 in a state where the nozzle unit 5 has been moved to the above-described maintenance position.
A number of M, 5Y, and 5B ink ejection ports are cleaned.

At the bottom of the housing 2, there is provided a paper feed cassette 7 accommodating a plurality of sheets in a stacked state.
A discharge tray 8 for discharging a sheet on which an image is printed is provided on an upper surface of the housing 2. Also, housing 2
A manual tray 9 for manually feeding paper is mounted on the right side wall in FIG. Further, in the housing 2, each nozzle head 5C, 5M,
Each of the colors (C:
(Cyan, M: magenta, Y: yellow, B: black)
Is provided.

The paper stored in the paper feed cassette 7 is taken out one by one from the uppermost one by the pickup roller 7a, or the paper supplied via the manual feed tray 9 is taken out one by one by the pickup roller 9a. The aligning roller 12 temporarily aligns the tip. On the other hand, a predetermined charge is applied to the outer peripheral surface 3a of the drum 3 rotated at a constant speed via the charging charger 4 in accordance with the feeding timing of the sheet aligned by the aligning roller 12, and A predetermined region of the outer peripheral surface 3a is charged to a predetermined potential.

Then, the paper aligned by the aligning roller 12 is supplied toward the outer peripheral surface 3 a charged to a predetermined potential, and the paper is electrostatically attracted to the outer peripheral surface 3 a of the drum 3. The sheet electrostatically attracted to the outer peripheral surface 3a of the drum 3 is moved in the sub-scanning direction with the rotation of the drum 3, and passes through a printing area between the nozzle unit 5 disposed at a printing position. Ink of each color is ejected through a number of ink ejection ports of each of the nozzle heads 5C, 5M, 5Y, and 5B of the nozzle unit 5, and a color image is formed on a sheet.

The paper on which the color image is formed in this manner is applied to the outer peripheral surface 3a of the drum 3 by a peeling claw (not shown).
, And are conveyed by being pinched and conveyed by a pair of feed rollers 13 and discharged onto a discharge tray 8 via a plurality of pairs of discharge rollers 14, 15 and 16.

Next, each of the nozzle heads 5C, 5M, 5Y,
A positioning mechanism of the present invention for positioning the 5B within the nozzle unit 5 with high accuracy will be described with reference to FIGS. FIG. 2 is a front view of the positioning mechanism as viewed from the front side of the printer 1, and FIG. 3 is a side view of, for example, the nozzle head 5C as viewed in the paper transport direction.

As shown in FIG. 2, the nozzle unit 5
It has four accommodating portions 21C, 21M, 21Y and 21B for mounting the respective nozzle heads 5C, 5M, 5Y and 5B. Each of the storage units 21C, 21M, 21Y, and 21B extends radially from the center axis 3c of the drum 3 with the nozzle unit 5 disposed at the illustrated printing position. The nozzle heads 5C, 5M, 5Y, and 5B are provided in the storage sections 21C, 21M, 21Y, and 21B from above the nozzle unit 5.
Is inserted and attached.

Since the positioning mechanisms for positioning the nozzle heads 5C, 5M, 5Y, and 5B in the accommodation sections 21C, 21M, 21Y, and 21B all have the same configuration, the following description focuses on one nozzle head 5C. Next, the positioning mechanism will be described.

As shown in FIG. 3, a substantially rectangular frame member 22 is fixedly provided at a lower end of the storage section 21C close to the drum 3. With the nozzle head 5C mounted inside the accommodating portion 21C, the inside of the frame member 22 where one end (left end in the drawing) along the longitudinal direction (left-right direction in the drawing) of the nozzle head 5C, that is, the main scanning direction is opposed. The wall functions as a reference surface 22a (see FIG. 4) serving as a reference for adjusting the position of the nozzle head 5C along the main scanning direction.

The other end of the nozzle head 5C (the right end in the figure)
A leaf spring 23 functioning as a first urging member is fixedly provided on the inner side wall of the housing section 21C facing the housing 21C. Spring 23
Presses the other end of the nozzle head 5C,
The nozzle head 5C is urged in a direction in which one end of C is pressed against the reference surface 22a.

On the other hand, one end of the nozzle head 5C pressed against the reference surface 22a by the spring 23 is provided on the side wall of the housing portion 21C, which is opposed to one end of the nozzle head 5C, against the urging force of the spring 23. An adjusting screw 24 (adjusting means) that pushes back in a direction away from the screw is screwed. The adjusting screw 24 is screwed from the outside of the side wall of the accommodating portion 21C, and the tip of the adjusting screw 24 contacts one end of the nozzle head 5C. That is, by adjusting the adjusting screw 24, the position along the main scanning direction in the housing portion 21C of the nozzle head 5C can be adjusted.

As shown in FIGS. 2 and 3, the upper end (rear end) of the nozzle head 5C separated from the drum 3
At both ends along the main scanning direction are provided upper end holding portions 26 functioning as holding means of the present invention.

As shown in more detail in FIG. 5, the upper end holding portion 26 has a pair of support shafts 25a and 25b (hereinafter collectively referred to as support shafts) extending from the upper end of the nozzle head 5C along the main scanning direction. 25), a bearing 27 (a supporting member) that rotatably holds the support shaft 25, and a fixing member 2 for fixing the bearing 27 to the upper end of the housing 21C.
8 and a screw 29 for attaching the bearing 27 to the fixing member 28.

On the other hand, a pair of regulating members 31 for regulating the lower end of the nozzle head 5C from moving to one side in the sub-scanning direction is provided on the frame member 22 fixed to the lower end of the storage section 21C. Is protruding. As shown in FIGS. 3 and 4, the pair of regulating members 31 are provided corresponding to both ends of the nozzle head 5C along the main scanning direction, and are in contact with one side near the lower end of the nozzle head 5C. , Nozzle head 5
The movement of the lower end of C is restricted.

On one side of the nozzle head 5C, a pair of leaf springs 32 (second biasing members) respectively acting on a pair of regulating members 31 provided at both ends in the main scanning direction.
Is installed. When the nozzle head 5C is inserted into the accommodating portion 21C, the pair of leaf springs 32 act on the corresponding regulating members 31, respectively, and urge the lower ends of the nozzle heads 5C in the direction of pressing against the regulating members 31.

The positioning mechanism configured as described above
It works as follows.

First, the bearing 27 is fitted into two support shafts 25a and 25b projecting from the upper end of the nozzle head 5C. Then, the nozzle head 5C to which the bearing portion 27 is attached as described above is inserted from the upper end of the storage portion 21C, and the nozzle head 5C is mounted in the storage portion 21C. At this time, the pair of leaf springs 32 attached near the lower end of the nozzle head 5C act so as to sandwich the pair of regulating members 31 protruding from the frame member 22 fixed to the lower end of the housing 21C. The lower end of the nozzle head 5C is
Pressed to. At the same time, a pair of bearings 27 attached to the upper end of the nozzle head 5C are fitted to a pair of fixing members 28 fixed to the upper end of the housing 21C.

The bearing part 27 fitted to each fixing member 28
Are fixed to the fixing members 28 by screws 29, respectively. As described above, by fixing the bearing portion 27 that rotatably holds the support shaft 25 of the nozzle head 5C to the fixing member 28 fixed to the upper end of the housing portion 21C, the nozzle head 5C is moved upward from the housing portion 21C. Can be prevented. In this state, the nozzle head 5C can swing around the support shaft 25 at the upper end thereof.

On the other hand, when the nozzle head 5C is inserted into the accommodating portion 21C, the other end of the nozzle head 5C in the main scanning direction is attached to the opposing inner wall of the accommodating portion 21C by the spring 23. The other end is pressed, and one end of the nozzle head 5C is pressed against the reference surface 22a of the frame member 22 fixed to the lower end of the housing 21C. The nozzle head has its upper end rotatably supported by the above-described upper end holding portion 26, and its lower end has a regulating member 31.
, It can be slightly moved in the main scanning direction.

For this reason, by pressing one end of the nozzle head 5C pressed against the reference surface 22a by the adjusting screw 24 against the urging force of the spring 23, the nozzle head 5C is moved in the main scanning direction. The position of the nozzle head 5C along the main scanning direction is adjusted.

As described above, according to the positioning mechanism of the present embodiment, the upper end of the nozzle head 5C is
The nozzle head 5C is held rotatably by pressing the lower end of the nozzle head 5C against the restricting member 31 to restrict the movement in the sub-scanning direction, and the position of the nozzle head 5C along the main scanning direction is adjusted by the adjusting screw 24. I do.

That is, the bearing head 27 rotatably supporting the support shaft 25 projecting from the upper end of the nozzle head 5C is fixed to the upper end of the housing 21C.
Can be prevented from falling out of the storage section 21C. In addition, since the upper end of the nozzle head 5C is rotatably held by the upper end holding portion 26 and the lower end of the nozzle head 5C is pressed against the regulating member 31, the backlash of the upper end of the nozzle head 5C can be prevented. Head 5
C can be positioned with high accuracy along the sub-scanning direction. Further, since one end of the nozzle head 5C along the main scanning direction is pressed against the reference surface 22a and the one end is pushed in a direction away from the reference surface 22a by the adjusting screw 24, the nozzle head 5C is moved in the main scanning direction of the nozzle head 5C. Along the position, it can be positioned with high accuracy and easily.

According to the positioning mechanism of the present invention, as described above, the nozzle head 5C can be positioned with respect to the nozzle unit 5 with high accuracy.

The nozzle head 5C can be inserted into and removed from the nozzle unit 5 from above the nozzle unit 5, and the nozzle head 5C can be easily removed simply by removing the screw 29 of the upper end holding portion 26.

Further, at the same time when the nozzle head 5C is inserted from above the nozzle unit 5, the lower end side of the nozzle head 5C can be automatically positioned at a predetermined position in the sub-scanning direction.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention.

[0044]

As described above, since the recording head positioning mechanism of the present invention has the above-described configuration and operation, the recording head can be positioned with high precision with respect to the transport surface.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an ink jet printer to which the present invention is applied.

FIG. 2 is a front view showing a schematic configuration of a nozzle unit incorporated in the inkjet printer of FIG.

FIG. 3 is a side view of a nozzle head incorporated in the nozzle unit of FIG. 2 as viewed along a sheet conveyance direction.

FIG. 4 is a partial perspective view partially showing a frame member provided in a housing portion for mounting the nozzle head to the nozzle unit.

FIG. 5 is a cross-sectional view illustrating components of a holding unit that holds the upper end of the nozzle head rotatably with respect to the upper end of a storage unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ink-jet printer, 2 ... Housing, 3 ... Drum, 3a ... Outer peripheral surface, 5 ... Nozzle unit, 5C, 5M, 5Y, 5B ... Nozzle head, 21C, 21M, 21Y, 21B ... Housing part, 22 ... Frame member, 22a: Reference surface, 23: Spring, 24: Adjusting screw, 25a, 25b: Support shaft, 26: Upper end holding portion, 27: Bearing portion, 28: Fixing member, 29: Screw, 31: Restriction member, 32: Leaf spring .

Claims (3)

[Claims] 1. A front end portion having a plurality of ink ejection ports in a second direction orthogonal to the first direction with respect to a conveyance surface for conveying a sheet-shaped recording medium in a first direction. A positioning mechanism for positioning a recording head, comprising: a reference surface disposed opposite to one end of the recording head along the second direction; and a reference surface along the second direction of the recording head. A first urging member that is provided to face the end, presses the other end so as to press the one end against the reference surface, and urges the recording head toward one end thereof; Adjusting means for pressing the one end in a direction away from the reference plane against the urging force of the member to adjust the position of the recording head along the second direction; and separating the recording head from the transport surface. Holding means for holding the rear end, A restricting member that is disposed on one side in the first direction near the portion and restricts the distal end from moving to the one side; and a restricting member that biases the distal end toward the restricting member. 2. A recording head positioning mechanism, comprising: 2. A rear end portion of the recording head has a shaft extending in parallel with the second direction, and the holding means has a support member rotatably supporting the shaft. 2. The recording head positioning mechanism according to claim 1, wherein: 3. The recording head positioning mechanism according to claim 1, wherein said second urging member has a leaf spring attached to said recording head acting on said regulating member.