JP2003118183A - Ink jet imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet imaging apparatus which can prevent recording paper from rubbing against a printing head when the recording paper is carried into a printing part without using special recording papers. SOLUTION: The ink jet imaging apparatus records images on the recording paper P when a carriage 16 moves back and forth in a horizontal scanning direction while the recording paper P is transferred between the printing head mounted on the carriage 16 and a platen 14 at the printing part 6. The space between the printing head and the platen 14 is made large when the recording paper P is carried into the printing part 6, and is narrowed when images are recorded at the printing part 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet image forming apparatus such as an inkjet printer.

[0002]

2. Description of the Related Art In an ink jet image forming apparatus, a print unit is provided with a carriage having a print head so as to reciprocate in a main scanning direction, and a platen for guiding a recording sheet is provided under a reciprocating movement path of the carriage. To be done. The recording paper is carried in between the platen and the print head of the carriage, the recording paper is conveyed, and the carriage reciprocates in the main scanning direction to record an image on the recording paper.

In such an ink jet image forming apparatus, in order to perform high quality printing, it is necessary to set the distance between the platen and the print head to a considerably small value.

However, when the distance between the platen and the print head is reduced, there is a problem that the print sheet is rubbed against the print head, especially when the print sheet is carried to the print start position of the printing section at high speed.

In order to solve such a problem, it has been proposed to chamfer a corner of the leading end of a recording sheet as described in Japanese Patent Laid-Open No. 2000-246992.

[0006]

However, in the ink jet image forming apparatus described in the above publication, it is necessary to use a special recording paper having a chamfered end portion, and a normal recording paper cannot be used.

The object of the present invention is to solve the above problems,
An object of the present invention is to provide an inkjet image forming apparatus that can prevent the recording sheet from rubbing against the print head when the recording sheet is carried into the printing unit without using a special recording sheet.

[0008]

In the ink jet image forming apparatus according to the present invention, the recording section conveys the recording paper between the print head mounted on the carriage and the platen, and the carriage moves in the main scanning direction. In an inkjet image forming apparatus in which an image is recorded on a recording sheet by reciprocating the recording sheet, the distance between the print head and the platen is wide when the recording sheet is carried into the printing section and narrow when the image is recorded in the printing section. It is characterized by what is done.

Usually, the platen is arranged under the reciprocating path of the carriage carrying the print head. The distance between the print head and the platen can be changed by the vertical movement of the carriage and the platen.

Since the distance between the print head and the platen is widened when the recording paper is carried into the printing section, even the normal recording paper does not rub against the print head. Further, since the distance between the print head and the platen is narrowed at the time of image recording in the printing section, high quality printing can be performed.

In the inkjet image forming apparatus of the present invention, for example, the platen moves up and down with respect to the carriage so that the distance between the print head and the platen can be changed.

As described above, since the platen is usually arranged under the reciprocating path of the print head, in that case, when the recording paper is carried into the printing section, the platen moves downward to move the print head to the print head. When the image is recorded in the printing section, the platen is moved upward so that the interval between the platen and the print head is narrowed.

According to this, since the platen that does not move in the main scanning direction is moved up and down instead of moving the carriage that reciprocates in the main scanning direction up and down, the mechanism for moving up and down is simple.

In the above-mentioned ink jet image forming apparatus, for example, a guide member arranged upstream of the platen in the recording sheet conveying direction and above the platen to guide the leading edge of the recording sheet moves up and down together with the platen. ing.

When the recording paper is carried into the printing unit, the guide member moves below the print head to prevent the recording paper from coming into contact with the print head. At the time of recording an image in the printing unit, the guide member moves above the print head so as not to prevent the upper surface of the recording sheet from approaching the print head.

According to this, when the recording sheet is carried into the printing section, it is possible to reliably prevent contact and rubbing between the front end and the surface portion of the recording sheet and the print head.

In the above ink jet image forming apparatus, for example, the vertical position of the platen can be changed by moving the carriage in the main scanning direction.

That is, the vertical position of the platen can be changed by the driving force when the carriage moves in the main scanning direction.

Normally, the carriage reciprocates in a portion having a predetermined print width at the time of image recording, and is closer to one end side in the main scanning direction than the portion having the print width at the time of standby or when the recording paper is carried into the printing portion. It is in the home position. In that case, when the carriage is located at the home position, the platen is located at the lower side, and when the carriage is located at the print width portion, the platen is located at the upper side.

According to this, since the platen can be moved up and down by the driving force generated by the movement of the carriage, an extra mechanism for moving the platen up and down is not required, and the size of the entire apparatus can be reduced.

In the ink jet image forming apparatus of the present invention, for example, in the main scanning direction, a part of the carriage is always positioned inside the maximum recording paper width.

According to this, the size of the device in the main scanning direction can be reduced and the device can be downsized.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments in which the present invention is applied to an ink jet printer will be described below with reference to the drawings.

FIG. 1 shows the overall schematic construction of an ink jet printer. In the following description, front, rear, left, and right are referred to as a conveyance direction of a recording sheet, which will be described later. According to this,
1 is the front, the right side of FIG. 1 is the rear, the front side of the paper of FIG. 1 is the left, and the back side of the paper of FIG. 1 is the right.

As shown in FIG. 1, the printer has a box-shaped casing (1) which constitutes the main body of the apparatus, and a paper feed tray (2) is arranged at the rear end of the casing (1). The discharge tray (3) is arranged at the front end of the housing (1). Between the paper feed tray (2) and the paper discharge tray (3) inside the housing (1), the paper feed section (4) and the transport section
(5), a printing unit (6) and a paper discharge unit (7) are provided.

On the paper feed tray (2), one or a plurality of recording papers (P) are placed with the printing surface facing forward and obliquely upward. The paper source (4) is for recording paper on the paper tray (2).
(P) is for feeding one by one to the transport section (5),
It is equipped with a separator (8) located slightly below and below the lower end of the recording paper (P) on the paper tray (2), and a paper feed roller (9) that comes into pressure contact with the separator (8) from above. ing. Further, the paper feed tray (2) is provided with a pressing device (10) for moving the recording paper (P) to the paper feed roller (9) side during paper feeding.

The carrying section (5) is for carrying the recording paper (P) supplied from the paper feeding section (4) into the printing section (6) and carrying it, and in front of the separating device (8). With the arranged guide plate (11),
It has a pair of upper and lower carry-in rollers (12) (13) arranged in front of it.

The printing section (6) is for printing on the recording paper (P) conveyed by the conveying section (5), and is in front of the pair of carry-in rollers (12) (13). The platen (14), the guide member (15) arranged above the rear part of the platen (14), and the carriage (16) arranged above the front part of the platen (14). There is. Details of the printing unit (6) will be described later.

The paper discharge unit (7) is for discharging the recording paper (P) printed in the printing unit (6) to the paper discharge tray (3), and is located at the lower front of the platen (14). The discharge rollers (17) arranged and the spur (18) pressed against the discharge rollers (17) from above.
It has and.

When printing is performed in the above printer, first, the lower end portion (front end portion) of the recording paper (P) on the frontmost side on the paper feed tray (2) is moved by the action of the pressing device (10). Pressed against the paper feed roller (9), the paper feed roller (9) rotates and the separation device
By the action of (8), only one sheet of this recording paper (P) is supplied to the carry-in rollers (12), (13) through the guide plate (11). The carry-in rollers (12) and (13) rotate in accordance with the operation of the printing unit (6) described below, and after the recording paper (P) is carried into the printing unit (6) at the predetermined print start position at high speed, the recording is performed. The paper (P) is conveyed forward by a predetermined pitch. In the meantime, printing is performed on the front surface (upper surface) of the recording paper (P). On the front side of the recording paper (P) that has been printed, the discharge roller (17) and spur (1
The recording paper (P) sent forward by 8) and printed on the entire surface is ejected from the ejection roller (17) and the spur (18) onto the ejection tray (3).

In the printing section (6), as will be described later in detail, the platen (14) and the guide member (15) move up and down in conjunction with each other, and the recording paper (P) is printed on the printing section (6). ), The platen (14) and the guide member (15) move downward, and when the recording paper (P) is being printed, the platen (14) and the guide member (15) move to the platen (14). The guide member (15) is adapted to move upward.

2 to 5 are enlarged views of the printing unit (6). 2 and 4 are enlarged cross-sectional views of the printing unit (6) of FIG. 1 viewed from the front side, and FIGS. 3 and 5 are cross-sectional views of FIG. 2 viewed from the left side. 2 and 3 show the carriage 16 in the leftmost home position, and FIGS. 4 and 5 show the carriage 16 in the print width portion on the right side of the home position. ing.

The printing section (6) is provided with a guide bar (19) extending in the left-right direction, which is the main scanning direction, and this guide bar (19).
A carriage (16) is movably attached to the.
The carriage (16) is provided with a print head (20).

A platen operating member (21) is attached to the guide rod (19) so as to be movable in the left-right direction. The actuating member (21) has a connecting portion (21) extending in parallel with the guide rod (19).
a) and plate-like operating parts (21b) and (21c) that are integrally formed at both left and right ends and extend downward.The operating parts (21b) and (21c) can slide left and right on the guide rod (19). Has been passed through. Connecting part (2
1a) extends in the left-right direction without interfering with the carriage (16). The actuating parts (21b) and (21c) are located on the left and right sides of the carriage (16), and when the carriage (16) moves to the left side, the carriage (16) moves the actuating part (2) on the left side of the actuating member (21).
Upon hitting 1b), the actuating member (21) is moved to the left.

The platen (14) is a horizontal plate-shaped substrate portion (14a).
And ribs (14b) projecting upward from a plurality of left and right portions of the upper surface of the substrate portion (14a) and extending in the front-rear direction. Induction member
(15) is a horizontal plate-shaped substrate portion (15a), and ribs (1) protruding downward from a plurality of locations on the lower surface of the substrate portion (15a) and extending in the front-rear direction.
It consists of 5b). The left and right ends of the platen (14) and the guide member (15) are connected by a connecting member (22).

The platen (14) can be moved up and down with respect to the housing (1) by an appropriate guide (not shown). Between the board portion (14a) of the platen (14) and the guide member (15), a regulating member (23) fixed to the housing (1) is provided, and the regulating member (23) has a plurality of left and right positions. The rib (14b) of the platen (14) is fitted from below into the slit (23a) formed in the plate. A compression coil spring (24) for biasing the platen (14) upward is provided between the base plate portion (14a) of the platen (14) and a portion of the housing (1) below the platen portion. Platen (14)
With no downward force on the platen (14)
The elastic force of the spring (24) causes the upper surface of the base plate portion (14a) to come into pressure contact with the lower surface of the restriction member (23) so that the rib (14b) causes the restriction member (23).
Stops at the upper end position, which protrudes a lot upwards from.

The upper ends of the ribs (14b) of the platen (14) are portions for guiding the recording paper (P). Induction member (15)
Ribs (15b) of the platen (14b) face the ribs (14b) of the platen (14) from above with a relatively small gap.

Protrusions (25) and (26) each having an inclined surface directed obliquely upward to the right are formed near the left and right ends of the upper surface of the platen (14). A stopper (27) protruding upward is provided at the right end of the upper surface of the platen (14). A compression coil spring that biases the actuating member (21) to the right around the guide rod (11) between the actuating portion (21b) on the left side of the actuating member (21) and the wall on the left side of the housing (1). (28) is provided.

When the carriage (16) is in the print width portion, as shown in FIG. 4 and FIG. 5, the actuating member (21) has a right actuating portion (21c) due to the elastic force of the spring (28). Platen
It has stopped at the right end position where it hits the stopper (27) of (14).
At this time, the lower ends of the two operating parts (21b) and (21c) are attached to the platen (14)
The platen (14) and the guide member (15) are located at the upper end positions on the right side of the protrusions (25) and (26) of the board portion (14a). The upper end of the rib (14b) of the platen (14) is close to the print head (20), and the lower end of the rib (15b) of the guide member (15) is above the lower end of the print head (20). Is located in.

When the carriage (16) moves to the right and reaches the vicinity of the home position, the carriage (16) hits the left operation part (21b) of the operation member (21) and moves the operation member (21) to the right. Let Therefore, the operating parts (21b) (21c) come into contact with the inclined surfaces of the protrusions (25) (26) of the platen (14), and
Move (14) downward. Then, when the carriage (16) stops at the home position, as shown in FIG. 2 and FIG. 3, both operating parts (21b) (21c) completely ride on the protrusions (25) (26), and the platen (14) is lifted. The platen (14) and the guide member (15) are stopped at the lower end position by pushing down to the lower end position. At this time, the upper ends of the ribs (14b) of the platen (14) are largely separated downward from the print head (20) and are substantially flush with the upper surface of the restriction member (23), and the guide member (15). The lower end of the rib (15b) is located below the lower end of the print head (20). In addition, the carriage (16) is always positioned inside the maximum recording paper width, including when the carriage (16) is at the home position.

When the recording paper (P) is carried into the printing start position of the printing section (6), the carriage (16) is stopped at the home position. Therefore, the platen (14) and the guide member (15) are moved to the lower end position, and the distance between the print head (20) and the platen (14) is large. Therefore,
The recording paper (P) does not rub against the print head (20). Further, since the lower end of the rib (15b) of the guide member (15) is located below the lower end of the printing unit (20), even if the recording paper (P) is lifted from the platen (14), It is possible to reliably prevent the upper surface of the paper (P) from coming into contact with the print head (20).

When printing is performed, the carriage 16 reciprocates in the left-right direction in the print width portion on the right side of the home position. Therefore, the platen (14) and the guide member
(15) has moved to the upper end position, and the distance between the print head (20) and the platen (14) has become small. Therefore, high quality printing can be performed. At this time, since the lower end of the rib (15b) of the guide member (15) is located above the lower end of the print head (20), the recording paper (P) approaches the print head (20). It does not prevent things.

In the above embodiment, since the guide member (15) moves up and down in conjunction with the platen (14), contact and rubbing between the leading end and the surface portion of the recording paper (P) and the carriage (16) are surely prevented. be able to. However, the guiding member (15)
Does not necessarily have to go up and down.

Further, in the above embodiment, the carriage (16)
However, since it is always located inside the maximum recording sheet width, the apparatus can be downsized, but it is not always necessary to do so.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of an inkjet printer showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the printing unit of the inkjet printer of FIG. 1 as seen from the front side.

3 is a cross-sectional view of the printing unit of FIG. 2 as viewed from the left side.

4 is a drawing corresponding to FIG. 2 showing a state different from FIG.

5 is a drawing corresponding to FIG. 3 showing a state different from that of FIG. 3;

[Explanation of symbols]

(14) Platen (15) Guide member (16) Carriage (20) Print head (P) Recording paper

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Claims (5)

[Claims] 1. An ink-jet image forming apparatus for recording an image on a recording sheet by conveying a recording sheet between a print head mounted on a carriage and a platen in a printing section and reciprocating the carriage in the main scanning direction. The inkjet image forming apparatus is characterized in that the distance between the print head and the platen is wide when the recording paper is carried into the printing unit and is narrow when the image is recorded in the printing unit. 2. The ink jet image forming apparatus according to claim 1, wherein the space between the print head and the platen can be changed by moving the platen up and down with respect to the carriage. 3. A guide member arranged upstream of the platen in the recording paper conveyance direction and above the platen for guiding the leading end of the recording paper is arranged to move up and down together with the platen. Item 2. The inkjet image forming apparatus according to item 2. 4. The ink jet image forming apparatus according to claim 2, wherein the vertical position of the platen is changed by the movement of the carriage in the main scanning direction. 5. A part of the carriage in the main scanning direction,
The inkjet image forming apparatus according to any one of claims 1 to 4, wherein the inkjet image forming apparatus is always positioned inside the maximum recording paper width.