JPH05138904A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device provided with a recording paper feed mechanism for guiding reversely a recording paper along a platen roller without providing a guide means in intervention with a recording head. CONSTITUTION:A heat transfer head 50 supported rotatably and rockably by a rotatable shaft 53 is rocked by a head operation mechanism 41 fixed to a cam shaft 43, and at the time of paper feeding in which a recording paper is retained by a clamper, the heat transfer head 50 is located in the paper feed position separated slightly from a platen roller 34 and the recording paper is fed between the platen roller 34 and the heat transfer head 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for holding a recording paper by a movable recording paper holding means and performing one-way scanning for forming an image on the recording paper by the movement thereof. The present invention relates to a guide structure for a recording paper when the recording paper is held by the recording paper holding means.

[0002]

2. Description of the Related Art As one of recording (image forming) systems in image forming apparatuses such as printers and facsimiles, a recording head movable in the width direction of the recording sheet or recording over the entire width direction of the recording sheet is performed. Some include a recording head in which elements are arranged, and an image is formed while moving a recording paper in a moving direction of the recording head or in a direction orthogonal to the element arrangement direction. That is, the main scanning is performed by the recording head, and the sub-scanning is performed by moving the recording paper. As a moving / conveying structure of the recording paper in the image forming apparatus for performing sub-scanning by moving the recording paper, a holding means (clamper) capable of holding the leading end of the recording paper is provided so as to be movable in the scanning direction of the recording paper. , There is a configuration in which the recording paper is moved and driven by holding and moving the leading edge of the recording paper with the clamper. This configuration enables accurate management of the movement of the recording paper. It is suitable for a color image forming apparatus that needs to form images a plurality of times on the same recording paper.

A platen roller whose surface is made of a material having a predetermined elasticity such as rubber is arranged opposite to the recording head so that the recording paper can be pressed against the recording head with a uniform pressing force. The recording paper, which is held by a clamper by the platen roller and is moved and driven (sub-scanning), is brought into pressure contact and close contact. When the recording paper is held by the clamper, it is necessary to convey and supply the recording paper between the recording head and the platen roller. Therefore, the recording head can be separated from the platen roller.

[0004]

In the image forming apparatus as described above, the platen roller and the recording head are arranged on one end side of the apparatus, and the recording paper supply section is arranged on the lower side of the other end side. It is rational to set the upper part of the section as the moving area of the clamper. However, in such a configuration, when the recording paper is held by the clamper, the recording paper is conveyed from the recording paper supply unit to the clamper by reversing the platen roller to change its direction. It will be. As a result, the rigidity (waist) of the recording paper may not be properly reversed along the platen roller, which may cause conveyance failure. Therefore, a guide means for regulating the recording paper conveyance direction around the platen roller is provided. Although required, this guide means cannot be provided at a position where it interferes with the recording head during image formation, and thus has a problem in recording paper conveyance.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has an image provided with a recording paper conveying structure capable of reversing and guiding a recording paper along a platen roller without providing guide means for interfering with the recording head. The purpose is to provide a forming apparatus.

[0006]

In order to achieve the above object, an image forming apparatus according to the present invention has a recording paper held by a movable recording paper holding means and a platen roller and the platen by moving the recording paper holding means. An image is formed by scanning and moving between recording heads arranged in the vicinity of rollers. The recording head is supported by a head support member that is rockably operated by a cam member provided on a rotation shaft, and a cam is formed. By the swinging of the head support member due to the rotation of
The recording head can be located at an image forming operation position close to the platen roller and a paper feeding position slightly separated from the platen roller, and when the recording paper holding unit holds the recording paper, the recording head moves to the paper feeding position. It is positioned so that the recording paper is conveyed and supplied between the platen roller and the recording head. According to this configuration, the recording head functions as a guide member that regulates the conveyance direction of the recording sheet during sheet feeding, and the recording sheet can be guided to the recording sheet holding unit in the reverse direction along the platen roller.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram corresponding to a vertical section of an image forming apparatus to which an embodiment of the image forming apparatus according to the present invention is applied. The illustrated image forming apparatus 1 is a so-called color image forming apparatus, and a plurality of times (magenta, cyan, yellow, black of magenta, cyan, yellow, and black are printed on the same recording paper based on image information separated into three colors of red, blue, and green. A color image is formed by performing image formation four times). The illustrated apparatus 1 is provided with a paper feed section 10 to which a recording paper cassette 2 accommodating recording papers 4 ... Can be attached and detached at the lower part of one end (the left end in the figure), and is ejected above the paper feed section 10. Paper tray 3
Is provided, the recording paper 4 accommodated in the recording paper cassette 2 is introduced from the paper feed unit 10, is conveyed to the end side opposite to the paper feed unit 10 and is inverted to the upper side, and thermal transfer described later is performed. The sublimation dye of the ink ribbon 63 is transferred by the head 50 to form an image, and the image is discharged onto the paper discharge tray 3.

The paper feed section 10 is provided with an opening into which the recording paper cassette 2 can be inserted, and the recording paper is introduced above the front end of the recording paper cassette 2 inserted into the opening. A roller 11 is provided, and at a position adjacent to the front end of the recording paper cassette 2, an introducing roller pair 12 in which the rollers are arranged in pressure contact with each other is provided. A conveyance roller pair 31 in which the rollers are arranged in pressure contact with each other is provided in front of the introduction roller pair 12 in the conveyance direction of the recording paper (on the right side in the drawing). The guide arm 20 having the guide portion 21 of the
It is pivotally supported by 3 and is approximately above it,
A platen roller 34 is provided. The outer peripheral surface of the platen roller 34 is formed of an elastic member having a predetermined elasticity such as rubber, and is driven in both forward and reverse directions (clockwise and counterclockwise in the figure) by a drive motor (not shown).
In addition to being rotationally drivable, a friction clutch that idles at a torque of a predetermined value or more is interposed in the rotational driving force transmission path.

The lower end of the guide arm 20 is connected via a spring 32 to the lower end of an operation arm 33 as an arm member which is swingably provided by a pin 14 on the right side of the drawing, and the elasticity of the spring 32 is provided. By the restoring force, the guide arm 20 is oscillated and urged counterclockwise in the figure, and the operation arm 33 is urged in the clockwise direction in the figure. A pinch roller 22 is rotatably provided at the upper end of the guide arm 20, and the pinch roller 22 is pressed against the platen roller 34 in the horizontal direction by the urging force of a spring 32, whereby the guide arm 20 swings. Is regulated to be in a substantially vertical state, and the lower end of the guide portion 21 is positioned in the conveyance path of the recording paper conveyed by the conveyance roller pair 31. A guide portion 23 is formed at the tip of the guide arm 20 so as to extend further along the outer periphery of the platen roller 34 than the pinch roller 22 mounting portion.

A cam follower 33A is rotatably provided at the upper end of the operation arm 33, and the spring 3
The urging force of 2 causes the cam follower 33A to abut on the outer peripheral cam surface of the roller pressing cam 42 fixed to the cam shaft 43 provided at the right end of the device 1 in the drawing, whereby the swinging of the operation arm 33 is performed. It is becoming regulated. That is, the elastic return force of the spring 32 urges the pinch roller 22 provided at the upper end of the guide arm 20 to the platen roller 34 and the cam follower 33 A of the operation arm 33 to the roller pressure contact cam 42. The amount of deformation of the spring 32 changes due to the swing of the operation arm 33 caused by the cam follower 33A following the displacement of the cam surface caused by the rotation of the roller pressure contact cam 42. As a result, the platen roller 34 of the pinch roller 22 is changed. The pressure contact force to is changed.

The roller pressing cam 42 has a large-diameter portion and a small-diameter portion formed in a predetermined angle range as shown in enlarged views of the relevant portion in FIGS. 2 to 4, and is operated when the cam follower 33A corresponds to the large-diameter portion. The arm 33 swings counterclockwise and the amount of deformation of the spring 32 increases, and the pressure contact force of the pinch roller 22 to the platen roller 34 increases. On the other hand, when the cam follower 33A corresponds to the small diameter portion, the pinch roller 22
The contact pressure of the platen roller 34 with the platen roller 34 is weakened. As a result, the pressure contact force of the pinch roller 22 to the platen roller 34 can be changed into two levels, strong and weak, by the rotation of the roller pressure contact cam 42 (that is, the rotation of the cam shaft 43). The cam shaft 43 is rotationally driven by a motor (not shown), and the motor is drive-controlled by the control device of the image forming apparatus in synchronization with image formation.

A recording paper guide plate 3 for supporting the recording paper to be conveyed is provided between the introducing roller pair 12 and the conveying roller pair 31, and between the conveying roller pair 31 and the guide arm 20.
5 are arranged, and the upper side of each of them and the recording paper introducing roller 1
1 above the recording paper support plate 3 in parallel with each other at a predetermined distance.
6 are provided. Guide part 2 of the guide arm 20
A recording paper withdrawal restricting member 37 formed of an elastic member is attached to an end of the recording paper support plate 36 facing the recording paper supporting plate 1, and the recording paper withdrawal restricting member 37 is directed obliquely upward toward the guide portion 21. , Its tip is provided in contact with the guide portion 21.

Above the platen roller 34, there is provided a thermal transfer head 50 in which a thermal head array 51 as a recording head across the width of the recording paper is supported by a head frame 52 as a head supporting member. The thermal transfer head 50 is pivotally supported on a chassis (not shown) of the apparatus 1 so as to be swingable by a pivot shaft 53 at substantially the center of the head frame 52, and is urged to rotate clockwise in the figure by a spring (not shown). .. A roller-like cam follower 54 is rotatably attached to the end opposite to the thermal head array 51 with the pivot shaft 53 interposed therebetween.
4 contacts the outer peripheral cam surface of the head operating cam 41 as a cam member fixed to the same cam shaft 43 to which the above-mentioned roller pressure contact cam 42 is fixed, and the head operating cam 41 rotates (that is, the cam shaft 43 rotates). The oscillating operation is performed following the displacement of the outer peripheral cam surface due to the rotation.

As shown in FIGS. 2 to 4, the head operating cam 41 is formed as an outer diameter (outer peripheral cam surface) whose radii differ in three steps within a predetermined angle range. As shown in FIG. 4, the cam follower 54 is the most. In a state corresponding to the large-diameter cam surface, the thermal head array 51 faces the upper side of the platen roller 34 and becomes a transfer operation position where the thermal head array 51 is brought into pressure contact with a predetermined pressing force,
As shown in FIG. 3, the thermal head array 51 is positioned slightly above the platen roller 34 in a state corresponding to the second-stage middle-diameter cam surface, and is spaced apart from the outer periphery of the platen roller 34 (1-1. 5 mm), and in the state corresponding to the smallest diameter cam surface as shown in FIG. 2, the thermal transfer head 50 swings largely clockwise and the thermal head array 51 is largely separated from the platen roller 34. It is set to the retracted position.

Here, the relationship between the cam surface displacement of the head operation cam 41 and the roller pressure contact cam 42 with which the cam follower of the operation arm 33 comes into contact (that is, the position of the thermal transfer head 50 and the pressure contact of the pinch roller 22 with the platen roller 34). The relationship of the force change) is substantially the pressure contact force of the pinch roller 22 to the platen roller 34 when the thermal transfer head 50 is in the transfer action position and in the retracted position (the state shown in FIGS. 2 and 4). Is weak, and the pressure contact force of the pinch roller 22 to the platen roller 34 is set to be strong when the thermal transfer head 50 is at the sheet feeding position (in the state shown in FIG. 3).
In the standby state shown in FIG. 1, the thermal transfer head 50 is in the retracted position, and the pinch roller 22 is the platen roller 34.
It is designed to come into contact with each other with a weak force.

An ink ribbon reel 61 on the delivery side is arranged below the thermal transfer head 50, and is rotationally driven by a motor (not shown) at a position substantially symmetrical to the ink ribbon reel 61 on the delivery side with the platen roller 34 interposed therebetween. The ink ribbon reel 62 on the take-up side is arranged. The ink ribbon reel 61 on the delivery side is wound with an ink ribbon 63 in which ribbons of each color to be transferred are sequentially connected by one page (one sheet) of recording paper, and the ink ribbon 63 on the take-up side is wound. It is adapted to be wound up on the ink ribbon reel 62. Thermal transfer head 5
At the time of image formation where 0 is at the transfer action position, the ink ribbon 63 is sandwiched between the platen roller 34 and the thermal head array 51 in a superposed state with the recording paper (the recording paper is on the platen roller 34 side at the ink ribbon 63 side). Is sandwiched between the thermal head array 51 side) and the recording paper, and is wound up from the delivery side ink ribbon reel 61 to the winding side ink ribbon reel 62 in synchronization with the movement of the recording paper.

Platen roller 34 and thermal transfer head 50
On the left side in the figure, a clamper 70 is slidably movable by a pair of left and right widthwise guide shafts 90 supported by a chassis (not shown) of the apparatus 1 and horizontally arranged in the front-rear direction. The clamper 70 is configured to include a holding roller pair 80 in which a metal upper roller 82 is arranged in pressure contact by a spring (not shown) on the upper side of a rotatable lower roller 81 having a rubber layer of a predetermined thickness formed on the surface thereof. ing. The clamper 70 is driven to move by a driving unit (not shown) and can move left and right along the guide shaft 90 in the figure, and has a sheet feeding position located at the right end in the figure adjacent to the platen roller 34 and the thermal transfer head 50. , And can be located at the discharge position at the left end in the figure.

Clamper drive gears (not shown), which are rotationally driven by drive means, are arranged at the portions corresponding to the front and rear ends (paper feed position and paper discharge position) of the stroke of the clamper 70 along the guide shaft 90. A gear (not shown) connected to the lower roller 81 of the clamper 70 meshes with the clamper drive gear at the paper feed position and the paper discharge position, and the lower roller 81 rotates counterclockwise in the figure by the rotation of the clamper drive gear. It is designed to be driven to rotate. That is, when the clamper 70 is located at the sheet feeding position and the sheet discharging position, the lower roller 81 can be driven to rotate. Also, on the left side of the clamper 70 at the paper discharge position in the drawing,
A paper discharge roller pair 38 in which rollers are arranged in pressure contact with each other is provided.

Thus, the image forming apparatus constructed as described above operates as follows to form an image. First, from the standby state shown in FIG. 1, the head operating cam 41 and the roller pressure contact cam 42 are rotated by the rotation of the cam shaft 43, so that the thermal transfer head 50 is slightly moved from the thermal transfer position of the thermal head array 51 as shown in FIG. The recording paper cassette is driven by the recording paper introducing roller 11 while the pinch roller 22 is in a state of being strongly pressed against the platen roller 34 while being located at the upper position so as to have a space between the platen roller 34 and the outer periphery of the platen roller 34. The recording paper 4 accommodated in the device 2 is stored in the device 1
It is introduced into the inside and is conveyed by driving the introduction roller pair 12 and the conveyance roller pair 31. At this time, the clamper 70 is at the sheet feeding position closest to the thermal transfer head 50 during the moving stroke.

The leading edge of the recording paper 4 is a guide arm 20.
Is guided by the circular arc-shaped guide portion 21 and deforms the recording paper retreat restricting member 37 while being bent and conveyed upward, and is caught between the platen roller 34 and the pinch roller 22.
By the rotation of the platen roller 34 which is driven to rotate counterclockwise in the drawing, the platen roller 34 is conveyed in a tangential direction directed obliquely upward of the platen roller 34 which is regulated by the tip guide portion 23 of the guide arm 20. At this time, the pinch roller 22 presses the recording paper 4 against the platen roller 34 with a large force, so that reliable conveyance driving can be performed. Then, the recording paper 4 abuts the lower surface of the thermal head array 51 located close to the upper side of the platen roller 34 at an angle (see FIG. 3), and the thermal head array 51 regulates the movement direction to the horizontal direction. And the upper and lower rollers 81, 8 of the holding roller pair 80 of the clamper 70 at the paper feeding position.
Go to the pressure contact part of 2. That is, at this time, the thermal head array 51 (thermal transfer head 50) functions as a guide that regulates the conveyance direction of the recording paper 4 along the horizontal tangent line of the pinch roller 22.

When the leading edge of the recording paper 4 reaches the pressure contact portion between the upper and lower rollers 81, 82 of the support roller pair 80 of the clamper 70, the lower roller 81 is rotationally driven counterclockwise in the figure to provide a space between the support roller pair 80. The recording paper 4 is bitten, and the rotational drive of the lower roller 81 is stopped in a state where the amount of biting is a predetermined amount. As a result, the leading edge of the recording paper 4 is held by the support roller pair 80 of the clamper 70 (FIG. 6). After that, the thermal transfer head 5 is rotated by the rotation of the head operation cam 41.
0 is set to the transfer action position, the pressing force of the pinch roller 22 to the platen roller 34 is weak, and the clamper 70 is moved to the left side in the drawing to move the recording paper 4 to move. The ink ribbon 63 is wound in synchronism with the movement of the sheet, and the thermal head array 51 forms an image (transfer) on the recording sheet 4 (FIG. 7). At this time, the platen roller 34 is not rotationally driven, but is rotated following the movement of the recording paper by the action of the friction clutch provided in the above-mentioned drive system, and the pinch roller 22 is pressed against the platen roller 34 by a pressing force. Is weak, the platen roller 34 does not hinder the movement of the recording paper.

Since this embodiment is a color image forming apparatus, this transfer process is carried out four times for magenta, cyan, yellow and black as described above. That is, after the first transfer process is completed, the clamper 70 is returned to the paper feeding position (the recording paper 4), and then the clamper 70 is driven to the left side in the drawing (the recording paper 4 is driven to move). ) The next transfer process is performed, and thereafter, this process is repeated a predetermined number of times. When the clamper 70 is returned to the paper feed position, the thermal transfer head 50 is set to the paper feed position, and the platen roller 34 rotates in the opposite direction (clockwise direction in the figure) to the case where the clamper 70 holds the recording paper. Driven. Further, the trailing end of the recording paper 4 is changed by the recording paper retreat restricting member 37 to reach the recording paper support plate 36 as shown in FIG. 8 and does not return to the paper feed section 10 side.

The clamper 70 is at the paper discharge position in a state where the transfer process of a predetermined number of times is completed (transfer of all colors is completed),
Here, the lower roller 81 of the clamper 70 is rotated counterclockwise in the drawing to convey the recording paper 4 held by the holding roller pair 80 to the paper discharge side (left side in the drawing) as shown in FIG. Is. The recording paper 4 sent from the clamper 70 is conveyed by the paper discharge roller pair 38 and discharged onto the paper discharge tray 3.

[0024]

As described above, according to the image forming apparatus of the present invention, when the recording paper holding means holds the recording paper, the recording head is set to the paper feeding position slightly separated from the platen roller. Since the recording paper is configured so as to be conveyed and supplied between the platen roller and the recording head, the recording paper is regulated in the conveying direction by the recording head, and the recording paper is supported by the platen without providing a guide unit that interferes with the recording head. It is possible to reverse guide along the rollers, and it is possible to reliably convey the recording sheet along the determined conveying path.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram corresponding to a longitudinal section of an image forming apparatus to which an embodiment of the image forming apparatus according to the present invention is applied in a standby state.

FIG. 2 is an enlarged view of a main part in which a thermal transfer head is in a retracted position.

FIG. 3 is an enlarged view of a main part in which a thermal transfer head is at a sheet feeding position.

FIG. 4 is an enlarged view of a main part in which a thermal transfer head is at a transfer position.

FIG. 5 is an explanatory diagram of an operation during image formation.

FIG. 6 is an explanatory diagram of an operation during image formation.

FIG. 7 is an explanatory diagram of an operation during image formation.

FIG. 8 is an explanatory diagram of an operation during image formation.

FIG. 9 is an explanatory diagram of an operation during image formation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 4 ... Recording paper 34 ... Platen roller 41 ... Head operating cam (cam member) 50 ... Thermal transfer head 51 ... Thermal head array (recording head) 52 ... Head frame (head support member) 70 ... Clamper (recording paper) Holding means)

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B41J 25/304 8604-2C B41J 25/30 U

Claims (1)

[Claims] 1. An image is formed by moving a recording paper held by a movable recording paper holding means between a platen roller and a recording head arranged near the platen roller by the movement of the recording paper holding means. The recording head is supported by a head support member that is rockably operated by a cam member provided on a rotation shaft, and the head support member is rocked by the rotation of the cam member,
At least the image forming operation position close to the platen roller and the paper feeding position slightly separated from the platen roller can be located, and at the time of paper feeding for holding the recording paper by the recording paper holding means, the recording operation is performed. An image forming apparatus, wherein the head is located at the paper feeding position, and the recording paper is configured to be conveyed and supplied through between the platen roller and the recording head.