JPS60245367A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate a color shift at color transfer by detaching a pressing roller from a platen during the time when a material to be transferred is not fed to the platen. CONSTITUTION:A solenoid 66 is excited until the tip of a form which is wound to a platen 10 and transferred at transfer operation reaches between the platen 10 and a pressing roller 20, and the roller 20 is detached from the platen. The second pressing roller 19 is also controlled by a solenoid 76 in the same way. The form is wound to the platen 10 and one color is transferred by a printing head 11. As a result, the form is returned to its original state, another color is transferred by the printing head again, and the color transfer is executed. The pressing rollers 19, 20 remain detached from the platen 10, therefore, a position shift of the form is prevented, and the color shift is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus that forms a color image by, for example, thermal transfer.

[Technical background of the invention and its problems] - This type of device wraps the transfer material around a platen (while conveying it back and forth with a blade, it transfers a plurality of colorants on the transfer material to the transfer material via a thermal transfer head). A color image is formed by transferring to a material, and when transferring, the transfer material and the material to be transferred are superimposed between the thermal transfer head and the platen, and then -
The transfer material is moved back and forth for each color to perform a transfer operation for a plurality of colors.

By the way, when the transferred material is moved back and forth during the transfer operation, if the transferred material slips on the platen surface, a transfer position shift will occur for each colorant during a series of transfer operations performed with different colorants. Conventionally, in order to solve this problem, a pair of pressing rollers are pressed against the surface of the platen at the front and back along the conveying direction of the transfer material with the thermal transfer head sandwiched between them. It was configured to be held between rollers and a platen and transported back and forth.

However, during the transfer operation, if the transfer material is always pressed between a pair of rollers and a platen and conveyed back and forth, no image can be formed on the transfer material (non-image areas along the conveyance direction of the transfer material). There was a problem that both ends) became large.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and its object is to be able to transport the transferred material back and forth without causing a transfer position shift during the transfer operation, and to An object of the present invention is to provide an image forming apparatus that can reduce the size of non-image areas where no image can be formed at both ends along the conveyance direction of a material.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention is directed to transferring a plurality of colorants on the transfer material through a print head while reciprocating the transfer material wound around the platen by the rotation of the platen. In an image forming apparatus that forms a color image by transferring it to a material, the device is placed in front and behind the printing head along the conveying direction of the material to be transferred, and is moved toward and away from the surface of the platen after the start of transfer. Before the leading edge in the conveying direction of the transfer material being transported back and forth reaches between the platen and the platen, the transfer material is separated from the platen, and after reaching the transfer material, a pair of pressure rollers and a transfer material are used to press and hold the transfer material against the platen. The press located in front of the print head along the material conveying direction is characterized by being provided with a guide member that guides the press to the contact portion between the roller and the platen.

[Embodiment of the Invention] First, the overall schematic configuration of an image forming apparatus, which is an embodiment of the present invention, will be described.

FIG. 1 is an overall external perspective view of an apparatus according to an embodiment of the present invention, FIG. 2 is a schematic perspective view showing the internal structure of the apparatus as a whole, and FIG. 3 is a longitudinal sectional side view of the apparatus.

In the figure, reference numeral 1 denotes a main body of an image forming apparatus, and an operation panel section 1a is formed on the upper front surface of the apparatus main body 1. As shown in FIG. Also, on the top surface of the main body 1, there is a document holding cover 3 on the left side.
The lower side of the document table 2 in the apparatus main body 1 is a document scanning section (scanner section) 4 that scans the original set on the document table 2.
The right side inside is an image forming section (printer section) 5.

In addition, as shown in FIG. 2, in the document scanning section 4, a movable scanning section 9 of an exposure optical system optically scans the document along the lower surface of the document table 2, and photoelectrically converts this optical information to form an image. Part 5
It is designed to be input.

Further, the image forming section 5 has a configuration as shown in FIGS. 2 and 3. That is, a platen 10 is disposed approximately in the center of the image forming section 5, and a print head such as a thermal transfer head (hereinafter simply referred to as a thermal head or A thermal head (referred to as a thermal head) 11 is arranged so as to be movable towards and away from the platen 10.

The thermal head 11 is attached to the rear end surface of the holder 12 via a heat dissipation plate integrally formed, and a thermal transfer ribbon cassette (hereinafter simply referred to as ribbon cassette) 14a as a thermal transfer material cassette is held. A thermal transfer ribbon 15 as a transfer material is interposed between the thermal head 11 and the platen 10.

Further, a paper feed roller 16 is provided diagonally below the platen 10, and is adapted to sequentially take out sheets of paper P as a transfer material stored in a paper feed cassette 17 one by one. The leading edge of the taken out paper P is aligned by a registration roller 18 disposed diagonally above the paper feed roller 16, and then transported toward the platen 10 and wound around the platen 10 by pressing rollers 19 and 20. The item will be sent correctly. Note that a manual feed guide 17 is located above the paper feed cassette 17 on the front side of the apparatus main body 1.
A is provided so that paper can be fed manually.

On the other hand, the thermal head 11 presses the paper P against the platen 10 via a thermal transfer ribbon 15 as a transfer material.
As shown in FIG. 4, the ink 21 as a colorant on the thermal transfer ribbon 15 is heated and melted and transferred onto the paper P.

The thermal transfer ribbon 15 is approximately the same size as the paper P, as shown by range A in FIG.
, 21c are arranged side by side, or yellow (Y), magenta (M), cyan (C),
Black (B) ink portions 21a, 21b, 1c, 2
1d are arranged side by side, and after transferring one color at a time, the paper P is returned to its original position and accurately stacked one after another.

A thermal transfer ribbon containing a black ink portion 21d is used when it is desired to produce black clearly, and even a ribbon without a black ink portion 21d can produce approximately black by overlapping three colors.

In this way, the paper P is reciprocated by the number of colors by the rotation of the platen 10, but the path of the paper P at that time is guided by the first and second guides 23 arranged sequentially along the lower surface of the paper ejection tray 22. .24.

That is, the explanation will be made with reference to FIGS. 6(a) to 6(d).

First, the paper P supplied from the paper feed cassette 17 is moved to the registration roller 18. Then, it passes through the placement part of the first distribution guide 25 and is wound around the platen 10 (see FIG. 6(a)).

Next, the platen 10 is rotated using a pulse motor (not shown) as a drive source to transport the paper P at a predetermined speed, and a heating element of a thermal head 11 (see FIG. (not shown) generates heat according to the image information, and the ink 21 of the thermal transfer ribbon 15
is transferred onto paper P.

Furthermore, the leading edge of the paper P that has passed through the platen 10 is located at the second
The paper is sent onto the first guide 23 provided along the lower surface of the paper ejection tray 22 by the sorting guide 26 [Fig.
(b) Reference].

In this way, the paper P onto which the ink 21 of one color has been transferred is transported backwards by reversing the platen 10, and the lower surface of the first guide 23 is moved by the rotational displacement operation of the first distribution guide 25. (see FIG. 6(c)).

In this way, by reciprocating the paper P a plurality of times, a plurality of colors are transferred.

Finally, the paper P onto which all the color inks 21 have been transferred is guided by the second distribution guide 26 to the paper discharge roller 27 and discharged onto the paper discharge tray 22 [see FIG. 6(d)].

FIG. 7 schematically shows the overall control system. That is, in the figure, reference numeral 40 denotes a main control unit that controls the entire device, and is mainly composed of, for example, a CPU (central processing unit) and its peripheral circuits, to which a pass line 41 is connected. There is. The pass line 41 includes the operation panel section 1a, display control circuit 42, storage section 43, scan control section 44, photoelectric converter 45, color conversion section 46, transport control section 47, thermal head drive section 48, and a thermal head temperature control section 49 are respectively connected. The display control circuit 42 operates in response to a signal sent from the main control section 40 via the pass line 41, and controls the display section 6 provided on the operation panel section 1a. The storage section 43 operates in response to a signal sent from the main control section 4 via the pass line 41, and stores information sent via the pass line 41 or reads out the stored information. Further, the scanning control section 44 operates in response to signals sent from the main control section 4o via the pass line 41, and controls the front lamp 9A of the movable scanning section 9, the photoelectric converter 45, and the scanning motor (not shown), respectively. Drive control. The photoelectric converter 45 detects an image on the document according to a signal sent from the main controller 40 via the pass line 41, and outputs a light color signal as described above. The color converter 46 receives and processes the signal output from the photoelectric converter 45, converts the signal into color signals of yellow, magenta, cyan, and black inks, and outputs the color signals to the pass line 41. The color conversion section 46 also performs color conversion on the signal sent from the pass line 41, and converts the new signal to the pass line 41.
It can also be output to . The conveyance control section 47 operates in response to a signal sent from the main control section 40 via the pass line 41, and includes a motor that drives the platen 10, a motor (not shown) that drives the core of the ribbon cassette 14a,
The paper feed roller 16. A motor that drives the registration roller 18, the paper ejection roller 27, etc., and the first motor. Second
It drives and controls a solenoid (not shown) that drives the distribution gates 25 and 26.

The thermal head driving section 48 operates in response to a signal sent from the main control section 40 via the pass line 41 and a signal from the thermal radar temperature control section 49 to drive the thermal head 11 .
drive and control the heating element of.

The thermal head temperature control section 49 outputs a temperature control signal to the thermal head driving section 48 in response to a signal sent from the main control section 40 via the pass line 41.

Next, the vicinity of the platen, which is the main part of the present invention, will be explained in detail.

FIG. 8 is a side sectional view of the vicinity of the platen. What is indicated by 50 in the figure is a frame, and the side frame 50
A, bottom frame 50B, and ribbon cassette 14a
It is integrally constituted by a ribbon cassette holding frame 50C that holds the ribbon cassette. Furthermore, side frame 5
At 0A, a pair of studs 51 are fixed in an upright position (in the front and back directions of the paper in FIG. 8) for positioning the ribbon cassette 14a and mounting it on the ribbon cassette holding frame 50G.

The ribbon cassette 14a has two parallel winding cores 31 and 32 around which both ends of the thermal transfer ribbon 15 are wound, and the middle part of the thermal transfer ribbon 15 is connected to the platen 1.
0 and the thermal head 11, and is enclosed in a case 33 with a portion thereof exposed.

A pair of openings 34 which are opened along the axial direction of the winding cores 31 and 32 are formed facing each other between the winding core accommodating parts 33a and 33b of the case 33. In the vicinity of the opening 34, a guide portion 37 for guiding the thermal transfer ribbon 15 being wound and displaced is curved and integrally formed with the case 33. The back surface of the guide portion 37 is inserted into the pair of studs 51 so as to sandwich the studs 51.

Further, a first pressing roller unit 60 is provided at the upper position of the platen 10, and a second pressing roller unit 70 is provided at the lower position.

Next, the detailed configuration of both units 60 and 70 will be explained based on FIGS. 9 and 10. For the first pressing, the roller unit 60 includes a bracket 61 of the unit, a shaft 62 pivotally supported by the bracket 61, a pair of levers 63 fixed to the shaft 62, and a free end of the lever 63 rotatably pivoted. The supported pressing is carried out by the roller 20 and the shaft 6.
2, a biasing member 65 that rotates and biases the operating lever in the direction of arrow x1, and a biasing member 65 that rotates the operating lever 64 in the direction of arrow Y1 against the biasing force of the biasing member 65. It consists of a rotating solenoid 66 and a paper guide 67, and the solenoid operates until the leading edge of the paper that is wrapped around the platen 10 and conveyed during the transfer operation reaches between the platen 10 and the pressing roller 20. When 66 is energized and the roller 20 is removed from the surface of the platen 10, and the paper P is located between them, the solenoid 66 is deenergized and the roller 20 is urged to press against the surface of the platen 10. The paper P is pinched and conveyed. Also, the second pressing is performed on the roller unit 70 using the bracket 71° and the shaft 72. Lever 73. Pressing is done by the roller 19° operating lever 74. Biasing member 75. It is composed of a solenoid 76° and a paper guide 77, and operates in the same manner. For the above pressing, the rollers 19 and 20 are the first
As shown in Figure 0, the platen 10 is divided along the axial direction, for example, divided into two parts, each of which is suspended independently. can be uniformly brought into close contact with the surface of the platen 10, and it is possible to prevent skewing of the transferred material caused by uneven nipping and conveying force and misalignment of the transfer position caused by this.

Further, the pressing rollers 19 and 20 are arranged so as to press the paper P against the platen 10 from a direction substantially perpendicular to the direction in which the paper P is transported while being wrapped around the platen. With this arrangement, the paper P is pressed and displaced by the rollers 19 and 20.
The extent to which the paper P obstructs the progress of the paper P is reduced, and bending of the leading edge of the paper can be prevented.

As shown in FIG. 11, the paper guide 67 is used as a ribbon guide in order to guide the paper P from the leading edge of the paper P toward the surface of the platen 10 in order to prevent the paper P being transported toward the rollers 20 from sagging, as shown in FIG. Each θ1 formed by the tangent between the platen 69 and the platen 10 and the guide surface is set to be smaller than 90°.

The paper guide 77 is an example of a guide member that pushes the paper fed from the downstream side and guides it between the roller 19 and the platen 10. For example, as shown in FIG. A curved surface 77A having a radius of curvature γg (7g>γp) approximately equal to the radius of curvature γp is formed. The paper guide 77 is pivotally supported at its intermediate portion and is rotatable, and takes the position shown in FIG. When a drive solenoid (not shown) for the distribution guide 25 is excited, it rotates against the biasing force of the biasing member 77B and assumes the position shown in FIG. 12(B).In particular, the paper guide When the ribbon guide 77 is in the position shown in FIG. 12(B), in order to smoothly guide the returned paper P toward the first distribution guide 25, the tangent line between the ribbon guide 79 and the platen 10 and the paper The angle q2 between the tip of P in the return conveyance direction and the tangent at the point of contact with the curved surface 77A is set to be smaller than 90°.

Each of the pressing number roller units 60 and 70 is removably arranged on the frame 50 for each unit. That is, as shown in FIG.
The roller unit 70 is screwed to the upper end surface of 0A, and the second pressing roller unit 70 is attached to the bottom frame 50 via a bracket 71.
It is screwed to the side end surface of B.

As shown in FIG. 8, the thermal head 11 is pressed against the surface side of the platen 10 during the transfer operation, and is separated from the surface side of the platen 10 during the return conveyance of the paper P, as indicated by the arrow mark M in the figure. It is possible to move in any direction. That is, to explain based on FIGS. 8 and 14, one end of a bushing rod 91 is fixed to the back side of the holder 12 via a mounting plate 90, and this bushing rod 91 is slidably attached to the ribbon cassette holding frame 50.
It is inserted in G. One end of a bushing lever 92 is pivotally supported at the other end of this bushing rod 91, and the other end of this bushing lever 92 can rotate integrally with a drive shaft 93. Note that this drive shaft 93 is pivotally supported by the ribbon cassette holding frame 50G. The bush lever 92 is biased by a biasing member 94, and the thermal head 11 is pressed against the surface of the platen 10 by the biasing force. A cam 95 is fixed to one end of the drive shaft 93, and this cam 95 engages with a cam roller 97 attached to a motor shaft 96A of a head drive motor 96, as shown by the eighth arrow '9M'.
It is designed to swing in the direction.

Next, when the paper P is transported back and forth, the platen 10, the thermal head 11, the pressing rollers 19 and 20, and the paper guide 7
7 will be explained based on FIGS. 15<a> to (h).

First, when the paper P is fed and conveyed near the platen 10, it becomes as shown in FIG. 15(a).

That is, the thermal head 11. Pressing is done by roller 19. The vapor guide 77 is pressed toward the platen 10, and the roller 20 is separated from the platen 10 when pressed on the upper side. The paper P fed and conveyed from the downstream side is smoothly guided to the contact area between the roller 19 and the platen 10 by the action of the paper guide 77 explained in FIG. 12(A), and the paper is pushed to the position shown in the figure. When the paper is transported, the thermal head starts transferring the paper.

When the leading edge of the paper P in the conveyance direction reaches between the platen 10 and the roller 20, the roller 20 is pressed against the surface of the platen 10, as shown in FIG. 15(b). This operation is performed when the leading edge of the paper P in the conveyance direction crosses a line segment connecting the rotation center of the platen 10 and the rotation center of the roller 20, and is performed during the transfer operation.

When the paper P is conveyed to the position shown in FIG. 15(C), the transfer of the first color is completed. After transfer, platen 10
When the rotation of the vapor guide 77 and the pressing roller 19 are stopped, the vapor guide 77 and the pressing roller 19 are separated from the surface of the platen 10.

Thereafter, the platen 10 is rotated in the opposite direction, and the paper P is conveyed back. The leading edge of the paper P in the conveying direction is the platen 10.
When the pressing reaches between the roller 19 and the roller 19, the
), the roller 19 is pressed against the surface of the platen 10, and the paper is subsequently conveyed back. This operation is performed between the center of rotation of the platen 10 and the pressing O-ra 1.
This is performed when the leading edge of the sheet P in the return conveyance direction crosses the line segment connecting the center of rotation of the sheet P.

Then, the roller 19 pinches the paper P and presses it onto the platen 10.
At the stage when the thermal head 11 is pressed, the thermal head 11 is separated from the front surface side of the platen 10, and as shown in FIG. The rotation of the platen 10 is stopped after being conveyed to the last position.

Next, the thermal head 11 is pressed against the surface side of the platen 10, and then the platen 10 is rotated and the sheet P is conveyed back again. Figure 15 (
As shown in parentheses [), the pressing moves the roller 20 away from the surface of the platen 10 and stops the return conveyance of the tray P.

Then, while conveying the paper P forward, transfer of the second color to the paper P is started, and as shown in FIG. When the line segment connecting the rotation centers of the platen 1o is crossed, the roller 2o is pressed against the surface of the platen 10, and the 15th
The transfer of the second color is completed when it is conveyed to the position shown in Figure 15 (h), and then Figures 15 (d), (e), (
f).

The operations shown in (0) and (h) are repeated to perform the transfer operation for all colorants. Note that after the M1100 transfer is completed, the paper guide 77 is separated from the platen 10 as shown in FIGS. ing.

As described above, in the apparatus of this embodiment, the pressing is performed by displacing the rollers 19, 20 and the thermal head 11 in the direction toward and away from the platen 10, depending on the conveyance state of the paper P, so that the pressing is carried out on the leading edge side in the conveyance direction of the paper. Or one of the rear end side is pressed by roller 19.2
Even when the paper is not pressed by the rollers 19 and 20, it is possible to reliably hold the paper against the surface of the platen 10, thereby reliably preventing misalignment of the transfer position. Since the transfer position shift can be prevented without pressing P against the platen 10, the colorant can be transferred to the vicinity of both ends of the paper in the conveying direction, and the non-image area on the paper where an image cannot be formed (paper P (both ends along the conveyance direction) can be made smaller.

In particular, in the pressing of this device, the rollers 19 and 20 press the paper P against the platen 10 from a direction substantially perpendicular to the traveling direction of the paper that is being conveyed while being wrapped around the platen 10, so the conveyance of the paper is obstructed. This prevents the leading edge of the paper from bending. In addition, since the pressing rollers 19 and 20 are divided along the axial direction of the platen 10, each part of the paper can be uniformly and reliably brought into close contact with the platen 10, and it is possible to prevent the paper from skewing or meandering. .

Further, since the vapor guide 77 has a curved surface 77A having a curvature approximately equal to the curvature of the surface of the platen 10, the paper can be guided smoothly.

It should be noted that the above embodiment is merely an example, and it goes without saying that various modifications can be made within the scope of the gist of the present invention. For example, a thermal head for a platen.

The contact and separation mechanism of the pressing roller is not limited to the embodiment. Further, the print head is not limited to the thermal head of the above embodiment, but can be replaced with various print heads such as a wire head type.

[Effects of the Invention] As detailed above, in the image forming apparatus of the present invention, the material to be transferred can be transported back and forth without causing a transfer position shift during the transfer operation, and it is possible to transport the material to be transferred back and forth in the transport direction of the material to be transferred. This has excellent effects such as being able to reduce the size of non-image areas on both ends along which no image can be formed.

[Brief explanation of the drawing]

FIG. 1 is an overall external perspective view of an apparatus according to an embodiment of the present invention, FIG. 2 is a schematic perspective view showing the internal structure of the entire apparatus, FIG. 3 is a longitudinal side view of the apparatus, and FIG. FIG. 5 is a perspective view for explaining the transfer operation state, FIG. 5 is a plan view showing the ink application state of the thermal transfer ribbon, and FIGS. 6 (A), (B), (C),
(D) is an explanatory diagram explaining the movement of paper during multicolor transfer, FIG. 7 is a configuration block diagram showing the entire control system, and FIG.
The figure is a side sectional view of the vicinity of the platen, Figure 9 is a schematic side view showing details of the pressing roller unit, Figure 10 is a partial perspective view showing details of the pressing roller unit, and Figure 11 is of the upper paper guide. Detailed explanatory diagram, Fig. 12 (A>, (B
) is a detailed explanatory diagram of the lower paper guide, Figure 13 is a perspective view showing the mounting structure of the pressing roller unit, and Figure 14 is a perspective view of the mounting structure of the pressing roller unit.
The figure is an exploded perspective view showing the displacement mechanism of the thermal head, and FIGS. 15(a) to 15(h) are explanatory diagrams of operations during reciprocating conveyance of paper. 10...Platen, 11...Print head, 19.20...Pushing roller, 77...
...Guide member, 77A...Curved surface. Figure 15 (b) Figure 15 (t) Figure 15 (9) (h)

Claims (4)

[Claims] (1) Image formation in which a color image is formed by transferring a plurality of colorants on the transfer material to the transfer material via a print head while the transfer material wrapped around the platen is conveyed back and forth by the rotation of the platen. In the apparatus, the device is arranged in front and behind the printing head along the conveying direction of the transferred material and moves toward and away from the surface of the platen, and the leading edge in the conveying direction of the transferred material that is reciprocated after the start of transfer is A pair of pressing rollers that separate from the platen before reaching between the transfer material and the platen and press and hold the transferred material against the platen after reaching the transfer material are rollers;
The press located in front of the print head along the conveyance direction of the transfer material is provided with a guide member that guides the transfer material supplied and conveyed from the downstream side of the roller to the contact area between the roller and the platen. An image forming apparatus characterized by: (2) In the pressing, the roller presses the transferred material against the platen from a direction substantially perpendicular to the traveling direction of the transferred material wrapped around the platen and conveyed. The image forming apparatus described in . (3) The image forming apparatus according to claim 1, wherein the pressing roller is divided into parts along the axial direction of the platen. (4) The image forming apparatus according to claim 1, wherein the guide member has a guiding curved surface substantially equal to the curvature of the platen surface and is displaced in a direction toward and away from the platen. .