JPH01196373A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To form a picture image with high accuracy in overlapping, by braking a recording medium into a tensive state, while the end of the recording medium is held by a gripper to be wound around a platen drum. CONSTITUTION:During the paper feeding, a driving roller 40a of a pair of resisting rollers 40 is rotated until the end of a paper P is held by a gripper 19. The paper P is successively wound around a platen drum 22 as the drum 22 rotates. However, since the medium part of the paper P after a distance (f) is pulled out between the driving roller 40a and a subordinate roller 40b which are in the stopped and pressed state, the paper P is braked into a tensive condition. Accordingly, the paper P can be brought into tight contact with respect to the platen drum 22 before a thermal head 21 applies pressure thereto. Therefore, the paper P can be in tight contact with the platen drum 22 from the printing time of a first color in the same manner as at the printing time of a second color and thereafter. Thus, a picture image can be formed with high accuracy in overlapping.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement in an image forming apparatus applied to, for example, a thermal transfer printer or a thermal transfer copying machine.

(Prior Art) In recent years, a recording medium (paper) is wound around a platen drum having a gripper that holds the edge of the recording medium and transported.
Y), magenta (M).

A thermal transfer image forming device was developed and put into practical use, which sequentially melts and transfers cyan (C) and black (B) colorants (inks) via a heat-sensitive recording head (thermal head) to form a desired color image. ing.

Conventionally, in this type of apparatus, a plurality of presser rollers consisting of driven rollers are brought into contact with each other around a platen drum, and the recording medium, whose tip end is held by a gripper and is wound around the platen drum, is pushed onto the platen by the presser rollers. It is designed to be placed in close contact with the drum.

(Problem to be solved by the invention rA) However, with such a conventional configuration, it is not possible to wrap the recording medium in a sufficiently tensioned state, and the printing of the first color and the printing of the second, third, and fourth colors are difficult. The conditions are different between 2. and 2. due to the difference in the adhesion of the recording medium to the platen drum.
3. The printing of the 4th color overlaps each other, whereas 1
There was a problem that the printed colors did not overlap.

The present invention has been made based on the above circumstances, and its purpose is to obtain good adhesion of the recording medium to the platen drum from the time of printing the first color as well as for the second and subsequent colors, and to achieve good adhesion with high overlay accuracy. The present invention aims to provide an image forming apparatus capable of forming images.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention wraps a recording medium around a platen drum having a gripper that holds the edge of the recording medium and transfers the recording medium. In a thermal transfer image forming apparatus that melts and transfers the colorant on a transfer material to a recording medium multiple times via a thermal recording head, a brake is applied to the recording medium that is wrapped around a platen drum with its edge held by the gripper. The structure is equipped with a brake means for applying tension.

(Function) That is, by having the above-described structure of the present invention, the recording medium that is wound around the platen drum with the end held by the gripper is wound with sufficient tension by the brake means, and the platen drum is wound with sufficient tension by the brake means. Adhesion of the recording medium to the drum can be obtained from the time of printing the first color in the same manner as from the second color onwards, and it is possible to form a good image with high overlay accuracy.

(Embodiment) Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 7.

FIG. 2 shows a schematic configuration of an image forming apparatus to which the present invention is applied. In the figure, reference numeral 1 denotes a main body of an image forming apparatus, and a document table 2 having a document holding cover 3 is provided on the upper surface of the device main body 1. Further, in the apparatus main body 1, a document scanning section (scanner section) 4 is provided in the upper part, which is located on the lower surface side of the document table 2 and scans the document set on the document table 2. A forming section (printer section) 5 is provided. In addition, a display section,
An operation panel (not shown) is provided on which operation/display components such as a numeric keypad and a start button are arranged.

The document scanning section 4 has a back portion surrounded by a reflector 6, an exposure lamp 7, and a first mirror 8, and moves along the document table 2 to scan the document surface and transmit optical information in a predetermined direction. a reflective first moving optical block 9;
A second mirror having a second mirror 10 and a third mirror 11 moves at half the speed of the first moving optical block 9 and reflects optical information reflected from the first moving optical block 9 toward the lens 13. a moving optical block 12, a fixed optical block 16 having a fourth mirror 14 and a fifth mirror 15 and reflecting optical information transmitted through the lens 13; and a fixed optical block 16 that reflects optical information transmitted through the lens 13; Exposure optical system 1 consisting of a photoelectric converter 17 that receives optical information
The image forming section 5 optically scans the document set on the document table 2 and photoelectrically converts this optical information.
It is designed to be input.

Further, the image forming section 5 has a configuration as shown in FIGS. 1 and 2. That is, a platen drum 22 serves as a sheet supporting and transporting means that holds a gripper 19 which is located approximately in the center of the apparatus main body 1 and holds the edge of a recording medium (hereinafter referred to as a sheet), and wraps around and transports the sheet P. In addition, a thermal recording head (hereinafter referred to as a thermal head) 21 is arranged so as to be able to approach and separate from the platen drum 22.

Furthermore, the thermal head 21 and the platen drum 22
A transfer material (hereinafter referred to as a thermal transfer ribbon) 27 is interposed between the two. This thermal transfer ribbon 27 is attached to a case (
(not shown) and is made into a cassette.
The cassette can be inserted and removed through a cassette insertion/ejection port (not shown) formed in the cassette.

Further, a paper feed cassette 35 is installed on one side of the apparatus main body 1, as shown in FIG.
The sheets P inside are taken out one by one by a sheet feeding roller 36 serving as a sheet feeding means. The taken out paper P passes through a paper inlet path 26 formed by the mutually opposing surfaces of the guide plates 23 and 24, and a paper inlet/outlet path 32 formed by the mutually opposing surfaces of the guide plates 30 and 31, to the platen. It is adapted to be guided by the gripper 19 of the drum 22. In addition, the paper loading path 26 and the paper loading/unloading path 32
A registration roller pair 40 is arranged between the
The leading edge of the paper P is aligned and the paper feeding timing is adjusted.

Further, above the paper loading path 26 and the loading position of the paper feed cassette 35, there is provided a paper loading path 33 that joins the paper loading path 26 near the pair of registration rollers 40. is guided to a pair of paper discharge rollers 48. This paper discharge path 33 is formed by mutually opposing surfaces of guide plates 37, 37, 38, 38, and has a configuration in which a pair of conveying rollers 34 is disposed in the middle. In addition,
Reference numeral 49 denotes a paper ejection tray that collects the paper P that is ejected to the outside of the apparatus main body 1 via a pair of paper ejection rollers 48 .

Furthermore, a movable guide 39 is disposed at the confluence of the paper output path 33 and the paper input path 26.

The registration roller pair 40 is composed of a drive roller 40a to which the driving force of a motor 52 is transmitted via a gear group 53, and a driven roller 40b that rolls into contact with the drive roller 40a. And the configuration is as shown in FIG. That is, Figures 3 and 4
As shown in the figure, the drive roller 40a has a support shaft portion 55.
Both ends of the frame 56, 57 are rotatably held via bearings 58, 58 fixedly held in the frame 56, 57.

The driven roller 40b is rotatably held at both ends of the support shaft 59 via bearings 61.61 which are held vertically movably through long holes 60.60 formed in the frame 56.57. has been done.

Further, coil springs 63 and 6B, which have both ends locked in locking holes 62 and 62 formed in the frames 56 and 57, are wound around the bearings 61 and 61 on the driven roller 40b side, and the coil springs 63 and 6B are wound around the bearings 61 and 61 on the driven roller 40b side. 40b is brought into contact with the drive roller 40a with a predetermined pressure due to the biasing force of these coil springs 63, 63. In addition, the drive roller 40
A gear 53a, which is one of the constituent gears of the gear group 53, is fitted into one end of the support shaft portion 55 of the gear a.

Further, the rotation direction of the motor 52 is controlled so that the drive roller 40a is rotated in the forward direction when the paper P is carried in, and the drive roller 40a is rotated in the reverse direction when the paper P is carried out. . The motor 52 also moves the platen drum 2 while the leading edge of the paper P is held by the gripper 19.
When the sheet P is wound around the platen drum 22, the driving roller 40a is controlled to be stopped, and a brake means 65 is configured to apply a brake to the sheet P wound around the platen drum 22 to make it tense.

Further, a presser roller 25 serving as a paper presser is in rolling contact with the platen drum 22.
The paper P wound around the platen drum 22 is held down so that it does not float up, and a good adhesion state can be obtained.

On the other hand, the thermal head 21 presses the paper P through the thermal transfer ribbon 27 against a portion supported by the platen drum 22, and as shown in FIG. The image is then transferred onto the paper P.

The thermal transfer ribbon 27 may be provided with yellow (Y), magenta (M), and cyan (C) ink portions arranged side by side in a size approximately equal to that of the paper P, as shown in range A in FIG.
Alternatively, yellow (Y), magenta (M), cyan (C), and black (B) ink portions are arranged side by side and have approximately the same size as the paper P, as shown by the range opening in FIG. A full color image is obtained by transferring each color one by one, returning the paper P, and overlapping each other accurately one after another.

Further, as shown in FIG. 7, the image forming apparatus includes a document scanning section (scanner section) 41, a color conversion section 45. Memory section 469 Image forming section (printer section) 5. and an overall control section 47.

Then, the green (G) detected by the original scanning unit 4
), yellow (Y), and cyan (C) are converted by the color converter 45 into the colors of the print medium, that is, magenta (M), yellow (Y), and cyan (C).
), and the color-converted values are stored in the memory unit 46 together with position information on the document for each color. The image forming section 5 uses magenta (M), yellow (Y), and cyan (C) according to the values read out from the memory section 46.
).

Black (B) [Black (B) is magenta (M), yellow (Y)
, cyan (C) AND outputs of the print medium are transferred onto the paper P. It should be noted that the overall control section 47 controls the document scanning section 41
Color conversion section 45. Memory unit 46° controls the entire image forming unit 5.

Further, as shown in FIG. 1, the thermal head 21 is moved to the platen drum by a head actuating means (not shown).
It is configured to be movable by a dimension X in the direction toward and away from 2. Then, the thermal head 21 and the platen drum 2
The configuration is such that a gap can be secured as necessary for the thermal transfer ribbon 27 stretched through ribbon guides 51 and 51 between the ribbon cassette 2 and the ribbon cassette. It can be done easily and reliably.

Next, the operation of the image forming apparatus configured as described above will be explained with reference to FIG. 1.

First, the paper P supplied from the paper feed cassette 35 is
As shown in , the paper passes through the paper entry path 26 and is guided to the registration roller pair 40 via the movable guide 39 in the solid line position state, and the driving roller 40a and the driven roller 40 in the stopped state.
The tip alignment is performed by hitting the junction with b. Next, as the motor 52 is driven in the forward direction, the drive roller 40a rotates in the direction indicated by the arrow, and the paper P passes through the paper loading/unloading path 32, with its leading end touching the platen drum 2.
It is fed into the gripper 19 of No. 2.

Then, when the leading edge of the paper P is held by the gripper 19, the platen drum 22 rotates in the C direction using a pulse motor (not shown) as a driving source, and brings the paper P to the printing leading edge position. At the same time, the thermal transfer ribbon 27 is sent in the direction of arrow d to the leading edge of the printing position.

Then, the thermal head 21 becomes pressurized, and
The platen drum 22 is transferred at a predetermined speed in the direction of arrow C, and the heating element (
(not shown) generates heat according to the image information, and the ink 41 of the thermal transfer ribbon 27 is transferred to the paper P.

After several times of printing, the thermal head 21 is released and the platen drum 22 is rotated in the C direction until the rear end of the paper P falls onto the guide plate 31 forming the paper loading/unloading path 32. let Thereafter, the platen drum 22 is rotated in the opposite direction (in the direction of arrow C'), the drive roller 40a of the registration roller 40 is rotated in the direction of arrow b', and the movable guide 39 is rotationally displaced to the position shown by the two-dot chain line. Then, the paper P is guided in the direction of arrow C and passed through the paper discharge path 33 and the pair of paper discharge rollers 48 to the paper discharge tray 4.
The paper will be ejected onto 9.

Also, during the above-mentioned paper feeding, the leading edge of the paper P is held at the gripper 1.
Drive roller 4 of registration roller pair 40 until gripped by 9
0a rotates and stops when the gripper 19 grips the leading edge of the paper P. Thus, the paper P whose leading end is held by the gripper 19 is wound around the platen drum 22 as the platen drum 22 rotates, but the middle part of the paper P is held by the pair of registration rollers 40 which are in a stopped state and in a state of pressure contact. The distance between the driving roller 40a and the driven roller 40b shown by the distance f in FIG. Until the pressure is applied, the paper P can be completely brought into close contact with the platen drum 22.

Therefore, the dense layering of the paper P with respect to the platen drum 22 can be obtained from the time of printing the first color in the same way as for the second and subsequent colors, and it is possible to form a good image with high overlay accuracy.

Note that the present invention is not limited to the above embodiment. That is, the registration roller pair 4 also serves as the brake means 65.
A locking mechanism 6 that prevents the rotation of the driven roller 40b of
6 may be provided to prevent the follower operation accompanying the transport of the paper P and to further enhance the braking effect on the paper P. As shown in FIGS. 8 and 9, for example, the locking mechanism 66 includes a windmill 67 fitted to the spindle 59 of the driven roller 40b, and a locking mechanism rotatably provided to engage and disengage the windmill 67. It is configured to include a locking lever 68 and a solenoid 69 that rotationally displaces the locking lever 68.

Further, although the brake means 65 is also used by the pair of registration rollers 40, the present invention is not limited to this, and the presser roller 25 that rolls into contact with the platen drum 22...
It is also possible to have the part used for both purposes. This is the 10th
As shown in the drawings and FIG. 11, the presser rollers 25 that contact the platen drum 22 are attached via a one-way clutch 70 so that they can rotate only in the direction of arrow g, and the paper P is wound around the platen drum 22. At this time, the brake may be applied by these pressing rollers 25 whose rotation is locked.

At this time, as shown in FIG.
... is attached to an arm 73 that is always biased in a predetermined direction by a rotatable bracket spring 72 with a support shaft 71 as a fulcrum. Then, press the presser roller 25 so as to evenly contact the platen drum 22 in the axial direction, and press the paper P.
to obtain the appropriate frictional force necessary to tension the Although all of the presser rollers 25 are attached via the one-way clutch 70, it is needless to say that the present invention is not limited to this.

Further, as shown in FIG. 12, the brake means 65 may be pressed by a presser plate spring 75 instead of the presser roller 25.

Furthermore, as shown in FIGS. 13 and 14, the brake means 65 may also be used as the paper feed roller 36. That is, the driving force of the motor 81 is transmitted to the paper feed roller 36 via the gear group 80, and the driving force of the motor 81 is transmitted to the paper feed roller 36 until the leading edge of the paper P is gripped by the gripper 19 during paper feeding, as in the above embodiment. The paper feed roller 36 rotates and stops when the gripper 19 grips the leading edge of the paper P. Then, the brake may be applied by the paper feed roller 36 in a stopped state of the paper P. In addition, in the case of this method, the distance h (see Fig. 14) between the leading edge position of the paper P and the paper feed roller 36 at the time of starting printing of the first color is longer than the length of the paper P of the minimum printable size. In this case, the effect of the present invention cannot be obtained, so the paper feed roller 3 is adjusted so that the distance is shorter than the length of the paper P of the minimum printable size.
The condition is to place 6.

In addition, in the description of the above-mentioned other embodiment, the same components as in the above-mentioned one embodiment are given the same reference numerals, and detailed explanation will be omitted.

In addition, it goes without saying that the present invention can be modified in various ways without departing from the gist thereof.

[Effects of the Invention] As explained above, according to the present invention, the recording medium, which is wound around the platen drum with the end held by the gripper, is wound with sufficient tension by the brake means, Adhesion of the recording medium to the platen drum can be obtained from the time of printing the first color in the same manner as from the second color onwards, and an image forming apparatus can be provided which can form a good image with high overlay accuracy.

[Brief explanation of the drawing]

1 to 7 show an embodiment of the present invention,
FIG. 1 is a schematic configuration diagram of the main parts, FIG. 2 is a schematic configuration diagram of the image forming apparatus, FIG. 3 is a partially cutaway side view showing a pair of registration rollers that also serve as brake means, and FIG. 4 The figure is a sectional view taken along the line IV-IV in Figure 3, Figure 5 is a perspective view showing the transfer operation state, Figure 6 is a plan view showing the thermal transfer ribbon, and Figure 7 is a block diagram showing the configuration of the control device. , FIG. 8 and FIG. 9 show the first other embodiment of the present invention,
FIG. 8 is a schematic side view partially cut away showing a pair of registration rollers that also serve as brake means, and FIG.
10 and 11 show a second embodiment of the present invention, FIG. 10 is a schematic diagram of the main part, and FIG. 11 is a diagram of the main part. , FIG. 12 is a schematic configuration diagram of the main parts showing a third other embodiment of the present invention, and FIG.
3 and 14 show a fourth alternative embodiment of the present invention, in which FIG. 13 is a schematic diagram of the main part, and FIG. 14 is a diagram for explaining printing conditions. P... Recording medium (paper), 19... Gripper, 21
...Thermal recording head (thermal head), 22...
Platen drum, 25... Presser roller, 27... Transfer material (thermal transfer ribbon), 36... Paper feed roller, 40...
・Registration roller pair, 41 ・Coloring material (ink), 6
5... Brake means, 75... Holder plate spring. Applicant's representative Patent attorney Takehiko Suzue, 1 Figure 4 Figure 6 Figure 9 Figure 11

Claims (1)

[Claims] A thermal transfer method in which the recording medium is wrapped around a platen drum with a gripper that holds the edge of the recording medium and transferred, and the colorant on the transfer material is melted and transferred multiple times to one recording medium via a thermal recording head. 2. The image forming apparatus according to claim 1, further comprising a brake means for applying a brake to tension the recording medium wound around the platen drum while the end thereof is held by the gripper.