JPH02182464A - Apparatus for formation of image - Google Patents

Abstract

PURPOSE:To allow both melting type and sublimable type ink ribbon to be available by providing switching means for switching the pressure contact force of a heat sensitive recording head to an image forming medium manually in response to the type of the image forming medium. CONSTITUTION:When a melting type ink ribbon 24a is employed, i.e., when the pressurizing force of a thermal head 21 to the ink ribbon 24a, may be small, a switching arm 42 is manually rotated in a direction of an arrow (a). Thus, a coil spring 39 is elongated to reduce a pressing force to decrease the pressurizing force of the thermal head 21 to the ink ribbon 24a. When a sublimable ink ribbon 24b is employed, i.e., when the pressurizing force of the thermal head 21 to the rink ribbon 24b must be increased, the switching arm 42 is rotated in a direction of an arrow (b). Thus, the coil spring 39 is compressed to increase a pressing force to increase the pressurizing force of the thermal head 21 to the ink ribbon 24b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object 1 of the Invention] (Field of Industrial Application) The present invention relates to an image forming apparatus that is applied as, for example, a thermal transfer printer or a thermal transfer copying machine.

(Prior Art) In recent years, a color photocopier has been developed as a thermal transfer type image forming apparatus and has been put into practical use.

In the case of full-color copying, such devices use a thermal head (thermal head) to overlay the four colors of ink (yellow, magenta, cyan, and black) of an ink ribbon (image forming medium) on Japanese paper (recorded material). Transfer by pressing the recording head), or print yellow, magenta,
Three colors of cyan are transferred in layers. Furthermore, in the case of a single color such as black, the transfer is performed in one transfer operation.

Incidentally, there are two types of ink ribbons: melting type and sublimation type.Usually, sublimation type ink ribbons are pressed against a thermal head with a pressure that is 2 to 4 times greater than that of melting type ink ribbons.

(Problem to be Solved by the Invention) However, in the past, the pressing force of the thermal head against the ink ribbon was constant regardless of the type of ink ribbon, so melting type ink ribbons were manufactured using special melting type machines or However, dye-sublimation ink ribbons can only be used with a dedicated dye-sublimation machine, making them inconvenient.

The present invention has been made in view of the above circumstances, and its object is to provide an image forming apparatus that can use either a melting type or a sublimation type ink ribbon.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention brings a thermal recording head into pressure contact with an image forming medium to melt-transfer the colorant of the image forming medium onto the recording medium. The thermal transfer type image forming apparatus is characterized by comprising a switching means for manually switching the pressing force of the thermal recording head against the image forming medium depending on the type of the image forming medium.

(Function) By bringing the thermal recording head into pressure contact with the recording medium at a pressure depending on the type of recording medium, it is possible to handle various types of recording bodies with a single device.

(Example) The present invention will be described below with reference to an example shown in the drawings.

FIG. 3 shows, as an example of the image forming apparatus of the present invention, a thermal transfer type color copying machine capable of making multicolor copies.

In the figure, reference numeral 1 denotes a main body of a copying machine, and an operation panel (not shown) is provided at the front of the upper surface of the main body 1.

At the top of the main body 1, there is a document table ("transparent glass").
A document scanning section 3 is provided to scan and read a document set on the document sheet 2, and an image forming section 4 is provided at the bottom thereof. Note that 5 is a document cover provided on the document table 2 so as to be openable and closable.

The document scanning section 3 includes an exposure lamp 7 whose back is surrounded by a reflector 6, a first mirror 8, a second mirror 9, and a third mirror.
Mirror 10. It is composed of a lens 11, a fourth mirror 12, a fifth mirror 13, and a photoelectric converter 14.

Further, the exposure lamp 7 and the first mirror 8 are mounted on a first carriage 15 that is movable along the lower surface of the document table 2, and the second mirror 9 and the third mirror 10 are mounted on a first carriage 15 that is movable along the lower surface of the document table 2. It is mounted on the carriage 16 of No. 2. The first carriage 15 and the second carriage 16 are configured to move in conjunction with each other by a drive mechanism (not shown), and the first carriage 15 and the second carriage 16 are moved in conjunction with each other by a drive mechanism (not shown).
The optical path length to the lens 11 is kept constant by moving in the same direction at a speed of .

When scanning the original, the first carriage 15 moves from left to right with the exposure lamp 7 turned on, and the m2 carriage 16 also moves in the same direction at 1/2 the speed. Then, the reflected light from the document plate is guided to the lens 11 via the first mirror 8, the second mirror 9, and the third mirror 10 in order, and the light that has passed through this lens 11 is guided to the fourth mirror 12 and the third mirror 10. The light is guided to the optical converter 14 via the fifth mirror 13 in sequence.

The photoelectric converter 14 separates and outputs the image of the original MD as color signals of cyan, green, and yellow (or red, green, and blue) light by charging and converting the reflected light from the original document. For example, it is mainly composed of a CCD type line image sensor.

In this case, the pixels of the document correspond to three elements (C, G, Y) of the CCD sensor. The photoelectric converter 14
The output is output to an A/D converter (not shown).

Further, the image forming section 4 has a configuration as shown in FIG.

That is, the platen drum 20 is provided approximately at the center of the image forming section 4 . This platen drum 20
is made of an elastic material such as rubber, and has a function as a platen roller for a thermal recording head (hereinafter referred to as a thermal head) 21.

The platen drum 20 has a gripper 22 that holds the leading edge of the paper P as a recording medium, and rotates clockwise to wrap the paper P and prevent the paper P from shifting during overlapping printing. ing.

Also, pressure rollers 23 are provided around the platen drum 20 at predetermined intervals to prevent the paper P from floating up from the platen drum 20. The circumference of the platen drum 20 is slightly longer than the longitudinal length of the maximum paper size.

The thermal head 21 is disposed diagonally below and to the left of the platen roller 20 . An ink ribbon 24 as an image forming medium is interposed between the platen drum 20 and the thermal head 21.

The cores 25 and 26 of the ink ribbon 24 are connected to a drive shaft of a motor (not shown) via a driving force transmission means (not shown), and are rotated as required.

On the other hand, a paper feed roller 3 is located at the lower part of the copying machine main body 1.
0 is provided, and the sheets P stored in the paper feed cassette 31 are taken out one by one. Paper feed roller 3
The sheet P taken out at 0 is sent to a pair of registration rollers 33 by a conveyance means 32 consisting of a feed roller and a separation roller, and its leading edge is aligned. Then, as the registration roller pair 33 rotates, it is further fed to the guide body pair 3.
4 and is conveyed toward the platen drum 20,
Its tip is held by a gripper 22. Then,
By rotating the platen drum 20 clockwise,
While being wound around the platen drum 20, the pressing is maintained without lifting along the rollers 23, and is accurately fed.

During image formation, the platen drum 20 is rotated and printing is performed by the thermal head 21. Then, each time one color is printed, the platen drum 20 rotates once and the next color is superimposed and transferred.

The paper P on which the image formation has been completed in this manner is peeled off from the platen drum 20, and is transferred to a pair of paper ejection guide plates 45, a pair of transport rollers 46, a pair of paper ejection guide plates 47, and a pair of transport rollers 4.
The paper is discharged onto a paper discharge tray 50 via a paper conveyance path 49 formed by a paper sheet 8 or the like.

That is, when the paper is ejected, the trailing edge of the paper P is in the paper transport path 4.
Rotate the platen drum 20 clockwise until it faces the base end of the platen drum 9.
is rotated counterclockwise, and the rear end of the paper P is separated from the platen drum 20 by a separating claw (not shown) and guided to a pair of paper discharge guide plates 45. Finally, the tip of the sheet 91P is released from the gripper 22, and the sheet is conveyed along the sheet conveyance path 49 and discharged onto the sheet discharge tray 50.

By the way, as shown in FIG. 1, the thermal head 21 is attached to a holder 35, and one end of the holder 35 is rotatably supported by a support shaft 36. Also,
A heat radiator 37 is integrally formed in the holder 35.

Furthermore, a rotating plate 38 is attached to the support shaft 36 of the holder 35, and a coil spring 39 is interposed between the rotating plate 38 and the holder 35. The thermal head 21 is pressed toward the platen drum 20 by the coil spring 39.

Furthermore, a switching means 40 is connected to the rotating plate 38 for switching the biasing force of the coil spring 39 depending on the type of ink ribbon used.

This switching means 40 includes a switching arm 42 whose midway portion is rotatably supported by a support shaft 41, and this switching arm 42.
2, and a pressure cam 43 fixedly provided at the tip of the rotary plate 38, and the pressure cam 43 is in contact with the rotating plate 38.

If the ink ribbon is, for example, a melt-type ink ribbon 24a, that is, if the pressure applied by the thermal head 21 to the ink ribbon 24a is small, the switching arm 4 may be used as the ink ribbon, as shown in FIG.
2 manually in the direction of arrow a. This results in
The coil spring 39 is expanded and the pressing force is reduced, and the pressing force of the thermal head 21 against the ink ribbon 24a is reduced.

In addition, a sublimation type ink ribbon 24b is used as an ink ribbon.
In other words, when the pressing force of the thermal head 21 against the ink ribbon 24b must be large, the switching arm 42 is rotated in the direction indicated by the arrow, as shown in FIG. As a result, the coil spring 39 is compressed, the pressing force is increased, and the thermal head 2
The pressure applied to the first ink ribbon 24b becomes large.

As described above, the pressure force of the thermal head 21 on the ink ribbons 24a, 24b is controlled by the ink ribbons 24a, 24b.
The ink ribbon 24a is switched depending on the type of ink ribbon 4b.
, 24b can be obtained. Therefore, each square ink ribbon 24a, 24
b can be used.

[Effects of the Invention] As explained above, according to the present invention, the pressure force of the thermal head against the ink ribbon is switched depending on the type of ink ribbon, so that it is possible to obtain a pressure force suitable for the type of ink ribbon. . Therefore, it is possible to use various ink ribbons with one apparatus.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIGS. 1 and 2 are explanatory views showing the switching operation of the pressure contact force of the thermal head, and FIG. 3 is an internal configuration diagram showing a color copying machine. 21... Thermal head (thermal recording head) 24...
- Ink ribbon (image forming medium), 40... switching means, P... paper (recording medium).

Claims (1)

[Claims] In a thermal transfer type image forming apparatus in which a thermal recording head is brought into pressure contact with an image forming medium to melt and transfer the colorant of the image forming medium to a recording medium, the pressing force of the thermal recording head against the image forming medium is defined as the pressure of the image forming medium. An image forming apparatus characterized by comprising a switching means for manually switching according to the type.