JPH04156345A - Printing apparatus - Google Patents

Abstract

PURPOSE:To obtain the good printing quality due to an electrophotographic system by a simple mechanism like a thermal transfer system by adsorbing toner on the surface of a toner transfer film coated with wax and melting the wax partially to bond the toner to the molten part and transferring the toner of a non-bonded part to printing paper. CONSTITUTION:Toner is held on a wax layer 19 by electrostatic attraction force and, when the wax layer reaches the front of a thermal head 3, heat is generated in a part generating no printing pixel. The heater 21 provided to the leading end of the thermal head 3 heats the PET layer 20 and wax layer 19 of the part (a) generating no printing pixel. In succession to this process, a toner transfer film 1 holds a definite gap from printing paper 4 by the tension roller 8 of the printing paper and the tension roller 10 of the toner transfer film to reach the front of a corotron 7. Herein, the toner of the part not heated at the position of the thermal head 3 is adsorbed on the printing paper 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dot matrix, which is one of the peripheral devices of personal computers and the like.

[Conventional technology] As prior art related to the present invention, (A) Electrophotographic printing device (B) Thermal transfer printing device There is.

Among these, electrophotographic printing devices charge the surface of a medium such as a photoreceptor drum or photosensitive film that generates/moves a charge upon photoexcitation in advance, and then exposes it to light to create an electrostatic latent image. A printed image is formed by transferring toner adsorbed to an electrostatic latent image onto printing paper.

In addition, a thermal transfer printing device presses a film surface coated with an ink material onto a printing paper, heats the film from the back surface using a minute heating element, and transfers the melted ink material onto the printing paper.

[Problems to be Solved by the Invention] Among the conventional techniques, in the case of electrophotography, the exposure device that controls printing is an obstacle to simplifying the mechanism. There was a problem with the structure.

Further, with regard to the thermal transfer method, there is a problem in that when the surface of the printing paper has low smoothness, uneven transfer occurs, resulting in poor quality of printed characters.

The present invention was invented to improve the problems of these conventional methods, and its purpose is to obtain good print quality like the electrophotographic method with a simple mechanism like the thermal transfer method. It is in.

[Means for Solving the Problems] The printing apparatus of the present invention includes means for charging a toner transport film coated with wax and adsorbing toner on the surface of the toner transport film, and a toner transport film adsorbing the toner. and a means for partially heating the toner transport film, and a means for heating the toner transport film, which is arranged via a printing paper that is transported without contact with the toner transport film, and a toner transport film that is partially heated by the heating means. The present invention is characterized in that it includes a transfer means for transferring the toner in the portion that was not present onto the printing paper.

1 action] The printing device of the present invention operates as follows.

Due to the operation of the toner adsorption means prior to printing, the toner transport film is energized 41'i, and the toner is adsorbed onto the surface. Next, when the heating means partially heats the toner transport film adsorbing the toner, the heated wax layer melts at 75 parts of the toner transport film, and the toner adheres to the wax in the melted parts. do.

Therefore, when the next step is to transfer toner to printing paper using a transfer means, only the toner in the areas where the wax has not melted (that is, the areas that have not been heated) will be transferred to the printing paper to form a printed image. It turns out.

[Embodiment] FIG. 1 shows a schematic perspective view of an embodiment of the printing apparatus of the present invention. Further, FIG. 2 shows a sectional view of FIG. 1. In the printing apparatus of this embodiment, when forming an image to be printed, toner is transferred onto printing paper and fixed by pressure. The l·ner used here is the same as the fine particles of resin containing pigment that have been conventionally used in electrophotographic printing apparatuses. Therefore, both the toner adsorption means that adsorbs the toner to the toner transport film and the transfer means that transfers the toner to the printing paper,
A method using electrical attractive force exerted by an electric field is employed. The configuration and printing procedure will be explained below using FIGS. 1 and 2.

1 is a toner transport film, and as shown in FIG.
℃ glycerin monostearard was evenly applied to a thickness of 2 pm. The surface coated with glycerin monostearard is the surface facing the printing paper 4. As the wax to be applied, paraffin wax, oleic acid amide, etc. can be similarly used, and polyhydric alcohol esters other than glycerin monostearard can also be used as long as their melting points are in the range of 50°C to 80°C.

The toner conveying film 1 is maintained without loosening/sagging by the tension roller 16, and is wound up by the film winding roller 2. At this time, the winding direction is as indicated by arrow B in FIG. )・The surface of the toner transport film 10 is covered with a magnetic roller 9 which serves as a toner adsorption means during movement.
When it reaches the front surface of the l-ner 18, it is adsorbed. Here, the container 17 contains a mixture of fine magnetic powder and toner, and the toner transport film 1 comes into contact with the toner that has adhered to the magnetic brush 11 generated in the magnetic lines of force on the surface of the magnetic roller 9. A voltage is applied to the magnetic roller 9 by an electrode 14 so as to generate a potential difference of about 300V to 700V between it and the electrode 15, and the toner 18 is attracted to the toner transport film 1 by the attraction force in the direction of the counter electrode 15. Adsorbs to the surface. Such means are similar to those conventionally used in electrophotographic printing apparatuses. It is similar to the so-called "developing process" in recent electrophotography, in which the I-ner is adsorbed by electrical attraction.
In particular, it is not necessary to supply toner by means of a magnetic brush, unless instability occurs.

Therefore, there is no restriction that the l.toner that should be in the toner storage container 17 must be of a two-component type mixed with magnetic powder. However, in this embodiment as well, it is necessary to adsorb the toner onto the toner transport film surface rriT in a manner as uniform as possible. In order to solve this problem, the toner 18 used in this example has a polystyrene resin as a component of 85% or more, and contains about 2% of a nigrosine derivative to give the toner a positively charged property. FIG. 3 shows the state after the toner transport film 1 has passed through the front surface of the container 17. Here, the toner 18 is held by the wax layer 19 by electrostatic attraction. When the toner transport film 1 in such a state reaches the front surface of the thermal head 3, which serves as a heating means, the thermal head 3 is driven by an electrical signal for printing control, and operates to generate heat in areas that do not produce printing pixels. This is illustrated using FIG. A heating element 21 at the tip of the thermal head 3 heats the PET layer 20 and wax layer 19 in a portion a where no printed pixels are generated. As a result, the heated part a
The wax layer 19 melts and retains the toner 18 by wetting the wax to the toner 18. On the other hand, the toner 18 is still only attracted by electrostatic attraction in the portion that has not been heated.

In a typical thermal transfer printing device, at this time, part of the heat is radiated to the printing paper that is in contact with the ink ribbon.

For this reason, the thermal energy required to actually print one pixel is often greater than the energy required to melt the wax ink.In contrast, in this example, only the wax portion melts. To do this, the required thermal energy is about 0.1 m joule per pixel.Following this process, the toner transport film 1 is heated by the tension roller 8 of the printing paper and the tension roller 10 of the I/toner transport film. The toner is kept at a constant gap from the printing paper 4 and reaches the front surface of the corotron 7, which is the transfer means.Here, the toner in the portion that was not heated at the position of the thermal head 3 mentioned above is removed from the printing paper 4. On the other hand, in the heated part, the wax melts and adheres the toner, and then solidifies again in about a few milliseconds, and the toner is not peeled off by the attraction force caused by the electric charge.

As a result, only the toner in the portions that were not heated in the previous process is transferred to the printing paper 4.

The printing paper 4 is conveyed in six directions indicated by arrows by paper feed rollers 5.1 and 12, and the attracted toner is fixed under pressure by a pressure roller 6. Further, the surface charge of the toner transport film 1 is removed by a static eliminating brush 13, and the toner transport film 1 is wound up by a winding roller 2.

The following effects can be pointed out in the printing apparatus realized by the embodiment described above.

First, the conveyance speed of the printing paper 4 and the conveyance speed of the toner conveyance film 1 do not need to be equal.

This is because the printing paper 4 and the toner transport film 1 are not in contact with each other, and cannot be realized by a printing apparatus using a normal thermal transfer method. In thermal transfer printing devices, there is a problem that a large amount of ink ribbon is consumed, but in this embodiment,
- By setting the feed speed of the toner transport film lower than the feed speed of the printing paper, 0.5 to 0.7 m of the toner transport film can be consumed for printing 1 m of printing paper.

Second, the wax 1 to be applied to the toner transport film 1
It can be pointed out that No. 9 is better in that it has a thinner layer compared to wax ink for thermal transfer printing equipment.

For this reason, the amount of heat input per pixel is 0°1m
Joule or more. Furthermore, since there is no contact with the printing paper 4, there is no excess heat radiated to the printing paper, which is suitable for reducing power consumption.

Third, the wax to be applied to the toner transport film 1]
9 has the advantage of being a single component.

In thermal transfer printing equipment, when pigments are included in wax ink, it is necessary to disperse them appropriately, and the addition of a dispersant is essential. The toner transport film of this embodiment also allows for an inexpensive construction in this respect.

Fourth, since the mechanism for forming an image is not in contact with the printing paper 4, it is possible to obtain printed character quality that does not depend on the smoothness of the surface of the printing paper.

The fifth advantage, and perhaps the biggest advantage, is that electrophotographic printing devices cannot stop a series of printing processes midway through, whereas this embodiment It can be pointed out that it is possible to stop the conveyance of the I-ner conveying film 1 and the printing paper 4 even at this point in time, and to interrupt the conveyance at -. Currently, many printing devices called page printers adopt a method of setting a description language that uniformly describes graphic pixels, character information, etc., and printing an image formed by successive translation of the description language. If such means are used,
It is known that a huge storage area is required when a processor in a printing device replaces graphics that occupy a large portion of a page with pixels. Like electrophotography method 1
If it is not possible to interrupt the process in the middle of printing a page, it is necessary to continuously transfer the pixels to the exposure device after all the pixels to actually be printed are generated, so at the very least, there is no chance of data transfer. This is because a storage area is required to hold the necessary number of pixels. However, since the cost of semiconductor memory is high compared to other parts of printing equipment, the uninterruptibility of the process is a factor that drives up the unit cost of equipment for electrophotographic methods. Ta. In contrast, in this embodiment, data transfer can be performed at the stage when the image has been developed and the print data has been completed, and can be interrupted any number of times. This reduces the burden on the processor of the control circuit, minimizes the amount of semiconductor memory that must be mounted, and, as a result, makes it possible to keep the unit price of the device low.

[Effects of the Invention] The present invention adsorbs toner on the surface of a toner transport film coated with wax, melts the wax partially by heating means, adheres the toner to the melted portion, and removes the toner from the unadhered portion. Since the image is transferred to the printing paper by a transfer means, an exposure device and a photosensitive medium are not required, and an image can be formed using an inexpensive and common mechanism (I2). Moreover, since the transfer is performed without contact between the toner transport film and the printing paper, even if the surface of the printing paper has low smoothness, there is no transfer unevenness and good print quality can be obtained. have

[Brief explanation of drawings]

FIG. 1 is a perspective view of the configuration of an embodiment of the printing apparatus of the present invention. FIG. 2 is a sectional view taken from the configuration diagram in FIG. 1. FIG. 3 is an explanatory diagram of l/ner adsorption. FIG. 4 is an explanatory diagram of the toner and thermal head portions. 1... Toner transport film 2... Film take-up roller 3... Thermal head 4... Printing paper 5... Paper feed roller 6... Pressure roller 7... Corotron charger 8...・Tension roller 16...Tension roller 18...Toboo-19...Wax layer 20...PET layer 21...Heating element and above Applicant Seiko Epson Co., Ltd. Representative Patent Attorney Kisanbe Meiki et al. 1 person

Claims (1)

[Claims] A means for charging a toner transport film coated with wax and adsorbing toner to the surface of the toner transport film, a means for partially heating the toner transport film that has adsorbed the toner, and a means for partially heating the toner transport film by the heating means. A transfer means is provided with respect to the toner transport film via the printing paper that is transported in a non-contact state with the toner transport film, and transfers the toner of the unheated portion of the toner transport film to the printing paper. A printing device featuring: