JPH07239627A - Image forming device and image forming method - Google Patents

Abstract

PURPOSE:To form bright images and to reduce the size and cost of an image forming device by providing the device with a means for forming a toner image by removing the unnecessary toners adhered onto a sheet by magnetic force and a means for transferring and fixing the toner images formed on this sheet to a recording material. CONSTITUTION:This image forming device has a heat resistant endless type sheet 7 supported by >=2 pieces of rollers, a toner supplying means for supplying magnetic toner 6 onto the sheet 7 and a thermal head 1 which is disposed on the rear surface side of the sheet 7 and heats the toner in contact with the sheet 7. This thermal head 1 melts the magnetic toner 6 to a half molten state by heating from the rear surface side of the heat resistant endless type sheet 7, thereby forming the toner image. The unnecessary toner on the sheet 7 where the heat energy by the thermal head 1 is not impressed is removed by magnetic force. The toner image formed on the heat resistant endless type sheet 7 is transferred and fixed onto the recording material. Since a voltage applying means is not used, the size of the device is reduced and splashing of the toner to the non-image parts does not arise. The bright image can be thus formed.

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 and an image forming method used for plain paper copying machines, printers, plain paper facsimiles and the like. More specifically, the present invention relates to an image forming apparatus and an image forming method for forming a toner image on a heat-resistant endless sheet by a thermal head using a heat-meltable magnetic toner, and transferring and fixing the toner image on a recording material.

[0002]

2. Description of the Related Art In recent years, as an image recording method for recording recorded information as an image, various printers and recording materials are used to form various images on the image. The method is known. Typical examples are laser beam printers,
Examples include electrophotographic printers such as LED printers, magnetography printers, wire dot printers, thermal printers (using a thermal head), and the like.

The electrophotographic printer described above is capable of forming a clear image, but has a problem that the apparatus itself is expensive and the running cost is high. Further, in the wire dot printer, although the device itself is not so expensive, there are problems that an obtained image is thin and not clear, and that a printing sound during image formation is loud.

On the other hand, the thermal printer has the advantage that it can form a clear image and the apparatus itself is inexpensive, but on the other hand, an expensive thermal image recording medium (so-called ink ribbon) or thermal paper must be used. Therefore, the running cost is high, and there is a problem that high smooth paper must be used.

Therefore, in the thermal printer,
It is desired to develop a product that solves the above problems while taking advantage of advantages such as a clear image and a low device cost, and various products have been proposed so far. Among them, a method of forming a toner image by a thermal head using a heat-meltable toner, and then transferring and fixing the toner image (Japanese Patent Laid-Open Nos. 2-173669 and 3-258,
JP-A-3-5191) and a method of simultaneously performing fixing while forming a toner image with a thermal head using a heat-meltable toner (Japanese Patent Publication No. 3-13).
No. 071) is the mainstream.

However, in these methods,
Once the toner layer is formed on the sheet, the printing cost increases when there is a large amount of unnecessary toner, and when collecting and reusing the unnecessary toner, the toner agglomerates collected by heat are collected and reused. Therefore, the sharpness of the image may decrease. Further, a method of applying a voltage at the time of applying toner is used, and there is a problem that the sharpness of an image is deteriorated when the chargeability of the toner changes depending on temperature and humidity. Further, in the case where the unnecessary toner is not removed before the transfer / fixing or the toner image is directly formed on the recording material by the thermal head, there are problems that the sharpness of the image is deteriorated and the background stain occurs. .

Therefore, the object of the present invention is to reduce the amount of unnecessary toner collected and to reduce the printing cost, and at the same time, to use the advantages of the above thermal printer without using a voltage applying means when applying toner or removing unnecessary toner. It is an object of the present invention to provide an image forming apparatus and an image forming method, which make it possible to reduce the size and cost of the apparatus while keeping the image clear.

[0008]

The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, as a result of carrying out the toner conveyance and the removal of unnecessary toner by magnetic force using a magnetic toner, a voltage applying means is provided. Therefore, the present invention has been completed, and the present invention has been completed.

That is, the gist of the present invention is (1) a heat-resistant endless sheet supported by two or more rollers, a toner supply means for supplying a magnetic toner onto the sheet, and a rear side of the sheet. A thermal head that heats the toner that is placed on the sheet and that heats the toner that is in contact with the sheet, a means that removes unnecessary toner that has adhered to the sheet by magnetic force, and a toner image that is formed on the sheet is transferred to a recording material. An image forming apparatus comprising: a fixing unit, and (2) a step of supplying magnetic toner onto a heat-resistant endless sheet supported by two or more rollers and bringing the magnetic toner into contact therewith, and The step of applying thermal energy according to image information from the back side of the sheet to the magnetic toner in contact with the magnetic toner and the unnecessary magnetic toner to which the thermal energy is not applied are magnetically applied. Forming a toner image is removed,
And an image forming method comprising a step of transferring and fixing the toner image formed on the sheet.

In the image forming method of the present invention, by using the magnetic capsule toner having a low temperature fixing property, the amount of heat supplied to the thermal head and the amount of heat necessary for fixing can be reduced to save power.

[0011]

According to the present invention, magnetic toner is supplied and brought into contact with a heat-resistant endless sheet supported by two or more rollers by utilizing magnetic force or the like, and the magnetic toner brought into contact with the sheet is backside of the sheet. From the side, thermal energy is applied from the side by a thermal head in accordance with image information to deposit the toner in a semi-molten state on the sheet, and magnetic energy is applied to the unnecessary magnetic toner that is not applied with thermal energy but is deposited on the sheet. The toner image formed on the sheet is transferred and fixed on the recording material after the toner image is removed by the above method to form a toner image.

In the present invention, the magnetic toner is conveyed and the unnecessary toner is removed only by the magnetic force without applying the voltage applying means at the time of applying the toner or removing the unnecessary toner, so that the apparatus can be downsized and the cost can be reduced. It is also possible to print on plain paper, and there is no need to use heat sensitive paper. Further, in the present invention, since the unnecessary magnetic toner is substantially removed after the application of heat energy, a clear image can be obtained, and the background stain particularly in the non-image portion can be reduced.

[0013]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

FIG. 1 is a block diagram showing an example of the image forming apparatus of the present invention. As shown in FIG. 1, the image forming apparatus of the present invention includes a heat-resistant endless sheet supported by two or more rollers, a toner supply unit for supplying magnetic toner onto the sheet, and a back side of the sheet. It has a thermal head that heats the toner that is disposed and that contacts the sheet.

A thermal head 1 has a function of applying thermal energy according to image information. Such a thermal head is not particularly limited as long as it can bring the magnetic toner into a semi-molten state by heating from the back surface side of the heat-resistant endless sheet, and is used for an ordinary heat-sensitive facsimile. Those used in thermal transfer printers can be used. Here, the semi-molten state is a state in which the toner adheres to the sheet to the extent that the toner is not separated from the sheet by the magnetic force of the unnecessary toner removing means described later.

A signal generator 2 is means for electrically supplying a signal as image information to the thermal head. This is also not particularly limited as long as these functions can be achieved by combination with the above-mentioned thermal head. For example, one used for a thermal type facsimile or one used for a thermal transfer printer can be used. it can.

Reference numeral 3 denotes a magnet roll, which is not limited in shape, material and the like as long as the magnetic toner attracts magnetic toner to the sleeve 4 by suction. It is possible to use an electrophotographic magnetic one-component system or one that can be used during the development of magnetography. At least one of the magnet roll 3 and the sleeve 4 may be rotated.

Reference numeral 4 denotes a sleeve, which has a function of supplying the toner attached to the surface by rotation to the heat-resistant endless sheet. As the sleeve 4, a non-magnetic one is usually used. In the present invention, since it is not necessary to apply a voltage to this sleeve and the heat-resistant endless sheet 7 described later, it is not necessary to use a conductive material for both.

A toner amount control blade 5 has a function of controlling the layer thickness of the toner on the sleeve 4 and controlling the amount of toner supplied onto the heat-resistant endless sheet to be uniform. As the blade, one having rigidity such as stainless steel, or one having elasticity such as urethane or silicon rubber is used.

The present invention is characterized in that the thermal head 1 (for example, a line type thermal head) is arranged on the opposite side of the toner supply means with the heat-resistant endless sheet 7 interposed therebetween. The head 1 is normally in contact with the back surface side of the heat resistant endless sheet 7, and the sleeve 4
Is preferably separated from the sheet so that the heat supplied to the sheet is not transferred. In the embodiment of FIG. 1, the toner supply unit and the thermal head are arranged facing each other and close to each other,
At the same time when the magnetic toner is supplied, thermal energy is applied by the thermal head.

As the heat-resistant endless sheet 7, for example, polyester such as polyethylene terephthalate and polybutylene terephthalate having a thickness of about 20 μm, polyimide,
It is possible to use an endless sheet or the like in which a heat-resistant resin such as polyetherimide is coated with a release layer of 10 μm at least on the image contact surface side with a conductive material added to a fluororesin such as Teflon or PFA.

The heat-resistant endless sheet 7 is usually supported by two or more rollers, but FIG. 1 shows an example in which it is supported by two supporting rollers and one heat roller. The number of support rollers is not particularly limited, and may be three, for example.
It may be four. One of these supporting rollers is used as a driving roller, and the rest is driven rollers, and the heat-resistant endless sheet 7 is driven by a rotation driving means (not shown) while applying tension to the heat-resistant endless sheet 7 in a constant circumferential direction without sagging. It can be transported at high speed.

In the above structure, by applying thermal energy corresponding to image information to the magnetic toner supplied on the heat-resistant endless sheet 7 from the back side of the sheet by the line type thermal head 1. The magnetic toner can be attached to the sheet in a semi-molten state. However, at this point of time, the toner adheres to the non-image portion as well, and it is necessary to remove the toner by a removing unit described later to form a toner image.

As shown in FIG. 1, the image forming apparatus of the present invention has means for forming a toner image by magnetically removing unnecessary toner on a sheet to which thermal energy is not applied by the thermal head 1. . By this method, the amount of unnecessary toner can be reduced as compared with the case where the toner is attached to the entire surface of the sheet and the unnecessary toner is removed.

Reference numeral 10 denotes a magnet roll, which may be similar to the above-mentioned toner supply means. The magnet roll may be fixed or rotating. Reference numeral 11 denotes a sleeve, which may be similar to the above, but the sleeve may be omitted. Magnet roll 1 if there is no sleeve
0 and the heat-resistant endless sheet 7 usually have a gap of 3.0 mm or less.

A scraping blade 12 removes the magnetic toner 6 adhered and removed on the sleeve 11 from the sleeve 1.
1 Has the function of scraping and collecting from above. As the scraping blade 12, a blade similar to the above toner amount regulating blade, a fur brush, or the like is used. By removing the unnecessary toner in this manner, a toner image made of semi-molten toner is formed on the heat-resistant endless sheet 7. FIG. 1 shows an example in which the unnecessary toner removing means is arranged so as to face the supporting roller. In this case, it is possible to obtain an effect that the sheet of the unnecessary toner removing portion does not bend. However, the present invention is not limited to the above-mentioned arrangement, and may be arranged at a position apart from the support roller as shown in FIG.

As shown in FIG. 1, the image forming apparatus of the present invention has means for transferring and fixing a toner image formed on a heat-resistant endless sheet to a recording material, which makes it possible to reduce the size and size of the apparatus. This makes it possible to form a clear image without toner scattering to the image area. As such means,
As shown in the figure, the heat roller 9 and the pressure roller 13 sandwich the heat-resistant endless sheet 7 and the recording material 14, and the total pressure is 4 to 20 k.
A means of pressing with g is used. Alternatively, in another embodiment of the present invention, the magnetic toner may be preheated on the heat-resistant endless sheet, and sandwiched by two pressure rollers and pressed against each other. A thermal head or the like may be used instead of the heat roller. In the embodiment of FIG. 1 of the present invention, the transfer and the fixing are simultaneously performed and the recording material is separated from the sheet. However, as shown in FIG. 3, after the transfer and the fixing, the sheet and the recording material are brought into close contact with each other, and the sheet is cooled. The recording material may be separated. As a result, it becomes possible to use a toner having a low melt viscosity that normally causes offset, and further power saving can be achieved.

As the pressure roller, a cored bar made of iron, aluminum or the like and coated with a rubber elastic layer is used. Regarding the rubber elastic body, it is necessary to adjust its heat resistance appropriately according to the fixing temperature, but from heat resistant materials such as heat resistant silicone rubber and fluoro rubber to inexpensive elastic materials such as urethane rubber are used as appropriate. can do.

As the heat roller, a quartz heater lamp, a halogen lamp, a heating element such as a heating element is used as a heat source in a cored bar made of iron, aluminum or the like, and the cored bar is coated with a thin film of Teflon, PFA or the like. Hard roller, or a soft roller having the same structure as the pressure roller,
Further, various types in which a cored bar is coated with a conductive elastomer can be used.

As described above, according to the present invention, the transfer and the fixing are simultaneously performed without applying the voltage. Therefore, the apparatus can be simplified, downsized and the cost can be reduced regardless of the charging behavior of the toner. Further, since the toner transfer efficiency is very high, the need for cleaning after transfer and fixing is small. If necessary, a cleaning pad made of felt impregnated with a releasing agent such as silicone oil may be provided. Further, it is possible to form a clear image without the toner scattering to the non-image portion. Further, it is possible to print on plain paper without the need to use a special recording material such as thermal paper.

The image forming method of the present invention comprises the steps of supplying and contacting magnetic toner onto a heat-resistant endless sheet supported by two or more rollers, and the magnetic toner contacting the sheet with the back surface of the sheet. From the side, a step of applying thermal energy according to image information by a thermal head, a step of removing unnecessary magnetic toner to which no thermal energy is applied by magnetic force to form a toner image, and a step of forming on the sheet It is characterized in that it has a step of transferring and fixing the toner image. The above-described image forming apparatus can be preferably used in the image forming method of the present invention.

The magnetic toner used in the image forming method of the present invention is not particularly limited as long as it is a heat-meltable magnetic toner. Therefore, the toner used is a magnetic toner obtained by a pulverization classification method, a magnetic polymerized toner, or
It may be any of magnetically encapsulated toners which are functionally separated from each other in storage stability, fixability and offset resistance.

Examples of the magnetic toner obtained by the pulverization / classification method include toners obtained by melting and kneading a magnetic material, a colorant, a charge control agent, a binder resin and other additives, pulverizing and classifying. . Examples of the magnetic polymerized toner include those obtained by dispersing a magnetic material, a colorant and the like in a polymerizable monomer.

As the magnetic capsule toner, for example, an interfacial polymerization method in which reactive substances are separately supplied from two liquid phases which are not mixed with each other to form a polymer phase at the interface, or a mixed aqueous solution of an ionic polymer colloid is used to surround a core substance. Complex coacervation method that causes phase separation in the polymer, in situ polymerization method in which a reactant is supplied only around the aqueous solution to polymerize the reactants around the core material, and the core material is dispersed in a polymer non-aqueous solution or a polymer emulsion, and this dispersion is performed. Capsule toner obtained by a generally known method such as a spray drying method in which a liquid is spray-dried (JP-A-58-176).
642, JP-A-58-176643, JP-A-61-56352, and JP-A-63-128357.
JP-A-63-128358, JP-A-1-
267660, JP-A-2-51175, etc.)
In the production of, a core material and / or a shell material containing a magnetic material may be used.

Among the above-mentioned toners, a low temperature fixing magnetic capsule toner capable of fixing at a low temperature is used to save power by reducing the amount of heat supplied to a thermal head for information application and fixing, and to use a fixing roller. In some cases, heat resistance is not required, so inexpensive rollers can be used, resulting in cost reduction and size reduction.

As such a low temperature fixable magnetic capsule toner, for example, the following thermal dissociation type capsule toner and capsule toner whose outer shell is made of amorphous polyester are preferably used.

As the heat dissociation type capsule toner, as described in JP-A-4-212169, a divalent or higher valent isocyanate compound and / or isothiocyanate is added to a monomer containing a colorant and optionally a wax. By polymerizing a polymerizable composition containing a compound, simultaneously with a compound having a divalent or more phenolic hydroxyl group and / or a thiol group, suspended in an aqueous dispersion medium in the presence of a dispersant. An example of the heat dissociation type encapsulated toner that is obtained is that the structure of the toner shell changes due to heat, and the core material is released and fixed when pressure is applied.

As a capsule toner having an outer shell made of amorphous polyester, as described in Japanese Patent Application No. 4-259088, a heat-meltable core material containing at least a thermoplastic resin and a colorant, and the core material thereof. A low-temperature fixing type capsule toner characterized in that it is composed of an outer shell provided so as to cover the surface of, and the outer shell is made of amorphous polyester.

As the recording material to be used, it is not necessary to use heat sensitive paper or highly smooth paper, and plain paper or even OHP film can be used.

The present invention is not limited to the above-mentioned embodiment, and it is possible to appropriately change the specifications such as the type and arrangement of each member based on the principle of the present invention.

Other aspects of the image forming apparatus of the present invention are as follows.

A heat-resistant endless sheet supported by two or more rollers, a toner supply means for supplying a magnetic toner onto the sheet, and a sheet facing the toner supply means sandwiching the sheet.
A thermal head that is arranged in close proximity to heat the toner that comes into contact with the sheet, a unit that removes unnecessary toner that adheres to the sheet by magnetic force to form a toner image, and a toner image that is formed on the sheet An image forming apparatus comprising: a unit for transferring and fixing to a recording material.

[0043]

According to the present invention, the following effects can be obtained. (1) Since the magnetic toner is conveyed and unnecessary toner is removed only by the magnetic force without using the voltage applying means, the apparatus can be simplified, downsized, and reduced in cost. (2) The toner system eliminates the need to use an expensive thermal image recording medium (so-called ink ribbon) or thermal paper. (3) After applying the heat energy, substantially all of the unnecessary magnetic toner is removed, so that a clear image can be obtained, and especially, the dirt on the non-image portion can be reduced. (4) Since the amount of unnecessary toner attached to the heat-resistant endless sheet and collected later is small, the toner consumption amount is small and the printing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an image forming apparatus of the present invention.

FIG. 2 is a schematic view showing an example of an image forming apparatus of the present invention.

FIG. 3 is a schematic view showing an example of an image forming apparatus of the present invention.

[Explanation of symbols]

 1 Thermal Head 2 Signal Generator 3 Magnet Roll 4 Sleeve 5 Toner Amount Control Blade 6 Magnetic Toner 7 Heat Resistant Endless Sheet 8 Support Roller 9 Heat Roller 10 Magnet Roll 11 Sleeve 12 Scraping Blade 13 Pressure Roller 14 Recording Material

Claims (3)

[Claims] 1. A heat-resistant endless sheet supported by two or more rollers, toner supply means for supplying magnetic toner onto the sheet, and toner provided on the back side of the sheet and contacting the sheet. A thermal head for heating, means for removing unnecessary toner adhering to the sheet by magnetic force to form a toner image, and means for transferring and fixing the toner image formed on the sheet to a recording material. An image forming apparatus characterized by. 2. A heat-resistant endless sheet supported by two or more rollers, toner supply means for supplying magnetic toner onto the sheet, and toner provided on the back side of the sheet and contacting the sheet. A thermal head for heating, a means for removing unnecessary toner adhering to the sheet by a magnetic force, which is arranged facing the supporting roller, to form a toner image, and a toner image formed on the sheet is transferred to a recording material. An image forming apparatus comprising a fixing unit. 3. A step of supplying and contacting magnetic toner onto a heat-resistant endless sheet supported by two or more rollers,
A step of applying thermal energy corresponding to image information from the back side of the sheet to the magnetic toner in contact with the sheet by a thermal head, and removing unnecessary magnetic toner to which no thermal energy is applied by magnetic force to obtain a toner image And a step of transferring and fixing the toner image formed on the sheet.