JPS6388563A - Exothermic sheet for thermomagnetic recorder - Google Patents

Abstract

PURPOSE:To increase the intensity of a magnetic field by distributing many nonconductors into a resistance layer or conductive layer at a prescribed density. CONSTITUTION:The many nonconductors 22 are distributed at the prescribed density into the resistance layer 18 or the conductive layer 20. The nonconductors are so specified as to satisfy d<=lambda/2<=5d to form the relative spacings to the extent at which about 2-10 particles of a magnetic toner stick between the noninversionally magnetized regions so as to correspond to the nonconductors of a magnetic latent image where the average grain size of the magnetic toner is designated as (d). The nonconductors are so formed as to satisfy l<=L/2 where the width size of the contact with the resistance layer is designated as L. Resins such as polycarbonate into which carbon particles are dispersed are used in addition to metals such as nickel chromium as the resistance layer. The magnetic toner is thereby uniformly stuck even to the central part of the magnetic latent image without generating much Joule heat.

Description

Detailed Description of the Invention Technical Field The present invention relates to a heat generating sheet for a thermomagnetic recording device, and in particular to a technique for preventing the phenomenon in which magnetic toner does not adhere to the center of a magnetic latent image pattern when developing a magnetic latent image pattern. It is related to.

2. Description of the Related Art A thermomagnetic recording device is known that forms a latent image on a magnetized film made of a ferromagnetic material by locally heating or generating heat. For example, JP-A-58-526
This is the device described in Japanese Patent Application Laid-Open No. 58-1) No. 178. Usually, such devices apply magnetism to a magnetized film by reversing the magnetization of a desired region of the magnetized film having a magnetization pattern such as - to form an image called magnetography or thermomagnetography. A latent image is formed. This reversal magnetization utilizes the so-called thermal remanent magnetization phenomenon, and is the remanent magnetization obtained by heating the magnetized film to around its Curie temperature and cooling it to room temperature in an external magnetic field. Compared to the case of magnetization using only a magnetic field, remanent magnetization close to saturation remanent magnetization can be obtained with a small external magnetic field.

By the way, when developing a magnetic latent image formed by reverse magnetization in a predetermined region of a magnetized film in a negative direction, magnetic toner tends to adhere to the periphery of the predetermined region, and toner tends to adhere to the center portion. On the other hand, there is a phenomenon in which it is difficult to adhere to the film, which has the disadvantage of impairing image quality.

On the other hand, by cooling the heated portion of the magnetized film in a high-frequency alternating magnetic field, the magnetic latent image can be made up of a collection of minute inverted magnetized portions, or the minute magnetic latent image should be formed in advance. By placing a magnetic layer with an infinite number of magnetized parts close to the magnetized film, and thereby locally magnetizing the heated part of the magnetized film, the magnetic latent image is made up of a collection of fine magnetized parts. It is considered to do.

Problems to be Solved by the Invention However, the above-mentioned former method requires a relatively large and expensive high-frequency power source and electromagnet to form a high-frequency alternating magnetic field, and the latter method requires The magnetization reversal could not be reliably performed unless the strength of the magnetic field was relatively weak and a large amount of Joule heat was generated in the resistance layer.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The gist of this is that in a thermomagnetic recording device that forms a magnetic latent image on a magnetized film and records an image based on the magnetic latent image, a current is locally passed through contact with an electrode. The magnetized film is provided with a resistive layer that generates heat exclusively locally, and the Joule heat generated locally in the resistive layer is transmitted to the magnetized film directly or indirectly through a conductive layer layered on the resistive layer. The heating sheet is characterized in that a large number of non-conductors are distributed at a predetermined density in the resistive layer or the conductive layer.

Operation and Effects of the Invention In this way, since a large number of non-conductors are distributed at a predetermined density in the resistive layer or the R conductive layer stacked on top of each other, the non-conductor is formed by passing current from the electrode to the conductive layer. When the heat in the heat generating region is conducted to the magnetized film in close contact with the four-electric layer, the magnetized film is heated except for the region corresponding to the location where the non-conductor is located. Therefore, in the magnetic latent image formed on the magnetized film, a large number of regions corresponding to the locations where the non-conductor is located are not reversely magnetized and remain at a predetermined density.

Therefore, it is possible to uniformly adhere the magnetic toner even in the center of the magnetic latent image without preparing a relatively large and expensive high-frequency power source and electromagnet or generating a large amount of Joule heat in the resistive layer. .

Here, if the interval period between the non-conductors is λ, and the average particle diameter of the magnetic toner used for developing the magnetic latent image is d, then the non-conductors preferably have d≦λ/2≦ 5d.

In other words, the state of adhesion of magnetic toner is determined by the fact that a relative interval is formed between regions of the magnetic latent image that are not reversely magnetized corresponding to non-conducting materials, such that about 2 to 10 particles of magnetic toner are attached. The density of the non-conductor or the size of the sides of the non-conductor is selected to achieve uniformity as desired.

Moreover, when the contact width dimension of the electrode with respect to the resistance layer is L, the non-conductor is preferably arranged so as to satisfy λ≦L/2. In other words, in order to maintain image resolution, it is desirable that the size of the heat-generating region formed by energization in the resistive layer be at least twice as large as the spacing period λ of the non-conducting material. The sizes of the body sides are selected accordingly.

In addition to metals with high specific resistance such as nickel chromium, the resistance layer may also be formed of a film having high specific resistance by dispersing carbon particles in a resin such as polycarbonate. Further, the conductive film is preferably formed of an aluminum or copper thin film. Further, the non-conductive material is distributed at a predetermined density in the resistive layer or the conductive layer, and preferably a material having a lower thermal conductivity than the conductive layer is selected.

For example, resin powder such as polyimide or ceramic powder is used.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, an electrode drive circuit 10 to which an image signal is supplied from a controller (not shown) selectively supplies a drive signal for drawing a magnetic latent image to a plurality of electrodes 12 arranged in a normal column. A current is made to flow from the heat generating sheet 12 to the heat generating sheet 14.

A magnetized 1i'J16 made of ferromagnetic material is brought into contact with the surface of the heat generating sheet 14 opposite to the surface that is in contact with the electrode 12. This magnetized film 16 constitutes the outer peripheral surface of a magnetic drum or magnetic belt of a thermomagnetic recording device. This magnetized film 16 is adapted to be moved relative to the electrode 12 together with the heat generating sheet 14.

As shown in FIG. 2, the heat generating sheet 14 consists of a resistor Ji 18 that is in sliding contact with the electrode 12 and a conductive layer 20 laminated thereon. The resistance layer 18 is made of a metal film having a relatively high resistance value, such as nickel chromium or tungsten, and a sheet resistance of about 10 to 10&Ω/hole. The conductive layer 20 is made of a good field material such as aluminum or copper,
The current flowing from the electrode 12 to the resistance layer 18 by contact with a roller electrode (not shown) for reflux is guided to the roller electrode. A large number of non-conductors 22 made of ceramic or resin are regularly dispersed in the conductive layer 20 at a predetermined density. The non-conductive material 22 is a fine particle having heat resistance and insulation properties, and has a lower thermal conductivity than the conductive layer 20. Let λ be the interval period between the non-conductors 22,
If the average particle size of the magnetic toner used to develop the magnetic latent image formed on the magnetized film 16 is d, then the non-conductor 22 has a shape that satisfies d≦λ.
/2≦5d.

That is, 2 to 10 magnetic toner particles are present between the regions that are not reversely magnetized and correspond to the non-conductive material 22 in the magnetic latent image.
It is desirable to form a relative interval such that approximately 100% of the magnetic toner adheres in order to obtain uniformity in the adhesion state of the magnetic toner. so selected. Furthermore, if the contact width dimension of the electrode 12 with respect to the resistance layer 18 is L, the non-conductor 22 is arranged so as to satisfy λ≦L/2. In other words, from the viewpoint of maintaining image resolution, it is desirable that the minimum width dimension of the heat generating area formed by energization in the resistive layer 18 is at least twice the interval period λ of the non-conductive material 22. The density of 22 or the individual size of non-conductors 22 is selected accordingly.

In the thermomagnetic recording device using the heat generating sheet 14,
When a drive current is supplied from the electrode drive circuit 10 to the electrode 12, the current is passed through the portion of the resistance layer 18 that is in contact with the electrode 12, as shown by the arrow pointing from the electrode 12 to the conductive layer 20 in FIG. This causes local heat generation due to Joule heat. At this time, since the non-conductor 22 (indicated by diagonal lines in the figure) is distributed at a predetermined density on the conductive layer 20 laminated on the back surface of the resistor 1) 8 as described above, Since the current flowing to the conductive layer 20 avoids the non-conductor 22 and concentrates on the remaining portion, the temperature of the portion in contact with the non-conductor 22 is relatively low in the heating region of the resistor N18, and the non-conductor 22 The temperature of the parts that are not in contact with is relatively high. During this heat generation, the magnetized film 16, which is uniformly magnetized in one direction, is brought into close contact with the heat generating sheet 14.

The heat in the heat generating region of the resistor 7518 is conducted to the magnetized film 16 closely attached to the heat generating sheet 14 through the conductive layer 20. The arrow pointing from the resistance layer 18 to the magnetized film 16 in FIG. 4 indicates the direction of heat conduction.

As a result, a region of the magnetized film 16 having a pattern similar to the heat generating region in the resistance layer 18 is heated to near the Chierly temperature. Since such heating is performed in an external magnetic field formed in a direction opposite to the magnetization direction of the magnetized film 16 by a magnetic field forming device (not shown), the magnetized film 16 is heated in the heat generating sheet 14 as shown in FIG. When the heated portion is cooled by being separated from the magnetized film 16, reversed magnetization in the same direction as the external magnetic field is formed in the locally heated portion of the magnetized film 16, thereby forming a magnetic latent image with a pattern similar to that of the heat generating region in the resistance layer 18. It is formed.

When the magnetized film 16 is heated by heat conduction from the resistive layer 18 to the conductive layer 20, the heat flow is blocked by the non-conductive material 22 uniformly distributed in the conductive layer 20, and the non-conductive material of the magnetized film 16 is The part corresponding to the body 22 is not heated so much and does not reach near the Curie temperature. For this reason,
In the magnetic latent image pattern formed on the magnetized film 16, a small region corresponding to the non-conductor 22 maintains the original magnetization direction, so that fine reversed magnetization is formed in the remaining region. P in FIG. 5 indicates such a magnetic latent image portion.

Therefore, when the magnetized film 16 on which the magnetic latent image is formed as described above is sent to a developing process and sprinkled with magnetic toner 24, the magnetic toner 24 adheres to the magnetic latent image portion of the magnetized film 16, and an image appears. However, as mentioned above, within the magnetic latent image pattern, the original magnetization direction is maintained in a small region corresponding to the non-conductor 22, and a finely reversed magnetization is formed in the remaining region, as shown in FIG. Furthermore, a leakage magnetic flux 26 is also formed in the central portion of the magnetic latent image, and the magnetic toner 24 is uniformly adhered to the peripheral portion. Therefore, it is possible to record images of a thermomagnetic recording device without preparing a relatively large and expensive high-frequency power source and electromagnet for forming a high-frequency alternating magnetic field, and without generating a large amount of Joule heat in the resistance layer. Quality can be improved. Note that in FIGS. 3 to 6, arrows in the magnetized film 16 indicate magnetization directions.

Next, another embodiment of the present invention will be described. In the following description, the same parts as in the above-mentioned embodiments are given the same reference numerals, and the description thereof will be omitted.

As shown in FIG.
28 and a conductive sheet 30 laminated thereon may be used. The non-conductor 34 distributed at a predetermined density in the conductive layer 30 is made of the same material as the non-conductor 22 described above, but is in the form of particles and has a conductive layer 34.
It is irregularly mixed in. Even in this case, the relationship between the non-conductive material 34, the average particle diameter d of the magnetic toner, and the width dimension (2) of the electrode 12 is the same as in the previous embodiment. In this embodiment as well, heat conduction from the resistive layer 28 to the magnetized film 16 is locally inhibited by the non-conductor 34 in the conductive layer 30, so that the same effect as in the previous embodiment can be obtained.

Further, as shown in FIG. 8, the heat generating sheet 40 is composed of only a resistive layer, and the electrodes 42 are in sliding contact with the resistive layer.
The heating sheet 40 may be made to locally generate heat by applying a voltage between them. Heat generating sheet 4 in this case
0, a non-conductive material similar to the conductive layer 20 or 30 of the above-described embodiment is distributed at a predetermined density. In this embodiment as well, the non-conductor does not generate heat in the local heat-generating portion of the heat-generating sheet 40, and heat is not sufficiently conducted to the portion of the magnetized film 16 corresponding to the non-conductor. is maintained and fine reversed magnetization is formed in the remaining area, so the magnetic toner adheres uniformly to the central part of the magnetic latent image as well as to the peripheral part.

Although the embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects.

For example, in the heat generating sheets 14 and 32 of FIGS. 2 and 7, the non-conductors 22 and 34 are distributed within the conductive layers 20 and 30, respectively, while the resistive layer 1
8 and 28.

In this case, the Joule heat generated in the resistors 1)B and 28 except for the small non-conducting portions 22 and 34 is transferred in the plane direction as it passes through the conductive layers 20 and 30, so the magnetized film There is a feature that the boundary line of the magnetic latent image at 16 is appropriately sized.

Furthermore, the non-conductors 22 and 34 in the above-mentioned embodiments do not need to be complete insulators; for example, the conductors 22 and 34
If the conductive layer is distributed within 30, it may be a metal having a higher resistivity than the conductive layer, such as copper or aluminum. In this case, the thermal conductivity is rather higher than that of the conductive layer 2.
Materials with lower thermal conductivity than 0 and 30 are suitable, and are expressed this way because generally speaking, the thermal conductivity is lower as the conductivity becomes poorer than that of the good conductor. Also, for example, the resistance layer 18
and 28, the non-conductor 22
and 34 need only be a material that has a higher specific resistance than the resistance layers 18 and 28 and generates relatively less Joule heat.

Furthermore, the resistive layer 18.28 may not only be made of a metal having a high specific resistance, but may also be made of, for example, a polycarbonate resin with carbon dispersed therein so as to have a predetermined sheet resistance value. .

Note that the above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing the configuration of a thermomagnetic recording device including an embodiment of the present invention. FIG. 2 is an enlarged perspective view illustrating the configuration of the heat generating sheet shown in FIG. 1. FIG. Figure 3, Figure 4,
and FIG. 5 are diagrams each illustrating the thermomagnetic recording operation of the apparatus shown in FIG. FIG. 6 is a diagram showing the state of adhesion of magnetic toner. FIG. 7 is a diagram corresponding to FIG. 2 showing another embodiment of the present invention. Figure 8 shows another type of thermomagnetic recording device.
FIG. 12.42: Electrodes 14.32, 40: Heat generating sheet 16: Magnetized film 18.28: Resistive layer 20.3 (l) Conductive layer 22.34: Non-conductive material Applicant Brother I Co., Ltd. Z Figure 4 Figure 6 I◇B

Claims (3)

[Claims] (1) In a thermomagnetic recording device that forms a magnetic latent image on a magnetized film and records an image based on the magnetic latent image, local heat is generated by bringing an electric current into contact with an electrode and locally flowing it. The heating sheet is provided with a resistive layer, and transmits Joule heat locally generated in the resistive layer to the magnetized film directly or indirectly via a conductive layer laminated on the resistive layer. A heat generating sheet for a thermomagnetic recording device, characterized in that a large number of non-conductors are distributed at a predetermined density in the resistive layer or the conductive layer. (2) The non-conductor has a spacing period of λ between the non-conductors.
The thermomagnetism according to claim 1, which is arranged so that d≦λ/2≦5d, where d is the average particle size of the magnetic toner used for developing the magnetic latent image. Heat generating sheet for recording devices. (3) The non-conductor has a spacing period of λ between the non-conductors.
The heat generating sheet for a thermomagnetic recording device according to claim 1, wherein the heat generating sheet for a thermomagnetic recording device is arranged so as to satisfy λ≦L/2, where L is a contact width dimension of the electrode with respect to the resistance layer.