JP2007296717A - Printing mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing mechanism which realizes the heating and the pressurization at a low cost, and at the same time, can be miniaturized. <P>SOLUTION: This printing mechanism is equipped with a printing paper feeding mechanism (36), a thermal head (33), and a pressure mechanism (70). In this case, the printing paper feeding mechanism (36) relatively feeds out a sheet-form medium (40) by a frictional force to the sheet-form medium (40). The thermal head (33) can perform a local heating to a surface in the sheet-form medium (40). The pressure mechanism (70) controls a pressure which is locally applied to the surface of the sheet-form medium (40). The pressure mechanism (70) can control at least two stages of a high pressure state to the sheet-form medium (40) and a low pressure state of which the pressure is lower than that of the high pressure state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing mechanism technique, and more particularly to a printing mechanism technique that realizes printing with a small number of members.

  2. Description of the Related Art Conventionally, an image forming system that forms an image using a capsule encapsulating a color former or the like is known. In this type of image forming system, the capsule wall film is composed of a film made of a photocurable resin. The capsule layer is formed on a substrate to form a sheet, and the capsule layer is formed into a desired image pattern. After the exposure, the capsules that have not been exposed (cured) are crushed by applying pressure, and the color former and the like come out and color is formed on the sheet.

FIG. 10 shows a thermal printer as the image forming system.
In this thermal printer, ink is sealed inside a wall film made of a predetermined resin to form a capsule, and a capsule layer is formed on a surface of a substrate to form a sheet, and the capsule layer is formed into a desired image pattern. In response to this, the glass film is heated to a temperature higher than the glass transition temperature of the wall film, and the capsule layer is pressurized to break the wall film of the capsule and discharge the ink inside. According to this technique, it is possible to provide an image forming system that is low in cost, has little waste, and can handle colors.

JP-A-11-170692

  However, it can be seen that the technique described in Patent Document 1 has a configuration in which three thermal heads and three heat generating parts are used (thermal heads 51, 52, 53, heat generating parts 56, 57, 58). Usually, it is known that the most expensive parts among the parts constituting the printer are a head group such as a thermal head. For this reason, a normal printer realizes full-color printing by reciprocating the recording paper three times.

On the other hand, the thermal printer of Patent Document 1 uses three thermal heads, which increases the cost.
In addition, the use of a plurality of thermal heads and heat generating units may increase the overall size of the printing mechanism.
Accordingly, it has been desired to develop a printing mechanism that can achieve heating and pressurization at low cost and that can reduce the size of the printing mechanism.

The invention described in claims 1 to 3 is a printing mechanism that realizes heating and pressurization at low cost, and provides a printing mechanism that can reduce the size of the printing mechanism.
According to a fourth aspect of the present invention, there is provided a printing method that can achieve heating and pressurization at a low cost and that can reduce the size of the printing mechanism.

(Claim 1)
A sheet feeding mechanism (36) that relatively feeds the sheet-like medium (40) by a frictional force against the sheet-like medium (40), and a thermal head capable of locally heating the surface of the sheet-like medium (40) (33), and a pressure mechanism (70) for controlling the pressure applied locally to the surface of the sheet-like medium (40), the pressure mechanism (70) is a high pressure for the sheet-like medium. The printing mechanism is capable of controlling at least two stages: a high pressure state where the pressure is applied and a low pressure state where the pressure is lower than the high pressure state.

(Function)
A sheet feeding mechanism (36) conveys the sheet medium (40). The thermal head (33) heat-treats the surface of the conveyed sheet-like medium (40). After the heat treatment, the thermal head (33) pressurizes the sheet-like medium (40). This pressurizing process is controlled in two stages by the pressure mechanism (70). That is, control is performed in a high pressure state in which a high pressure is applied to the sheet-like medium and in a low pressure state at a pressure lower than the high pressure state. In other words, since the pressure mechanism (70) adjusts the pressure treatment of the thermal head (33) in two steps, high pressure and low pressure, when printing the sheet-like medium (40), stepwise and in multiple colors. Can develop color.

(Claim 2)
The invention described in claim 2 limits the print mechanism described in claim 1.
That is, the pressure mechanism (70) includes a rotating shaft (71) that enables rotation in a direction in which the thermal head (33) is pressed against the sheet-like medium (40), and a sheet-like medium with respect to the rotating shaft (71). (40) a biasing means (72, 73) for applying a biasing force in the pressing direction, and a switching mechanism (72, 73, 76, which can switch the biasing force for the biasing means (72, 73) in two stages. 78,).

(Function)
The thermal head (33) pivoted and supported by the rotation shaft (71) presses the sheet-like medium (40) by expansion or contraction of the urging means (72, 73). The urging means (72, 73) can be switched between the high pressure and the low pressure using the switching mechanism (72, 73, 76, 78).
By including the switching mechanism (72, 73, 76, 78), the applied pressure can be changed without using a plurality of thermal heads (33). For this reason, a printing mechanism with excellent cost merit can be realized.

(Claim 3)
The invention described in claim 3 limits the print mechanism described in claim 2.
That is, the switching mechanism (72, 73, 76, 78) includes a low pressure spring (72) for creating a low pressure state and a high pressure spring (73) for creating a high pressure state, and the low pressure spring (72). ) And one end of the high-pressure spring (73) are fixed to the opposite side of the head portion (33a) with respect to the rotation shaft (71) of the thermal head (33), and the non-pressure position where the high-pressure spring (73) does not work. A rotating cam (76) capable of realizing at least two stages of a high pressure position that creates a high pressure state, a motor that controls the rotation of the rotating cam (76), and the circumference of the rotating cam (76) rotated by the control of the motor An L-shaped insulator (78) that moves the surface and presses the thermal head (33) is provided.

(Function)
The rotating cam (76) is rotated by the rotating action transmitted from the motor.
If the rotary cam (76) is in the high pressure state, the high pressure spring (73) contracts, the L-shaped insulator (78) presses the thermal head (33), and the head portion (33a) becomes the recording sheet (40). Pressurize.
On the other hand, when the rotary cam (76) rotates and reaches the low pressure position, the high pressure spring (73) expands, so that the L-shaped insulator (78) moves away from the thermal head (33) and the thermal head (33) Only the head portion (33a) pressurizes the recording sheet (40).
That is, by providing the switching mechanism (72, 73, 76, 78,), when applying pressure to the recording sheet (40), a single thermal head (33) can realize different pressures of low pressure and high pressure. it can. For this reason, the printing mechanism which implement | achieves heating and pressurization at low cost is formed. Further, since the number of parts is reduced, the print mechanism can be downsized.
The high pressure spring (73) and the low pressure spring (72) may be formed as the same spring.

(Claim 4)
The invention according to claim 4 includes a paper feed mechanism that relatively feeds the sheet-like medium with a frictional force against the sheet-like medium, a thermal head capable of locally heating the surface of the sheet-like medium, And a pressure mechanism for controlling a pressure applied locally to the surface of the sheet-like medium.
That is, a sheet feeding step of moving the printing position of the sheet-like medium to the position of the thermal head by the sheet feeding mechanism, and the sheet-like medium is heated at a low temperature by the thermal head under a low pressure state by the pressure mechanism. A step, a high pressure step for applying a high pressure state by the pressure mechanism to a portion after the low temperature heating, a medium temperature heating step by the thermal head, and a medium temperature heating step for the portion after the high pressure step. In the printing method, printing on the sheet-like medium is performed on the finished portion by including a high-temperature heating step by the thermal head.

According to the first to third aspects of the invention, it is possible to provide a printing mechanism that can achieve heating and pressurization at low cost, and that can reduce the size of the printing mechanism. It was.
According to the invention described in claim 4, it is possible to provide a printing method that can achieve heating and pressurization at low cost and can reduce the size of the printing mechanism.

  Embodiments of the present invention will be described with reference to the drawings. The drawings used here are FIGS. 1 to 9. FIG. 1 is a front view showing a printing mechanism in a high-pressure state, FIG. 2 is a front view showing a printing mechanism in a low-pressure state, and FIGS. 3 to 6 are diagrams explaining a printing sheet, FIG. 7 is a schematic view showing another form of the print mechanism, FIG. 8 is a schematic view of an image forming apparatus equipped with the print mechanism, and FIG. 9 is a schematic view showing another form of FIG. FIG.

The print mechanism 30 includes a sheet feed roller (paper feed mechanism) 36 that relatively feeds the recording sheet 40 with a frictional force against the recording sheet 40, and a thermal head 33 that can locally heat the surface of the recording sheet 40. The platen roller 32 disposed opposite to the thermal head 33 and sandwiching the recording sheet 40, the pressure mechanism 70 for controlling the pressure applied locally to the surface of the recording sheet 40, and the printing mechanism 30 are controlled. And a control unit 51.

(Sheet feeding roller)
The sheet feeding roller 36 (FIG. 7) is positioned in contact with the uppermost recording sheet 40 of the sheet storage case 50, and is rotationally driven by a motor (not shown) based on a control signal from the control unit 51. . When the sheet feed roller 36 rotates, the uppermost recording of the sheet storage case 50 is interlocked with the rotation of the sheet feed roller 36 by the frictional force generated between the recording sheet 40 and the sheet feed roller 36 by the biasing force of the spring. The sheet 40 is conveyed toward the thermal head 33. The control unit 51 controls the position and the feed amount of the recording sheet 40 by controlling the rotation amount of the motor (sheet feed roller 36) based on the control signal.

(Thermal head)
The thermal head 33 includes a heating element array in which a plurality of heating elements are arranged in a line in the main scanning direction. The thermal head 33 causes each heating element to generate heat in a pattern corresponding to an image to be formed while the heating element array is in contact with the recording sheet 40. In the present embodiment, each heating element has at least three states of a non-heating state, a low temperature heating state, and a high temperature heating state, and one of these three states is selected by the control unit 51.

  The heat generation temperature of each heat generating element is controlled by the time during which a current flows through a resistor connected to the heat generating element. The control unit 51 controls the pulse width of the strobe signal that defines the time during which a current flows to each heating element of the thermal head 33 according to the heating time. The thermal head 33 may be capable of adjusting a plurality of heat generation temperatures according to the gradation of the image data in each of the low temperature coloring state and the high temperature coloring state.

(Platen roller)
The platen roller 32 is provided on the opposite side across the conveyance path of the recording sheet 40. The platen roller 32 rotates according to the conveyance of the recording sheet 40, and stabilizes the contact state between the recording sheet 40 and the heating element of the thermal head 33. A pair of conveyance auxiliary rollers that sandwich and convey the recording sheet 40 discharged from the discharge port may be provided on the downstream side of the conveyance path adjacent to the platen roller 32 and the thermal head 33.

The pressure mechanism 70 has a function capable of controlling at least two stages of a high pressure state and a low pressure state at a pressure lower than the high pressure state.
The pressure mechanism 70 has a rotary shaft 71 that enables the thermal head 33 to rotate in the direction in which the thermal head 33 is pressed against the recording sheet 40, and an urging unit that applies a biasing force in the direction in which the thermal shaft 33 is pressed against the recording sheet 40. And a switching mechanism capable of switching the urging force for the urging means in two stages.

  The switching mechanism uses the aforementioned urging means. That is, a low pressure spring 72 for creating a low pressure state, a high pressure spring 73 for creating a high pressure state, and one end of the low pressure spring 72 and the high pressure spring 73 are opposite to the head portion 33 a with respect to the rotating shaft 71 of the thermal head 33. A rotating cam 76 capable of realizing at least two stages of a non-pressure position where the high-pressure spring 73 does not work and a high-pressure position that creates a high pressure state, and a motor that controls the rotation of the rotating cam 76 (not shown) And a stepping motor that can easily control the rotation angle) and an L-shaped insulator 78 that moves the peripheral surface of the rotating cam 76 rotated by the control of the motor and presses the thermal head 33.

(Spring)
One end 72 a of the low-pressure spring 72 is formed in a hook shape, and is connected to a low-pressure spring support portion 33 b fixed to the thermal head 33. Similarly, the other end 72b in the shape of a hook is connected to a second low-pressure spring support portion 33b disposed to face the low-pressure spring support portion 33b.
One end 73 a of the high-pressure spring 73 is also formed in a hook shape, and is connected to a high-pressure spring support portion 78 b fixed to the L-shaped insulator 78. The hook-shaped other end 73b is connected to a second high-pressure spring support portion 78c that is disposed opposite to the high-pressure spring support portion 78b.
The high pressure spring (73) and the low pressure spring (72) may be formed as the same spring.

(L-shaped eggplant)
The L-shaped insulator 78 is rotatably coupled to the thermal head 33 and the rotary shaft 71, and includes an abutting portion 78a that abuts the upper portion 33d of the thermal head 33 at one end located on the thermal head 33 side. The head 33 is fixed to the side opposite to the head portion 33 a with respect to the rotation shaft 71. The other end 78d of the L-shaped insulator 78 is connected to the notch 76a of the rotating cam 76, and the high-pressure spring 73 expands and contracts according to the rotating operation of the rotating cam 76, thereby creating a high-pressure state and a low-pressure state.

(Rotating cam)
The rotating cam 76 is a rotating body that rotates in the same direction when a driving force is transmitted from the motor, and includes a notch 76a on the circumference thereof. Further, it has a function capable of realizing at least two stages of a low pressure position where the high pressure spring 73 is not effective and a high pressure position that creates a high pressure state.
That is, the state shown in FIG. 1 is a state where the end of the L-shaped insulator 78 is engaged with the notch 76a. This state is a high pressure state, and the contact portion 78a of the L-shaped insulator 78 is in contact with and pressed against the upper portion 33d of the thermal head 33. For this reason, in addition to the pressing force of only the thermal head 33, the pressing force of the L-shaped insulator 78 is also applied.

  Further, the state shown in FIG. 2 is a state in which the rotary cam 76 rotates in the direction of the arrow and the end of the L-shaped insulator 78 is detached from the notch 76a. This state is a low pressure state (no pressure), and the contact portion 78 a of the L-shaped insulator 78 is detached from the upper portion 33 d of the thermal head 33. For this reason, the pressing force which the urging | biasing force only by the low pressure spring 72 produces is applied.

Further, the cutout portion 76a of the rotating cam 76 may be configured as a cutout portion 76b as shown in FIG. In this case, the relationship between the position of the rotating cam 76, the L-shaped lever 78 and each spring is as follows.
When the L-shaped insulator 78 is at the position α in the notch 76 b, the two spring forces of the high pressure spring 73 and the low pressure spring 72 are applied to the recording sheet 40.
When the L-shaped insulator 78 is at the position β in the notch 76 b, only the high-pressure spring 73 is applied to the recording sheet 40.
When the L-shaped lever 78 is at the position γ in the notch 76b, the spring force of the high pressure spring 73 and the low pressure spring 72 is released.
Note that the spring force is released at the position of γ because the platen roller 32 made of rubber is plastic if it is stored for a long time without releasing the force between the thermal head 33 and the platen roller 32. This is because it will be deformed. For this reason, the L-shaped insulator 78 is normally located at γ.

Further, the print mechanism 30 has a paper jam discharge function.
When the link mechanism 75 of the L-shaped lever 78 is pushed rightward in FIG. 7, the L-shaped lever 78 rotates in the clockwise direction. Since the L-shaped insulator 78 contacts the end of the thermal head 33, the thermal head 33 rotates in the clockwise direction together with the L-shaped insulator 78. Then, the thermal head 33 is separated from the recording sheet 40. For this reason, a gap can be made between the thermal head 33 and the platen roller 32, and even when the paper is jammed, it can be easily discharged.

(Recording sheet)
Next, the recording sheet 40 used in this embodiment will be described with reference to FIGS.
FIG. 3 is a cross-sectional configuration diagram of the recording sheet 40 used in the present embodiment.
As shown in FIG. 3, the recording sheet 40 is configured by, for example, laminating a high-temperature coloring layer 43, a mixing preventing layer 45, a low-temperature coloring layer 47, and a protective layer 49 in this order on a substrate 41.
The recording sheet 40 includes a low-temperature color development inhibiting capsule 28 in addition to the low-temperature color development capsule 27 in the low-temperature color development layer 47. The recording sheet 40 is pressed after the low temperature coloring capsules 27 are colored at the time of image formation, and the low temperature coloring suppression capsules 28 are broken and fixed at a low temperature. Thereafter, the high temperature coloring capsule 23 is colored at a high temperature.

The substrate 41 is made of, for example, polyester or polyethylene terephthalate (PET). The base material 41 is white or transparent.
The high temperature coloring layer 43 is configured by dispersing the high temperature coloring capsule 23, the developer, and, if necessary, a basic substance or an acidic substance in a binder material. The high temperature coloring capsule 23 contains a coloring agent, for example. For example, when the high temperature coloring layer 43 reaches a temperature higher than a temperature T3 (eg, 330 ° C.) shown in FIG. 4, the color former contained in the high temperature coloring capsule 23 reacts with the developer in the high temperature coloring layer 43. Color.

  The high-temperature coloring capsule 23 is a so-called microcapsule, and its wall is made of polyurea or polyurethane having a glass transition point of 300 to 350 ° C. The high-temperature coloring capsule 23 has a characteristic that the material permeability (permeability) increases before and after the glass transition point. As a result, as shown in FIG. 5A, when the temperature is less than T3 (non-high temperature), the developer does not penetrate into the high temperature color capsule 23 and the color developer in the high temperature color capsule 23 does not develop color. On the other hand, as shown in FIG. 5B, when the temperature becomes T3 or higher (above-mentioned high temperature state), the developer in the high-temperature coloring layer 13 penetrates into the high-temperature coloring capsule 23, and the developer and the high-temperature coloring capsule The coloring agent in 23 reacts to form a dye to develop color.

The wall of the microcapsule in this embodiment such as the high-temperature coloring capsule 23 is formed of a synthetic resin such as a thermosetting resin or a thermoplastic resin. Specifically, melamine-formaldehyde polymer, urea-formaldehyde polymer, or the like is used as the wall of the high-temperature coloring capsule 23.
The average particle size of the microcapsules is, for example, about 3 to 4 μm, and the glass transition point is defined by the wall material. The microcapsule not only keeps the reacting substances in a multi-layered structure, but also disperses them in micron across the wall of the microcapsule so that it can coexist in a thin coating film of several microns at room temperature. While maintaining sufficient isolation, it has the function of giving sufficient material permeability instantaneously during heating.

The high-temperature coloring capsule 23 is configured such that, when the high-temperature coloring capsule 23 is in the above-described high temperature state, the wall is melted and the coloring agent in the capsule flows out of the capsule and reacts with the developer outside the capsule to develop color. Also good.
In the present embodiment, the combination of the color former and the developer that reacts with the color developer includes, for example, a combination of a diazo compound (color developer) and a coupler (developer), or an electron-donating colorless dye (color developer). And an electron-accepting compound (developer). It is known that an arbitrary hue can be colored by a combination of a chemical structure of a diazo compound and a chemical structure of a coupler, or a combination of a chemical structure of an electron-donating colorless dye and a chemical structure of an electron-accepting compound.

The diazo compound is, for example, tricresyl phosphate. The diazo compound is an electron donating dye precursor (dye precursor), and reacts with a coupler in a basic atmosphere to develop a color. The coupler is, for example, resorcil or phloroglucin, and forms a dye by coupling with a diazo compound in a basic atmosphere. The basic atmosphere is made of a hardly water-soluble or water-insoluble basic substance or a substance that generates alkali by heating (for example, an organic ammonium salt).
The electron-donating colorless dye is, for example, a leuco dye, and the electron-accepting compound is, for example, a phenolic acidic substance. In this combination, the leuco dye is adsorbed by the developer, which is an acidic substance, and oxidized to develop a color.

Moreover, as said coupler, 2-hydroxy-3 naphthoic acid anilide etc. are used, for example.
Moreover, as said electron-accepting compound, acidic substances, such as a phenol compound, an organic acid or its metal salt, and oxybenzoic acid ester, are used, for example.

  Further, in the present embodiment, the case where the color former is encapsulated in the microcapsule is exemplified. For example, the color former and the developer are dispersed and arranged in the binder, and the binder is melted by overheating to cause the color former. The developer may react with the developer.

  The mixing preventing layer 45 is a layer for preventing the capsules from being mixed between the high temperature coloring layer 43 and the low temperature coloring layer 47.

  The low-temperature coloring layer 47 is constituted by dispersing a low-temperature coloring capsule 27, a developer, a low-temperature coloring suppression capsule 28, and, if necessary, a basic substance or an acidic substance in a binder material. The low-temperature coloring capsule 27 encloses a coloring agent, and the glass transition point of the wall is a low temperature of 90 to 140 ° C., for example. For example, when the low temperature coloring layer 47 is in a low temperature state at a temperature T1 (eg, 110 ° C.) or higher shown in FIG. 4, the color former contained in the low temperature coloring capsule 27 reacts with the color former in the low temperature coloring layer 47. Color develops. Except for the glass transition point of the wall of the low temperature coloring capsule 27, the principle of coloring is the same as that of the high temperature coloring capsule 23.

  In the present embodiment, no pressure is required as a condition for the reaction between the color former contained in the high-temperature color-development capsule 23 and the low-temperature color-development capsule 27 and the external developer.

As shown in FIG. 6A, the low-temperature color development inhibiting capsule 28 contains a low-temperature color development inhibitor that inhibits the color development function of the low-temperature color development layer 47 in a normal pressure (non-destructive pressure) state.
As shown in FIG. 6 (B), the low temperature coloring suppression capsule 28 is in a broken state (or infiltrated state) when a pressure higher than the breaking pressure P1 shown in FIG. 3 is applied. The capsule 28 is allowed to flow out.
The breaking (penetration) pressure of the microcapsules such as the low-temperature color development inhibiting capsule 28 is defined by the relationship between the diameter and wall thickness of the microcapsules and the wall material.
The low-temperature color development inhibitor contained in the low-temperature color development inhibition capsule 28 includes, for example, one or more substances among a color development agent in the low-temperature color development capsule 27, a developer in the low-temperature color development layer 47, a basic substance, and an acidic substance. It has the function of changing the chemical structure so as not to cause a chemical reaction, or the function of preventing the formation of a dye even when a chemical reaction occurs.
The low-temperature color development inhibiting capsule 28 may have a function of suppressing the color development reaction by changing the material permeability of the capsule wall of the low-temperature color development capsule 27 to reduce the permeability.
In this embodiment, the temperature condition is not particularly necessary as a condition for the low temperature color development inhibitor contained in the low temperature color development inhibition capsule 28 to flow out of the capsule.

When the low-temperature coloring layer 47 develops a color with a combination of an electron-donating colorless dye (color-developing agent: for example, a leuco dye) and an electron-accepting compound (developer: for example, an acidic substance), Phosphoric acid esters, tetrahydrophthalic acid, fatty acid esters, dihydric alcohol esters, epoxy plasticizers, or trimet acid plasticizers are used.

  The protective layer 49 is a layer for protecting the low temperature coloring layer 47. The protective layer 49 has, for example, a heat resistance function.

  In the present embodiment, the thickness of the high temperature coloring layer 43 and the low temperature coloring layer 47 is, for example, 1 to 4 μm.

The operation of the printing mechanism 30 described above is as follows.
The sheet feeding roller 36 conveys the recording sheet 40 stored in the sheet storage case. The head portion 33a of the thermal head 33 heats the surface of the conveyed recording sheet 40. After the heat treatment, the head portion 33 a of the thermal head 33 performs a pressure treatment on the recording sheet 40. This pressurization process is controlled in two stages, low pressure and high pressure.

When a command for low-pressure processing is given, the other end 78d of the L-shaped insulator 78 is grounded to the peripheral surface other than the notch 76a of the rotating cam 76. Accordingly, the high-pressure spring 73 extends between the high-pressure spring support portion 78b and the second high-pressure spring support portion 78c, and the contact portion 78a of the L-shaped lever 78 is separated from the upper portion 33d of the thermal head 33. In this state, the recording sheet 40 is pressurized only by the thermal head 33.

  When a high-pressure processing command is issued, the rotating cam 76 rotates counterclockwise (in the direction of the arrow), and the other end 78d of the L-shaped insulator 78 is fitted into the notch 76a. Then, the high-pressure spring 73 contracts between the high-pressure spring support portion 78b and the second high-pressure spring support portion 78c, and the contact portion 78a of the L-shaped insulator 78 contacts and presses the upper portion 33d of the thermal head 33. In this state, the pressure of the L-shaped insulator 78 is applied to the pressure of the thermal head 33 on the recording sheet 40. The control of the low pressure and the high pressure is controlled by a control unit (not shown).

That is, since the pressurizing process can be adjusted in two stages, high pressure and low pressure, when the recording sheet 40 is printed, a plurality of colors can be developed step by step without requiring a plurality of thermal heads. This contributes to the realization of a low-cost printing mechanism. In addition, since this printing mechanism is composed of a single thermal head, it contributes to miniaturization of the printing mechanism.

(Image forming device)
FIG. 8 is a schematic diagram of an image forming apparatus 90 equipped with the print mechanism 30B.
In the print mechanism 30B, the angles of the thermal head 33 and the L-shaped lever 78 are different, but the configuration of the print mechanism 30 described above is the same except for the above.
The image forming apparatus 90 employs a one-head, one-pass method that can continuously color the high-temperature coloring layer and the low-temperature coloring layer. Here, one head is the thermal head 33, and one pass is a printing method in which an image can be formed by the recording sheet 40 only passing through the thermal head 33 once.

The image forming apparatus 90 includes a plurality of photoconductors that carry a latent image, a charging unit that charges the surface of the photoconductor, and an exposure unit that exposes the surface of the charged photoconductor based on image data and writes the latent image. A developing means for supplying toner to the latent image formed on the surface of the photosensitive member to make it visible; a transferring means for transferring the visible image on the surface of the photosensitive member to transfer paper or an intermediate transfer member; And at least cleaning means for cleaning the surface of the photoreceptor.
Since the image forming apparatus 90 is equipped with the print mechanism 30B, heating and pressurization can be realized at a low cost. Further, since the printing mechanism is downsized, it contributes to downsizing of the image forming apparatus 90.

FIG. 0 is a schematic diagram of an image forming apparatus 90 equipped with a print mechanism 30C.
The printing mechanism 30 </ b> C is that the low-pressure spring 72 and the high-pressure spring 73 are installed and the tip of the L-shaped insulator 78 is pivotally supported by the rotating shaft 71 and connected to the thermal head 33. Other than the above, the other configurations are the same as those of the print mechanism 30 and the print mechanism 30B described above.
In this way, since the protruding portion can be reduced, the image forming apparatus 90 can be further downsized.

  Note that although the print mechanism 30 in the present embodiment is applied to an image forming apparatus, the present invention is not limited to this. For example, it can also be used for an imaging device (camera with a printing mechanism).

It is the front view which showed the printing mechanism of the high voltage | pressure state. It is the front view which showed the printing mechanism of the low voltage | pressure state. It is a section lineblock diagram of a recording sheet. FIG. 4 is a diagram for explaining the characteristics of a high-temperature coloring capsule, a low-temperature coloring capsule, and a low-temperature coloring suppression capsule in the recording sheet shown in FIG. 3. It is a figure for demonstrating the color development principle of the color capsule shown in FIG. It is a figure for demonstrating the coloring suppression effect of the low temperature coloring suppression capsule shown in FIG. It is the schematic which showed the other form of the printing mechanism. 1 is a schematic view of an image forming apparatus equipped with a print mechanism. It is the schematic which showed the other form of the image forming apparatus carrying a printing mechanism. It is the figure which showed a part of conventional thermal printer.

Explanation of symbols

23 High temperature coloring capsule 27 Low temperature coloring capsule 28 Low temperature coloring suppression capsule 30, 30B, 30C Printing mechanism 32 Platen roller 33 Thermal head 33a Head portion 33b Low pressure spring support portion 33c Second low pressure spring support portion 33d Upper portion 36 Sheet feed roller 40 Recording sheet 41 Substrate 43 High-temperature coloring layer 45 Mixing prevention layer 47 Low-temperature coloring layer 49 Protective layer 50 Sheet storage case 51 Control unit 70 Pressure mechanism 71 Rotating shaft 72 Low-pressure spring 72a, 73a One end 72b, 73b The other end 73 High-pressure spring 75 Link mechanism 76 Rotating cams 76a, 76b Notch portion 78 L-shaped insulator 78a Contact portion 78b High pressure spring support portion 78c Second high pressure spring support portion 78d Other end 90 Image forming apparatus

Claims (4)

A paper feeding mechanism that relatively feeds the sheet-like medium with frictional force against the sheet-like medium;
A thermal head capable of locally heating the surface of the sheet-like medium;
A pressure mechanism for controlling a pressure applied locally to the surface of the sheet-like medium,
The printing mechanism is capable of controlling at least two stages of a high pressure state in which a high pressure is applied to a sheet-like medium and a low pressure state in which the pressure is lower than the high pressure state. The pressure mechanism includes a rotation shaft that enables rotation in a direction in which the thermal head is pressed against the sheet-like medium;
A biasing means for imparting a biasing force in a direction of pressing the sheet-shaped medium against the rotation shaft;
The printing mechanism according to claim 1, further comprising a switching mechanism capable of switching an urging force to the urging means in two stages. The switching mechanism includes a low pressure spring for creating a low pressure state and a high pressure spring for creating a high pressure state,
One end of the low-pressure spring and the high-pressure spring is fixed to the opposite side of the head portion with respect to the rotation axis of the thermal head, and at least two stages of a non-pressure position where the high-pressure spring does not work and a high-pressure position that creates a high-pressure state are realized. Possible rotating cams,
A motor for controlling the rotation of the rotating cam;
The printing mechanism according to claim 2, further comprising an L-shaped lever that moves the circumferential surface of the rotating cam rotated by the control of the motor and presses the thermal head. A paper feeding mechanism that relatively feeds the sheet-like medium with frictional force against the sheet-like medium;
A thermal head capable of locally heating the surface of the sheet-like medium;
A pressure mechanism for controlling a pressure applied locally to the surface of the sheet-like medium, and a control method for a printing mechanism,
A paper feeding step of moving the printing position of the sheet-like medium to the position of the thermal head by the paper feeding mechanism;
For the sheet-like medium, a low-temperature heating step by the thermal head under a low pressure state by the pressure mechanism,
A high-pressure process for giving a high-pressure state by the pressure mechanism to the part that has finished the low-temperature heating;
For the part that has finished the high-pressure process, an intermediate temperature heating process by the thermal head,
A printing method for executing printing on the sheet-like medium by including a high-temperature heating step by the thermal head for a portion where the intermediate temperature heating step has been completed.