KR20160104465A - Thermosensitive sheet - Google Patents

Abstract

The present invention relates to a thermosensitive sheet. According to an embodiment of the present invention, the thermosensitive sheet comprises: a base layer having a first surface and a second surface facing the first surface; a reaction layer laminated on the first surface of the base layer; and a coating layer laminated on the first surface of the base layer. The coating layer is laminated more remotely from the first surface of the base layer than the reaction layer, and includes a hydrophobic material or an ultraviolet curable resin. Therefore, the thermosensitive sheet can suppress discoloration phenomena.

Description

Thermal Response Sheet {THERMOSENSITIVE SHEET}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-reactive sheet, and more particularly, to a heat-sensitive sheet used in a portable photo printer.

With the development of digital technology, miniaturized cameras have been installed in various mobile devices including mobile terminals. Thus, the user can easily take a picture regardless of place and time. Furthermore, a portable printer has been developed that adopts a printing system that is simple in structure and can be miniaturized, in accordance with a demand of a user who wants to output a photographed image immediately from anywhere.

In the dye sublimation method, heat is applied to the print head to dissolve the thermosensitive ink ribbon, and the ink ribbon is transferred to print a predetermined shape on the paper. The dye sublimation method may include a space for mounting the ink ribbon in the photo printer and a separate means for driving the ink ribbon.

On the contrary, in the direct thermal method in which a special paper which expresses a predetermined color in response to heat is used, a separate ink ribbon is not needed because the dye is already included in the production of the paper, so that the disadvantage of the above- can do.

The paper used in the photo printer forming an image through the above-described direct thermal method is a thermal reaction sheet.

Such a thermal reaction sheet has a multi-layer structure. Generally, the thermal reaction sheet is laminated in the order of a base layer, a reaction layer, and a coating layer. More specifically, the base layer functions as a support for the reaction layer and the coating layer, and the reaction layer exhibits a predetermined hue upon heating, and the coating layer plays a role of protecting the reaction layer from external shocks or foreign substances .

On the other hand, most of the coating layer which is a constituent of the conventional heat-sensitive sheet mainly contains a hydrophilic polymer. However, when a coating layer is formed using a hydrophilic polymer, a significant problem arises. Specifically, when the thermally responsive sheet on which image formation is completed is left for a long time in an exposed state rather than in a closed space, a phenomenon that the hydrophilic polymer of the coating layer reacts with moisture in the air causes discoloration or durability deterioration .

That is, as time elapses, the image formed on the heat-responsive sheet can not maintain the initial sharpness for a long time. As a result, the coating layer that is laminated to protect the reactive layer can rather have the adverse effect of reducing the sharpness of the color expressed in the reactive layer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-resistant sheet capable of suppressing discoloration due to moisture by improving moisture resistance.

According to an aspect of the present invention, there is provided a semiconductor device comprising: a base layer having a first surface and a second surface opposite to the first surface; a reaction layer stacked on the first surface of the base layer; And a coating layer laminated on the first surface of the base layer, wherein the coating layer is laminated farther from the first surface of the base layer than the reaction layer and comprises a hydrophobic substance or a UV curable resin , A heat-responsive sheet is provided.

The effect of the heat-sensitive sheet according to the present invention will be described below.

According to at least one embodiment of the present invention, moisture resistance is improved by using a hydrophobic substance as a main component of the coating layer, thereby preventing discoloration of the coating layer due to bonding with moisture.

Alternatively, according to at least one of the embodiments of the present invention, a coating layer is formed using a material having a glass transition temperature lower than the reaction temperature, at which the reaction layer exhibits a predetermined color, The fluidity of the reaction layer reaching the temperature can be secured. Thereby, color reproduction of the reaction layer can be performed quickly and smoothly.

According to at least one of the embodiments of the present invention, by forming a buffer layer between the reaction layer and the coating layer, it is possible to reduce the phenomenon that a force due to thermal deformation or expansion of the reaction layer affects the coating layer have.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

1 is a block diagram for explaining a photo printer related to the present invention.
2 is an exploded perspective view of a photo printer according to the present invention.
3 is a perspective view of the photo printer related to the present invention as viewed from the outside.
4 is a side cross-sectional view taken along the line AB shown in FIG. 3 (a) for explaining a sheet feeding process of the photo printer related to the present invention.
FIG. 5 is an exemplary view for explaining a process of forming an image on a sheet of paper according to the present invention.
6 is a cross-sectional view schematically showing a multilayer structure of a general thermal reaction sheet.
7 is an exemplary view for explaining a durability deterioration phenomenon occurring in the thermal reaction sheet shown in Fig.
8 is an exemplary view showing a multi-layer structure of a thermal reaction sheet according to an embodiment of the present invention.
9 is a cross-sectional view illustrating various multilayer structures that a thermal reaction sheet according to an exemplary embodiment of the present invention may have.
FIG. 10 is a graph exemplarily showing reaction conditions that the three different reaction layers shown in FIG. 9 (b) can have.
FIG. 11 is an exemplary view showing a state in which only one of the reaction layers of the thermal reaction sheet shown in FIG. 9 (b) is expressed.
FIG. 12 is an exemplary view showing a state in which two or more colors of the reaction layers of the heat-reactive sheet shown in FIG. 9 (b) are expressed.
13 is an exemplary view showing a multilayer structure of a thermal reaction sheet according to another embodiment of the present invention.
14 is an exemplary view showing a multilayer structure of a thermal reaction sheet according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals are used to designate identical or similar elements, and redundant description thereof will be omitted. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. , ≪ / RTI > equivalents, and alternatives.

Terms including ordinals, such as first, second, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

1 is a block diagram for explaining a photo printer 100 according to an embodiment of the present invention.

1, a photo printer 100 according to an exemplary embodiment of the present invention includes a communication unit 110, an operation unit 120, an output unit 130, a sensing unit 140, a memory 150, a power unit 160, A transfer unit 170, an image forming unit 180, and a control unit 190. [

The communication unit 110 connects the photo printer 100 to an external device through a wired / wireless network. Here, the external device is not limited to a portable electronic device such as a smart phone, but may be a fixed electronic device such as a desktop, and is not particularly limited as long as the device can communicate with the photo printer 100. The communication unit 110 is connected to an external device and can transmit / receive various information including image data (e.g., photographed photo file) from an external device. To this end, the communication unit 110 may include at least one module that enables wired communication or wireless communication. Specifically, the communication unit 110 may include a short-range communication module 111 and a wired communication module 112.

The near field communication module 111 supports contactless communication with an external device. The short-range communication module 111 may be at least one of Bluetooth, Radio Frequency Identification (RFID), Infrared Data Association (IrDA), ZigBee, Near Field Communication (NFC), and Wi-Fi It is possible to receive image data and various commands or information related to the operation of the photo printer 100 from an external apparatus by supporting short-range communication using one.

The wired communication module 112 supports contact communication with an external device. The wired communication module 112 may include a memory card port, a USB port, and the like, and is directly connected to an external device to support transmission and reception of various information including image data, as in the case of the near field communication module 111.

The operation unit 120 includes at least one operation module operatively associated with the operation of the photo printer 100. [ For example, the operation unit 120 may include a first operation module 121 and a second operation module 122. [ The first operation module 121 can be interlocked with the power on / off function of the photo printer 100. The first operation module 121 can operate power on / off of the photo printer 100 in a physical manner such as a slide switch method or a button method. For example, the user can move the first operation module 121 to the left side to turn the power of the photo printer 100 on or move the power to the right side to turn off the power. The second operation module 122 may be a reset button.

The memory 150 stores data supporting various functions of the photo printer 100. [ The memory 150 may store application programs necessary for driving the photo printer 100, data for performing various operations related to image printing, and image data received through the communication unit 110 together with instructions. At least some of these applications may be stored in the memory 150 from the time of shipment. Alternatively, at least a part of the application program may be transmitted from an external server or an external device via the communication unit 110. An application program stored in the memory 150 may be installed in the photo printer 100 under the control of the control unit 190. [

The sensing unit 140 may sense various information generated inside or outside the photo printer 100. The sensing unit 140 may include a paper detection sensor 141, a temperature sensor 142, an opening and closing sensor 143, a horizontal sensor 144, and a mark recognition sensor. First, the paper detection sensor 141 is disposed in the paper conveyance path, and detects the presence or absence of the paper in the conveyance path. For example, the paper detecting sensor 141 may be disposed at a position adjacent to the loading unit 165 on which the paper is loaded. It is determined whether the illuminance value, which varies as the paper is covered by the paper, is less than a predetermined value, Can be detected. Alternatively, the paper detecting sensor 141 may include a light emitting portion and a light receiving portion. The paper detecting sensor 141 may detect whether or not the paper is seated in the loading portion according to the distance or time that light emitted through the light emitting portion is reflected and returned to the light receiving portion have. If the control unit 190 receives the print command for the predetermined image data in a state in which the paper is not detected through the paper detection sensor 141, the control unit 190 can guide the user to the absence of paper through the output unit 130 . The temperature sensor 142 detects whether the battery or the motor is operating at a temperature within the normal range.

The temperature sensor 142 transmits a corresponding signal to the control unit 190 when the battery or the motor is operating at a temperature outside the normal range (i.e., low temperature or superheat), and the control unit 190 controls the output unit 130, The information corresponding to the signal input from the temperature sensor 142 can be output in a form recognizable to the user.

The horizontal sensor 144 detects whether the photo printer 100 is placed horizontally with respect to the ground. The controller 190 detects the angle of the gravitational direction with respect to the main body of the photo printer 100 based on the information provided from the horizontal sensor 144, It can be judged whether or not it is horizontally seated on the ground. When the control unit 190 determines that the photoprinter 100 is not horizontally mounted on the ground, the predetermined information is output through the output unit 130 so that the user can select the inclination of the photoprinter 100 You can be guided to change your posture.

The opening / closing sensor 143 senses whether or not the first case 101A and the second case 101B, which will be described later, are fastened together. The control unit 190 can stop the operation of the image forming unit 180 when it senses that the first case 101A and the second case 101B are not engaged with each other through the opening and closing sensor 143. [

A mark recognition sensor (not shown) reads the mark displayed on the paper and recognizes information about the paper. For example, on the bottom surface of the paper, information related to the characteristics of the paper may be displayed in a barcode format. The mark recognition sensor sequentially reads the barcode information of the paper along the paper feed direction. The image forming unit 180 is controlled in accordance with the detected barcode information, so that an image can be printed with an optimum image quality suited to the sheet.

The output unit 130 outputs information on the status of the photo printer 100 to the outside. The output unit 130 may include a light emitting module 131, a display module 132, a haptic module 133, a sound module 134, and the like.

The light emitting module 131 may flicker or change color at different periods according to the state of the photo printer 100. The plurality of light emitting modules 131 may be provided at different positions in the body of the photo printer 100.

The display module 132 displays various information processed by the photo printer 100. For example, the display module 132 may display print progress, failure information, remaining battery power, battery information, a preview image of an image to be formed, and the like. The display module 132 may be coupled to the photo printer 100 so as to be tiltable along one side thereof.

The sound module 134 outputs sound corresponding to the state of the photo printer 100 (e.g., completion of charging, paper jam, no paper, printing completion, and the like).

The haptic module 133 generates vibration having a predetermined intensity or pattern according to a predetermined condition or input. The intensity or pattern of the vibration generated by the vibration module 212 may be different for each state of the photo printer 100. [ For example, when the image data is transmitted from the external device through the communication unit 110, the haptic module 133 vibrates once for a long time to the first intensity, and when the printing according to the received image data is completed, the haptic module 133 vibrates twice .

The power supply unit 160 receives an external power supply or an internal power supply under the control of the controller 190 and supplies power required for operation of each component. The power supply unit 160 may include a battery. The battery may be an internal battery configured to be rechargeable, and may be detachably coupled to the case and replaced with another battery. In addition, the power supply unit 160 may include a charging port 161 connected to an external power source for charging the battery. For example, the charging port may be a micro USB type port. The charging port can be connected to a wired cable in addition to the power supply, and can have a function of transmitting and receiving data.

The transfer unit 170 includes at least one motor 171 and a pickup roller 172. The pick-up roller 172 rotates in the forward direction (the direction in which the sheet is fed along the sheet feeding direction) or the reverse direction through the driving force transmitted from the motor 171, Lt; / RTI > The motor 171 may be driven or stopped under the control of the controller 190, or the rotational speed of the pickup roller 172 may be increased or decreased by varying the driving force.

The image forming unit 180 forms an image on a sheet conveyed by the conveying unit 170. [ The image forming unit 180 converts electrical energy supplied from the power supply unit 160 into heat energy through a plurality of heat generating resistors, and applies the heat energy to the paper. The paper is gradually conveyed along the paper feeding direction through the conveying unit 170 and at the same time, different colors are developed according to the size and time of the heat applied from the image forming unit 180, so that the images from the front end to the rear end are formed do.

The control unit 190 controls the overall operation of the photo printer 100. The control unit 190 processes signals, data, information, and the like input or output through the above-described components or drives an application program stored in the memory 150 so that an image corresponding to the image data can be properly formed on the paper . The control unit 190 generates print data that can be processed by the image forming unit 180 based on the image data transmitted from the external device. The control unit 190 may control the power supply unit 160 to supply appropriate power to the respective heating resistors of the thermal head 181 according to the print data.

1 are not essential to the implementation of the photo printer 100, so that the photo printer 100 described herein may have more or fewer components than the components listed above, Lt; / RTI >

2 is an exploded perspective view of a photo printer 100 according to an embodiment of the present invention.

Referring to FIG. 2, various components may be mounted inside the case while forming the appearance of the photo printer 100, and some components may be partially exposed to the outside through the outer surface of the case. Such a case may include a first case 101A and a second case 101B. The first case 101A and the second case 101B are provided on the outermost side of the photo printer 100 to support internal components and function as a buffer.

The first case 101A separates the various components disposed therein from the ground by a predetermined distance. The second case 101B may be formed to be engageable with the first case 101A. For example, one end of the second case 101B may be hinged to one end of the first case 101A. In addition, the other end of the second case 101B may be formed in a structure detachable from the other end of the first case 101A. All or a part of each of the components described above with reference to Fig. 1 may be disposed in the inner space formed by the first case 101A and the second case 101B.

Specifically, the loading unit 165, the transfer unit 170, the guide unit 210, and the image forming unit 180 may be disposed in the inner space of the first case 101A. That is, since the stacking unit 165, the transferring unit 170, and the image forming unit 180 are arranged in parallel along one row, the total size of the photo printer 100 can be reduced.

The paper is seated in the loading section 165. Since the paper size may have a predetermined error, the loading unit 165 may be formed to have a predetermined value larger than the predetermined paper size so that the clearance can be provided. The mounting portion 165 may be formed with a stepped portion having a predetermined height downwardly from the upper end of the first case 101A. The left end, the right end, and the rear end of a plurality of sheets are supported by such a step, and can be stably stowed on the stacking unit 165. The height of the step can be designed variously according to the number of sheets which can be set at one time.

The transfer unit 170 may be disposed in parallel with the front end of the loading unit 165 along the paper feeding direction. The conveyance unit 170 may include a motor 171, a pickup roller 172 and a gear assembly (not shown). The conveyance unit 170 may convey the paper, which is placed on the loading unit 165, And can be transferred to the image forming unit 180. The pickup roller 172 can be disposed adjacent to the front end of the loading section 165 so that the paper loaded in the loading section 165 can be transported in the paper feeding direction.

At this time, the length of the stacking unit 165 may be shorter than the length of the sheet, so that a part of the front end of the sheet placed on the stacking unit 165 contacts the outer peripheral surface of the pickup roller 172 along the width direction, 172, respectively. When the motor 171 is driven under the control of the control unit 190, the driving force of the motor 171 is transmitted to the pick-up roller 172, Can be fed in the feeding direction.

The gear assembly is interposed between the motor 171 and the pickup roller 172 and includes at least one gear for transmitting the driving force of the motor 171 to the pickup roller 172. On the other hand, when the pickup roller 172 is disposed at a position where it can directly receive the driving force of the motor 171, all or a part of the gear assembly may be omitted.

At this time, the first paper detecting sensor 141A may be disposed at a position substantially parallel to the rotation axis of the pickup roller 172 in the upper surface of the conveying path. Further, the second paper detecting sensor 141B may be disposed at a position adjacent to the image forming unit 180. [ In this case, the control unit 190 determines whether or not to start printing on the print data in accordance with whether or not the paper is detected by the first paper detecting sensor 141A. When the paper is detected by the second paper detecting sensor 141B, It is possible to judge whether or not a paper jam has occurred in the path.

The pressing portion 200 can be mounted on the lower surface of the second case 101B, that is, the surface facing the upper surface of the first case 101A. The pressing portion 200 may include a pressing plate 201 and an elastic member 202. The rear end of the pressure play portion can be hinged to one side of the rear end of the second case 101B. The elastic member 202 is interposed between one side of the front end of the pressing plate 201 and the second case 101B to elastically support the pressing plate 201. [ Such an elastic member 202 may be, for example, a coil spring, but is not limited thereto. The pressing portion 200 may further include a stopper 203 for limiting a range in which the elastic member 202 is deformed between the lower end of the second case 101B and the pressing plate 201. [ One end and the other end of the stopper 203 are rotatably coupled to the pressure plate 201 and the second case 101B respectively so that the stopper 203 is pushed by the auxiliary member 202 so that the elastic member 202 does not extend beyond a certain range. can do.

The guide unit 210 guides the front end of the sheet conveyed through the conveying unit 170 to the image forming unit 180. The paper conveyed through the conveying unit 170 is spaced apart from the conveying unit 170 by a gap formed between the guide unit 210 and the conveying unit 170, To the image forming unit 180 through the intermediary of the image forming unit.

On the other hand, the paper on which the image is formed in the photo printer 100 according to the present invention may be a thermal paper having dye-based color ink including cyan (C), magenta (M), and yellow have. In this paper, a heat-meltable protective member can be laminated together with the color ink layer. The image forming unit 180 is configured to apply heat to the paper so that the ink layer stacked on the paper can react and form an image. The image forming unit 180 includes a thermal head 181, a heating member, And a roller 182.

Specifically, the heat radiating member 183 may include first to fourth heat radiating members 183A, 183B, 183C and 183D as shown in FIG. First, the first heat discharging body 183A abuts on the upper surface of the thermal head 181 directly or through a heat insulating body, so that the heat radiated from the thermal head 181 can be absorbed quickly. A portion of the upper surface of the first heat discharging body 183A is fixed to the first case 101B by a bracket 184 and a portion of the upper surface of the first heat discharging body 183A The second heat discharging body 183B and the third heat discharging body 183C may be sequentially stacked. At this time, the bracket 184 may serve to fix the first heat discharging body 183A and to maintain the pressing strength of the thermal head 181 against the paper to a predetermined level or higher. The second heat discharging body 183B and the third heat discharging body 183C may be made of a silicone material. In this case, the contact area with the first heat discharging body 183A The heat emitted from the thermal head 181 can be transmitted to the outside more effectively. The fourth heat discharging body 183D may be disposed above the third heat radiating body 183C and the heat transmitted through the first to third heat radiating bodies 183A, 183B and 183C Diffuse outward. For this, the fourth heat discharging body 183D may be formed to have a wider area than the first to third heat discharging bodies 183A, 183B and 183C. However, the first to fourth heat sinks 183A, 183B, 183C and 183D are not essential components, and some of them may be omitted. For example, the second heat discharging body 183B and the third heat radiating body 183C may be integrally manufactured or may not include any one of the second heat radiating body 183B and the third heat radiating body 183C.

A more detailed structure of the image forming unit 180 will be further described below with reference to FIG. 4 and the like.

The outlet (H) may be formed in the first case (101A) or the second case (101B). The paper can be discharged from the front end through which the image forming unit 180 prints (that is, image formation) is completed first through the outlet H and out of the case.

3 is a perspective view of the photo printer 100 according to the present invention viewed from the outside.

3 (a) is an exemplary view for explaining a state in which the first case 101A and the rear end of the second case 101B are engaged (that is, the state in which the cover is closed), and FIG. 3 Fig. 11 is an exemplary view for explaining a state in which one case 101A and the rear end of the second case 101B are separated (i.e., the cover is opened).

Referring to FIGS. 3A and 3B, the second case 101B can function as a cover of the photo printer 100. In the cover fixing state, when the paper is separated or foreign matter (for example, dust, ) Can be blocked.

When the first case 101A and the second case 101B are hinged to each other, the first case 101A and the second case 101B are fixed to the other end with a locking ring 102 One or more fixing grooves 103 may be formed. Also, a fixing release button 104 connected to the fixing ring 102 may be disposed outside the first case 101A. When the release button 104 is pressed, the engagement between the retainer ring 102 and the fixing groove 103 is released so that the other end of the second case 101B can be separated from the other end of the first case 101A. In a state in which the engagement of the first case 101A and the second case 101B is released, the user can insert the paper into the loading section 165. [ 3 shows the first case 101A in which the fixing ring 102 and the fixing release button 104 are formed and is formed in the fixing groove 103 in the second case 101B, It goes without saying that the fixing ring 103 may be formed in the case 101A and the fixing ring 102 may be formed in the second case 101B.

The first case 101A and the second case 101B may each have receiving grooves 105 and insertion protrusions 106 and an opening and closing sensor 143 may be provided inside the receiving grooves 105 . When the other end of the first case 101A is engaged with the other end of the second case 101B, the insertion protrusion 106 formed in the second case 101B is formed in the first case 101A, do. When the insertion protrusion 106 is inserted into the receiving groove 105 and the opening and closing sensor 143 provided inside the receiving groove 105 is pressed downward, the opening and closing sensor 143 detects that the first case 101A The control unit 190 can transmit a signal indicating that the two cases 101B are closed.

At least one light emitting module 131 may be disposed on one side of the first case 101A. When the light emitting module 131 is disposed on the upper surface of the first case 101A, a through hole 107 is formed in the second case 101B at a position facing the light emitting module 131 of the first case 101A . The light emitted from the light emitting module 131 of the first case 101A is transmitted through the through holes of the second case 101B regardless of whether the second case 101B is opened or closed with respect to the first case 101A 107). ≪ / RTI >

The first light emitting module 131A emits light when the image is printed under the control of the controller 190, and can terminate the emission of light when the image is printed. That is, the first light emitting module 131A can emit light until the printing of the image data is completed through the outlet H from the start of printing of the predetermined image data. The second light emitting module 131B can blink or change the color depending on the battery remaining amount or the battery temperature of the power supply unit 160 in conjunction with the power supply unit 160. [ For example, the second light emitting module 131B emits light of a first color when the battery is fully charged, and emits light of a second color different from the first color when the battery temperature exceeds the normal range can do. The third light emitting module 131C may blink a predetermined number of times when an error occurs in the printing process. However, it is merely an example, and it is apparent to those skilled in the art that each light emitting module can output the information about the state of the photo printer or the printing process through light in various other ways. The light emitting module 131 may be an LED, an LCD, or the like, but is not limited thereto. The light emitting module 131 is not particularly limited as long as the light can be blinked or the color of light can be changed under the control of the controller 190.

The first operation module 121, the second operation module 122, and the power supply port 161 may be disposed on one side of the first case 101A. The user can turn on or off the photo printer 100 by operating the first operation module 121 and can reset the photo printer 100 by operating the second operation module 122. [ The power port 161 may be connected to an external power source through a USB cable or the like to function as a connection path for charging the battery or supplying power to each component.

4 is a cross-sectional side view taken along the line A-B shown in FIG. 3 (a) to explain the sheet feeding process of the photo printer 100 related to the present invention.

Referring to FIG. 4, a plurality of sheets can be seated on the upper surface of the stacking unit 165. Specifically, the loading section 165 may have a top surface on which the paper is loaded, and side walls that support the left, right, and rear ends of the paper placed on the top surface. At this time, the length of the loading section 165 may be shorter than the length of the paper, and thus, a part of the front end of the paper loaded on the loading section 165 may be a pickup roller, And the outer circumferential surface of the outer ring 172. That is, the pickup roller 172 may partially take charge of the function of the loading unit 165 in a state in which printing is not in progress.

When the rear end of the second case 101B is fastened to the rear end of the first case 101A (i.e., the cover is in the closed state), the front end of the pressurizing plate 201 is moved in a direction perpendicular to the paper feed direction, And one side of the outer peripheral surface of the pickup roller 172 can be pressed downward along the direction parallel to the rotation axis of the pickup roller 172 through the elastic force of the elastic member 202. [ The paper positioned between the pressing plate 201 and the pickup roller 172 can be pressed downward by the elastic force of the elastic member 202 and fixed to the upper surface of the loading section 165. [ For example, even when the user wiggles or tilts the photo printer 100, the sheet can be stably held in the loading unit 165 by the pressing force of the pressing unit 200. [

The paper P1 directly contacting the pick-up roller 172 among the plurality of sheets vertically seated on the upper surface of the stacking unit 165 is guided by the pickup roller 172, And is conveyed to the image forming portion 180 along the guide of the guide portion 210 by a frictional force generated between the guide portion 210 and the image forming portion 180. [

As shown in Fig. 4, the image forming unit 180 includes a thermal head 181 disposed on the upper side of the paper feeding path and a platen roller 182 disposed on the lower side. The sheet P1 conveyed to the image forming unit 180 through the guide unit 210 is interposed between the thermal head 181 and the platen roller 182 as shown in FIG. An image is formed while being applied with the heat radiated from the thermal head 181.

Specifically, the thermal head 181 applies heat to the sheet P1 conveyed through the guide portion 210, discolors the heat applied portion, and forms an image on the sheet P1. The thermal head 181 can be formed by laminating a heat generating resistor on a substrate. The plurality of heat generating resistors may be arranged in parallel along a line orthogonal to the sheet feeding direction. An electrode formed on the substrate is connected to each heat generating resistor. The control unit 190 adjusts the power supplied to each electrode according to a color to be formed on the sheet through each heat generating resistor, so that the heat generating resistor converts electric energy into heat energy . The control unit 190 may calculate the heat to be generated through each heat generating resistor based on the print data and may control the power supply unit 160 to transmit the power corresponding to the calculated heat to each heat generating resistor.

The heat radiating member 183 is configured to radiate heat generated in the thermal head 181 to the outside as described above. At least a part of the heat radiating member 183 may be formed in a concavo-convex shape in order to increase the contact area with air.

The platen roller 182 may be spaced apart from the lower portion of the thermal head 181. That is, the platen roller 182 and the heat generating resistor may be arranged to face each other up and down along a line orthogonal to the feeding direction. The platen roller 182 supports the lower surface of the paper and also presses the paper toward the thermal head 181 upward. Accordingly, the heat released from the heat generating resistor of the thermal head 181 can be applied to the paper interposed between the thermal head 181 and the plastic pick-up roller 172. [

At this time, the platen roller 182 rotates at a predetermined speed to discharge the printed paper P1 through the discharge port H to the outside of the photo printer 100. The rotation of the platen roller 182 may be caused by a rotational force transmitted from a motor or may be caused by a frictional force generated by contact with a sheet conveyed along the sheet feeding direction. At this time, the rotational speed of the platen roller 182 may be a speed corresponding to the printing speed of the paper by the thermal head 181. [

FIG. 5 is an exemplary view for explaining a process of forming an image on a sheet of paper by the photo printer 100 according to the present invention.

Referring to FIG. 5, the control unit 190 can calculate the amount of heat generated for each of the plurality of heat generating resistors S included in the thermal head 181 based on the image data.

Specifically, the control unit 190 can generate print data of m rows and n columns by sampling image data having a predetermined resolution.

For example, assuming that n heat generating resistors S are provided in the thermal head 181, the print data is written in the column a (n? A? 1) during printing for the row b (m? B? 1) Information about how much heat is to be generated for the a-th heat generating resistor S corresponding to the heat generating resistor S, that is, information about the heat generation amount of each heat generating resistor S.

A pickup roller 172 is disposed below the thermal head 181 at a position opposite to the paper feed direction to feed the paper. At this time, as described above, the first paper detecting sensor 141 is disposed at a position close to the pickup roller 172, so that the presence or absence of paper on the paper feeding path can be detected.

In this structure, when the image formation for the first to n-th rows of the b-th row (m? B? 1) is completed, the control unit 190 causes the motor to drive the platen roller 182 at a distance So as to control the thermal head 181 to form an image of the portion corresponding to the next row (i.e., row b + 1) of the print data on the sheet. The control unit 190 repeats the above-described process from the first row to the mth row, and can print an image corresponding to the image data on the sheet.

On the other hand, the control unit 190 can generate different print data according to the feeding speed (or the printing speed) even if it is the same image data.

In the foregoing, the photo printer 100 related to the present invention has been schematically described with reference to FIGS. 1 to 5. FIG. Hereinafter, with reference to FIGS. 6 to 14, a thermal reaction sheet (corresponding to 'paper' in FIGS. 1 to 5) used in photo printing will be described in more detail.

6 is a cross-sectional view schematically showing a multilayer structure of a general heat-reactive sheet 1. Fig.

Referring to FIG. 6, a general thermal reaction sheet 1 may include a base layer 2, a reaction layer 3, and a coating layer 4.

The base layer 2 supports the reaction layer 3 and the coating layer 4. The reaction layer 3 is heated by a heat source such as the thermal head 181, and when the reaction temperature reaches a specific reaction temperature, the reaction layer 3 develops a predetermined color in response thereto.

At this time, the coating layer 4 included in the conventional thermal reactive sheet 1 is generally disposed at a greater distance from the base layer 2 than the reaction layer 3, and at present, mainly in forming the coating layer 3 The material used is a hydrophilic material. For example, a hydrophilic polymer may be used as the hydrophilic substance.

In the present invention, the hydrophilic polymer is a generic term for polymers that can be dissolved by reacting with water. For example, polyvinyl alcohol, polyacrylic, vinyl alcohol, cellulose and the like may belong to a hydrophilic polymer. However, this is only an illustrative example, and all kinds of natural resins or synthetic resins including other hydroxyl groups (-OH), carboxyl groups (-COOH), carbonyl groups (-CO), etc. can be used for the formation of hydrophilic polymers have.

Such a hydrophilic polymer has a strong affinity with water. For example, when the user touches the coating layer 4 with water-wet hands or when exposed to a high humidity environment for a long time, the hydrophilic polymer reacts with water There is a problem of discoloring.

7 is an exemplary view for explaining a durability deterioration phenomenon occurring in the heat-reactive sheet 1 shown in Fig.

In the air, as shown in FIG. 7, a large number of water molecules (H ₂ O) may exist in an invisible gas form.

When the thermal reaction sheet 1 is exposed to air, the water molecules contained in the air approach the coating layer 4, and the hydrophilic polymer contained in the coating layer 4 is bonded or reacted with water molecules, . ≪ / RTI > In addition, as the coating layer 4 reacts with water molecules, properties such as heat resistance and chemical resistance may be deteriorated.

On the other hand, a method of adding a fluorine-based or silicone-based material to the hydrophilic polymer may be considered, but the added fluorine-based or silicone-based material is detached from the coating layer according to the surrounding environment.

The present invention solves the problems of the conventional heat-reactive sheet 1 described above with reference to FIGS. 6 and 7, and can be modified to change the material used to form the coating layer, Is deposited between the coating layer and the reaction layer.

FIG. 8 is an exemplary view showing a multilayer structure of a thermal reaction sheet 10 according to an embodiment of the present invention.

8, the heat-reactive sheet 10 according to an embodiment of the present invention may also include a base layer 11, a reaction layer 12, and a coating layer (not shown) similar to the heat- 13).

Specifically, the base layer 11 has a first surface and a second surface. The first and second surfaces are opposed to each other on opposite sides along the thickness direction. The base layer 11 supports the reaction layer 12 and the coating layer 13 which are sequentially laminated on the first or second surface. Hereinafter, for convenience of explanation, it is assumed that the reaction layer 12 and the coating layer 13 are laminated on the first surface side of the base layer 11. The first face is defined as the upper face in the vertical direction.

The material used for forming the base layer 11 is not particularly limited as long as it can provide a supporting force equal to or higher than a certain level with respect to the reaction layer 12 and the coating layer 13. For example, materials such as a polyester resin, a polyvinyl chloride, a polystyrene resin, an acryl resin, polycarbonate, cellulose acetate, and polyethylene terephthalate are used for forming the base layer 11 .

When the base layer 11 is disposed below the coating layer 13 and the reaction layer 12 as shown in the figure, the hue is expressed in the reaction layer 12 stacked on top of the base layer 11, Permeability may not be necessary. At this time, the base layer 11 may be formed to have white or light reflectivity.

On the other hand, unlike the case shown, when the base layer 11 is disposed above the coating layer 13 and the reaction layer 12, the hue is expressed in the reaction layer 12 stacked below the base layer 11, 11 is essentially required.

The reaction layer 12 has reaction conditions required for hue development. The reaction conditions may be determined only by the reaction temperature alone or may be determined by considering the reaction time together with the reaction temperature.

Specifically, each reaction layer 12 has its own reaction temperature. When the temperature of heat emitted from the thermal head 181 rises up to the reaction temperature, the reaction layer 12 expresses its own hue. Alternatively, each reaction layer 12 can express its own hue only when the reaction time is longer than the reaction time after the reaction temperature rises to the reaction temperature.

The reactive layer 12 may include a coloring agent and a developer. A coloring agent is a substance that develops color by reaction with a developing agent. Specifically, the coloring agent maintains a colorless crystalline state before reacting with the color developing agent, and causes a molecular change according to the contact with the color developing agent, and thus, it can express its own hue. For example, the coloring agent may be a leuco dye having an electron donor. The leuco dye may be a dye such as lactone, fluororan, phenothiazine, or triarylpyridine which is produced through the reduction of the dye. In the reduced state, the dye is colorless. When it is oxidized, the dye returns to the original dye, ≪ / RTI >

A color developing agent is a substance that induces the color expression of a coloring agent. The color developer may be a substance that is activated at a specific temperature and generates an acid (e.g., an organic acid) or the like. For example, the developing agent may be an electron-accepting material. Leuco dyes, which can be used to form coloring agents, can react with acids provided by the color developer to develop unique colors.

In addition, the reaction layer 12 may include a thermal sensitizer that promotes the reaction between the coloring agent and the color developing agent upon heating. Such a heat sensitizer may occupy a predetermined ratio (e.g., 3%) with respect to the total weight of each reaction layer 12.

The reaction conditions of each reaction layer 12 can be determined depending on various parameters such as the amount of the coloring agent, the amount of the coloring agent, the ratio between the coloring agent and the coloring agent, and the kind and amount of the other additives.

8, the reactive layer 12 is illustrated as having a single layer structure, but the present invention is not limited thereto. That is, the reaction layer 12 may be formed by stacking two or more lower reaction layers (for example, first to third reaction layers) including dyes having different colors. This will be separately described with reference to FIG.

The coating layer 13 has an important difference from the hydrophilic coating layer 4 shown in Fig. 6 in that it has hydrophobicity. For example, the hydrophobicity of the coating layer 13 can be realized by synthesizing a hydrophilic polymer and a fluorine-based material by using a known organic synthesis technique, or by synthesizing a hydrophilic polymer and a silicon-based material. In this case, a known synthesis technique can be utilized. As a result of this synthesis, fluorine or silicon can be attached to the backbone of the hydrophilic polymer.

Fluorine has high electronegativity and reacts easily with other elements and can achieve very stable bonding due to low polarization between atoms. For example, the low intermolecular attraction of the C-F bond can result in hydrophobic / non-polar properties. Fluoride has a low coefficient of friction such as Teflon and can improve the water resistance, heat resistance and chemical resistance of other synthetic materials. For example, according to the synthesis of fluorine and the hydrophilic polymer, a fluororesin whose main chain is a straight chain carbon chain and having a fluorine atom as a substituent can be used as the coating layer 13.

When the hydrophilic polymer is synthesized with a fluorine-based substance or a silicon-based substance, the molecular bond length is shorter than the intermolecular bond length of a common hydrocarbon compound, and the reactivity with water molecules is remarkably lowered. As a result, the surface tension of the coating layer 13 is lowered, and the water molecules containing hydrogen bonds have a relatively large surface tension, so that due to the difference in surface tension between the coating layer 13 and water molecules, (13) and can not react with the coating layer (13), thereby improving the water resistance.

In addition, since the chemical bond due to the synthesis of the hydrophilic polymer and the fluorine or silicone material lasts semi-permanently in a normal environment, the uniformity over the entire region of the coating layer 13, compared with the case of simply adding the fluorine- A hydrophobicity can be implemented for a relatively long period of time.

9 is a cross-sectional view showing various multilayer structures that the thermal reactive sheet 10 according to an embodiment of the present invention may have.

9 (a) and 9 (b), the thermal reaction sheet 10 according to an embodiment of the present invention may include a plurality of reaction layers 12A-12C. As the plurality of reaction layers 12A-12C are heated by the thermal head 181, they emit different colors.

9 (a), a heat-reactive sheet 10 including two reaction layers 12A and 12B is illustrated.

The first reaction layer 12A may correspond to any color of cyan, magenta, or yellow. In addition, the second reaction layer 12B may correspond to any one of two colors other than the hue corresponding to the first reaction layer 12A.

As shown in FIG. 9A, when the number of the reaction layer 12 is two, the first reaction layer 12A and the second reaction layer 12B are expressed in different colors under different reaction conditions, A richer color can be realized as compared with the heat-reactive sheet 1 shown in the figure.

The intermediate layer 15 laminated between the first reaction layer 12A and the second reaction layer 12B can prevent the flow of heat transmitted to the first reaction layer 12A through the second reaction layer 12B . Specifically, the heat applied to the second reaction layer 12B is transmitted to the first reaction layer 12A after being delayed by the time corresponding to the thickness of the intermediate layer 15, or the heat applied to the second reaction layer 12B Some of them may pass through the intermediate layer 15 and may be dissipated and then transferred to the first reaction layer 12A.

9 (b), the heat-reactive sheet 10 including three reaction layers 12 is illustrated. At this time, the first reaction layer 12A may correspond to any color of cyan, magenta, or yellow. The second reaction layer 12B may correspond to any one of the two hues other than the hue corresponding to the first reaction layer 12. The third reaction layer 12C may correspond to a color other than the hue corresponding to the first reaction layer 12A and the second reaction layer 12B.

The first intermediate layer 15A is laminated between the first reaction layer 12A and the second reaction layer 12B and the second intermediate layer 15B is laminated between the second reaction layer 12B and the third reaction layer 12C ). ≪ / RTI > The intermediate layers 15A and 15B can block, reduce or delay the flow of heat between the two reaction layers stacked on both sides, thereby alleviating the thermal interference between the reaction layers 12A-12C.

The first reaction layer 12A to the third reaction layer 12C are expressed in three different colors under different reaction conditions so that the colors are mutually combined so that the thermal reaction sheet 10 is in full color ) Can be implemented.

9A and 9B, the reactive layer 12, the intermediate layer 15 and the coating layer 13 are laminated on the first surface of the base layer 11, But is not limited thereto. For example, at least one of the first reaction layer 12A to the third reaction layer 12C may be laminated on the second surface of the base layer 11. The base layer 11 may replace the role of the intermediate layer 15 when two reactive layers that exhibit different colors are stacked on the opposite sides with the base layer 11 interposed therebetween.

FIG. 10 is a graph exemplarily showing reaction conditions that the three different reaction layers shown in FIG. 9 (b) can have. For convenience of explanation, it is assumed that the first reaction layer 12A corresponds to yellow, the second reaction layer 12B corresponds to magenta, and the third reaction layer 12C corresponds to cyan color. The first reaction layer 12A is laminated on the lower side of the second reaction layer 12B and the second reaction layer 12B is laminated on the lower side of the third reaction layer 12C, It is assumed that the heat released is first applied to the third reaction layer 12C.

The reaction conditions of each of the reaction layers 12A-12C may be determined by at least one of reaction temperature or reaction time.

Referring to FIG. 10 (a), each of the first reaction layer 12A to the third reaction layer 12C can express their own hue when they are heated at the same reaction temperature for different reaction times. Specifically, since all of the three reaction layers have the same reaction temperature, the reaction time of the third reaction layer 12C is relatively short so that color can be expressed in the order of approach to the thermal head 181, The reaction time of the layer 12C is relatively long and the reaction time of the second reaction layer 12B should be between the reaction times of the first reaction layer 12A and the third reaction layer 12C.

Referring to FIG. 10 (b), each of the first reaction layer 12A to the third reaction layer 12C can express their own hue when they are heated over different reaction temperatures in the same reaction time. Specifically, since all of the three reaction layers have the same reaction time, the reaction temperature of the third reaction layer 12C is relatively highest, so that the color can be expressed in the order close to the thermal head 181, The reaction temperature of the reaction layer 12C is relatively lowest and the reaction temperature of the second reaction layer 12B should be between the reaction temperature of the first reaction layer 12A and the third reaction layer 12C.

10 (c), the reaction temperature and the reaction time of each of the first reaction layer 12A to the third reaction layer 12C are different from each other, Reaction conditions. Specifically, the first reaction layer 12A is yellow in a relatively long reaction time? T1 and the relatively low reaction temperature T1, and the third reaction layer 12C is expressed in a relatively short reaction time? T3. And the second reaction layer 12B is expressed in magenta at a relatively intermediate reaction time DELTA t2 and at a relatively medium reaction temperature T < 2 >. 10 (c), since the regions corresponding to the reaction temperature and the reaction time of the first reaction layer 12A to the third reaction layer 12C are different from each other, as shown in FIGS. 10A and 10B, The interference phenomenon is less likely to occur between the three colors than the reaction conditions shown.

On the other hand, it is preferable that at least one of the reaction temperature or the reaction time of the first reaction layer 12A to the third reaction layer 12C is set so that there is no overlapping range. If the reaction temperature and the reaction time overlap each other between two different reaction layers, color development of each of the reaction layers 12A-12C may not be independently performed.

11 is an exemplary view showing a state in which only one of the reaction layers of the thermal reaction sheet 10 shown in FIG. 9 (b) is expressed. For convenience of explanation, it is assumed that the heat-responsive sheet 10 has the reaction conditions shown in Fig. 10 (c). It is also assumed that the temperature due to the heat emitted from the thermal head 181 is T and the delay time of T by the intermediate layers 15A and 15B is negligibly small.

At this time, the thermal head 181 may be provided with a heat generating resistor S at the lower end thereof and a protective film SM covering the exposed portion of the heat generating resistor S.

11 (a) illustrates a color development process for the third reaction layer 12C. The temperature T of T3 or higher can be applied to the third reaction layer 12C by the heat emitted from the thermal head 181 in order to express the hue of the third reaction layer 12C.

At this time, since T is higher than T1 and T2, when T is directly transferred to the second reaction layer 12B or the first reaction layer 12A, color reproduction of only the third reaction layer 12C is impossible.

The control section can operate the thermal head 181 only for a period of time such that T is not transmitted to the second reaction layer 12B or lower. For example, T can be maintained for a time of less than? T3 and less than? T2. The first reaction layer 12A and the second reaction layer 12B do not react to T because T is formed only in the third reaction layer 12C during t3 to exhibit cyan color while the holding time of T is shorter than t2 Do not.

11 (b) illustrates a color development process for the second reaction layer 12B. T is transferred to the second reaction layer 12B through the third reaction layer 12C, but since only the color of the second reaction layer 12B should be expressed, T must have a size of T2 to less than T3. That is, the relationship of T2? T <T3 must be satisfied.

As the temperature of the second reaction layer 12B rises to T by the thermal head 181, the color of the second reaction layer 12B is expressed as shown. On the other hand, the inverse of the third reaction layer 12C located in the heat transfer path from the thermal head 181 to the second reaction layer 12B may also increase to T, but since T is less than T3, The reaction layer 12C can keep the colorless state regardless of T. [

Also, the hue of the first reaction layer 12A should not be expressed. Since T is larger than T2 and T2 is larger than T1, when T is transferred to the first reaction layer 12A, interference phenomenon that yellow is expressed in the first reaction layer 12A may occur. In this case, the coloring of the first reaction layer 12A can be blocked by allowing T to remain only for at least t2 and less than t1.

11 (c) illustrates a color development process for the first reaction layer 12A. The heat generated by the thermal head 181 is applied from the uppermost portion of the thermal reaction sheet 10 and the first reaction layer 12A is stacked below the second reaction layer 12B and the third reaction layer 12C , T must be smaller than T2 and T3 and have a size of T1 or more.

Further, T must be applied so as to be maintained at? T1 in the first reaction layer 12A. As a result, since T is smaller than T2, the third reaction layer 12C and the second reaction layer 12B do not undergo any change before and after the formation of T, (12A) alone can express the color.

FIG. 12 is an exemplary view showing the appearance of two or more colors of the reaction layers of the heat-reactive sheet 10 shown in FIG. 9 (b). For convenience of explanation, it is assumed that the heat-responsive sheet 10 has the reaction conditions shown in Fig. 10 (c). The temperature caused by the heat emitted from the thermal head 181 will be referred to as T.

12 (a) illustrates the color development process for the third reaction layer 12C and the second reaction layer 12B.

According to FIG. 12A, the holding time of T higher than T3 is adjusted so that the colors of the third reaction layer 12C and the second reaction layer 12B except for the first reaction layer 12A can be expressed have.

Specifically, when the holding time of T is less than? T2 and less than? T1, T will be formed only in the second reaction layer 12B and the third reaction layer 12C except for the first reaction layer 12A.

Since the relationship between T, T 2 and T 3 satisfies T> T 3> T 2, magenta color is firstly expressed in the second reaction layer 12B after the cyan color is expressed first in the third reaction layer 12C. On the other hand, although T> T1, the yellow color is not expressed because the holding time of T is less than the reaction time Δt1 in the reaction condition of the first reaction layer 12A.

As a result of the combination of the cyan color and the magenta color, the heating area by the thermal head 181 has a blue color.

Of course, the hue of any one of the third reaction layer 12C and the second reaction layer 12B may be first expressed, and then the color of the remaining reaction layer may be expressed, It will be apparent to those skilled in the art.

FIG. 12 (b) illustrates the color development process for the second reaction layer 12B and the first reaction layer 12A.

12 (b), the holding time of T, which is less than T3 and is T2 or more, is adjusted so that the colors of the second reaction layer 12B and the first reaction layer 12A except for the third reaction layer 12C are expressed .

Specifically, when the thermal head 181 is controlled so that the holding time of T is equal to or greater than? T1, T is formed from the third reaction layer 12C to the first reaction layer 12A via the second reaction layer 12B will be. Since the relationship between T, T 1, T 2 and T 3 satisfies T 3> T> T 2> T 1, the cyan color development process in the third reaction layer 12 C is omitted and the first reaction layer 12 B After the magenta color is developed, a yellow color is expressed in the first reaction layer 12A.

As a result of the combination of magenta color and yellow color, the heating area has a green color.

Of course, the hue of any one of the second reaction layer 12B and the first reaction layer 12A may be firstly expressed, and then the color of the remaining reaction layer may be expressed, It is apparent to those skilled in the art that a state can be implemented.

FIG. 12 (c) illustrates the color development process for the first reaction layer 12A to the third reaction layer 12C.

According to (c) of FIG. 12, the color of the first to third reaction layers 12A to 12C can be all expressed by adjusting the holding time of T higher than T3.

Specifically, when the thermal head 181 is controlled such that the holding time of T is equal to or greater than? T1, which is the reaction time of the first reaction layer 12A, T is the temperature of the third reaction layer 12C, the second reaction layer 12B, And then sequentially formed on the first reaction layer 12A.

Since the relationship between T, T 1, T 2 and T 3 satisfies T> T 3> T 2> T 1, the cyan color is firstly expressed in the third reaction layer 12 C, And then yellow color is expressed in the first reaction layer 12A.

As a result of the combination of cyan, magenta and yellow colors, the heating zone has a black color.

Of course, the hue of any one of the first reaction layer 12A to the third reaction layer 12C may be firstly expressed, and then the hue of any one of the remaining two reaction layers may be expressed, It is obvious to those skilled in the art that the color development state shown in FIG.

FIG. 12D illustrates the color development process for the third reaction layer 12C and the first reaction layer 12A. Since the third reaction layer 12C and the first reaction layer 12A are stacked on the opposite sides with the second reaction layer 12B interposed therebetween, It may not be possible to respectively express the hue of the reaction layer 12C and the color of the first reaction layer 12A. Therefore, in this case, the hue of any one of the third reaction layer 12C and the first reaction layer 12A should be expressed preferentially, and the color of the other reaction layer should be expressed.

11 (a) for color development of the third reaction layer 12C and the process of FIG. 11 (c) for color development of the first reaction layer 12A are performed once separately, the second reaction The hue of only the third reaction layer 12C and the first reaction layer 12A can be expressed in a state in which the coloring of the layer 12B is omitted.

On the other hand, the color density of each reaction layer can be adjusted according to the heating time. For example, the longer the heating time, the higher the color density of each reactive layer can be towards the limit. For example, in the case where only the color concentration of the third reaction layer 12C is intended to be thickened, it can be achieved by repeatedly performing the process shown in FIG. 11A with a time difference.

13 is an exemplary view showing a multilayer structure of a thermal reaction sheet 20 according to another embodiment of the present invention. For convenience of explanation, it is assumed that the heat-responsive sheet 20 has the reaction conditions shown in Fig. 10 (c). It is also assumed that the temperature T due to heat emitted from the thermal head 181 is higher than the reaction temperature T3 of the third reaction layer 12C.

13 (a) to 13 (c), the heat-reactive sheet 20 includes a coating layer 14 made of a material having a glass transition temperature within a specific range, (1, 10) shown in Fig.

On the other hand, each of the reaction layers 12A-12C can express its own color as it is phase-shifted over its own reaction temperature. In this phase change process, a volume change may be essential.

That is, each of the reaction layers 12A-12C is maintained in a crystalline state before the reaction temperature is reached, and changes to an amorphous state at a reaction temperature or higher. In the amorphous state, The movement becomes active, and thermal deformation, for example, the volume expands. In other words, in order for the color development process to proceed appropriately, volume expansion is required so that each component of the reaction layer can be evenly mixed.

On the other hand, if the coating layer 14 laminated on the reaction layers 12A-12C has a hardness that can not accommodate the volume expansion of the reaction layers 12A-12C, (For example, a coloring agent and a coloring agent) are in contact with each other to reduce the chance of reacting, the initial intended color may not be accurately expressed even when the reaction temperature is exceeded. Further, when the coating layer 14 is hard enough to not accommodate the thermal deformation of the reaction layers 12A-12C, the thermal deformation of the reaction layers 12A-12C may cause heat transfer between the coating layer and the reaction layers 12A-12C And the coating layers 4 and 13 may peel off from the heat-deformable sheets 1 and 10 if they are severely damaged.

13 (a), a thermal reaction sheet 20 including a coating layer 14 having a glass transition temperature Tg lower than the reaction temperature T1 of the first reaction layer 12A I would like to propose. However, for the sake of convenience of explanation, it is assumed that T is higher than T3 and maintained only for? T3 and lower than? T2.

The coating layer 14 may be formed using, for example, an ultraviolet ray curable resin having a glass transition temperature within a specific range. The ultraviolet ray curable resin can form a coating film by reaction between unsaturated double bonds and can have a solid structure (i.e., a high crosslink density) as compared with other compounds, so that a relatively high resistance to various solvents such as water .

Such an ultraviolet ray-curable resin may be formed using various oligomers, monomers, photopolymerization initiators, and the like. Examples of the monomer that can be used for forming the ultraviolet-curable resin include 2-HEA (2-Hydroxy Ethyl Acrylate) and 2-HPA (2-Hydroxy Propyl Acrylate). 2-Hydroxyethyl acrylate (2-HEA) can be prepared by using ethylene oxide and acrylic acid in the presence of a catalyst.

The glass transition temperature of the ultraviolet ray-curable resin can be changed by adjusting the kinds or mixing ratios of the materials used for forming the ultraviolet ray-curable resin. For example, increasing the proportion of an acrylate monomer having one functional group can lower the crosslinking density and lower the glass transition temperature in response to the decrease in crosslinking density. Alternatively, a plasticizer may be added to increase the firing of the ultraviolet-curing resin.

13 (b), the coating layer 14 included in the heat-sensitive sheet 20 is glass-transferred at a temperature Tg lower than the reaction temperature T3 of the third reaction layer 12C, 3 &lt; / RTI &gt; reaction layer 12C. That is, the coating layer 14 may have a large change in fluidity at a temperature higher than the glass transition temperature. For example, the coating layer 14 may have fluidity corresponding to the fluid.

When the glass transition temperature Tg of the coating layer 14 is lower than T3, the coating layer 14 undergoes glass transition before the hue of the third reaction layer 12C is developed, and the volume expansion of the third reaction layer 12C It can become an acceptable standby state.

The glass transition temperature of the coating layer 14 may be in the range of 0 degree to 100 degrees, preferably in the range of 5 degrees to less than 40 degrees, in consideration of the daily use environment (i.e., optimal operating environment of the photo printer) . &Lt; / RTI &gt; If the glass transition temperature of the coating layer 14 exceeds 100 degrees, the coating layer 14 becomes excessively hard, which can not properly accommodate deformation due to moisture or the like, or hinders color development in the reaction layer.

The glass transition temperature of the coating layer 14 can be changed, for example, by controlling the ratio of acrylates having different numbers of functional groups (monofunctional, difunctional, trifunctional).

Referring to (c) of FIG. 13, after the coating layer 14 has undergone glass transition, color development of the third reaction layer 12C proceeds with a T higher than T3. As shown, the heating region can bulge exponentially due to thermal deformation in the hue of the third reaction layer 12C, and the coating layer 14, which has been glass transitioned and relatively retracted, is deformed by deformation of the third reaction layer 12C So that they can be convexly shaped.

Accordingly, the space in which the various components included in the third reaction layer 12C can be smoothly mixed with each other is secured, so that the color intended by the user can be displayed more accurately on the heat-reactive sheet 20. [ Also, the phenomenon that the coating layers 4 and 13 are pushed outward due to the expansion of the third reaction layer 12C and peeled off from the heat-deformable sheets 1 and 10 can be reduced.

13, the intermediate layer laminated between the reaction layers is formed to have a lower glass transition temperature than that of T1 so as to more reliably accommodate thermal deformation of the respective reaction layers. You may.

FIG. 14 is an exemplary view showing a multilayer structure of a thermal reaction sheet 30 according to another embodiment of the present invention. For convenience of explanation, it is assumed that the heat-responsive sheet 30 has the reaction conditions shown in Fig. 10 (c). It is also assumed that the temperature T due to heat emitted from the thermal head 181 is higher than the reaction temperature T3 of the third reaction layer 12C and is maintained only for at least t3 and less than t2.

The heat-reactive sheet 30 shown in FIG. 14A has a structure in which a buffer layer 16 is additionally laminated between the coating layer 17 and the third reaction layer 12C. In FIGS. 6 to 11 Is different from the heat-reactive sheets (1, 10, 20) shown. At this time, the coating layer 17 may have hydrophobic property 13 as shown in FIG. 8, or may have a glass transition temperature 14 within a specific range as shown in FIG.

Specifically, the buffer layer 16 can be formed using a material having transparency and stretchability. For example, zinc sulfide (ZnO), indium tin oxide (ITO), graphene, metamaterial or the like can be used as a material for forming the buffer layer 16. However, this does not limit the kinds of materials usable for forming the buffer layer 16, and is not particularly limited as long as it is a material having a light transmittance and stretchability of a predetermined level or more.

Among them, graphene is a compound which forms a hexagonal honeycomb structure by mutual bonding of carbon, and can serve as a buffer through the hollow space of the honeycomb structure. That is, although the shape of the honeycomb structure itself may be partially deformed when an external force is applied, the connection state does not easily change. Further, since graphene has a very high thermal conductivity (at least twice as high as the diamond temperature), the heat of the thermal head 181 can be quickly transferred to the reaction layer, which can help color appearance of the reaction layer more quickly.

The buffer layer 16 may be formed by various known techniques such as a chemical vapor deposition method, a metal organic chemical vapor deposition method, a molecular beam epitaxy method, a metal organic molecular beam epitaxy method Metal organic molecular beam epitaxy (ALM), pulsed laser deposition (ALD), atomic layer deposition (ALD), sputtering, and RF magnetron sputtering.

Specifically, according to FIGS. 14B and 14C, T passes through the buffer layer 16 and is transferred to the third reaction layer 12C. The third reaction layer 12C reacts with T to generate thermal deformation and develop cyan color. At this time, since the thermal deformation (for example, volume expansion) of the third reaction layer 12C is transmitted to the buffer layer 16 before the coating layer 17, deformation of the coating layer 17 can be reduced. That is, the expansion force generated from the third reaction layer 12C is gradually relaxed through the buffer layer 16, so that the buffer layer 16 is formed in a state in which the volume expansion of the third reaction layer 12C is directly transferred to the coating layer 17 .

In addition, the buffer layer 16 may be formed to have a thickness equal to or less than a predetermined ratio with respect to the total thickness of the heat- This is because as the thickness of the buffer layer 16 increases, the light transmittance decreases or the change in the refractive index increases. For example, the buffer layer 16 may be formed to be about 10% or less of the total thickness of the reaction layer 12, the intermediate layer 15, and the buffer layer 16. In this case as well, the buffer layer 16 may be formed to have a thickness of about 25% or more of the thickness of the third reaction layer 12 so as to accommodate the volume expansion of the reaction layer 12. If the thickness of the buffer layer 16 is less than 25% of the thickness of the reactive layer 12, thermal deformation of the reactive layer 12 may not be fully accommodated.

As shown in the figure, the third reaction layer 12C is partially deformed convexly by volume expansion, and the buffer layer 16 is recessed concavely corresponding to the deformation of the convex third reaction layer 12C, May have the same state before and after thermal deformation of the third reaction layer 12C. As a result, the outer surface of the coating layer 17 has a uniform roughness even after printing.

When the outer surface of the coating layer 17, that is, the surface on which the user confirms the printing result has a non-uniform roughness, the light is scattered at the outer surface of the coating layer 17, Distortion may occur. On the other hand, according to FIG. 14, since the coating layer 17 is improved by interposing the buffer layer 16, it is possible to further enhance the consistency between the colors actually displayed and the visible colors in the reaction layers.

14A to 14C illustrate that the buffer layer 16 is laminated only between the coating layer 17 and the third reaction layer 12C, but this is merely an example. For example, the buffer layer 16 may be laminated so as to contact the first reaction layer 12A or the second reaction layer 12B.

In the above description, the colors corresponding to the reaction layers are cyan, magenta, and yellow. However, the present invention is not limited thereto, and it is apparent to those skilled in the art that other colors may be used.

The embodiments of the present invention described above are disclosed for the purpose of illustration, and the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

10, 20, 30: thermal reaction sheet
11: base layer
12: Reaction layer
13, 14, 17: coating layer
15: Middle layer
16: buffer layer
100: Photo printer
181: Thermal head

Claims (12)

A base layer having a first surface and a second surface opposite to the first surface;
A reaction layer deposited on the first surface of the base layer; And
A coating layer laminated on the first surface of the base layer;
&Lt; / RTI &gt;
Wherein the coating layer comprises:
Wherein the reaction layer is laminated away from the first surface of the base layer and comprises a hydrophobic substance or an ultraviolet ray curable resin. The method according to claim 1,
The hydrophobic substance contained in the coating layer may be,
Fluorine, or silicon. The method according to claim 1,
The ultraviolet-curing resin preferably has a weight-
And a glass transition temperature lower than the reaction temperature of the reaction layer. The method of claim 3,
The ultraviolet-curing resin preferably has a weight-
And has a glass transition temperature of 5 degrees or more and 40 degrees or less. The method according to claim 1,
In the reaction layer,
And the first reaction layer to the third reaction layer which are different in color under different coloring conditions are laminated in order. 6. The method of claim 5,
A first intermediate layer laminated between the first reaction layer and the second reaction layer; And
A second intermediate layer formed between the second reaction layer and the third reaction layer;
Further comprising a heat-resistant sheet. 6. The method of claim 5,
Wherein the reaction temperature of the first reaction layer is lower than the reaction temperature of the second reaction layer and the reaction temperature of the second reaction layer is lower than the reaction temperature of the third reaction layer. 6. The method of claim 5,
The first reaction layer to the third reaction layer may be formed,
Wherein the heat-sensitive sheet comprises different kinds or ratios of color developing agent and developer. The method according to claim 1,
A buffer layer laminated between the coating layer and the reaction layer;
Further comprising a heat-resistant sheet. 10. The method of claim 9,
The buffer layer,
Wherein the reaction layer absorbs thermal deformation of the reaction layer between the coating layer and the reaction layer. 10. The method of claim 9,
The buffer layer,
ZnS, graphene, or ITO. &Lt; Desc / Clms Page number 13 &gt; 10. The method of claim 9,
The buffer layer,
Wherein the reaction layer has a thickness of 25% of the thickness of the reaction layer.

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