JP5433626B2 - Thermal transfer recording method and thermal transfer recording apparatus - Google Patents

Description

  Embodiments described herein relate generally to a thermal transfer recording method and a thermal transfer recording apparatus.

  Conventionally, as a method of recording a face image on an image display body containing a face image for personal authentication such as a driver's license, passport, credit card, membership card, etc., a sublimation type thermal transfer recording method has become the mainstream. . This sublimation type thermal transfer recording method comprises a thermal transfer ribbon obtained by coating a sublimable (or heat transferable) dye on a film-like support so as to allow thermal transfer, and a recording layer having a receiving layer capable of receiving the sublimable dye. The thermal transfer ribbon is selectively heated based on the image data by a thermal head or the like by superimposing the medium, and a desired image is sublimated and recorded on the recording medium.

  According to this sublimation type thermal transfer recording method, it is widely known that a color image with rich gradation can be easily recorded. However, the sublimation type thermal transfer recording method has a drawback in that the material that can be dyed with a sublimable material is limited and can be applied only to a limited recording medium. In addition, sublimation dyes generally have a defect that image durability such as light resistance and solvent resistance is inferior. Furthermore, there is no ultraviolet-excited fluorescent dye in the sublimable dye, and a forgery prevention measure must be provided separately.

  On the other hand, the melt-type thermal transfer recording method selectively heats a thermal transfer ribbon formed by coating a film-like support with a color pigment or dye dispersed in a binder such as a resin or wax to form a recording medium. The image is transferred together with the binder to record a desired image.

  According to this melt type thermal transfer recording method, it is possible to select inorganic and organic pigments which are generally said to have good light resistance as a coloring material. Moreover, since resin, wax, etc. used for a binder can be devised, solvent resistance can be improved. Basically, any recording medium having adhesiveness to the binder may be used, and there is an advantage over the sublimation type thermal transfer recording method that a wide recording medium can be selected.

  However, since the melt-type thermal transfer recording method uses a dot area gradation method in which gradation recording is performed by changing the size of the transferred dots, multi-gradation recording can be performed by accurately controlling the dot size. Various ideas are required. For example, there is a method in which the arrangement of transfer dots is recorded in a so-called zigzag pattern (hereinafter referred to as an alternate driving method). When this alternate driving method is used, the thermal interference between the heating elements adjacent to the thermal head can be reduced, and the dot size can be controlled without being affected by the adjacent pixels. Can do.

  In addition, in order to accurately control the dot size, it is necessary that the surface condition of the recording medium is good, but this hinders the advantages of the melt-type thermal transfer recording method having a wide range of recording medium selectivity. End up.

  Therefore, an indirect transfer recording method has been devised in which multi-tone recording is performed on an intermediate transfer body having an image receiving layer with a good surface condition, and then the image receiving layer of the intermediate transfer body is transferred to a recording medium. . According to this method, it is not necessary to select a recording medium as long as the intermediate transfer member is adjusted so that it can be transferred to the recording medium. Can be performed.

However, the above method also has the following problems.
For example, when the image resolution increases, it is necessary to control the dot size to a smaller size, but the conventional ink ribbon having an ink layer thickness of 1 μm or more cannot follow at a resolution of 300 dpi or more, and the image quality deteriorates. There is a problem of end.

  If the thickness of the ink layer of the ink ribbon is 1 μm or less, it becomes possible to follow high resolution. However, when alternately driven by a conventional thermal head in which one pixel is formed by one heating element, the central part of the heating element is Since the temperature becomes too high, there is a problem that the ink layer is destroyed and the image quality is deteriorated.

  In addition, when gradation recording is performed by a thermal transfer recording method, particularly melt type thermal transfer recording, if the surface smoothness of the platen roller for pressing the thermal head, the ink ribbon, and the recording medium is low, unevenness on the surface of the platen roller is caused. There is a problem in that the contact between the ink layer and the image receiving layer of the recording medium is hindered and the image quality deteriorates.

  When performing multi-gradation recording, it is necessary to drive alternately, and when recording a binary image such as a character image, it must be set to drive according to the pixel arrangement. This setting is performed by a certain image processing unit, which not only complicates the image processing unit but also increases the price.

  Also, black ink for recording binary images such as character images and fluorescent ink for preventing counterfeiting have a composition different from that of color ink for recording multi-tone images such as face images. In the multi-tone recording of black-scaled gray scales and fluorescent images that have been created, they are realized by recording with a pseudo-tone method such as dither, or by superimposing black gray scales or color inks. It was. For this reason, there is a problem that the image quality deteriorates and the consumption of color ink increases, resulting in an increase in cost.

Japanese Patent Publication No. 6-59739

  The problem to be solved by the present invention is to record a multi-valued image such as a color image rich in gradation, a binary image such as a character image, and a fluorescent image capable of preventing falsification as high-quality images. It is an object to provide a thermal transfer recording method and a thermal transfer recording apparatus that can be used.

In the thermal transfer recording method according to the embodiment, a plurality of color heat-meltable ink layers are formed on one surface of a film-like support, and the thickness of the plurality of color heat-meltable ink layers is 0.4 to 0.4. A thermal transfer ink ribbon set to a desired value between 1 μm and an image receiving layer capable of thermally transferring the inks of the plurality of heat-meltable ink layers from the thermal transfer ink ribbon are formed on one surface of the film-like support. The intermediate transfer body, the edge-type thermal head formed by arranging a plurality of heating elements in a line, and the rubber hardness that presses the thermal head, the thermal transfer ink ribbon, and the intermediate transfer body are 80 degrees. A platen roller formed of the elastic body described above, and selectively energizing each heating element of the thermal head in accordance with the image data to be recorded, so that the heat transfer ink ribbon is heated and melted. An image is formed on the image receiving layer of the intermediate transfer member by thermally transferring the ink of the ink layer to the image receiving layer of the intermediate transfer member, and the image receiving layer of the intermediate transfer member on which the image is formed is applied to the recording medium with pressure. Image recording is performed by transferring by heat. When recording a multi-valued image, the two heating elements of the thermal head are set as one set , and a driving current is passed in series to these two heating elements. When heat is generated to form one pixel and even-numbered and odd-numbered pixels are alternately formed for each recording line to record a binary image, the heat generated in the thermal head array is formed. Pixels are formed in the direction of body alignment.

The figure which shows the example of arrangement | positioning of a dot when the heat generating body of the thermal head which concerns on embodiment is driven alternately. FIG. 3 is a schematic view showing a temperature distribution in an ink layer of a heating element and a thermal transfer ink ribbon of the thermal head according to the embodiment. FIG. 3 is a schematic diagram illustrating a schematic configuration of a heating element of the thermal head according to the embodiment and a temperature distribution in an ink layer corresponding to the configuration. 1 is a schematic configuration diagram of a thermal head according to an embodiment. The circuit diagram which shows the electrical equivalent circuit of the heat generating body of the thermal head which concerns on embodiment. FIG. 4 is a longitudinal side view schematically showing the configuration of the intermediate transfer member according to the embodiment. BRIEF DESCRIPTION OF THE DRAWINGS The structure of the thermal transfer ink ribbon which concerns on embodiment is shown typically, (a) A figure is a top view, (b) A figure is a vertical side view. 1 is a block diagram schematically showing a printer system according to an embodiment. Schematic which shows the pixel arrangement | sequence of the image information which concerns on embodiment. Schematic which shows the pixel arrangement | sequence of the image information which concerns on embodiment. The schematic block diagram which shows typically the structure of the printer in FIG. FIG. 12 is a diagram for explaining the operation of the printer of FIG. 11. 6 is a graph showing the characteristic of reflection density with respect to the thickness of the ink layer according to the embodiment. The graph which shows the characteristic of the reflection density with respect to the hardness of the platen which concerns on embodiment. The graph which shows the characteristic of the reflection density with respect to the press-contact force of the thermal head and platen which concerns on embodiment.

Hereinafter, embodiments will be described with reference to the drawings.
First, the alternate driving of the heating elements of the thermal head according to the present embodiment, specifically, a method of recording by arranging dots in a staggered manner will be described.

  The alternate driving of the heating elements of the thermal head is a method of alternately driving odd-numbered heating elements of odd lines and even-numbered heating elements of even lines for each recording line. When alternately driven in this way, the recorded dots 1 are arranged in a zigzag pattern as shown in FIG. 1 to form an image. Here, the main scanning direction is the direction in which the heating elements of the thermal head are arranged, and the sub-scanning direction is a direction perpendicular thereto.

  FIG. 2 shows the temperature distribution in the ink layer of the thermal head heating element and the thermal transfer ink ribbon, and reference numeral 2 in the figure denotes the thermal head heating element. When recording is performed by driving all the heating elements 2 instead of alternating driving, as shown in FIG. 2A, the distance between the adjacent heating elements 2 is narrow, so that thermal interference occurs and the temperature distribution is flat. (A solid line a in the figure). That is, there is no temperature contrast between adjacent heating elements 2. For this reason, accurate dot size modulation cannot be performed, and multi-tone recording becomes difficult.

  On the other hand, as shown in FIG. 2B, in the case of alternating driving in which the adjacent heating elements 2 are not driven for each recording line, the distance between the driving heating elements 2 is wide (more specifically, the heating element arrangement pitch). Heat twice escapes to the heating element 2 that is not driven in the thermal head, so that thermal interference hardly occurs and the temperature distribution has a steep shape (solid line b in the figure). That is, a temperature contrast can be obtained between the adjacent heating elements 2.

  In this way, by alternately driving, isolated dots can be reliably formed, and the dot size can be reliably modulated without being affected by adjacent dots, and multi-gradation utilizing area gradation Recording is possible.

  FIG. 3 shows a schematic configuration of a heating element of the thermal head and a temperature distribution in the ink layer corresponding to the thermal head, and FIG. 4 shows a schematic configuration of the thermal head. In the present embodiment, the thermal head is an edge-type thermal head 3 as shown in FIG. 4A, and the heating element 2 is formed near the tip of the thermal head 3. As shown in FIG. 11 described later, the edge-type thermal head 3 can be installed at an angle with respect to the tangential direction of the platen pressing portion, so that the recording medium can be easily fed, and the flat-type thermal head 3 can also be used. Since a space is not required as compared with the thermal head, there is an advantage that it is advantageous in downsizing the apparatus.

  Further, as shown in FIG. 3A, the edge type thermal head 3 of the present embodiment has a configuration in which one pixel is formed by combining two heating elements 2a and 2b. As shown by an arrow c in the drawing, the current that flows to generate heat from the heating element passes through the two heating elements 2a and 2b in series, and returns to the power source through a drive circuit (not shown). That is, the current paths are not shared with the other sets of heating elements except for the wiring to the power source.

  On the other hand, the normal planar thermal head 4 shown in FIG. 4B has a configuration in which one pixel is formed by one heating element 2 as shown in FIG. 3B. As shown by the arrow d in the figure, the current that flows to generate heat from the heating element passes through the heating element 2 and returns to the power source through the common electrode 5 to which all the heating elements 2 are connected.

  FIG. 5 shows this as an electrical equivalent circuit. 5A shows the edge type thermal head 3 and FIG. 5B shows the flat type thermal head 4. Ri1 and Ri2 in FIG. 5A indicate the resistances of the heating elements 2a and 2b. Ri in FIG. 5B indicates the resistance of the heating element 2, and Rc indicates the resistance of the common electrode 5. As shown in FIG. 5B, the heating element 2 of the planar thermal head 4 can be expressed as a parallel resistance group connected in series with the common electrode 5. Since the resistance Rc is smaller than Ri, when there are few heating elements to be driven, the voltage drop there is negligible.

  However, as the number of heating elements to be driven increases, the value of the entire heating element that is a parallel resistance group decreases, so the voltage drop at the resistor Rc cannot be ignored, the voltage applied to the heating element decreases, and the amount of heat generation decreases. End up. That is, the amount of generated heat changes with the number of drives. On the other hand, as shown in FIG. 5A, in the edge thermal head 3, since there is no common electrode 5, the voltage applied to the heating element does not change depending on the number of driving. For this reason, the edge-type thermal head 3 has an advantage that the control according to the number of drives is not required unlike the flat-type thermal head 4 and the drive control is simplified.

  Further, since the edge type thermal head 3 has two heat generating elements 2a and 2b as one set, the temperature distribution in the ink layer is the center of the heat generating element as indicated by e in FIG. However, the temperature between the two heating elements 2a and 2b is somewhat lowered, and the central portion of the pixel does not become high.

  On the other hand, in the flat type thermal head 4, since one heating element 2 generates heat, the temperature distribution in the ink layer is in the central portion of the heating element 2 as indicated by f shown in FIG. The temperature is high.

  In the case of alternate driving, it is necessary to heat the transfer temperature to the position of the adjacent heating element. Therefore, in the flat thermal head 4, the temperature of the central part of the heating element is excessively increased, and the ink ribbon may be damaged. there were. On the other hand, the edge-type thermal head 3 in which the high temperature portion approaches the adjacent heating element and the center portion of the pixel does not become high temperature has an advantage that the ink ribbon is not damaged even if alternately driven. .

Next, the intermediate transfer member and the thermal transfer ink ribbon according to this embodiment will be described.
FIG. 6 schematically shows the structure of the intermediate transfer member according to this embodiment. The intermediate transfer body 6 is formed by laminating a release layer 8 made of wax, a protective layer 9 made of resin, and an image receiving layer 10 in this order on one surface of a long film-like support 7. For the support 7, for example, a film-like synthetic resin such as polyethylene terephthalate (hereinafter simply referred to as PET) or polyethylene naphthalate (hereinafter simply referred to as PEN) is preferably used. In the present embodiment, for example, PET having a thickness of 25 μm is used.

  The image receiving layer 10 is required to be compatible with the ink layer of the ink ribbon described later, and to have a smooth image receiving surface, and is a urethane resin, an epoxy resin, an acrylic resin, a thylene resin, or a mixture thereof. Resins are preferably used. In this embodiment, for example, a mixed resin mainly composed of a urethane resin and an epoxy resin is used, and the thickness is 5 μm and the support is coated on the support.

  Here, the protective layer 9 is often provided with a falsification preventing measure such as a hologram. Also in this embodiment, a hologram-coated one is used. The thickness of the protective layer 9 was 10 μm.

  FIG. 7 schematically shows the configuration of the thermal transfer ink ribbon according to the present embodiment. The thermal transfer ink ribbon 11 is formed on one surface of a long film-like support 12 with a yellow ink layer 13, a magenta ink layer 14, a cyan ink layer 15, a black ink layer 16, and a fluorescent ink as heat-meltable ink layers of a plurality of colors. Layers 17 are formed in that order. Here, the order of the ink layers 13 to 17 is not necessarily the order described above, and may be arranged in the order determined by the transparency of the ink layers.

  The support 12 is, for example, a synthetic resin film such as PET having a thickness of 2 to 6 μm. In the present embodiment, the PET has a thickness of 4.5 μm. Each of the ink layers 13 to 17 is obtained by dispersing an inorganic pigment, an organic pigment, and fine particles in a binder made of resin or the like.

  The binder is a heat-meltable material such as vinyl acetate-vinyl chloride copolymer, vinyl acetate-ethylene copolymer, saturated polyester resin, epoxy resin, acrylic resin, or styrene resin, and is colorless and transparent or monochromatic. A transparent resin having a melting point of about 60 ° C. to about 100 ° C. is preferably used. In the present embodiment, a binder mainly composed of a saturated polyester resin is used in view of compatibility with the intermediate transfer member 6. The fine particles are a pigment dispersant or the like, but in the present embodiment, silica is contained.

  In the present embodiment, the dots of each color ink are transferred one on top of the other in order to express a desired color.Thus, if the previously transferred ink is thick, it is strongly affected by the unevenness of the dots, and transfer defects and Since dots may be missing, the thickness of the ink layers 13 to 17 is preferably as thin as possible.

  Further, in order to express a low density region, it is necessary to reproduce dots having a size as small as possible, and in order to reproduce small dots, it is desirable that the ink layer is thin. As will be described later, the thickness of the ink layers 13 to 17 is desirably 0.4 μm to 1 μm. In this embodiment, the thickness is 0.4 μm. Although the ink layer pressure is changed for each color from the relationship of the overlapping order of the ink dots and the recording density, all are adjusted to fall within the range of 0.4 μm to 1 μm.

Next, the printer system according to this embodiment will be described.
FIG. 8 schematically shows the configuration of the printer system according to the present embodiment. This printer system has a configuration in which a personal computer (hereinafter simply referred to as a personal computer) 41 having a display 42 and a printer 43 are connected by a bidirectional communication means 44. The personal computer 41 is provided with an image processing unit 45 as image processing means and an image development processing unit 46 as image development processing means. The printer 43 is provided with a recording control circuit 47 as recording control means.

  For example, face image information, character image information, and other multi-value image information are input to the personal computer 41 as image information to be recorded by the printer 43, for example, from a scanner or digital camera (not shown). In the personal computer 41, the image processing unit 45 performs image processing such as color conversion and edge enhancement on the input face image information and other multi-valued image information. The character image information is converted from a desired font into bitmap data.

  The multi-value image information that has been subjected to image processing by the image processing unit 45 and the character image information that has been converted into bitmap data are subjected to image development by the image development processing unit 46. That is, the image development processing unit 46 determines whether the input information is a character image or a multi-valued image. If the determination result is character image information, the bitmap data is recorded in the recording control circuit 47 of the printer 43. Transmit as image information.

  On the other hand, when the determination result is multi-value image information, for example, after arranging the pixels as shown in FIGS. 9 and 10, the information is transmitted to the recording control circuit 47 of the printer 43 as image information to be recorded. FIG. 9 shows a pixel arrangement of the image information sent from the image processing unit 45 to the image development processing unit 46, and the numbers in the figure are the numbers of pixels in the main scanning direction and the sub-scanning direction. The recording of one line in the sub-scanning direction (for example, sub-scanning line number 1-main scanning line number 1-512 in the figure) is developed into thermal head driving data, and then mounted on a thermal head (not shown). One line of data is transferred to the circuit, and the thermal head is driven.

  In the alternate driving of the heating elements of the thermal head, the odd-numbered heating elements of the odd-numbered lines and the even-numbered heating elements of the even-numbered lines in the sub-scanning direction are alternately driven for each recording line. In addition, data not to be recorded (the heating element is not driven), in this example, “0” data is arranged in a staggered manner, and pixel information to be recorded according to image information is arranged in a portion that is not “0” data. Become a thing.

  As described above, the image development processing unit 46 converts the pixel array shown in FIG. 9 into the pixel array shown in FIG. 10 and then transmits it to the recording control circuit 47 of the printer 43 as image information to be recorded.

  The recording control circuit 47 of the printer 43 and the personal computer 41 are connected by a bidirectional communication means 44 such as SCSI or USB, and transmits image information to be recorded from the personal computer 41 to the recording control circuit 47 of the printer 43. Or sending a recording start signal. The recording control circuit 47 of the printer 43 receives image information from the personal computer 41 via the bidirectional communication means 44, converts it into a thermal head drive signal, and controls the overall recording operation. .

  As described above, by performing the pixel array for alternate driving in the image development processing unit 46 of the personal computer 41, the recording control circuit 47 of the printer 43 only needs to convert it into a thermal head driving signal, making the circuit complicated. There is nothing. For this reason, the recording control circuit 47 can be made simpler and cheaper.

Next, the printer 43 shown in FIG. 8 will be described in detail.
FIG. 11 schematically shows the configuration of the printer 43. In FIG. 11, a thermal head 22 as a thermal recording means is provided on a platen roller 21 made of an elastic body such as rubber. As described above, the thermal head 22 is an edge-type thermal head, and is provided on the platen roller 21 so as to be able to contact and separate via the thermal transfer ink ribbon 11 and the intermediate transfer body 6 described above. The thermal transfer ink ribbon 11 is supplied between the platen roller 21 and the thermal head 22 by the supply core 23 and is taken up by the take-up core 24.

  In the vicinity of the platen roller 21, a clamp roller 25 that receives and conveys the intermediate transfer member 6 that is carried out is provided on the carry-out side of the intermediate transfer member 6. On the clamp roller 25, a clamp 26 for gripping the intermediate transfer member 6 is provided. On the carry-out side of the clamp roller 25, a carrying roller 27 for carrying the intermediate transfer member 6 carried out by the clamp roller 25 is provided.

  In front of the conveyance roller 27, a heat roller 28 as a transfer unit and a counter roller 29 facing the heat roller 28 are provided. The heat roller 28 overlaps and presses the intermediate transfer member 6 supplied by the conveying roller 27 and the separately supplied recording medium 30 (not shown) by the counter roller 29 and rotates while the intermediate transfer member 6 rotates. The intermediate transfer body 6 is transferred to the recording medium 30 by applying heat to the recording medium 30.

  After the intermediate transfer body 6 is supplied between the platen roller 21 and the thermal head 22 by the supply core 31, it is supplied to the heat roller 28 via the clamp roller 25 and the conveying roller 27, and is transferred here. It is wound around a winding core (not shown) through the peeling roller 32.

  In such a configuration, when a recording start signal is supplied from the personal computer 41, the thermal transfer ink ribbon 11 is wound up by the winding core 24 to the recording start position. Subsequently, the intermediate transfer body 6 is gripped by the clamp 26 and the clamp roller 25, and the thermal head 22, the thermal transfer ink ribbon 11, and the intermediate transfer body 6 are brought into pressure contact with the platen roller 21 side at a desired pressure, thereby performing a recording operation. Is started.

  In the recording operation, the thermal head 22 is driven by a thermal head drive signal corresponding to the image information sent from the recording control circuit 47, and the intermediate transfer member is composed of the clamp 26 and the clamp roller 25 as shown in FIG. This is performed by rotating the clamp roller 25 at a rotational speed corresponding to the recording cycle while grasping 6. At this time, the platen roller 22 is not forcedly rotated due to the problem of position accuracy.

  When the recording of the first color is completed, the thermal head 22 and the thermal transfer ink ribbon 11 are separated from the intermediate transfer body 6, while the supply core 31 and the clamp roller 25 are rotated in the opposite direction to that during the recording operation. Is discharged to the supply core 31 side to the recording start position. Subsequently, the recording operation is repeated again, and three colors are recorded in sequence.

  When all three colors are recorded, the supply core 31 and the clamp roller 25 discharge the intermediate transfer member 6 to the supply core 31 side to the recording start position, and the intermediate transfer member 6 is released from the clamp 27.

  Next, as shown in FIG. 12B, the intermediate transfer body 6 released from the clamp 26 is supplied to the heat roller 28 by the conveyance roller 27. When the intermediate transfer member 6 is supplied to the heat roller 28, the recording medium 30 is supplied from a recording medium supply tray (not shown). Here, the image area front end of the intermediate transfer body 6 and the front end of the recording medium 30 are aligned, and the intermediate transfer body 6 and the recording medium 30 are pressed against each other by the heat roller 28 and the opposing roller 29. The Next, the heat roller 28 rotates, and heat is applied to the intermediate transfer body 6 while being transferred to the recording medium 30 and discharged to the peeling roller 32 side.

  The peeling roller 32 peels the support 7 from the release layer 8 of the intermediate transfer body 6, and transfers the protective layer 9 and the image receiving layer 10 to the recording medium 30. When the rear end of the recording medium 30 passes the heat roller 28, the transfer operation of the intermediate transfer body 6 is completed. When the transfer operation of the intermediate transfer member 6 is completed, the intermediate transfer member 6 is rewound by the supply core 31 to the recording start position of the intermediate transfer member 6, and the same recording operation as described above is started again.

  Next, the effect of the pressure contact force between the thermal transfer ink ribbon 11, the platen roller 21, the thermal head 22 and the platen roller 21 according to the present embodiment will be described.

  FIG. 13 representatively shows the reflection density of a multi-valued image when the thickness of the black ink layer is changed. FIG. 4A shows the minimum reproducible density, and FIG. 4B shows the maximum density. This figure shows the average density when a gradation pattern is recorded by the printer 43 and the density of 10 points is measured for the minimum density part and the maximum density part by a Macbeth densitometer. Although the required minimum density depends on the image, the present embodiment mainly aims to record a face image, and is desirably 0.2 or less. In FIG. 5A, the thickness of the ink layer at which the reflection density is 0.2 or less is 1.0 μm or less.

  The required maximum density also depends on the image, but it is preferably 1.5 or more in order to record a face image. According to FIG. 5B, the thickness of the ink layer having a maximum density of 1.5 or more is 0.4 μm or more. That is, it can be seen that the thickness of the ink layer needs to be 0.4 to 1.0 μm in order to make the minimum density 0.2 or less and the maximum density 1.5 or more. In the present embodiment, since all the ink layers are 1 μm or less, any ink layer can be used to record a multi-value image, and a sufficient density can be obtained even in a binary image. A high-quality image can be realized.

  FIG. 14 shows the reflection density variation of the black ink of the multi-valued image when the rubber hardness of the platen 21 is changed. The distance between the two horizontal lines (length of the vertical line) in the figure represents the standard deviation. The figure shows the standard deviation when a halftone solid pattern having a reflection density of 1.0 is recorded and the density at 10 points is measured by a Macbeth densitometer.

  When a face image is recorded, it is desirable that the reproducibility of the halftone area is particularly good, and the variation range thereof is desirably ± 1% or less. As shown in FIG. 14, when the rubber hardness of the platen 21 is 80 degrees or more, the variation (standard deviation) range can be ± 1% or less. That is, it can be seen that the rubber hardness of the platen 21 needs to be 80 degrees or more.

  FIG. 15 shows the reflection density variation of the multi-value image when the pressure contact force between the thermal head 22 and the platen roller 21 is changed. The distance between the two horizontal lines (length of the vertical line) in the figure represents the standard deviation. The figure shows the standard deviation when a halftone solid pattern having a reflection density of 1.0 is recorded and the density at 10 points is measured by a Macbeth densitometer. As shown in the figure, the variation in reflection density can be made ± 1% or less when the pressure contact force is 3.0 N / cm or more.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  2, 2a, 2b ... heating element, 3 ... edge type thermal head, 6 ... intermediate transfer member, 7, 12 ... support, 8 ... release layer, 9 ... protective layer, 10 ... image receiving layer, 11 ... thermal transfer ink ribbon , 13 ... yellow ink layer, 14 ... magenta ink layer, 15 ... cyan ink layer, 16 ... black ink layer, 17 ... fluorescent ink layer, 21 ... platen roller, 22 ... thermal head, 28 ... heat roller, 30 ... recorded Medium 41... PC (computer) 42. Display 43. Printer 44. Two-way communication means 45. Image processing unit 46. Image development processing unit 47.

Claims (5)

A plurality of color heat-meltable ink layers are formed on one surface of a film-like support, and the thickness of the plurality of color heat-meltable ink layers is set to a desired value between 0.4 and 1 μm. A thermal transfer ink ribbon, an intermediate transfer body in which an image receiving layer capable of thermally transferring ink of the plurality of heat-meltable ink layers from the thermal transfer ink ribbon is formed on one surface of the film-like support; An edge-type thermal head in which heating elements are arranged in a line, and a platen formed of an elastic body having a rubber hardness of 80 degrees or more that is in pressure contact with the thermal head, the thermal transfer ink ribbon, and the intermediate transfer body. And having a roller
By selectively energizing and driving each heating element of the thermal head in accordance with image data to be recorded, the ink of the heat-meltable ink layer is thermally transferred from the thermal transfer ink ribbon to the image receiving layer of the intermediate transfer body. An image is formed by forming an image on an image receiving layer of a transfer member, and transferring the image receiving layer of the intermediate transfer member on which the image has been formed to a recording medium by pressure and heat. When the two heating elements of the thermal head are made into one set , and a heating current is passed through these two heating elements in series to generate heat, one pixel is formed, and even and odd numbers are formed. A thermal transfer recording method in which pixels are alternately formed for each recording line, and when a binary image is recorded, the pixels are formed in the arrangement direction of the heating elements arranged in a line of the thermal head. An edge-type thermal head in which a plurality of heating elements are arranged in a line;
A plurality of color heat-meltable ink layers are formed on one surface of a film-like support, and the thickness of the plurality of color heat-meltable ink layers is set to a desired value between 0.4 and 1 μm. The thermal transfer ink ribbon and an intermediate transfer body in which an image receiving layer capable of thermally transferring the ink of the plurality of heat-meltable ink layers from the thermal transfer ink ribbon is formed on one surface of the film-like support. A platen roller formed of an elastic body having a rubber hardness of 80 degrees or more in pressure contact with the head,
By selectively energizing and driving each heating element of the thermal head in accordance with image data to be recorded, the ink of the heat-meltable ink layer is thermally transferred from the thermal transfer ink ribbon to the image receiving layer of the intermediate transfer body. When an image is formed on an image receiving layer of a transfer body and a multi-value image is recorded, two heating elements of the thermal head are made into one set , and a driving current is passed in series to these two heating elements. When heat is generated to form one pixel and even-numbered and odd-numbered pixels are alternately formed for each recording line to record a binary image, the heat generated in the thermal head array is formed. A recording control unit for driving the thermal head so as to form pixels in the arrangement direction of the body;
A transfer section for recording an image on a recording medium by transferring the image receiving layer of the intermediate transfer body on which the image is formed to the recording medium by pressure and heat;
A thermal transfer recording apparatus comprising:   The thermal transfer recording apparatus according to claim 2, wherein the heat-meltable ink layers of the plurality of colors of the thermal transfer ink ribbon are mainly composed of a colorant and a binder resin.   The thermal transfer recording apparatus according to claim 2, wherein the pressure contact force between the thermal head and the platen roller is 3.0 N / cm or more.   3. The thermal transfer recording apparatus according to claim 2, wherein the heat-meltable ink layers of the plurality of colors of the thermal transfer ink ribbon are made of cyan ink, magenta ink, yellow ink, black ink, and colorless or light-colored fluorescent ink excited by ultraviolet rays.

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