Photographic paper for a printing device

Abstract: The photographic paper (210) is intended for use with a printer with which a vaporisable dye from the latter is absorbed on a receptor layer (211) provided as an upper layer of a photographic paper base. A light absorbing layer (212) formed by a light absorbing agent is provided between the photographic paper base and the receptor layer. The light absorbing can be whitened in colour hue by thermal defraction either of the light absorbing agent itself by a light radiating element of the associated printer, or of a capsule enclosing a whitening agent mixed with the light absorbing layer.

Description: The present is a division of European patent application No. 93 402 529.7 filed on October 14, 1993. BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a photographic paper for a printing device of the type that prints a still picture, such as a picture formed by a video camera or a still television picture, using a vaporised dye. Description of the Related Art There has hitherto been known a printing device, such as a sublimation printer, in which a sublimation ink ribbon, coated with a sublimable dye, is superposed on the photographic paper, and an electric energy corresponding to the picture information is applied to a thermal head for subliming the dye on the ink ribbon under a heat energy supplied from the thermal head for transcribing the sublimed dye onto the photographic paper. The sublimation ink ribbon is prepared by dissolving a sublimable dye in e.g. a solution of acetate or polyester and adding a dispersant to the resulting solution to form a colloidal solution in the form of an ink which is mixed with a binder and subsequently coated on a base paper. The photographic paper usually has a receptor layer of a heat transfer recording material on a photographic base paper. Among the heat transcription recording materials in current use is a dye-like resin, such as polyester or polycarbonate resin, admixed with a lubricant. The thermal head is a device which translates an electrical energy into a heat energy, that is a device in which the dye is sublimed from the sublimation ink ribbon under the Joule heating generated on flowing the current through a resistor for transcribing the sublimated dye onto the photographic paper. When the recording picture is formed on the photographic paper by the above-mentioned sublimation ink ribbon and thermal head, the receptor layer of the photographic paper undergoes the following changes, as explained below. When the heat energy is applied from the thermal head, the polyester resin, for example, of the receptor layer undergoes glass transition and softening and is thereby turned into the liquid, at the same time that the dye in the sublimation ink ribbon is transferred onto the receptor layer so as to be dissolved or dispersed in the layer to form the recording picture. With the above-described sublimation printer, in which printing is made on the photographic paper using the sublimation ink ribbon and the thermal head, it is necessary to provide an ink ribbon takeup mechanism for rewinding the ink ribbon and a heat radiating mechanism for the thermal head. On the other hand, the thermal head usually has a heat conversion efficiency of not higher than 10%, thus leading to considerable power consumption. Thus it has been difficult with the conventional sublimation type printer to realize saving in power and reduction in size and costs. On the other hand, the sublimation ink ribbon can be used only once for each picture and hence is not economically desirable. Besides, the used-up ink ribbon cassette cannot be regenerated and hence is to be discarded introducing problems about not destroying the earth's environment. Besides, the printing by such printing device is carried out by stacking dyes of yellow (Y), magenta (M) and cyan (C), so that it becomes necessary to perform three cycles of the complicated and time-consuming operations of feeding the ink ribbon, vertically moving the thermal head and feeding the photographic paper. The thermal head generally has the line-head structure of thin resistors generated by sputtering being arranged in a line, thus the size of the printing paper cannot be set freely. Since it is generally desirable to heat the receptor layer on the photographic paper when subliming and transcribing the sublimable dye onto the photographic paper by the thermal head, it has been a conventional practice to increase the thrusting force of the thermal head to raise the tightness of contact between the ink ribbon and the photographic paper and to apply heat to the receptor layer of the photographic paper by the thermal head. It should be noted that, if the force of thrusting he thermal head to the ink ribbon and the photographic paper is increased, the driving force necessary for the movement of the thermal head, rewinding of the ink ribbon and the feed of the photographic paper has to be correspondingly increased. In addition, since the ink ribbon is prepared by coating the dye processed into an ink on the base paper, as described above, the heat reaches the receptor layer via the base paper and the dye layer. Besides, since air layers tend to be produced between the respective layers, the heat to be applied to the receptor layer needs to be set to take account of heat losses produced in each layer, thus lowering the heat efficiency. On the other hand, the produced picture tends to be lowered in quality if the photographic paper is not whitened at least directly after printing. Document EP-A-0 366 461 further discloses an optical recording medium responsive to thermal energy for forming a dye image, wherein the basic structure comprises a base layer, an underlayer comprising a near infrared absorbent material and a heat-sensitive colour developer layer containing a colourless dye and an organic developer. OBJECTS AND SUMMARY OF THE INVENTION In view of the above-described status of the art, it is an object of the present invention to provide a photographic paper a receptor layer of which may be heated efficiently by a printing device to assure high picture quality of the printed picture. According to the present invention, there is provided a photographic paper comprising a receptor layer provided as an upper layer of a photographic paper base for absorbing a vaporised vaporisable dye, and a light absorbing layer formed by a light absorbing agent provided between the photographic paper base and said receptor layer, characterised in that the light absorbing agent comprises whitening means for whitening the light absorbing layer in colour hue upon radiation. According to a specific embodiment, the light absorbing agent has a pale colour hue which is extinguished on radiation emitted from a light radiating element in a printing device. As the light absorbing agent, an infrared ray absorber capable of absorbing infrared rays may be employed. Some of the infrared ray absorbers exhibit colour extinguishing characteristics. Typical of the light absorbing agent is a functional near-IR absorption colouring matter manufactured by SHOWA DENKO KK under the trade name of IR 820B which exhibits maximum absorption for the light having a wavelength of 825 nm. If it is allowed to exist along with an ammonium salt of organic boron, such as tetrabutyl ammoniumbutyl triphenyl borate, in a solution, it absorbs the near IR rays, so that its colour is extinguished. According to another specific embodiment, the light absorbing agent comprises a capsule enclosing a whitening agent therein and being mixed in the light absorbing layer which is whitened by thermal destruction of the capsule by a light radiating element in a printing device. Examples of the whitening agents include titanium oxide, zinc oxide and calcium oxide. The capsules employed for enclosure of the whitening agents may be formed of condensates, such as polyurea or polyurethane, homopolymers such as polyethylene or polyvinyl alcohol or waxes such as paraffins or lipids. The present invention can be used with a printing device in which a vaporisable dye is thermally transcribed onto a receptor layer provided as an upper layer of the photographic paper base, comprising a light radiating body for whitening the colour of a light absorbing agent of a light absorbing layer provided between the photographic paper base and the receptor layer. Preferably, the light emitting body radiates a laser light. Preferably, the photographic paper comprises a protective layer which is formed of a highly heat-resistant and non-hygroscopic material and disposed between the photographic paper base and the light absorbing layer. The photographic paper can also comprise a protective layer which is formed of a highly heat-resistant and non-hygroscopic material and disposed under the photographic paper base. The term "vaporisable dye" s used in the present invention means collectively a solidified disperse dye, a liquefied disperse dye, a vaporised disperse dye, a sublimable dye and a disperse dye. Thus the vaporisable dye is defined as a dye having a temperature domain, in a temperature range of from 25°C up to a decomposition temperature, for which temperature domain the vapour pressure is not less than 0.01 Pascal, on the proviso that, if the dye molecules are associated in a gaseous phase at an average association number of n, the vapour pressure divided by the average number of association n is not less than 0.01 Pascal. Although a sublimable dye changed from its solid state to a gaseous state may be contemplated as the vaporisable dye, a dye having the state of a liquid between a solid state and a gaseous state is also included within the meaning of the vaporisable dye. Among a variety of the vaporisable dyes, a yellow dye, having a colour index number "C. I. Disperse yellow 201", manufactured by SUMITOMO KAGAKU KK under the trade name of "ESCYellow 155" and a cyan dye having a colour index number "C. I. Solvent Blue 63", manufactured by SUMITOMO KAGAKU KK under the trade name of "ESC- Blue 655" are employed in the printing device of the present invention. As a magenta dye, a tricyanomethine dye manufactured by MITSUBISHI KASEI KK under the trade name of "HSR-2031" is employed. With the printing device implementing the present invention, the dye tank stows the particulate vaporisable dye, and the entrance section liquefies the vaporisable dye and transports the thus liquefied dye to a vaporising section, which vaporises the liquefied dye transported by the entrance section under the heat of vaporisation supplied by the laser light for transcription of the vaporised dye onto the photographic paper. The heat generating effect of the vaporising section is improved by the laser light to enable the size of the heat radiating mechanism to be reduced. Printing becomes possible without employing an ink ribbon or a thermal head, as a result of which power saving and reduction in size and costs may be achieved. By preliminary heating within a low heat conducting material and employing the heat corresponding to the intensity of the laser light for vaporisation, the heat efficiency may be improved. The degree of freedom in photographic paper size may be increased because no ink ribbon is necessitated. By providing a light absorbing layer in the photographic paper, the operating efficiency is improved. Besides, the printing time may be shortened. It is also possible to conduct the liquefied vaporisable Ydye to the vaporising section by taking advantage of the capillary phenomenon with the aid of beads, or to use beads in the vaporising section. Since the receptor layer of the photographic paper may be heated by the laser light, the portions of the photographic paper other than the receptor layer are not affected by heat. If the laser light has a flat light intensity distribution, the photo-thermal conversion efficiency may be improved. With the sublimation type printing device according to the present invention, the containing section stows the particulate vaporisable dye, and the entrance section liquefies the particulate vaporisable dye and transports the thus liquefied dye to a vaporising section, which vaporises the liquefied dye transported by the entrance section under the heat of vaporisation corresponding to the laser light intensity for transcription of the vaporised dye onto the photographic paper. In this manner, printing becomes possible without employing an ink ribbon or a thermal head so that the printing device may be reduced in size and weight. Dye exchange may be facilitated because the containing section stowing the dye therein may be dismounted and exchanged for new ones. Since the heat of vaporisation corresponds to the laser light, excess heat or heat radiation is not required to enable the energy saving. Since the dye may be supplied singly, the photographic paper needs to be fed only once so that the printing time may be shortened. Freesize printing becomes possible because there is no limitation as to the photographic paper size imposed by the ink ribbon. Besides, since the light absorbing layer formed of a light absorbing agent capable of generating heat by efficiently absorbing the light is provided between the receptor layer and the photographic paper base, the receptor layer may be heated directly to assure a high quality of the printed picture. In addition, since a light radiating body interposed between the receptor layer and the photographic paper base of the photographic paper whitens the colour of the light absorbing agent of the light absorbing layer to assure the high quality of the printed picture. Consequently, if printing is made on the above-mentioned photographic paper by the above-mentioned printing device, the printing efficiency may be improved and the thrusting force between the dye and the receptor layer may be reduced, while resistance to abrasion may be improved. The picture quality may be improved because the light absorbing agent may be whitened in colour. If the laser light radiated by a laser block as the abovementioned light radiating body may be of equalised light intensity distribution, it becomes possible to equalise the heat conversion occurring at the light absorbing layer of the photographic paper. The above and other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments and the claims. BRIEF DESCRIPTION OF THE DRAWINGS (Figures 1 to 21 inclusive illustrate the construction and operation of a printer suitable for use with the photographic paper of the present invention). Fig.1 is a perspective view showing essential portions of a printer according to a first example. Fig.2 is a cross-sectional view showing essential portions of the first example. Fig.3 is a perspective view showing essential portions of a vaporisable portion of the first example. Fig.4 is a cross-sectional view showing essential portions of a first example employing beads in the vaporisable portion. Fig.5 is a back side view showing essential portions of the first example. Fig.6 is an illustrative view showing essential portions of the first example. Fig.7 is a perspective view showing a typical printing mechanism for the first example. Fig.8 is a perspective view showing essential portions of a printer according to a second example. Fig.9 is a perspective view showing a typical printing mechanism for the second example. Fig.10 is a back side view showing a laser block provided for the printing mechanism shown in Fig.9. Fig.11 shows an arrangement of an optical system for equalising the distribution of the laser light intensity. Fig.12A is a graph showing the distribution of the laser light intensity in case of not employing the optical system shown in Fig.11. Fig.12B is a graph showing the distribution of the laser light intensity in case of employing the optical system shown in Fig.11. Fig.13 is a perspective view showing essential parts of a printer according to a third example. Fig.14 is a perspective view showing the construction of a dye pack playing the role of a container for the third example. Fig.15 is a cross-sectional view showing a connecting portion between a dye feed pre-stage and the dye pack playing the role of a container for the third example. Fig.16 is a perspective view showing the dye supply pre-stage of a printer according to a third example. Fig.17 is a perspective view showing an inner structure of a feed supply post-stage and the feed supply pre-stage for the third example. Fig.18 is a schematic perspective view showing essential portions of a laser block according to the third embodiment. Fig.19 is a schematic perspective view showing a fourth example. Fig.20 is a reverse side view showing a laser block for the second example. Fig.21 is a perspective view showing a modified inner structure of a dye supply pre-stage. Fig.22 is a diagram illustrating the composition of the photographic paper according to a first embodiment of the invention. Fig.23 is a diagram illustrating the composition of the photographic paper according to a second embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, preferred embodiments of the printing device useable with the invention and the photographic paper according to the present invention will be explained in detail. In the first example of the above-mentioned type of printing device, a vaporisable dye is employed as a dye. The vaporisable dye collectively means a solidified disperse dyes, liquefied disperse dyes, vaporised disperse dyes, sublimable dyes and disperse dyes, in which a temperature range with a vapour pressure of not lower than 0.01 pascal exists in a temperature range from 25°C to the dye decomposition temperature. If the dye molecules are associated. in the gaseous phase with one another with a mean number of association of n, the vapour pressure divided by the mean number of association is to be not less than 0.01 Pascal. In the present first example, among the above-mentioned vaporised dyes, a vaporised dye manufactured by SUMITOMO KAGAKU KK under a trade name of "ESC -Yellow 155" having a colour index number of "C. I. Disperse Yellow 201" is employed as a yellow dye, referred to herein as Y. As a C dye, a dye manufactured by SUMITOMO KAGAKU KK under the trade name of "ESC-Blue 655", having a colour index number of "C. I. Solvent Blue 63" is employed. As an M dye, a tricyanomethine dye of the following chemical formula manufactured by MITSUBISHI KASEI KK under the trade name of "HSR2031" is employed. With the first example, the above-mentioned vaporisable dyes Y, C and M are ultimately vaporised and thermally transcribed onto the photographic paper. Therefore, a printer of the first example is referred to hereinafter as a sublimation type printer. The sublimation type printer of the first example, main portions of which are shown schematically in Fig.1, includes a main body 10, formed of special high melting plastics, such as polyimide, having low heat conductivity and devoid of heat moldability, dye tanks 11, 12 and 13 containing the abovementioned vaporisable Y, M and C dyes in a powdery state, entrance sections 14, 15 and 16 for dissolving the powdery dyes Y, M and C contained in the dye tanks 11 to 13 to the melting points thereof for transporting the dissolved liquefied dyes, and vaporising sections 17, 18 and 19 for vaporising the vaporisable dyes, dissolved and liquefied by these entrance sections 14 to 16, under the heat of vaporisation supplied by a laser light beam. The vaporised dyes are deposited on a photographic paper 21 via vaporisation openings, not shown, in the bottom parts of recesses or sinks 20 for dyes for each of the vaporising sections 17 to 19. These vaporising sections 17 to 19 are irradiated with laser beams from laser emitting sections for dyes Y, M and C, not shown, as shown by arrows 35, 36 and 37, respectively. A transparent section 22, formed of a glass material with high transmittance to permit a laser light to be transmitted therethrough without losses, is also irradiated with another laser light beam, as shown by an arrow 38, from a laser radiating section, not shown. Fig.2 shows a detailed construction of a sublimation type printer according to the present first example. In Fig.2, which is a sectional view showing essential portions shown in Fig.1, a laser radiating portion 34 and vaporisation openings 23, not shown in Fig.1, are shown. Meanwhile, since the dye tanks 11 to 13, entrance sections 14 to 16 and the vaporising sections 17 to 19 are each of an identical construction, only the dye tank 11 for dye Y, entrance section 14 and the vaporising section 17 are explained herein for brevity. The entrance section 14 and the vaporising section 17 are associated with a first heating member 31 designed for not imparting the heat directly to the photographic paper 21. The first heating member 31 has its one end 31a bent substantially vertically upwards and introduced into the dye tank 11. The first heating member 31 has its other end 31b extended up to a terminal end of the vaporising section 17. The vaporisable dye Y, dissolved and liquefied by being heated by the end 31a of the first heating member 31, referred to herein as the liquefied vaporisable dye 32, is transported by the entrance section 14 up to the entrance section 14. The entrance section 14 is associated with the first heating member 31, as mentioned above. This first heating member 31 is formed e.g. of carbon or silicon compounds and capable of radiating the heat of 50°C to 300°C on current conduction therethrough to liquefy the vaporisable dye and to maintain the latter in the liquefied and heated state. Besides, the first heating member 31 is of a capillary construction having superficial grooves and is adapted for transporting the liquefied vaporisable dye 32 up to the vaporising section 17. That is, the first heating member 31 transports the vaporisable dye 32, liquefied under the heat e.g. of 50°C to 300°C, as far as the vaporising section 17, while keeping the dye warm enough not to be solidified or thickened. The vaporising section 17 includes a first heating member similar to that provided in the entrance section 14. The first heating member 31 of the vaporising section 17 has a plurality of dye sinks recesses 20 for stowing the liquefied vaporisable dye. The bottom of each dye sink recess 20 has a large number of vaporising openings 23 which are fine through-holes each being of a diameter of several microns. The vaporising section 17 is provided with a second heating member, not shown, in addition to the first heating member 31. The second heating member is formed as layer of a semitransparent light absorbing agent coated on the surface of the first heating member 31 and each of the dye sink recesses 20. The second heating member is occasionally referred to herein as a light absorbing layer. The light absorbing layer efficiently translates the laser light indicated by arrow 35 from laser emitting section 34 into heat. That is, the liquefied vaporisable dye 32, transported by the entrance section 14 as far as the vaporising section 17, is heated up to the vaporising temperature by the light absorbing layer adapted for efficiently translating the laser light indicated by arrow 35 from laser radiating section 34 into heat. The vaporised dye is transferred onto the receptor layer 21a of the photographic paper 21 via the vaporising openings 23 formed in the bottom of the dye sink recesses 20. The concrete construction of the vaporising section 17 is shown in Fig.3. In this figure, the semi-transparent light absorbing agent, as the above-mentioned second heating member, is coated on the first heating member 31 and on the surface of the bottom of the dye sink recesses 20. The liquefied vaporisable dye 32, shown in Fig.2, transported as far as the vaporising section 17 by the first heating member 31 having a trenched or grooved structure, is stowed in the dye sink recesses 20. At this time, the laser light is radiated from the laser radiating section 34 shown in Fig.2 onto the dye sink recesses 20 so that the laser light is efficiently translated into heat by the light absorbing layer of the light absorbing agent for vaporising the liquefied vaporisable dye 32. The vaporised dye is absorbed by diffusion into the fine vaporising openings 23 each of a diameter not larger than several microns, formed in the bottom of the dye sink recesses 20. Since the vaporising openings 23 are formed so as to be passed through a protective layer 33 so that the vaporised dye is transcribed by diffusion onto the receptor layer 21a of the photographic paper 21 shown in Fig.2. Besides, part of the laser light is transmitted through the semi-transparent light-absorbing layer as far as the photographic paper 21. Part of the light which has reached the photographic paper 21 is used for heating the receptor layer 21a to aid in deposition of the vaporisable dye vaporised by the vaporising section 17. The operation of the sublimation type printer according to the above-described first embodiment is hereinafter summarised by referring to Figs.1 to 3. With the sublimation type printer of the first embodiment, the vaporisable dye contained within the dye tank 11 is liquefied by being heated by the first heating member 31 of the entrance section 14 up to its melting point. The liquefied vaporisable dye 32 is transported to the vaporising section 17 by the capillary phenomenon of the entrance section 14. The entrance section 14 heats the liquefied vaporisable dye 32 by its first heating member 31 to keep its temperature. In addition to the first heating member 31, which is the same as that provided in the entrance section 14, a semi-transparent light absorbing layer as the second heating member is provided in the vaporising section 17 for translating the laser light into heat. The vaporised dye is transferred onto the receptor layer 21a of the photographic paper 21 by a phenomenon of diffusion brought about by the vaporising openings 23 in the bottom of each of the dye sink recesses 20 of the vaporising section 17. The vaporising section 17 of the sublimation type printer according to the first example may also be designed for transcribing the vaporised dye onto the receptor layer 21a of the photographic paper 21 by the diffusion phenomenon brought about by beads, as shown in Fig.4. In Fig.4, the dye tank for the dye Y, as an essential portion, is shown in cross-section. In this figure, the first heating member 43 has its one end 43a introduced into a dye supply opening 42 formed in the lower end of the dye tank 41. This one end 43a of the first heating member 43 melts and liquefies the vaporisable dye. The liquefied vaporisable dye is supplied to the entrance section 44. In the entrance section 44, a number of beads 45 are arrayed along the first heating member 43. Each bead 45 has its upper part bonded to the first heating member 43 with an adhesive and its lower end covered by a protective layer 46. Similarly, a number of beads 45 are bonded to the first heating member 43 and to a second heating member 48. The lower part of the beads 45 of the vaporising section 47 are not covered. The first heating member 43 and the second heating member 48 are bonded to a base 49. The base 49 is transparent or otherwise formed with a through-hole in a light transmitting portion thereof for transmitting the light. Besides, it needs to be of as thin a structure as possible. To this end, a reinforcement 50 is provided on the top of the base 49. The adhesive employed for bonding the beads 45, first heating member 43 and the second heating member 48 is heat resistant and transparent. The protective layer 46 is employed for preventing intrusion of impurities or dust and dirt, so that it is formed of a material which is resistant to heat and abrasion and which is low in heat conductivity. The beads 45 are also heat-resistant and are formed of glass or a heat-resistant synthetic material. As for the vaporising section 47 for depositing the vaporised dye onto the photographic paper 21 by relying upon the capillary phenomenon brought about by the beads 45, the beads 45 are arrayed along the first heating member 43 and the second heating member 45, so that the arraying area for the beads 45 is extended as shown in Fig.5 which is a back side view showing the vaporising section 47 and the entrance section 44. The second heating member 48, employed in the vaporising section 47 along with the first heating member 43, is formed of a light absorbing material. In the vaporising section 47, the second heating member 48 is surrounded in its entirety by the first heating member 43, as shown in Fig.6, which is a view similar to Fig.5 except that the beads 45 are not shown. The operation of the vaporising section 47, employing the beads 45, is hereinafter explained by referring to Figs.4 to 6. The vaporisable dye contained in the dye tank 41 is heated to e.g. 50°C to 300°C by the first heating member 43 so as to be turned into the liquefied vaporisable dye which is then permeated through voids defined between beads 45 kept at the above temperature by the first heating member 43. The liquefied vaporisable dye is then guided under the capillary phenomenon brought about by beads 45 to reach the vaporising section 47. The liquefied vaporisable dye which has reached the vaporising section 47 is vaporised by being heated by the second heating member 48 adapted for efficiently generating the heat by the laser light radiated from a laser generating section 51. The dye thus vaporised is passed through voids defined by adjacent beads 45 by diffusion so as to be transcribed onto the receptor layer 21a of the photographic paper 21 via the lower ends of the beads 45 not covered by the protective layer 46. As a modification of the above-described embodiment in which the beads 45 are employed in the vaporising section 47, carbon compounds or light absorbing materials may be contained in or otherwise coated on the surface of the beads so that the beads 45 may simultaneously be employed as the light absorbing material for the second heating member 48. With the use of the beads 45 in the vaporising section 47, the vaporising openings are of uniform size to assure a constant amount of vaporisation of the vaporisable dye. The light absorbing agent may be coated on or contained in the beads 45 for simplifying the construction. The capillary phenomenon may be easily brought about with a material that cannot be etched. Gradation control may be facilitated by the constant amount of vaporisation. Besides, the bead size may be suitably chosen for controlling the air quantity and adjusting the amount of the heat storage. The heat efficiency may be improved by combining the reinforcement with base 49. Intrusion of dust and dirt or impurities may be inhibited by coating an area other than the vaporising openings with the protective layer 46. The beads may be used simultaneously as the wear-resistant layer in contact with the photographic paper 21 to simplify the construction. An illustrative example of a printing mechanism employing the sublimation type printing device according to the abovedescribed first embodiment is explained by referring to Fig.7. The printing mechanism includes vaporising units 51, 52 each consisting in a laser emitting unit built into a sublimation type printer of the first embodiment the essential part of which is shown in Fig.1. The two vaporising units 51, 52 are of identical construction comprising dye layers 11, 12 and 13, entrance sections 14, 15 and 16, vaporising sections 17, 18 and 19, four laser radiating sections and a transparent section 22. These vaporising units 51, 52 arc connected to signal lines 53, 54 and are moved by a vaporising unit feed shaft 55 and a vaporising unit supporting shaft 56 in the vaporising unit feed direction indicated by arrow L. The photographic paper 21 is fed by a photographic paper driving roll 57 in the paper feed direction indicated by arrow N. The vaporising units 51, 52 and the photographic paper 21 are pressed into tight contact with each other by a vaporising unit supporting roll 58. The photographic paper 21 is introduced into a space between the vaporising units 51, 52 and the vaporising unit supporting roll 58. With the printing mechanism shown in Fig.7, the two vaporising units 51, 52 are provided for printing in two sections, with the vaporising unit being fed in one line. The vaporisable dyes Y, M and C are simultaneously heated and melted by the heating members within the vaporising units 51, 52 so as to be turned into liquefied vaporisable dyes. The vaporisable dye liquefied in the vaporising units 51, 52 is heated by the laser light beams associated with picture signals from the Y, M and C laser radiating units so as to be turned into the vaporised dye which is transcribed onto the receptor layer 21a of the photographic paper 21. After completion of one-line printing, the photographic paper 21 is fed by one-line length by a photographic paper driving roll 57. Printing is started sequentially for each colour and performed in a similar manner after the third dot. A second example concerning a printing device according to the present invention is hereinafter explained by referring to Fig.8. Each dye employed in the present second embodiment is similar to the sublimable dye employed in the sublimation type printer according to the first example. Since the vaporisable dyes Y, C and M of the present second example are also ultimately vaporised and thermally transcribed onto the photographic paper, the present device is referred to herein as a sublimation type printer according to the second embodiment. The sublimation type printer according to the second embodiment, essential parts of which are shown schematically in Fig.8, includes dye tanks 61, 62 and 63 containing powdered vaporisable dyes Y, M and C, entrance sections 64, 65 and 66 for liquefying the vaporisable dyes supplied from the vaporising sections 67 to 69 and transporting the liquefied dyes and vaporising sections 67, 68 and 69 for vaporising the vaporisable dyes liquefied by these entrance sections 64 to 66 by the vaporising heat supplied by the laser light from laser light emitting means, not shown. The vaporisable dye is transcribed onto the photographic paper 21 via the vaporising openings formed in the vaporising sections 67 to 69. It is noted that a plurality of each of the vaporising sections 67 to 69 are provided along each of the entrance sections 64 to 66. For example, a number of the vaporising sections 67 corresponding to the number of dots of a picture are provided along the line direction of the photographic paper shown by arrow L in Fig.8. The same is true of the vaporising sections 68 and 69. The operation of the sublimation type printer according to the second embodiment is explained in connection with the dye tank 61, entrance section 64 and the vaporising sections 67 shown in Fig.8. A first heating member 71 at the entrance section 64 heats the vaporisable dye in the dye tank 61 so that the vaporisable dye is turned into a liquefied vaporisable dye. The entrance section 64 transports the liquefied vaporisable dye up to the vaporising sections 67 under a capillary phenomenon as in the case of the sublimation type printer of the previously explained first example. The liquefied vaporisable dye from the dye tank 61 is transported by the entrance section 64 onto the plural vaporising sections 67 which are sequentially irradiated with the laser light radiated by laser radiating means, not shown. That is, the first heating member 71 of the entrance section 64 liquefies the vaporisable dye contained in the dye tank 61 at its one end and transports the liquefied vaporisable dye as far as the vaporising sections 67 by its capillary structure provided by the beads or flutes as it maintains the temperature of 50°C to 300°C of the dye to prevent its solidification. The vaporising sections 67 are also provided with the first heating member 71 similar to that provided for the entrance section 64. Each vaporising section 67 is provided with a plurality of fine vaporising openings each being of a diameter of several microns. Besides the first heating member 71, a second heating member 72 is also provided for the vaporising sections 67. The second heating member is a light absorbing layer formed by coating a semi-transparent light absorbing agent on the first heating member 71 and the vaporising openings. The second heating member efficiently translates the laser light from a laser radiating section, not shown, into heat, so that the vaporisable dye introduced into the vaporising sections 67 is vaporised so as to be transcribed onto the receptor layer of the photographic paper via the vaporising openings formed in the vaporising sections 67. The same construction is employed for the dye tanks 62, 63, entrance sections 65, 66 and the vaporising sections 68, 69. Besides, since the light absorbing layer is semitransparent, part of the light which has reached the photographic paper 21 is used for heating its receptor layer 21a to aid in deposition of the vaporisable dye vaporised by the vaporising sections 67. An illustrative example of a printing mechanism employing the sublimation type printer according to the second example is hereinafter explained by referring to Fig.9. This printing mechanism comprises a sublimation type printer of the second embodiment, the essential portions of which are shown schematically in Fig.8, and a pair of movable laser blocks 82, 83 of identical construction for radiating the laser light on the laser block 81 for printing. The sublimation type printer is secured in position as a head block. Each of the laser blocks 82, 83, the reverse side of which is shown in Fig.10, has a laser light outgoing opening 89a for Y printing, a laser light outgoing opening 89b for M printing, a laser light outgoing opening 89c for C printing and a laser light outgoing opening 89d for the photographic paper. These laser blocks 82, 83 are connected to a signal line 84 for laser light and is moved by a laser block feed shaft 85 and a laser block supporting shaft 86 in the line direction as indicated by arrow L. At this time, the laser light outgoing opening 89a for Y printing, the laser light outgoing opening 89b for M printing and the laser light outgoing opening 89c for C printing are positioned directly above the vaporising sections 67, 68 and 69 of the head block 81, respectively. The photographic paper 21 is fed by paper driving rolls 87 in the paper feed direction indicated by arrow N. The photographic paper 21 is pressed by the paper supporting roll 88 into intimate contact with the head block 81. The photographic paper 21 is inserted into a space between the head block 81 and the supporting roll 88. The vaporising sections 67, 68 and 69 are arrayed in alignment with the printing direction indicated by arrow N, with the number of each of the vaporising sections 67 to 69 along the line direction indicated by arrow L being the same as the number of pixels. The laser light radiating openings in the laser blocks 82, 83 are set so as to be in register with the vaporising sections 67, 68 and 69 of the head block 81 in the paper feed direction or printing direction and arrayed at a rate of the number of the openings to the number of the vaporising sections 67 to 69 of the head block 81 in the line direction of 1 : 1 or 1 : 1/n. If the laser light radiating openings are arranged at a number rate of 1 : 1 with respect to the vaporising sections in the head block 81, the laser radiating openings may be provided in the laser block 81. Even if the laser light radiating openings are arranged at a number rate of 1 : n with respect to vaporising sections in the head block 81, the laser radiating openings may be provided in the laser bloc 81 at a number rate of 1/n. The vaporisable dyes Y, M and C are heated simultaneously by the first heating member within the head block 81 so as to be turned into the liquefied vaporisable dye. The vaporisable dyes, liquefied by the vaporising sections 67, 68 and 69 within the head block 81, are additively heated by the laser light beams corresponding to the picture signals from the laser blocks 82, 83 so as to be transcribed onto the receptor layer 21a of the photographic paper 21 via the vaporising openings which provide for dye diffusion. If the laser radiating openings are provided at the number rate of 1/n with respect to the vaporising sections, the laser blocks 82, 83 are moved in the line direction indicated by arrow N for completing the printing for one line. The same operation is performed for each of the dyes M and C. The printing for three lines at the start and end of printing is made sequentially and that for the remaining lines is performed simultaneously for the Y, M and C dyes. On completion of printing for one line, the photographic paper 21 is fed by one line by the photographic paper driving roll 87. Thus, with the present sublimation type printer according to the present second embodiment, the head block 81, provided with a plurality of each of the vaporising sections 67 to 69, is fixed, while the laser blocks 82, 83, having the laser radiating openings thereof aligned with the vaporising sections 67 to 69, are moved and the vaporisable dyes, liquefied by the laser light beams corresponding to the picture signals, are additively heated and vaporised for transcription on the photographic paper. Meanwhile, each vaporising section of the sublimation type printer according to the second embodiment may also be arranged in accordance with the principle of the capillary phenomenon brought about by beads. It should be noted that, if a laser light is radiated on the vaporising sections of the sublimation type printer according to the first or second example after being equalised in intensity in the laser generating section and in the laser blocks over its range of distribution, heat transformation in the light absorbing layer may be equalised and, besides, the energy transformation efficiency may be maximised. If a semiconductor laser having a light distribution in which the energy density becomes higher towards its mid portion is radiated onto a light absorbing layer is provided in close proximity thereto, a non-uniform thermal energy having only poor efficiency as the energy used for transcribing the dye is produced. Besides, since the energy density is high at the mid region, the receptor layer of the photographic paper onto which the dye is transferred tends to be dissolved or even scorched under the high heat. Also, in view of the angle of light diffusion, the distance between the light source and the an object receiving the light tends to be limited. In addition, because of the non-uniform light distribution, the density of transcription tends to be thicker and thinner towards the mid region and towards the rim portion of the photographic paper, respectively. It may be contemplated to expand the light distribution of the laser light from the laser light source by a diffusion plate or a concave lens for providing a uniform light distribution on the irradiated surface. That is, it suffices to diminish the degree of concentration towards the mid region in the abovedescribed energy distribution to relax the light concentration to provide a flat light distribution. Fig.11 shows an optical system for generating a laser light having an equalised range of distribution of laser light intensity. Referring to Fig.11, showing such optical system, a laser light radiated from a semiconductor laser 91 is collimated by a collimator lens 92 which is converted into diffused light by e.g. a flat plate micro-lens 93 of a fine micro-lens array construction. The diffused light is then caused to fall on a convex lens 94 which condenses the diffused light to radiate a light having a uniform light intensity distribution onto a light absorbing layer. In this manner, the light distribution similar to a Gaussian distribution, as shown in Fig.12A, is converted into a trapezoidal light distribution as shown in Fig.12B. Therefore, if the distribution of irradiation of the laser light, employed for generating the heat of vaporisation at a vaporising section, is equalised by the optical system shown in Fig.11, the light energy may be converted into a heat energy at a high efficiency. Besides, the use of the above-described optical system leads to a uniform transcription density and coloration with high resolution. The distance between the light source and the irradiated member may be set freely. Besides, a suitable size of coloration may be achieved depending on the manner of designing of the optical system and the semiconductor laser power. A third example of the printing device is hereinafter explained by referring to Fig.13. In the present third example, a particulate vaporisable dye, consisting in a mixture of the vaporisable dyes Y, M and C as used in the sublimation type printer of the first or second embodiment and a dispersant compatible with the vaporisable dyes, such as a volatile binder, is employed and vaporised so as to be transcribed under heat onto the photographic paper. For this reason, the third embodiment is referred to herein as a sublimation type printer according to the third embodiment. The sublimation type printer according to the third example, shown schematically in Fig.13, comprises a dye pack 110 having separate tanks for the particulate Y, M and C dyes, a dye supply pre-stage section 120 for shifting the particulate vaporisable dyes from the dye pack 110 in one predetermined direction, a dye supply post-stage section 140 for receiving the particulate vaporisable dye from the pre-stage section 120, a vaporising section, not shown, for receiving and vaporising the particulate vaporisable dye supplied from the post-stage section 140, a laser block 150 for radiating a laser light onto the vaporising section for generating the heat of vaporisation therein, a paper feed roll 102 for feeding a photographic paper 21 in a direction shown by arrow N so that the vaporised dye is transcribed thereon, and a photographic paper tray 103 for storing a roll of the photographic paper 21. Referring to Fig.14, the construction of the dye pack 110 is first explained. The dye pack 110 has three separate tanks, that is a Y-tank 111, an M-tank 112 and a C-tank 113, in which the above-mentioned particulate vaporisable dyes Y, M and C are stored, respectively. The dye pack 110 is dismountable for exchange and has a hermetically sealed structure to prevent intrusion of humidity or foreign matter or vaporisation of the dyes under the effect of ambient light. However, the dye pack 110 also has a fine pore area 114 to permit air venting. As the dye pack 110 is secured to the dye supply pre-stage section 120 shown in Fig.3 by set screws 104a to 104d, the particulate vaporisable dyes are fed onto the dye supply prestage section 120 via a Y-dye outlet 115, an M-dye outlet 116 and a C-dye outlet 117, each in the form of protrusions, provided on the bottom of the pres-stage section 120. These dye outlets 115 to 117, in the form of protrusions, are introduced into a Y-dye reception opening 121, an M-dye reception opening 122 and a C-dye reception opening 123, formed in the dye supply pre-stage section 120 shown in Fig.13. This state is shown in the cross-sectional view of Fig.15. Although only the structure of a connecting portion between the Y-dye outlet 115 shown in Fig.14 and the Y-dye receiving opening 121 shown in Fig.13 is shown in the cross-sectional view in Fig.15, the same structure is used for connecting portion between the Mdye outlet 116 and the C-dye outlet 117 and that between the Cdye outlet 117 and the M-dye outlet 123. First, a simplified resilient valve 115b is provided at a tubular portion 115a of the dye outlet 115 to permit the dye pack 110 to be hermetically sealed under the usual condition of the dye pack in which the dye pack is not mounted onto the dye supply pre-stage section 120. A spring section 124 and a lid 125 having a conical portion 125b formed with flutes 125a is provided in the vicinity of the dye receiving opening 121 of the dye supply prestage section 120 to permit the pre-stage section 120 to be hermetically sealed under the usual condition in which the dye pack 110 is not mounted in position on the pre-stage section 120. When the dye pack 110 is mounted on the pre-stage section 120, the lid 125 fitted with the conical portion 125b formed with the flutes 125a is thrust upwards for opening slit-shaped openings 118 and 127 formed in the pre-stage section 120 and the dye outlet 115. At this time, the conical portion 125b of the lid 125 formed with the flutes 125a thrusts the valve 115b at the dye outlet 15 open, so that the particulate vaporisable dye contained in the dye pack 110 descends along the flutes 125a of the lid 125 which has thrust open the valve 15b of the dye outlet 115. The dye is then guided via the slit-shaped openings 18, 27 towards the dye supply pre-stage section 120. A resilient member 126 is mounted in the vicinity of the dye supply pre-stage section 120 for maintaining a hermetically sealed structure after connection of the pre-stage section 120 to the dye pack 110. The flutes 125a may be designed to allow passage only of the particulate dye having a size not larger than a predetermined size. Referring to Figs.16 and 17, the constructions of the dye supply pre-stage, the dye supply post-stage section 140 and vaporising sections are hereinafter explained. The dye supply pre-stage section 120 separately receives the particulate vaporisable dyes Y, M and C, separately contained in the Y-tank 111, M-tank 112 and in the C-tank 113 of the dye pack 110, shown in Fig.14, in its Y-dye supply pre-stage section 128, M-dye receiving pre-stage section 129 and in the C-dye receiving pre-stage section 130, respectively, by virtue of the connection between the Y-dye outlet 115, M-dye outlet 116 and the C-dye outlet 117 of the dye pack 110, on one hand, and the Y-dye receiving opening 121, M-dye receiving opening 122 and the C-dye receiving opening 123, on the other hand. The particulate vaporisable dyes Y, M and C, supplied to the Y-dye supply prestage section 128, M-dye receiving pre-stage section 129 and the C-dye receiving pre-stage section 130, are rollingly moved along the direction shown by arrow E. Such rolling movement of the particulate vaporisable dyes Y, M and C is rendered possible by the internal structure of the dye supply pre-stage section 120 as shown in Fig.17, in which the internal structure of the Y-dye supply pre-stage section 128, Mdye supply pre-stage section 129 and the C-dye supply pre-stage section 130 is shown with a lid 120b of the pre-stage section 120 detached from a casing section 120a. The Y-dye supply pre-stage section 128, M-dye receiving pre-stage section 129 and the C-dye receiving pre-stage section 130 are provided with feed screws 134, 135 and 136, respectively, which are formed in shafts 131, 132 and 133, respectively. These feed screws 134 to 136 are rotated about their own axes by a rotational torque which the shafts 131 to 133 receive from a gear 105, shown in Fig.16, which is rotated under a driving force of feeding the photographic paper 21. Thus the particulate vaporisable Y-dye 137, for example, is rollingly moved in the direction shown by arrow E in Fig.16. The particulate vaporisable Y-dye, for example, is fed onto the dye supply post-stage section 140 via through-holes 138. The internal structure of the post-stage section 140 is also shown in Fig.17. The dye supply post-stage section 140 is formed by stacking a plate 140a, formed of a glass material having low light absorbance and a low heat conductivity, on a plate 141 formed with a number of slits 148, each being several microns in diameter. The post-stage section 140 also includes a Y-dye supplying patterned groove 142, about 50 to 80 µm deep, for conducting the particulate vaporisable dye 137 fed via the through-holes 140. An M-dye supplying patterned groove 143 and a C-dye supplying patterned groove 144 are formed in a similar manner. These grooves 142, 143 and 144 are each formed with a plurality of vaporising sections 145, 146 and 147, respectively. The particulate vaporisable Y-dye 137 is fed in a direction shown by arrow F in the Y-dye supplying groove 142, for example, so as to be stored in the vaporising section 145. The laser light transmitted through a lid 140b formed of a glass material exhibiting high transmittance is radiated on the particulate vaporisable Y-dye 137 stored in the vaporising section 145. Each of the vaporising sections 145 to 147, irradiated with the laser light from a laser block 150 via the lid 140b, absorbs about one half of the volume of the laser light to transform it into heat for vaporising the dye. The remaining one-half of the laser light is used for heating the reception layer on the photographic paper 1. The dye vaporised by the vaporising sections 145 to 147 is permeated towards below through the vaporising openings 148 formed in the plate 141 under the capillary phenomenon so as to be transcribed on the receptor layer of the photographic plate 21. Each of the particulate dyes which has not been stowed in the vaporising sections 145 to 147, that is not vaporised, is circulated via the grooves 142, 143 and 144 of the dye supply post-stage section 140 to the dye supply pre-stage section 120. The laser block 150 is explained by referring to Fig.18. The laser block 150 has its arms 151, 152, 153 and 154 secured to a base section 161. Each of these arms 151 to 154 is provided with a plurality of semiconductor laser devices so that several laser light beams 155, 156, 157 and 158 are radiated simultaneously from these arms 151 to 154 in a downward direction, that is towards the vaporising sections 145,146 and 147. The driving of the laser block 150 in the direction of arrow G is controlled by e.g. a rotary actuator 159, such as an electric motor, so that the laser block is advanced and receded each in e.g. three stages via an offset cam 160. The driving of the rotary actuator 159 is carried out in a timed relation to the Y, M and C colour signals. The driving of the laser block 150 in the direction of arrow H is controlled e.g. by a feed mechanism or by a linear motor. This enables the number of the laser devices to be reduced to lower the costs and to improve the yield. The driving in the direction of arrow H or in the transverse direction is carried out in a timed relation to the colour dot signals. With the sublimation type printer according to the third embodiment, the particulate vaporisable dyes Y, M and C, contained in separate tanks of the dye pack 110, are transported in one direction by the dye supply pre-stage section 120 up to the vaporising sections 145, 146 and 147 of the dye supply poststage 140, so as to be vaporised in the vaporising sections 145, 146 and 147 by the vaporising heat corresponding to the laser light for transcription onto the photographic paper 21. Thus there is no necessity of providing an ink ribbon or a thermal head and the device may be reduced in size while dye exchange may be facilitated. Besides, any excess dye left in the vaporising sections 145, 146 and 147 may be circulated for achieving saving to assure printing with high picture quality. Referring to Fig.19, a fourth example of the printing device is explained. In the present fourth example, similarly to the above-described third embodiment, the particulate vaporisable dye is employed and vaporised so as to be thermally transcribed onto the photographic paper. Thus the device of the present fourth example is hereinafter referred to as a sublimation type printer according to the fourth example. Although the dye pack in the sublimation type printer is not shown in Fig.19 showing the schematic arrangement of the printer, the construction of the printer and the manner of feeding the dye to the dye supply pre-stage section 171, corresponding to the dye supply pre-stage section 120 according to the third example, is similar to the sublimation type printer according to the third example. Besides, the manner of transporting the dye within the dye supply pre-stage section 171 is similar to that performed with the sublimation type printer according to the third example. With the sublimation type printer according to the fourth example, a head block 170, comprised of a dye pack, not shown, the dye supply pre-stage section 171 and a dye-supply post-stage section 172 having a vaporising section, not shown, is fixed, and laser blocks 173, 174, for radiating the laser light onto the head block 170, are moved for performing the printing on the photographic paper 21. The laser blocks 173, 174 are of identical construction. The laser blocks 173, 174, the back sides of which are shown in Fig.20, are each formed with Y-printing laser outgoing openings 176a, M-printing laser outgoing openings 176b, Cprinting laser outgoing openings 176c and outgoing openings for a laser for photographic paper 176d, and are connected to a signal line for laser 175. The laser blocks 173, 174 are moved by a laser block feed shaft 177 and a laser block supporting shaft 178 so as to be moved in the line direction as indicated by an arrow L. At this time, the Y-printing laser outgoing openings 176a, M-printing laser outgoing openings 176b, Cprinting laser outgoing openings 176c and the outgoing openings for laser for photographic paper 176d of the laser blocks 173 and 174 are positioned directly above the vaporising sections formed in the dye supply post-stage section 172 of the head block 170. Referring to Figs.19 and 20, the operation of the sublimation type printer according to a fourth example is hereinafter explained. The photographic paper 21 is fed by a photographic paper driving roll 179 is the paper feed direction shown by arrow N. The photographic paper 21 is pressed by a printing paper supporting roll 180 into intimate pressure contact with the head block 170. The photographic paper 21 is introduced into a space between the head block 170 and the photographic paper supporting roll 180. The vaporising sections of the head block 170 are arrayed in alignment with the printing direction indicated by arrow N, with the number of each of the vaporising sections in the head block 170 along the line direction indicated by arrow L being the same as the number of pixels. The laser light radiating openings in the laser blocks 173, 174 are set so as to be in register with the vaporising sections in the paper feed direction or printing direction, and are arrayed at the number rate of 1 : 1 or 1 : 1/n in the line direction. If the laser light radiating openings are arranged at the number rate of 1 : 1 with respect to the vaporising sections, the laser radiating openings may be provided in the laser block 170. Even if the laser light radiating openings are arranged at the number rate of 1 : n with respect to the head block 170, the laser radiating openings may be provided in the laser block at the number rate of 1/n. The vaporisable dyes in the vaporising sections within the head block 170 arc vaporised by the laser light corresponding to picture signals from the laser blocks 173 and 174 so as to be transcribed onto the photographic paper 21. If the number of the laser radiating openings bears a ratio of 1/n with respect to the number of the vaporising sections, the laser blocks 173, 174 are moved in the line direction indicated by arrow N a distance corresponding to the number of pixels to complete one line. The same operation is performed for the dyes M and C. The Y, M and C dyes are printed sequentially for three printing start and end lines and simultaneously for the remaining lines. After the end of printing for one line, the photographic paper 21 is fed by one line by the printing paper driving roll 179. Thus, with the sublimation type printer according to the present fourth example, since the head block 170 is fixed, and the laser blocks 173, 174, having the respective laser radiating openings aligned with the vaporising sections, are moved, for vaporising the particulate vaporisable dyes, moved in one direction by the dye supply pre-stage section 171, by the laser light corresponding to the picture signals, for transcription onto the photographic paper 21, there is no necessity of providing an ink ribbon or a thermal head, so that the device may be reduced in size. Besides, dye exchange may be simplified. In addition, since any excess dye left in the vaporising sections 145, 146 and 147 may be circulated for achieving the saving in the dye to assure the printing with high picture quality. It is noted that, with the sublimation type printers according to the third and fourth embodiments, the particulate vaporisable dye is contained in the dye pack and used in circulation. Alternatively, the particulate vaporisable dye contained in the dye pack may also be deposited in the dye supply pre-stage section on the surfaces of spherical-shaped beads, each being several microns in diameter, so as to be moved in one direction for being supplied to the vaporising sections formed in the dye supply post-stage section. The dye may also be circulated in the manner as described above. The beads, on the surfaces of which the particulate vaporisable dye is deposited, may also be moved in one direction by transverse vibrations as shown in Fig.21. In such case, the particulate vaporisable dye supplied from the dye pack, herein not shown, via dye reception openings 191, 192 and 193 is moved through the inside of the dye supply pre-stage section 190 by a transverse oscillation generating device 194, so as to be supplied to a dye supply post-stage section 200 having the vaporising sections formed therein. The transverse oscillation generating device 194 generates transverse oscillation by a shaft 195. Shafts 196, 197 are also the shafts for generating transverse oscillation in transverse oscillation generating devices, not shown, having the same construction as the transverse oscillation generating device 194. The beads, on the surfaces of which the particulate or powdered vaporisable dye is deposited, may also be moved by pneumatic feed means, in a manner not shown. On the other hand, if the laser light radiated on the sublimation type printers according to the third and fourth examples is radiated in each laser block with equalised intensity distribution, as in the case of the sublimation type printer according to the first and second examples, it becomes possible to equalise the transformation into heat in the light absorbing layer and to maximise the energy conversion efficiency. Meanwhile, with the sublimation type printers according to the first to fourth embodiments, the vaporised dye is deposited on the photographic paper 21 for printing. In any of these examples, the receptor layer on the surface of the photographic paper 21 may be heated to aid in deposition of the vaporised dye. Referring to Figs.22 and 23, first and second embodiments of the present invention, relating to the photographic paper capable of heating the receptor layer efficiently, will be explained. In the following, the fifth and sixth examples are referred to as a photographic paper according to the fifth example and a photographic paper according to the sixth example, respectively. Referring first to Fig.22, the photographic paper according to a first embodiment of the invention includes, looking from the upper side, a receptor layer 211 which is formed of a resin, such as cellulose resin, and which is capable of transmitting the light therethrough and absorbing the vaporisable dye, a light absorbing layer 212 formed of a light absorbing agent capable of efficiently absorbing the laser light and generating the heat efficiently, a first protective layer 213 formed of a highly heat-resistant and non-hygroscopic material, such as polypropylene, a photographic paper base 214 formed e.g. of polyethylene terephthalate, and a second protective layer 215 having properties similar to those of the first protective layer 213 and playing the role of not causing the warping of the photographic paper of the first embodiment 210, these layers 211 to 215 being bonded and stacked one upon the other with the aid of an adhesive, not shown. The receptor layer 211 absorbs the dye vaporised under the heat of vaporisation generated by a laser light from a printing device, not shown. That is, a semi-transparent heating member, provided within a vaporising section of the printing device, not shown, generates the heat efficiently by the laser light to vaporise the vaporisable dye. The vaporised dye is released via the vaporising openings provided in the vaporising section so as to be deposited on the receptor layer 211. Part of the laser light is transmitted through the semi-transparent heating member so as to be radiated on the photographic paper 210. Since the receptor layer 211 formed on the surface of the photographic paper transmits the light, the laser light reaches the light absorbing layer 212. The light absorbing layer 212 is formed e.g. of a light absorbing agent, such as an IR absorber, and hence absorbs the laser light efficiently, so that heat may be generated efficiently. The heat generated in the light absorbing layer 212 is transmitted to the receptor layer 211 and tends to be transmitted to the first protective layer 213. However, since the first protective layer 213 is formed of a highly heatresistant and low heat conducting material, such as polypropylene, it is transmitted only to the receptor layer 211 without being transmitted to the first protective layer 213. Thus the receptor layer 211 is heated efficiently by the light absorbing layer 212. In general, the light absorbing agent, used for absorbing the light, reflects the light if the agent has a white hue. For this reason, the light absorbing layer 212 has a pale colour hue, instead of a white hue. Such colour hue of the light absorbing layer 212 deteriorates the quality of the printed picture. For this reason, the light absorbing layer 212 needs to be whitened after printing. For whiting the light absorbing layer 212 after printing, the light absorbing agent, such as the above-mentioned IR light absorber, which has its colour extinguished on irradiation with a laser light, is employed. As such light absorbing agent, a functional near-infrared ray absorbing colouring matter, manufactured by SHOWA DENKO KK under the trade name of IR 820B, is employed. This functional near-infrared ray absorbing colouring matter IR 820B, exhibits an absorption maximum for the light having a wavelength of 825 nm, such that, if it is used along with an ammonium salt of organic boron, such as tetrabutyl ammoniumbutyl triphenyl borate, in a solution, it absorbs the near infrared rays to extinguish the colour. Thus, with the photographic paper 210 of the first embodiment, the receptor layer 211 may be directly heated by the light absorbing layer 212, while the pale colour of the light absorbing layer 212 is extinguished by the laser light, so that the printed picture is not degraded in picture quality. The construction of the photographic paper according to a second embodiment of the present invention is now explained. The construction of the photographic paper according to the sixth embodiment shown in Fig.23 is approximately similar to that of the above-described first embodiment shown in Fig.22, so that similar parts or components are depicted by the same numerals and the corresponding description is omitted for simplicity. The photographic paper 220 of the present second embodiment includes, looking from the upper side, a receptor layer 211, a light absorbing layer 221, a first protective layer 213, a photographic paper base 214 and a second protective layer 215, bonded and stacked together with the aid of an adhesive, not shown, applied between the adjacent layers. The light absorbing layer 221 efficiently absorbs a laser light, not shown, for generating the heat efficiently, as in the case of the photographic paper of the first embodiment. The receptor layer 211 is heated by the light absorbing layer 221. With the photographic paper 220 according to the second embodiment, a capsule having an enclosed whitening agent is destroyed by the laser light for permeating the whitening agent for whitening the light absorbing layer 221. That is, the light absorbing layer 221 contains a light absorbing agent and a whitening agent, such as titanium oxide, enclosed in a number of capsules 222 formed e.g. of polyurea, as shown in Fig.23. The capsule 222 is thermally destroyed by the laser light for permeating the whitening agent into the light absorbing agent for extinguishing the colour of the light absorbing agent for whitening the light absorbing layer 221. The whitening agents may be enumerated by titanium oxide, zinc oxide or calcium oxide. The capsule for enclosing the whitening agent may be formed of condensates, such as polyurea or polyurethane, homopolymers such as polyvinyl alcohols or waxes, such as paraffin or lipid. Thus, with the photographic paper 220 of the present second embodiment, the receptor player 211 may be heated directly by the light absorbing layer 221 to assure a high heat efficiency, while the light absorbing layer 221 is whitened by the whitening agent which is distributed on thermal capsule destruction to maintain a high picture quality of the printed picture. With the use of the photographic paper according to the first or second embodiment, the light absorbing layer 211 or 221 of the photographic paper 210 or 220 may be whitened by the laser light which has its output increased by employing a transparent section of vaporising sections 51, 52, corresponding to the transparent section 22 in Fig.1, if the above-mentioned typical printing mechanism shown in Fig.7 provided with the sublimation printer according to the first example is employed. In such case, the laser light employed in the vaporising sections 51, 52 is of a four-beam construction. With the illustrative printing mechanism, provided with the sublimation type printer according to the above-mentioned second embodiment, as shown in Fig.9, a laser light which has its output increased is radiated after the end of printing on the transparent section of the head block 81, corresponding to the transparent section 70 of Fig.8, via the laser radiating opening 89d for photographic paper formed in the laser locks 82, 83, for whitening the light absorbing layers 211 or 221 of the photographic papers 210 or 220, respectively. With the sublimation type printer according to the third example, shown in Fig.13, the light absorbing layers 211 or 221 of the photographic paper 210 or 220 may be whitened by onehalf of the laser light from the laser block 150. With the sublimation type printer according to the fourth example, shown in Fig.19, the light absorbing layers 211 or 221 of the photographic paper 210 or 220 may be whitened by radiating a laser light of an increased output via the laser radiating opening for photographic paper 176d formed in the laser block 173 or 174 after the end of printing. Referring to Figs. 8 and 9, the operation of the sublimation type printer of the second example up to the whitening of the light absorbing layer 211 or 221 is explained. With the sublimation type printer according to the second example, the vaporisable dye contained in e.g. the dye tank 61 is liquefied or melted by being heated by the first heating member 71 of the entrance section 64. The vaporisable dye thus liquefied is moved by the capillary phenomenon of the entrance section 64 onto the vaporising section 67. The entrance section 64 heats the liquefied vaporisable dye by the first heating member and maintains its temperature. The liquefied vaporisable dye, moved onto the vaporising section 67, is vaporised under the heat of vaporisation from the second heating member which efficiently generates heat by the laser light radiated from the laser block 82 or 83. The vaporised dye is passed through the vaporising openings in the vaporising section 67 by the diffusion phenomenon so as to be deposited on the receptor layer 211 or 211 of the photographic paper 210 or 220. At this time, the light absorbing layers 211 or 221 of the photographic paper 210 or 220 is heated by the laser light transmitted through the semitransparent second heating member of the vaporising section 67 for heating the receptor layer 211 or 211 to aid in transcription of the vaporised dye. Subsequently, the laser light transmitted through the transparent section 70 thermally destroys the light absorbing agent of the light absorbing layer 211 or 221 or the capsules 222 enclosing the whitening agent for whitening the colour hue of the light absorbing layer 211 or 221. The order of the intensity or temperature of the laser light may be expressed by (the laser light for dye transcription) < (laser light for heating the receptor layer) < (laser light for whitening the light absorbing layer). It is noted that the photographic paper according to the present invention is not limited to the above-described first and second embodiments. For example, the receptor layer, light absorbing layer, first protective layer, photographic paper base and the second protective layer may be formed of materials different from those given above if these layers are endowed with the properties required of them. The same may be said of the light absorbing agents, whitening agents or capsules provided in the light absorbing layer. The whitening of the light absorbing layer may also be realised by the combination of thermal destruction of the light absorbing agent and thermal destruction of the whitening agent enclosing capsules brought about by the laser light.

Claims: A photographic paper (21; 210; 220) comprising a receptor layer (211; 221) provided as an upper layer of a photographic paper base (214) for absorbing a vaporised vaporisable dye (C, M, Y), and a light absorbing layer (212; 221) formed by a light absorbing agent provided between said photographic paper base and said receptor layer, characterised in that said light absorbing agent comprises whitening means for whitening the light absorbing layer in colour hue upon irradiation. The photographic paper according to claim 1, characterised in that said light absorbing agent has a pale colour hue which is extinguished on radiation emitted from a light radiating element in a printing device. The photographic paper according to claim 1, characterised in that said light absorbing agent comprises a capsule enclosing a whitening agent therein and being mixed in said light absorbing layer (221) which is whitened by thermal destruction of the capsule by a light radiating element in a printing device. The photographic paper according to claim 3, characterised in that said whitening agent includes titanium oxide, zinc oxide or calcium oxide. The photographic paper according to any one of claims 1 to 4, characterised in that it further comprises a protective layer (213) which is formed of a highly heat-resistant and non-hygroscopic material and disposed between said photographic paper base (214) and said light absorbing layer (212; 221). The photographic paper according to anyone of claims 1 to 5, characterised in that it further comprises a protective layer (215) which is formed of a highly heat-resistant and non-hygroscopic material and disposed under said photographic paper base (214).

Inventors: ITO KENGO, OGATA MASANORI, SATO SHUJI, SHIOTA HIROYUKI, ITO, KENGO, OGATA, MASANORI, SATO, SHUJI, SHIOTA, HIROYUKI
Applicants: SONY CORP, SONY CORPORATION
Application year: 1993
Main classification: B41J2
IPC codes: B41M5, G03C1, B41J2