Stamp apparatus

Abstract: A stamp apparatus (10) includes a supporting case (11) which supports a printing sheet (1), an ink supply port (17) through which ink is fed to the second surface (1B) of the printing sheet, and a dispersing device (12) provided between the printing sheet and the supporting case. The dispersing device disperses ink supplied from the ink supply port uniformly over the surface of the printing sheet.

Description: The present invention relates to a stamp apparatus using a printing sheet. As disclosed by Japanese Laid-Open Patent Application No. 7-251558, there is known a stamp apparatus using a porous printing sheet in which ink can be impregnated. A pattern is formed on a surface of the printing sheet, including a print portion which allows the permeation of ink and a non-print portion which block the permeation of ink. That is, ink is permeated through the printing sheet according to the pattern. The printing sheet is provided to the bottom of a body of the stamp apparatus. In order to repeatedly use the stamp apparatus without feeding ink thereto, the stamp apparatus is provided with an ink pad in which the ink is impregnated, the ink pad being interposed between the body and the printing sheet. When a user grips the body and urges the printing apparatus onto the medium so that the printing sheet is urged onto the medium, ink impregnated in the ink pad is transmitted through the printing sheet and transferred onto the medium. However, such a stamp apparatus has a disadvantage such that the ink pad must be replaced (together with the printing sheet) when the ink impregnated therein has been used up. Such replacement increases the running cost of the stamp apparatus. Another proposed stamp apparatus has an ink supply port (instead of the ink pad) provided in the body, through which ink can be fed to the printing sheet. However, there is a tendency that the amount of ink fed to the location (on the printing sheet) far from the ink supply port is smaller than the amount of ink fed to the location close to the ink supply port. Accordingly, ink is not uniformly fed over an entire surface of the printing sheet, which causes a deviation of the ink density of the pattern printed on the medium. US-A-3 277 819 discloses a stamp apparatus according to the preamble of claim 1. According to a first aspect of the present invention there is provided a stamp apparatus including: a printing sheet made of a porous sheet having first and second surfaces, which selectively allows the permeation of ink therethrough according to a predetermined pattern; a supporting case which supports said printing sheet with said first surface facing outwardly so that said first surface is able to be urged against a medium; an ink supply port associated with said supporting case, through which port ink may be fed to said second surface of said printing sheet; and an ink dispersing device provided between said printing sheet and said supporting case to disperse ink supplied from said ink supply port uniformly over said second surface of said printing sheet, said dispersing device including: a base plate facing said second surface of said printing sheet; and a plurality of ink holes formed in said base plate, through which holes ink may flow to said second surface of said printing sheet; characterised in that: said ink holes have different diameters so that, as the distance from the ink supply port to an ink hole increases, the diameters of said ink holes increase. The present invention will be more clearly understood from the following description, given by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a perspective view illustrating a printing sheet; Fig. 2 is a side sectional view illustrating an embodiment of stamp apparatus in accordance with the present invention; Fig. 3 is a sectional view taken along a line III-III of Fig. 2; Fig. 4 is a plan view illustrating a dispersing device; Fig. 5 is a partially cut perspective view of the dispersing device; A printing sheet and an embodiment of stamp apparatus according to the present invention are described with reference to Figs. 1 to 5. Fig. 1 is a perspective view of a printing sheet. The printing sheet 1 is made of a porous sheet having pores in which ink can be impregnated. One surface (a print surface 1a) of the printing sheet 1 includes a print portion 3 and a non-print portion 2. The pores of the non-print portion 2 is sealed so as to block the permeation of ink, while the pores of the print portion 3 is not sealed so as to allow the permeation of ink. Thus, the printing sheet 1 selectively allows the permeation of ink according to a predetermined pattern ("E" in the example of Fig. 1). The printing sheet 1 has a rectangular shape. Fig. 2 is a side sectional view of the embodiment of stamp apparatus 10. The stamp apparatus 10 is arranged to hold the printing sheet 1 at one end portion thereof. A pattern is printed on a medium 26 (such as a paper) placed on a table 25. In the description hereinafter, the terms "top", "bottom", "upward" and "downward" are defined at a condition where the stamp apparatus 10 is placed so that the printing sheet 1 faces the medium 26 as shown in Fig. 2. The stamp apparatus 10 includes a supporting case 11 which supports the printing sheet 1. The supporting case 11 is a flat box-shaped case with a bottom surface opened, including a rectangular top plate 11b and side plates 11a extended downward from the periphery of the top plate 11b. The printing sheet 1 is fit into the supporting case 11 so that a printing surface 1a faces downward. The four edges of the printing sheet 1 are surrounded by the side plates 11a of the supporting case 11. A dispersing device 12 (detailed below) is interposed between the printing sheet 1 and the top plate 11b of the supporting case 11. An outer frame 13 is provided to cover and to movably support the supporting case 11. The outer frame 13 is a box-shaped case with a bottom surface opened, including a top plate 13b and side plates 13a extended downward from the periphery of the top plate 13b. The side plates 11a of the supporting case 11 is vertically slidable with respect to the inner surfaces of the side plates 13a of the outer frame 13, so that the supporting case 11 is vertically movable with respect to the outer frame 13. The outer frame 13 is further provided with a guide portion 19 formed on the top plate 13b, which is covered by the grip 14 (described below) from above. A grip 14 is provided above the outer frame 13 with a spring unit 15 interposed therebetween. The grip 14 is cap-shaped and includes a top plate 14b and a skirt 14a extending downward from the periphery of the top plate 14b. When the grip 14 covers the guide portion 19 of the outer frame 13, the internal surface of the skirt 14a contacts the guide portion 19. In order to couple the grip 14 and the supporting case 13, three coupling members 16 are integrally provided on the top plate 11b of the supporting case 11, which are protruded upward through holes 18 formed on the top plate 13a of the outer frame 13. The grip 14 is provided with three tubular supports 20 extending downward from the top plate 14a of the grip 14 so that the coupling members 16 are fit into the tubular supports 20. Thus, the grip 14 is vertically slidable (together with the supporting case 11) with respect to the outer frame 13. One of three coupling members which is located at the center of the supporting case 11 includes a vertically extending passage. The passage serves as an ink supply port 17 through which ink can be supplied to the printing sheet 1. A spring unit 15 is provided between the bottom of the tubular support 20 and the top plate 13b of the outer frame 13. The spring unit 15 includes a bent plate spring 21 and urges the outer frame 13 downward with respect to the supporting case 11 and the grip 14. When no force is applied to the grip 14, the bottom end of the outer frame 13 is positioned lower than the print surface 1a of the printing sheet 1 (due to the force of the spring unit 15) by an amount H1 as shown in Fig. 2. Thus, the printing sheet 1 is retracted in the outer frame. The interval between the bottom end of the skirt 14a and the top plate 13b of the outer frame 13 is set to H2 which is greater than H1. When a user pushes the grip 14 downward, the grip 14 and the supporting case 11 are moved downward resisting the force of the spring unit 15, so that the printing sheet 1 can be pressed onto the medium 26. Fig. 3 is a sectional view of the stamp apparatus 10 taken along a line III-III of Fig. 2. Figs. 4 and 5 are a plan view and a partially cutaway perspective view of the dispersing device 12. As shown in Fig. 3, the dispersing device 12 includes a base plate 22 which is faced with a back surface 1b (a surface opposite to the printing surface la) of the printing sheet 1. Struts 23 are provided on the base plate 22 at a predetermined interval, which are protruded upward toward the top plate 11b of the supporting case 11. As shown in Fig. 5, spaces are created between adjacent struts 23 and between the top plate 11b and the base plate 22. The spaces are connected with each other. As shown in Fig. 4, the base plate 22 is provided with ink holes 24a, 24b, 24c and 24d which penetrate the base plate 22 and open in the spaces between respective struts 23. The ink supplied onto the upper surface of the base plate 22 is transmitted to the back surface 1b of the printing sheet 1 through the ink holes 24a, 24b, 24c and 24d. Further, the ink holes 24a, 24b, 24c and 24d have different diameters so that, as the distance from the ink supply port 17 increases, the diameter of the ink hole increases. In particular, the ink hole 24a is located at the closest position to the ink supply port 17, with ink hole 24b, 24c and 24d following in that order. The ink hole 24d has the largest diameter, with the ink hole 24c, 24b and 24a following in that order. There is a tendency that the amount of ink fed to the location far from the ink supply port 17 is smaller than the amount of ink fed to the location close to the ink supply port 17. However, due to the setting of the diameter of the ink holes 24a, 24b, 24c and 24d, ink is uniformly fed to the back surface 1b of the printing sheet. As constructed above, ink supplied from the ink supply port 17 is uniformly fed to the back surface 1b of the printing sheet 1 (through the ink holes 24a, 24b, 24c and 24d) and is uniformly impregnated in the printing sheet 1. When the stamp apparatus 10 is used, a user holds the grip 14 to place the stamp apparatus 10 on the medium 26 and pushes the grip 14 downward. The movement of the grip 14 moves the supporting case 11 (and the printing sheet 1) downward resisting the force of the spring unit 15, so that the printing sheet 1 is pressed against the surface of the medium 26. When the user releases the grip 114, the printing sheet 1 quickly departs from the medium 26. Accordingly, the printing sheet 1 quickly contacts and departs from the medium 26. Since ink is uniformly impregnated in the printing sheet 1, ink is uniformly transmitted on the medium 26. Accordingly, the density of the pattern formed on the medium 26 becomes uniform. Particularly, the blur of the periphery of the pattern can be prevented. Further, because of the spaces between the struts 23, ink supplied from the ink supply port 17 is smoothly fed to the location far from the ink supply port 17. Thus, the uniformity of the density of the pattern is further improved. In this embodiment, the above described components of the stamp apparatus 10 can be made of a synthetic resin. Further, it is possible to divide the space (on the base plate 22) into several sections and to provide several ink supply ports for respective sections. It enables color print, by using inks of several colors in respective sections. It is further possible to replace the spring unit 15 with a coil spring provided around the coupling member 16. Further, it is possible to provide through holes penetrating the top plate 11b of the supporting case 11 and to use the through holes instead of the ink supply port 17. Further, the stamp apparatus can be constructed by providing a grip 14 to the upper surface of the top plate 11b of the supporting case 11, without the outer frame 13 and the spring 15. Additionally, a detachable cover (not shown) can be provided to the lower end of the outer frame 13 or the supporting case 11 to cover the printing surface 1a of the printing sheet 1. Finally, a manufacturing process of the printing sheet 1 is briefly described. The printing sheet 1 is manufactured by a not shown manufacturing device provided with a flash bulb capable of irradiating infrared rays. A porous sheet (in which ink can be impregnated) is used as a base material of the printing sheet. A black film having a surface coated with carbon is used to heat the surface of the porous sheet. An original sheet is made of a material which allows the permeation of infrared rays, while a pattern (such as a character, figure, or the like) is formed by a material which blocks infrared rays. The porous sheet, the black film and the original sheet are overlapped and laid on a transparent plate. The overlapped sheets are pressed so that the porous sheet contacts the black film and the black film contacts the original sheet. Then, the flash bulb irradiates infrared rays to the original sheet through the transparent plate. Infrared rays irradiated onto the pattern on the original sheet are blocked, whereas infrared rays irradiated onto non-pattern portion pass through the original sheet. The infrared rays passing through the original sheet reach the black film causing the black film to generate heat. The heated surface of the porous sheet is caused to melt such that pores near the surface thereof are sealed. Conversely, since the infrared rays are blocked by the pattern of the original sheet, the portion of the black film which corresponds to the pattern does not generate heat, so that the pores near the surface of the porous sheet corresponding thereto are not sealed. Thus, a print portion 3 in which pores are opened and a non-print portion 2 in which pores are sealed are formed on the surface of the porous sheet as shown in Fig. 1. With such a process, the printing sheet 1 is formed. It is alternatively possible to disperse carbon grains or other material (for example, silver chloride or silver bromide) which absorbs infrared rays. The porous sheet can be made of a foamed resin made of polyolefin resin, polyvinyl chloride resin, polyurethane resin or other material which shows flexibility and softness when formed into the porous sheet. Pores are disposed over a surface of the porous sheet (before the pattern is formed on the surface of the porous sheet). Particularly, the thickness of the porous sheet is 1 to 5 mm. When such porous sheet is overlapped with the original sheet and exposed to the infrared rays irradiated through the original sheet, the porous sheet absorbs infrared rays and generates heat itself. Thus, it is not necessary to provide a black film. It is preferred that the content of the carbon in the porous resin sheet 38 is in the range of 0.01 - 15 wt%. With this, the porous resin sheet is gray and, when heated, turns black. Accordingly, it can be confirmed which of various colors of ink has been impregnated in the porous resin sheet. Further, since the carbon is greater than or equal to 0.01 wt%, the porous resin sheet is easily heated (such that the pores at the surface thereof are sealed) by a standard flash bulb. The original sheet is made of a material (such as a copy paper) which allows the permeation of light, on which a pattern is formed using ink or paint which blocks the transmission of light. The porous sheet is overlapped with the original sheet with a transparent film sandwiched therebetween. The transparent film is made of a material having a high melting point and the thickness thereof is 0.025 to 0.2 mm. The porous sheet, the transparent film and the original sheet are overlapped and laid on the transparent plate so that the pattern on the surface of the original sheet contacts the transparent film. Then, the flash bulb irradiates infrared rays to the original sheet through the transparent plate. Infrared rays irradiated onto the pattern on the original sheet are blocked, whereas infrared rays irradiated onto non-pattern portion pass through the original sheet. The infrared rays passing through the original sheet reach the porous sheet, causing the carbon black to generate heat. The heated portion melts such that pores thereof are sealed. Conversely, since the infrared rays are blocked by the pattern of the original sheet, the portion of the porous sheet which corresponds to the pattern does not generate heat, so that the pores of the porous sheet corresponding thereto are not sealed. Thus, the print sheet 1 is formed. In the above described process, the pattern on the original sheet tends to be heated by the irradiation of the infrared rays. However, since the heat of the pattern of the original sheet is dispersed in the transparent film, the heat of the pattern of the original sheet does not affect the porous sheet to melt. Although the structure of a stamp apparatus is described herein with respect to the preferred embodiments, many modifications and changes can be made without departing from the scope of the invention as defined in the appended claims.

Claims: A stamp apparatus (10) including: a printing sheet (1) made of a porous sheet having first and second surfaces, which selectively allows the permeation of ink therethrough according to a predetermined pattern; a supporting case (11) which supports said printing sheet (1) with said first surface (1a) facing outwardly so that said first surface (1a) is able to be urged against a medium (26); an ink supply port (17) associated with said supporting case (11), through which port (17) ink is fed to said second surface of said printing sheet (1); and an ink dispersing device (12) provided between said printing sheet (1) and said supporting case (11) to disperse ink supplied from said ink supply port (17) uniformly over said second surface of said printing sheet (1), said dispersing device (12) including: a base plate (22) facing said second surface of said printing sheet (1); and a plurality of ink holes (24) formed in said base plate (22), through which holes ink flows to said second surface of said printing sheet; characterised in that : said ink holes (24) have different diameters (24a, 24b,24c,24d) so that, as the distance from the ink supply port (17) to an ink hole increases, the diameters of said ink holes increase. A stamp apparatus according to claim 1, wherein said dispersing device (12) includes a plurality of struts (23) provided on said base plate (22) in such a manner that spaces are created between adjacent struts. A stamp apparatus according claim 1 or claim 2, wherein said supporting case (311,411) is divided into a plurality of sections by at least one partition wall (329,429) and wherein a plurality of ink supply ports (316) are provided to supply ink to respective ones of said plurality of sections. A stamp apparatus according to claim 3, wherein a plurality of printing sheets (1) are provided, each being associated with a different one of said plurality of sections. A stamp apparatus according to claim 3, wherein a single printing sheet is provided to cover all of said plurality of sections. A stamp apparatus according to any one of the preceding claims, further comprising: an outer frame (13,113) in which said supporting case (11,111) is movably supported; and a grip (14,114) provided to said outer frame (13,113) with a spring member (21,122) disposed therebetween, said grip being coupled with said supporting case (11,111) and being movable with respect to said outer frame, and wherein said spring member (21,122) urges said supporting case (11,111) and said grip (14,114) so that said printing sheet (1) is retracted in said outer frame (13,113). A stamp apparatus according to any one of the preceding claims, said printing sheet (1) comprising: a print portion (3) formed on said first surface (1a), which allows the permeation of ink; and a non-print portion (2) formed on said first surface (1a), which blocks the permeation of ink, said print portion and said non-print portion being formed according a predetermined pattern.

Inventors: KOBAYASHI SHINJI, SUDA MITSUNOBU, KOBAYASHI, SHINJI, SUDA, MITSUNOBU
Applicants: BROTHER IND LTD, BROTHER KOGYO KABUSHIKI KAISHA
Application year: 1997
Main classification: B41K1
IPC codes: B41K1