EP0414936A1 - Printing head for resistive ribbon type printing apparatus - Google Patents
Printing head for resistive ribbon type printing apparatus Download PDFInfo
- Publication number
- EP0414936A1 EP0414936A1 EP89115960A EP89115960A EP0414936A1 EP 0414936 A1 EP0414936 A1 EP 0414936A1 EP 89115960 A EP89115960 A EP 89115960A EP 89115960 A EP89115960 A EP 89115960A EP 0414936 A1 EP0414936 A1 EP 0414936A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- printing
- electrodes
- printing head
- grooves
- ceramic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
- B41J2/335—Structure of thermal heads
- B41J2/33505—Constructional details
- B41J2/3351—Electrode layers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
- B41J2/335—Structure of thermal heads
- B41J2/33545—Structure of thermal heads characterised by dimensions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
- B41J2/335—Structure of thermal heads
- B41J2/33555—Structure of thermal heads characterised by type
- B41J2/33565—Edge type resistors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
- B41J2/335—Structure of thermal heads
- B41J2/33555—Structure of thermal heads characterised by type
- B41J2/3357—Surface type resistors
Definitions
- the present invention relates to an electrothermal printing apparatus, and more particularly, to a printing head for a resistive ribbon type printing apparatus.
- the ribbon used in such a printing apparatus comprises a flexible base insulating (or conductive) film, a layer of thermal transferable ink facing a paper, and an electrical resistive layer facing the printing head.
- a printing head is produced by printing a conductive paste including a hard metal such as W, Mo and Mn over the entire surface of a ceramic green sheet, sintering the printed green sheet, and selectively etching the sintered metal layer (metallized layer) to form a plurality of electrodes, by a photolithography process.
- the printing head comprises a ceramic substrate made of magnesia and silicon dioxide and having a hardness of from 500 to 600 Hv, and tungsten electrodes having a hardness of about 700 Hv and a density of 3 electrodes per mm. When the printing head is operated, the substrate and electrodes come into contact with the ribbon simultaneously.
- a conventional ceramic substrate has a relatively high hardness, and therefore, the electrodes should have a higher hardness, which leads to the problem of an insufficient formation of fine pattern electrodes, as it is difficult to selectively etch the hard metal (W) layer to form fine electrodes.
- a printing head is produced by depositing a conductive layer over the entire surface of ceramic substrate by a vacuum evaporation or sputtering process, forming a plating layer on the conductive layer by an electrodes plating process, and selectively etching the layers to form a plurality of electrodes by a photolithography process.
- the ceramic substrate is made of magnesia and silicon dioxide and has a hardness of from 500 to 600 Hv
- the electrodes are made of Ni-W plating layer having a thickness of 10 ⁇ m and a hardness of about 800 Hv. Since it is difficult to selectively etch such a hard alloy plating layer to form fine pattern electrodes, the obtained electrodes have an electrode density of 3 lines/mm.
- a conventional printing head 11 including the printing heads disclosed in JUPP Nos. 60-214972 and 60-214971 comprises a ceramic substrate 12 and a plurality of printing electrodes 13 formed on a top flat surface of the substrate 12.
- the printing head 11 chafes the resistive layer of the ribbon, and when an electric arc is occasionally generated between the electrodes and the resistive layer during the operation of the head 11, a portion (i.e., residue) of the resistive layer is removed and adheres to and accumulates on the top surface of the substrate 12 between the adjacent electrodes 13. This accumulation of this residue of the resistive layer will cause a short-circuiting between adjacent electrodes 13, and thus the quality of the printed image is greatly reduced.
- a printing head 15 as shown in Fig. 2, comprising a ceramic substrate 16 having a plurality of grooves having a segmentary cross section, which grooves are filled with electrodes 17 consisting of a lower plating layer 18 and a main plating layer 19.
- the head 15 is produced by etching the substrate 16 to form the grooves, forming the lower plating layer 18 in the grooves by an electroless (non-electrolytic) plating process and a selective etching process, depositing the main plating layer 19 by an electrolytic plating process, and grinding off any excess of the layer 19 to make the top surface of the head 15 flat.
- the electrodes do not project above the surface of the substrate, the adhesion and accumulation of the residue of the resistive layer can be reduced. Nevertheless, when an electric arc is occasionally generated between the electrodes and the resistive layer of the ribbon, the arc will melt a portion of the resistive layer and the molten portion may adhere to an upper edge portion 20 of the substrate 16 as well as the electrodes 17. This adhered portion (i.e., resistive layer residue) forms an undesirable extension of the electrode and may cause short-circuiting between adjacent electrodes 17. Moreover, since the segment shaped grooves are formed by a photoetching process including the etching of the ceramic in a lateral direction (i.e., undercutting), the density of the formed electrodes is limited by the need for such undercutting.
- Another object of the present invention is to provide a printing head having fine pattern electrodes by which the printed image quality is improved.
- a printing head for a resistive ribbon type printing apparatus which head comprises an insulting ceramic substrate and a plurality of printing electrodes, characterized in that the ceramic substrate is provided with a plurality of U-shaped grooves, and each of the printing electrodes is formed within each of the grooves and has a thickness smaller than the depth of the groove.
- the ceramic to be used includes a machinable ceramic, alumina ceramic and the like.
- a machinable ceramic such as a mica ceramic is used.
- the U-shaped groove has a depth of from 10 to 40 ⁇ m (micrometers), measured from a top surface of the ceramic substrate. This is because a groove having a depth of less than 10 ⁇ m does not provide a satisfactory prevention of short-circuiting, and a groove having a depth greater than 40 ⁇ m causes a decrease of a contact pressure of the electrode on the ribbon, as the side surface of the head is usually arranged at a certain angle to the ribbon or paper.
- a dicing machine is used to form the U-shaped grooves, since a dicing machine is provided with a very thin rotary cutter and is widely used for cutting a silicon wafer into a large number of pellets during the production of a semiconductor device.
- a printing head 1 comprises an insulating ceramic substrate 2 of, e.g., alumina ceramic provided with a plurality of U-shaped grooves 3, and printing electrodes 4 formed within the grooves 3 and having a thickness smaller than the depth of the groove 3.
- each of the printing electrodes 4 consists of, e.g., a Cu electroless plating layer 5 and a hard Cr electrolytic plating layer 6.
- the printing head 1 for a resistive ribbon type printing apparatus is produced as follows.
- the alumina ceramic substrate 2 is prepared and is set in a dicing machine, and a rotary disc blade of the dicing machine then cuts the top surface of the substrate 2 to form U-shaped grooves having a depth of 30 ⁇ m, a width of 30 ⁇ m, and a pitch of 62.5 ⁇ m, as shown in Fig. 3.
- a machinable ceramic or the like may be used instead of the alumina ceramic, for the substrate 2.
- machinable ceramic e.g., mica ceramic
- A the underlying plating layer 5
- an electroless alloy plating layer composed of, e.g., Ni-P, Ni-B, Ni-W-P, Co-P, Co-B, Co-W-P or the like, may be used instead of the Cu plating layer, and instead of the hard Cr plating layer 6, an alloy plating of an iron family element such as Fe, Co and Ni and a refractory metal such as W, Mo and Re may be used; the alloy plating being composed, for example, of Ni-W, Co-W, Ni-Mo, Co-Mo or the like.
- the alloy plating may contain distributed hard particles such as Al2O3 , Cr3C2 , Cr2O3 , WC, SiC and Si3N4 and/or lubricating particles such as BN and MoS
- the end side surfaces of the electrodes 4 are brought into contact with a resistive layer of a ribbon 7, to cause a thermal transferable ink layer thereof to come into contact with a paper 8.
- a roller 9 of, e.g., rubber, is arranged in such a manner that the ribbon 7 and the paper 8 are sandwiched between the roller 9 and the head 1.
- the roller 9 pushes the ribbon 7 and paper 8 against the electrode 4 and the substrate 2, and further, conveys the paper 8.
- Some of the electrodes 4 are selectively supplied with an electric current, in accordance with an image to be printed, and this current is passed to a portion of the resistive layer through the selected electrodes to generate Jule heat at the portion through which the current flows.
- the generated Jule heat melts a corresponding portion of the ink layer, and the molten ink is transferred onto the paper 8 to form the printed image 10.
- U-shaped grooves 3a having a shallow depth of, e.g., 20 ⁇ m, and U-shaped grooves 3b having a deeper depth of, e.g., 40 ⁇ m, are formed alternately in the substrate 2. Namely, the adjacent grooves 3a and 3b have different depths.
- This U-shaped groove formation also can be easily carried out by using the dicing machine.
- Plating layers 5 and 6 of the printing electrodes 4 are formed in the same manner as by the above-mentioned plating process, and thus all of the electrodes 4 have a same thickness which is smaller than the depth of the shallow grooves 3a.
- the deeper U-shaped grooves 3b have a deeper recess above the electrode 4, which recess can accommodate a larger amount of the resistive layer residue, and thus provided a greater prevention of short-circuiting.
- the Cu plating layer 5 is formed in a U-shape along the side surfaces and a bottom surface of the U-shaped grooves 3, instead of the flat shape shown in Fig. 3, and therefore the hard Cr plating layer 6 is formed in a U-shape and the electrode 4 also has a U-shape.
- the electrode 4 has a thickness smaller than the depth of the groove 3, and the two ends of the U-shaped electrode 4 are lower than the top surface of the substrate 2.
- the patterning of the Cu plating layer 4 in this embodiment is easier than the patterning of the layer 4 shown in Fig. 3.
- the projecting portions of the ceramic substrate between the adjacent U-shaped grooves and the recess above the printing electrodes within the U-shaped grooves prevent short-circuiting due to the adhering of resistive layer residue thereto. Further, since each of the printing electrodes is surrounded on three sides by the ceramic substrate, the electrodes and the ceramic are continuously worn away at the same rate. Furthermore, a plurality of the electrodes are formed in the ceramic substrate at an increased electrode density (lines per mm), and thus a high quality printed image is obtained.
Abstract
A printing head (1) which comprises an insulating substrate (2) and a plurality of printing electrodes (4) for a resistive ribbon type printing apparatus, in which a ribbon (7) composed of a layer of thermal transferable ink and an electrical resistive layer is supplied with an electric current through selected printing electrodes (4) so that the current passes through a portion of the resistive layer to generate Joule heat and melt a portion of the ink layer, and the molten ink (10) is transferred to a paper. The ceramic substrate (2) is provided with a plurality of U-shaped grooves (3), and each of the printing electrodes (4) is formed in each of the grooves (3) and has a thickness smaller than the depth of the grooves.
Description
- The present invention relates to an electrothermal printing apparatus, and more particularly, to a printing head for a resistive ribbon type printing apparatus. The ribbon used in such a printing apparatus comprises a flexible base insulating (or conductive) film, a layer of thermal transferable ink facing a paper, and an electrical resistive layer facing the printing head. When an electric current is made to flow through a portion of the resistive layer from the printing electrodes coming into contact with the resistive layer, Jule heat is generated at the portion at which the current is flowing, to melt a portion of the ink layer, and the molten ink is transferred onto a paper to form a printed image.
- Such a resistive ribbon type printing apparatus and the printing head thereof have been proposed in, e.g., U.S. Patent Nos. 3744611, 4350449, and 4456915. Also such printing heads are disclosed in, e.g., Japanese Unexamined Patent Publication (JUPP) Nos. 60-214972 and 60-214971.
- According to JUPP No. 60-214972, a printing head is produced by printing a conductive paste including a hard metal such as W, Mo and Mn over the entire surface of a ceramic green sheet, sintering the printed green sheet, and selectively etching the sintered metal layer (metallized layer) to form a plurality of electrodes, by a photolithography process. In this case, for example, the printing head comprises a ceramic substrate made of magnesia and silicon dioxide and having a hardness of from 500 to 600 Hv, and tungsten electrodes having a hardness of about 700 Hv and a density of 3 electrodes per mm. When the printing head is operated, the substrate and electrodes come into contact with the ribbon simultaneously. Nevertheless, a conventional ceramic substrate has a relatively high hardness, and therefore, the electrodes should have a higher hardness, which leads to the problem of an insufficient formation of fine pattern electrodes, as it is difficult to selectively etch the hard metal (W) layer to form fine electrodes.
- According to JUPP No. 60-214971, a printing head is produced by depositing a conductive layer over the entire surface of ceramic substrate by a vacuum evaporation or sputtering process, forming a plating layer on the conductive layer by an electrodes plating process, and selectively etching the layers to form a plurality of electrodes by a photolithography process. In this case, for example, the ceramic substrate is made of magnesia and silicon dioxide and has a hardness of from 500 to 600 Hv, and the electrodes are made of Ni-W plating layer having a thickness of 10 µm and a hardness of about 800 Hv. Since it is difficult to selectively etch such a hard alloy plating layer to form fine pattern electrodes, the obtained electrodes have an electrode density of 3 lines/mm.
- As shown in Fig. 1, a
conventional printing head 11 including the printing heads disclosed in JUPP Nos. 60-214972 and 60-214971 comprises aceramic substrate 12 and a plurality ofprinting electrodes 13 formed on a top flat surface of thesubstrate 12. In this case, theprinting head 11 chafes the resistive layer of the ribbon, and when an electric arc is occasionally generated between the electrodes and the resistive layer during the operation of thehead 11, a portion (i.e., residue) of the resistive layer is removed and adheres to and accumulates on the top surface of thesubstrate 12 between theadjacent electrodes 13. This accumulation of this residue of the resistive layer will cause a short-circuiting betweenadjacent electrodes 13, and thus the quality of the printed image is greatly reduced. - To minimize this accumulation of residue of the resistive layer and prevent such short-circuiting, the present inventor proposed a
printing head 15, as shown in Fig. 2, comprising aceramic substrate 16 having a plurality of grooves having a segmentary cross section, which grooves are filled withelectrodes 17 consisting of alower plating layer 18 and amain plating layer 19. Thehead 15 is produced by etching thesubstrate 16 to form the grooves, forming thelower plating layer 18 in the grooves by an electroless (non-electrolytic) plating process and a selective etching process, depositing themain plating layer 19 by an electrolytic plating process, and grinding off any excess of thelayer 19 to make the top surface of thehead 15 flat. In this case, since the electrodes do not project above the surface of the substrate, the adhesion and accumulation of the residue of the resistive layer can be reduced. Nevertheless, when an electric arc is occasionally generated between the electrodes and the resistive layer of the ribbon, the arc will melt a portion of the resistive layer and the molten portion may adhere to anupper edge portion 20 of thesubstrate 16 as well as theelectrodes 17. This adhered portion (i.e., resistive layer residue) forms an undesirable extension of the electrode and may cause short-circuiting betweenadjacent electrodes 17. Moreover, since the segment shaped grooves are formed by a photoetching process including the etching of the ceramic in a lateral direction (i.e., undercutting), the density of the formed electrodes is limited by the need for such undercutting. - An object of the present invention is to prevent short-circuiting between adjacent printing electrodes of a printing head.
- Another object of the present invention is to provide a printing head having fine pattern electrodes by which the printed image quality is improved.
- These and other objects of the present invention are realized by providing a printing head for a resistive ribbon type printing apparatus, which head comprises an insulting ceramic substrate and a plurality of printing electrodes, characterized in that the ceramic substrate is provided with a plurality of U-shaped grooves, and each of the printing electrodes is formed within each of the grooves and has a thickness smaller than the depth of the groove.
- The ceramic to be used includes a machinable ceramic, alumina ceramic and the like. Preferably, a machinable ceramic such as a mica ceramic is used.
- Also preferably, the U-shaped groove has a depth of from 10 to 40 µm (micrometers), measured from a top surface of the ceramic substrate. This is because a groove having a depth of less than 10 µm does not provide a satisfactory prevention of short-circuiting, and a groove having a depth greater than 40 µm causes a decrease of a contact pressure of the electrode on the ribbon, as the side surface of the head is usually arranged at a certain angle to the ribbon or paper.
- Preferably, a dicing machine is used to form the U-shaped grooves, since a dicing machine is provided with a very thin rotary cutter and is widely used for cutting a silicon wafer into a large number of pellets during the production of a semiconductor device.
- The present invention will be more apparent from the description of the preferred embodiments set forth below, with reference to the accompanying drawings, in which:
- Fig. 1 is a partial perspective view of a prior art printing head for a resistive ribbon type printing apparatus;
- Fig. 2 is a partial perspective view of another printing head according to the prior art;
- Fig. 3 is a partial perspective view of a printing head according to a first embodiment of the present invention;
- Fig. 4 is a schematic sectional view of the printing head, a ribbon, a paper, and a roller, during a printing operation;
- Fig. 5 is a partial perspective view of another printing head according to a second embodiment of the present invention; and
- Fig. 6 is a partial perspective view of a printing head according to a third embodiment of the present invention.
- Referring to Fig. 3, a
printing head 1 according to the present invention comprises an insulatingceramic substrate 2 of, e.g., alumina ceramic provided with a plurality ofU-shaped grooves 3, andprinting electrodes 4 formed within thegrooves 3 and having a thickness smaller than the depth of thegroove 3. In this case, each of theprinting electrodes 4 consists of, e.g., a Cuelectroless plating layer 5 and a hard Crelectrolytic plating layer 6. - The
printing head 1 for a resistive ribbon type printing apparatus is produced as follows. - First, the alumina
ceramic substrate 2 is prepared and is set in a dicing machine, and a rotary disc blade of the dicing machine then cuts the top surface of thesubstrate 2 to form U-shaped grooves having a depth of 30 µm, a width of 30 µm, and a pitch of 62.5 µm, as shown in Fig. 3. - Then a Cu electroless plating layer is deposited to a thickness of 2 µm over the entire surface of the
substrate 2 including thegrooves 3, and is selectively etched by a conventional photoetching process to formCu layers 5 on the bottom surface of each of thegrooves 3. Next, using theCu layers 5 as negative electrode in an electroplating process, hard Cr plating layers 6 (having a thickness of about 5 µm and a hardness of 930 Hv) are deposited on thelayer 5, and thus the desired printing head is obtained. - A machinable ceramic or the like may be used instead of the alumina ceramic, for the
substrate 2. As machinable ceramic (e.g., mica ceramic) has a good machinability, and thus such a ceramic is preferable. A= theunderlying plating layer 5, an electroless alloy plating layer composed of, e.g., Ni-P, Ni-B, Ni-W-P, Co-P, Co-B, Co-W-P or the like, may be used instead of the Cu plating layer, and instead of the hardCr plating layer 6, an alloy plating of an iron family element such as Fe, Co and Ni and a refractory metal such as W, Mo and Re may be used; the alloy plating being composed, for example, of Ni-W, Co-W, Ni-Mo, Co-Mo or the like. The alloy plating may contain distributed hard particles such as Al₂O₃ , Cr₃C₂ , Cr₂O₃ , WC, SiC and Si₃N₄ and/or lubricating particles such as BN and MoS₂. - A sputtering process, vacuum evaporation process, ion-plating process or the like may be used for forming the
printing electrode 4 of a suitable conductive (metal) material, instead of the above-mentioned plating process. In this case, the metal material is deposited on the top surfaces of projecting portions of the substrates and on the bottom surfaces of the grooves, and any excess deposited on the top surface is removed by a suitable grinding method. - When the obtained
printing head 1 is operated, as shown in Fig. 4, the end side surfaces of theelectrodes 4 are brought into contact with a resistive layer of a ribbon 7, to cause a thermal transferable ink layer thereof to come into contact with a paper 8. A roller 9 of, e.g., rubber, is arranged in such a manner that the ribbon 7 and the paper 8 are sandwiched between the roller 9 and thehead 1. The roller 9 pushes the ribbon 7 and paper 8 against theelectrode 4 and thesubstrate 2, and further, conveys the paper 8. Some of theelectrodes 4 are selectively supplied with an electric current, in accordance with an image to be printed, and this current is passed to a portion of the resistive layer through the selected electrodes to generate Jule heat at the portion through which the current flows. The generated Jule heat melts a corresponding portion of the ink layer, and the molten ink is transferred onto the paper 8 to form the printedimage 10. - Although residue of the above-mentioned resistive layer is produced, this residue lies and accumulates in a recess of each of the
U-shaped grooves 3, and the projecting portion of theceramic substrate 2 prevents contact between the accumulated residue inadjacent grooves 3, and thus the problem of short-circuiting does not arise. - The produced
printing head 1 hasfine pattern electrodes 4 at an electrode density of 16 lines/mm, which is greater than that (3 lines/mm) of a conventional printing head of the above-cited JUPP Nos. 60-214972 and 60-214971. Therefore, the produced printing head can print images in a finer mode, compared with the conventional printed image of JUPP Nos. 60-214972 and 60-214971. - As shown in Fig. 5, according to a second embodiment of the present invention, U-shaped
grooves 3a having a shallow depth of, e.g., 20 µm, and U-shapedgrooves 3b having a deeper depth of, e.g., 40 µm, are formed alternately in thesubstrate 2. Namely, theadjacent grooves printing electrodes 4 are formed in the same manner as by the above-mentioned plating process, and thus all of theelectrodes 4 have a same thickness which is smaller than the depth of theshallow grooves 3a. Note, as the difference in the level of theadjacent electrode 4 is very small (20 µm), no problem arises with regard to the printed image. In this case, the deeperU-shaped grooves 3b have a deeper recess above theelectrode 4, which recess can accommodate a larger amount of the resistive layer residue, and thus provided a greater prevention of short-circuiting. - As shown in Fig. 6, according to a third embodiment of the present invention, the
Cu plating layer 5 is formed in a U-shape along the side surfaces and a bottom surface of theU-shaped grooves 3, instead of the flat shape shown in Fig. 3, and therefore the hardCr plating layer 6 is formed in a U-shape and theelectrode 4 also has a U-shape. In this case, theelectrode 4 has a thickness smaller than the depth of thegroove 3, and the two ends of theU-shaped electrode 4 are lower than the top surface of thesubstrate 2. The patterning of theCu plating layer 4 in this embodiment is easier than the patterning of thelayer 4 shown in Fig. 3. - According to the present invention, the projecting portions of the ceramic substrate between the adjacent U-shaped grooves and the recess above the printing electrodes within the U-shaped grooves prevent short-circuiting due to the adhering of resistive layer residue thereto. Further, since each of the printing electrodes is surrounded on three sides by the ceramic substrate, the electrodes and the ceramic are continuously worn away at the same rate. Furthermore, a plurality of the electrodes are formed in the ceramic substrate at an increased electrode density (lines per mm), and thus a high quality printed image is obtained.
- It will be obvious that the present invention is not restricted to the above-mentioned embodiment and that many variations are possible for persons skilled in the art without departing from the scope of the invention.
Claims (8)
1. A printing head for a resistive ribbon type printing apparatus, which printing head comprises an insulating ceramic substrate and a plurality of printing electrodes, characterized in that said ceramic substrate is provided with a plurality of U-shaped grooves, and each of said printing electrodes is formed within each of said grooves and has a thickness smaller than a depth of said grooves.
2. A printing head according to claim 1, wherein said ceramic is selected from the group consisting of machinable ceramic and alumina ceramic.
3. A printing head according to claim 2, wherein said machinable ceramic is a mica ceramic.
4. A printing head according to claim 1, wherein each of said printing electrodes is composed of a conductive metal layer.
5. A printing head according to claim 4, wherein said conductive metal layer is a plating material.
6. A printing head according to claim 1, wherein said U-shaped groove has a depth of from 10 to 40 µm.
7. A printing head according to claim 1, wherein adjacent grooves of said plurality of U-shaped grooves have different depths.
8. A method of producing a printing head for a resistive ribbon type printing apparatus, comprising forming a plurality of printing electrodes on an insulating ceramic substrate, characterized in that said method comprises steps of forming a plurality of U-shaped grooves in said ceramic substrate with a dicing machine; and depositing a conductive metal in said grooves to form said electrodes having a thickness smaller than the depth of said grooves.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP89115960A EP0414936A1 (en) | 1989-08-30 | 1989-08-30 | Printing head for resistive ribbon type printing apparatus |
US07/693,058 US5070343A (en) | 1989-08-28 | 1991-04-30 | Printing head for resistive ribbon type printing apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP89115960A EP0414936A1 (en) | 1989-08-30 | 1989-08-30 | Printing head for resistive ribbon type printing apparatus |
Publications (1)
Publication Number | Publication Date |
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EP0414936A1 true EP0414936A1 (en) | 1991-03-06 |
Family
ID=8201818
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP89115960A Withdrawn EP0414936A1 (en) | 1989-08-28 | 1989-08-30 | Printing head for resistive ribbon type printing apparatus |
Country Status (1)
Country | Link |
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EP (1) | EP0414936A1 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4539576A (en) * | 1983-12-16 | 1985-09-03 | International Business Machines Corporation | Electrolytic printing head |
US4835552A (en) * | 1987-07-16 | 1989-05-30 | Fuji Xerox Co., Ltd. | Recording head |
-
1989
- 1989-08-30 EP EP89115960A patent/EP0414936A1/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4539576A (en) * | 1983-12-16 | 1985-09-03 | International Business Machines Corporation | Electrolytic printing head |
US4835552A (en) * | 1987-07-16 | 1989-05-30 | Fuji Xerox Co., Ltd. | Recording head |
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