EP0143467B1 - Adjusting device for dimensionally adjusting a gap between a platen and a print head assembly and printer using the adjusting device - Google Patents
Adjusting device for dimensionally adjusting a gap between a platen and a print head assembly and printer using the adjusting device Download PDFInfo
- Publication number
- EP0143467B1 EP0143467B1 EP84114467A EP84114467A EP0143467B1 EP 0143467 B1 EP0143467 B1 EP 0143467B1 EP 84114467 A EP84114467 A EP 84114467A EP 84114467 A EP84114467 A EP 84114467A EP 0143467 B1 EP0143467 B1 EP 0143467B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- platen
- shaft
- adjusting
- cam
- gap
- 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.)
- Expired
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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
- B41J11/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, for supporting or handling copy material in sheet or web form
- B41J11/20—Platen adjustments for varying the strength of impression, for a varying number of papers, for wear or for alignment, or for print gap adjustment
Description
- The present invention relates to an adjusting device for dimensionally adjusting a gap between a platen and a print head assembly according to the preamble of the main claim. The invention also relates to a printer using this adjusting device. The invention is in the field of an impact type printer in which the printing heads are selectively hammered to print upon a printing sheet set on a platen, and refers more particularly to an adjusting device in the impact type printer which dimensionally adjusts a gap defined between the platen and the printing heads.
- In an impact type printer, it is essential to maintain a constant-dimension gap between a printing sheet and the printing head in order to ensure uniform printing quality. However, if the dimension of the gap between the platen and printing heads is incapable of being adjusted, the varying thicknesses of printing sheets which can be utilized will therefore artifically vary the dimension of the gap so that the optimum dimension needed for proper print quality will be destroyed. This problem is particularly acute when a number of print sheets with carbon paper disposed therebetween is utilized. Accordingly, if the striking force of the printing head is constant, then the resultant prints become non-uniform in density as the dimension of the gap changes to deleteriously affect the printing quality.
- In order to overcome this problem, conventional printing adjustment is typically accomplished by moving the printing heads relative to a fixed position platen to change the gap between the printing sheet on the platen and the printing heads, for example, to compensate for the thickness of the printing sheet being used. However, this method is disadvantageous in that whenever the printing heads are moved, they must be fixedly secured at their new position. Accordingly the mechanism to accomplish such movement is necessarily intricate thereby increasing the manufacturing cost of the printer.
- In an adjusting device in accordance with DE-A-25 00 418, a non-rotating platen is mounted in side plates which are slidably mounted in side walls and which after adjustment of the gap have to be secured in position by clamping screws.
- It is therefore an object of the present invention to provide an adjusting device for dimensionally adjusting a gap defined between a rotating platen and a print head assembly in a convenient and precise way, which is simple in construction and low in manufacturing cost. This object is solved by the adjusting device as defined in the main claim. Further advantageous features of the adjusting device according to the invention are evident from the subclaims 2 and 3. The invention also provides for a printer which takes advantage of the adjusting device and which is disclosed in claim 4. Further advantageous features of this printer are evident from the subclaims 5 to 7.
- According to the present invention, a printing adjusting device is provided in an impact type printer in which the dimension of the gap between the platen and the printing heads can be positively adjusted to compensate for the varying thicknesses of printing sheets, for example, and which is simple in construction and low in manufacturing cost.
- The printing adjusting device of the present invention is particularly well suited for use in a printer in which printing heads are hammered to print upon a printing sheet fed along the cylindrical surface of a platen. The adjusting device generally includes first and second guide shafts supported on a pair of base frames in such a manner that the guide shafts are in parallel orientation with one another. A printing mechanism carrying printing heads is movably mounted on the guide shafts for reciprocal rectilinear movements therealong. A pair of side frames to journally mount the platen therebetween are coupled to the first guide shaft and are pivotal in a vertical plane about the axis established by the first guide shaft. The side frames are also coupled through cams to the second guide shaft. Thus, upon pivotal movement of the second guide shaft, the cams pivot the side frames about the first guide shaft. In such a manner, the platen, being mounted on the side frames, is displaced through an arc towards and away from the printing heads in dependence upon the direction of pivotal movement of the side frames.
- Further aspects and advantages of the present invention will become more clear after careful consideration is given to the following detailed description thereof when read in conjunction with the accompanying drawings.
- Reference will hereinafter be made to the accompanying drawings wherein like reference numerals throughout the various Figures denote like structural elements and wherein:
- Fig. 1 is a perspective view showing essential components of an impact-type printer in which the printing adjustment device of the present invention is utilized;
- Fig. 2 is an exploded perspective view of the printer shown in Fig. 1;
- Fig. 3 is a side elevational view of the adjusting device of the present invention;
- Fig. 4 is an enlarged perspective view showing the interaction between an eccentric cam and a side frame of the present invention; and
- Fig. 5 is a side elevational view, similar to Fig. 3, but showing the operating movements of the present invention.
- As shown in Figures 1 and 2, the present invention includes a pair of
base frames 11 which are rigidly fixed on abase plate 10 in such a manner thatbase frames 11 are separated yet in parallel orientation with one another. Parallel adjusting and supportingshafts base frames 11. A recessed cut section 12b is defined in the cylindrical surface of the adjustingshaft 12 and extends for a predetermined dimension between thebase plates 11 in the longitudinal direction ofshaft 12. - A
head carriage 14 is mounted for reciprocal movements along both of the adjustingshaft 12 and the supportingshaft 13. More specifically, the supportingshaft 13 is inserted into hole 14a defined through the body 14b of thehead carriage 14, while the adjustingshaft 12 is inserted through alignedholes 14c formed through a pair of supporting frames 141 which extend from the body 14b of thehead carriage 14 towardssupport wall 26. (Only one frame 141 and itscorresponding hole 14c are shown in Figures 1 and 2.) Aprinting mechanism 16 is fixedly provided on thehead carriage 14 and includes a plurality ofprinting heads 15 arranged in side-by-side fashion in the direction of a printing line upon a printing sheet (e.g. parallel to the longitudinal direction ofshafts - A pair of
side frames 17 are provided on the outer surfaces of thebase frames 11, respectively. Two end portions 12a of the adjustingshaft 12 protrude outwardly from the outer surfaces 11 a ofbase frames 11 and are fixedly mated with arespective aperture 17a defined substantially at the middle portions of theside frames 17 as shown more clearly in Figure 2. Theside frames 17 definecam grooves 171 which are sized and configured to accept a respective one of the rotatableeccentric cams 18 provided at both ends of the supportingshaft 13. Preferably,cam grooves 171 are defined by a pair of vertically separatedplanar surfaces 171a, 171b which permit free eccentric rotation ofcams 18 therebetween and thus provide bearing surfaces against which thecams 18 bear. Therefore, as the supportingshaft 13 rotates, theside frames 17 pivot about an axis established by the adjustingshaft 12 through an angle corresponding to the amount of eccentricity (1) of theeccentric cams 18 due to thecams 18 eccentrically bearing against thesurfaces 171a, 171b ofcam grooves 171. - A
platen 20 is journally supported between theside frames 17 by means ofcentral shaft 21. More specifically, theside frames 17 define receivinggrooves 172 respectively formed in theupper edge portions 172a thereof. End portions 21a of thecentral shaft 21 longitudinally extend from both ends of theplaten 20 and define an annular recess 21 b registrable with receivinggrooves 172 so as to be rotatably supported thereby. Thus, theplaten 20 is positioned over the twoshafts side frames 17 in such a manner that theplaten 20 confronts theprinting heads 15. As theside frames 17 pivot about the axis established by the adjustingshaft 12 as described above, theplaten 20 is responsively moved through a slight arc so as to be displaced towards or away from theprinting heads 15 in dependence upon the direction of pivotal movement of theside frames 17 aboutshaft 12. - An
arcuate paper guide 22 is fixedly held between thebase frames 11 and is positioned in such a manner that a gap of predetermined dimension is defined between theplaten 20 and thepaper guide 22. A printing sheet is thus insertable into the gap and is arcuately guided along theplaten 20 by thepaper guide 22. A plurality ofslots 23 are formed in the bottom of thepaper guide 22 in such a manner that theslots 23 are aligned in the longitudinal direction of thepaper guide 22 so as to accept respective ones of a plurality ofpressure rollers 24. Thus, a portion of eachroller 24 extends through itsrespective slot 23 so as to press a printing sheet against theplaten 20. - The
pressure rollers 24 are longitudinally arranged relative toplaten 20 on a respectiveleaf spring member 25. Eachpressure roller 24 has acentral shaft 241 rotatably engaged withopposing recesses 251 formed in theleaf spring member 25. The leaf spring member is preferably a rectangular flat plate with thepressure rollers 24 extending across rectangular holes 251a formed in theleaf spring member 25. Oneside portion 25a of theleaf spring member 25 is coupled to the upper edge 26a ofmounting wall 26 on thebase plate 10. The oneside portion 25a of theleaf spring member 25 is preferably secured to the upper edge 26a of themounting wall 26 by mating engagement between the supportingpieces 261 ofwall 26 and mountingholes 252 formed in the oneside portion 25a. The other side portion 25b of theleaf spring member 25 rests upon the recessed cut portion 12b of the adjustingshaft 12. - Therefore, as the adjusting
shaft 12 rotates, theleaf spring member 25 is vertically displaced against its bias force through an angle corresponding to the step between the cylindrical surface of theshaft 12 and the recessed cut portion 12b. In such a manner, the recessed cut portion 12b and the cylindrical surface of theshaft 12 establishes a cam which displaces thepressure rollers 24 into and out of pressing engagement relative to the printing sheet on theplaten 20 in response to rotation of theshaft 12 in opposite rotational directions, respectively. - The printing sheet is inserted from above between the
platen 20 and thepaper guide 22 and is held between theplaten 20 and thepressure rollers 24 as previously described. As theplaten 20 rotates about its longitudinal axis established bycentral shaft 21, the printing sheet is respectively moved along the cylindrical surface of theplaten 20, guided by thepaper guide 22, so that it exits towards theleft platen 20 as viewed in Fig. 3. Theprinting heads 15 of theprinting mechanism 16 are then caused to confront printing hammers (not shown), such that theprinting heads 15 are selectively hammered to print upon the printing sheet on theplaten 20. - The
guide shaft 13 is manually pivotal through a predetermined angle by manipulation of an adjustinglever 30. Thus, upon pivotal movement ofshaft 13, theeccentric cams 18 are responsively pivoted about their eccentric axis (established by shaft 13) in thecam grooves 171, respectively, so that theside frames 17 are pivoted in a vertical plane through an arc as indicated by thearrow 100a in Figures 4 and 5. As the side frames 17 pivot, theplaten 20 coupled to the side frames 17 is thus responsively moved towards or away from the printing heads 15 as indicated by thearrow 101 in Figure 5 to change the dimension of gap d defined between theplaten 20 and the printing heads 15. Thus, the gap d defined between theplaten 20 and printing heads 15 can be adjusted to an optimum dimension for uniform printing purposes so as to accommodate the particular thickness of the printing sheet being utilized, for example. Accordingly, the printing pressure of the printing heads 15 can be set to an optimum value in dependence upon the thickness of a printing sheet. - In addition to the line impact-type printer described above, the present invention is also applicable to a serial-type printer. Moreover, the present invention can also be advantageously utilized with a pin feed type printer or a tractor- feed type printer in addition to the friction-feed type printer described above.
Guide shaft 13 could also be pivoted automatically through e.g. motor drive units rather than manually as described herein.
Claims (7)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP22511083A JPS60116485A (en) | 1983-11-29 | 1983-11-29 | Printer |
JP225110/83 | 1983-11-29 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0143467A2 EP0143467A2 (en) | 1985-06-05 |
EP0143467A3 EP0143467A3 (en) | 1985-07-10 |
EP0143467B1 true EP0143467B1 (en) | 1988-08-31 |
Family
ID=16824131
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP84114467A Expired EP0143467B1 (en) | 1983-11-29 | 1984-11-29 | Adjusting device for dimensionally adjusting a gap between a platen and a print head assembly and printer using the adjusting device |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0143467B1 (en) |
JP (1) | JPS60116485A (en) |
DE (1) | DE3473746D1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB8722622D0 (en) * | 1987-09-25 | 1987-11-04 | Halo Retail Systems Ltd | Dot-matrix printers |
JPH0538851A (en) * | 1991-08-07 | 1993-02-19 | Seiko Epson Corp | Printing apparatus |
EP0761964B1 (en) * | 1995-08-28 | 2002-03-27 | Grégoire Alexandroff | Wind turbine with twin rotor |
JP3488366B2 (en) * | 1997-07-18 | 2004-01-19 | スター精密株式会社 | Printer |
US6450710B1 (en) * | 2000-07-14 | 2002-09-17 | Lexmark International, Inc. | Frame system for an ink jet printer |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL6912334A (en) * | 1968-09-05 | 1970-03-09 | ||
DD111850A1 (en) * | 1974-03-11 | 1975-03-12 | ||
JPS5394720U (en) * | 1976-12-28 | 1978-08-02 | ||
JPS5615379A (en) * | 1979-07-17 | 1981-02-14 | Ricoh Co Ltd | Platen displacing device |
DE3008540C2 (en) * | 1980-03-06 | 1982-07-22 | Triumph-Adler Aktiengesellschaft für Büro- und Informationstechnik, 8500 Nürnberg | Device on the platen bearing frame of writing or similar machines for adjusting the platen in the direction of the print |
JPS57195678A (en) * | 1981-05-28 | 1982-12-01 | Ricoh Co Ltd | Mechanism for adjusting printing of printing device |
-
1983
- 1983-11-29 JP JP22511083A patent/JPS60116485A/en active Granted
-
1984
- 1984-11-29 DE DE8484114467T patent/DE3473746D1/en not_active Expired
- 1984-11-29 EP EP84114467A patent/EP0143467B1/en not_active Expired
Non-Patent Citations (2)
Title |
---|
PATENTS ABSTRACTS OF JAPAN, Vol. 5, No. 61, (M-65) (733), April 24, 1981 & JP-A-56 15 379 (RICOH K.K.) (14-02-1981) * |
PATENTS ABSTRACTS OF JAPAN, Vol. 7, No. 47, (M-196) (1192), February 24, 1983 & JP-A-57 195 678(RICOH K.K.) (01-12-1982) * |
Also Published As
Publication number | Publication date |
---|---|
EP0143467A3 (en) | 1985-07-10 |
EP0143467A2 (en) | 1985-06-05 |
DE3473746D1 (en) | 1988-10-06 |
JPS60116485A (en) | 1985-06-22 |
JPH0214197B2 (en) | 1990-04-06 |
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