EP0338514B1 - Low-noise printer head assembly - Google Patents
Low-noise printer head assembly Download PDFInfo
- Publication number
- EP0338514B1 EP0338514B1 EP19890106942 EP89106942A EP0338514B1 EP 0338514 B1 EP0338514 B1 EP 0338514B1 EP 19890106942 EP19890106942 EP 19890106942 EP 89106942 A EP89106942 A EP 89106942A EP 0338514 B1 EP0338514 B1 EP 0338514B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- stopper plate
- printer head
- armature
- print position
- 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 - Lifetime
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Images
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
- B41J29/00—Details of, or accessories for, typewriters or selective printing mechanisms not otherwise provided for
- B41J29/10—Sound-deadening devices embodied in machines
Definitions
- the present invention relates generally to dot matrix printer heads, and more specifically to a low-noise dot matrix printer head.
- the printer head comprises a print wire movable between a non-print position and a print position, an armature connected to the print wire, a stopper plate, a return spring for biasing the armature into contact with the stopper plate, and an electromagnet which drives the armature against the spring in response to energization of the electromagnet so that the print wire is moved from the non-print position to the print position and causes the spring to restore the armature to the non-print position in response to deenergization of the magnet.
- a heat sink In thermal contact with the electromagnet is a heat sink having a rear part that extends beyond the stopper plate to an elastic rear panel to form a sound absorption air chamber therebetween.
- a dot matrix printer head assembly is illustrated.
- the head assembly is composed of a plurality of print heads 1.
- 24 print heads are radially arranged and mounted on a front panel structure 2 within an aluminum heat sink 3 at 15° annular intervals.
- Each print head 1 comprises a magnetic core 4, a coil 5, an armature 6, and a print wire 7 which extends through guides 8 to the front end of the assembly.
- Armature 6 has its lower end firmly secured to the rear end of print wire 7 and is normally biased by a spring 9 to the right into contact with a stopper 10a of a stopper plate 10. All print wires 7 are arranged on the front end of the assembly in a 4 x 6 matrix array.
- Heat sink 3 has an annular inner wall which is in intimate contact with the cores 2 to extract heat therefrom and extends rearward beyond the stopper plate 10 to define an air chamber 11 with a rubber rear panel 12.
- the air chamber 11 is open to the outside through an opening 11a formed on the bottom of the assembly to allow heat produced in the cores 4 to escape to the outside.
- the armature 6 Upon energization of the coil 5, the armature 6 rotates clockwise about a pivot point 6a against the spring 9 so that the print wire 7 moves forward from a non-print position to a print position.
- the energy stored in the spring 9 is liberated, causing the associated armature 6 to return to the normal position and hit the stopper 7a with a substantial amount of force.
- the impact force on the stopper 10a causes stopper plate 10 and the air in the chamber 11 to vibrate, generating noise in the air chamber 11.
- the noise is insulated by the heat sink 3 and absorbed by the elastic rear panel 12.
- the noise level of the printer head assembly can be reduced by approximately 1.5 dB and by the provision of the air chamber 11 behind the stopper plate 10, the noise level can be further reduced in proportion to the distance "L" between it and the rear panel 12.
- the noise level was reduced by more than 3 dB with a distance of 3 mm in comparison with a printer head without the elastic rear panel and a noise reduction of about 4 dB was achieved with a distance of 10 mm. Since the air chamber 11 can be communicated with the interior of a printer through opening 11a when the head assembly is installed, the noise energy generated by the printer head can be further reduced by aborption by the printer housing.
Landscapes
- Impact Printers (AREA)
- Accessory Devices And Overall Control Thereof (AREA)
Description
- The present invention relates generally to dot matrix printer heads, and more specifically to a low-noise dot matrix printer head.
- With prior art dot matrix printer heads such as the printer head disclosed in JP-A-58 132 567, print wires are arranged in a matrix array and each wire is driven by an armature when it is pulled against the action of a return spring by an electromagnet in response to a drive pulse applied thereto. Upon deenergization of the magnet, the energy stored in the return spring is released, causing the armature to return to the normal position and hit a stopper with a substantial amount of impact. Since the printers of this type are used in low-noise environment, noise suppression is important. Approaches to the noise problem include enclosing a printer in a sound-insulation box or developing a noise-absorptive printer mechanism. However, the cost of these approaches and their effects are not still satisfactory for wide acceptance.
- It is therefore an object of the present invention to provide an inexpensive, low noise printer head.
- According to the present invention, the printer head comprises a print wire movable between a non-print position and a print position, an armature connected to the print wire, a stopper plate, a return spring for biasing the armature into contact with the stopper plate, and an electromagnet which drives the armature against the spring in response to energization of the electromagnet so that the print wire is moved from the non-print position to the print position and causes the spring to restore the armature to the non-print position in response to deenergization of the magnet. In thermal contact with the electromagnet is a heat sink having a rear part that extends beyond the stopper plate to an elastic rear panel to form a sound absorption air chamber therebetween.
- The present invention will be described in further detail with reference to the accompanying drawings, in which:
- Fig. 1 is a side cross-sectional view of a dot matrix printer head assembly of the present invention;
- Fig. 2 is a cross-sectional view taken along lines 2-2 of Fig. 1;
- Fig. 3 is a cross-sectional view taken along lines 3-3 of Fig. 1; and
- Fig. 4 is a graphic representation of noise level generated by the printer head assembly of the invention, with the noise being plotted as a function of distance between the stopper plate and rear panel of the printer head assembly of Fig. 1.
- Referring to Figs. 1 to 3, a dot matrix printer head assembly according to the present invention is illustrated. The head assembly is composed of a plurality of
print heads 1. In a typical example, 24 print heads are radially arranged and mounted on afront panel structure 2 within analuminum heat sink 3 at 15° annular intervals. Eachprint head 1 comprises amagnetic core 4, acoil 5, anarmature 6, and aprint wire 7 which extends throughguides 8 to the front end of the assembly.Armature 6 has its lower end firmly secured to the rear end ofprint wire 7 and is normally biased by aspring 9 to the right into contact with astopper 10a of astopper plate 10. Allprint wires 7 are arranged on the front end of the assembly in a 4 x 6 matrix array. -
Heat sink 3 has an annular inner wall which is in intimate contact with thecores 2 to extract heat therefrom and extends rearward beyond thestopper plate 10 to define anair chamber 11 with a rubberrear panel 12. Theair chamber 11 is open to the outside through an opening 11a formed on the bottom of the assembly to allow heat produced in thecores 4 to escape to the outside. - Upon energization of the
coil 5, thearmature 6 rotates clockwise about apivot point 6a against thespring 9 so that theprint wire 7 moves forward from a non-print position to a print position. When each coil is deenergized, the energy stored in thespring 9 is liberated, causing the associatedarmature 6 to return to the normal position and hit the stopper 7a with a substantial amount of force. - The impact force on the
stopper 10a causesstopper plate 10 and the air in thechamber 11 to vibrate, generating noise in theair chamber 11. However, the noise is insulated by theheat sink 3 and absorbed by the elasticrear panel 12. - Experiments showed that, by the provision of the elastic
rear panel 12, the noise level of the printer head assembly can be reduced by approximately 1.5 dB and by the provision of theair chamber 11 behind thestopper plate 10, the noise level can be further reduced in proportion to the distance "L" between it and therear panel 12. As shown in Fig. 4, the noise level was reduced by more than 3 dB with a distance of 3 mm in comparison with a printer head without the elastic rear panel and a noise reduction of about 4 dB was achieved with a distance of 10 mm. Since theair chamber 11 can be communicated with the interior of a printer throughopening 11a when the head assembly is installed, the noise energy generated by the printer head can be further reduced by aborption by the printer housing.
Claims (6)
- A printer head comprising a print wire movable between a non-print position and a print position, an armature connected to said print wire, a stopper plate, spring means for biasing said armature into contact with said stopper plate, electromagnetic drive means for driving said armature against said spring means in response to energization thereof so that said print wire is moved from said non-print position to said print position and causing said spring means to return said armature to said non-print position in response to deenergization thereof, a heat sink in thermal contact with said electromagnetic drive means, characterized by comprising an elastic rear panel spaced a distance from said stopper plate, and in that said heat sink extends beyond said stopper plate to said rear panel to define an air chamber behind said stopper plate.
- A printer head as claimed in claim 1, wherein said air chamber is open to the outside through an opening formed on a bottom portion of said printer head.
- A printer head as claimed in claim 1 or 2, wherein a dimension of said air chamber between said stopper plate and said rear panel is in the range between 3 mm and 10 mm.
- A matrix printer head assembly comprising:
a stopper plate;
a plurality of printer heads each including a print wire movable between a non-print position and a print position, an armature connected to said print wire, spring means for biasing said armature into contact with said stopper plate, electromagnetic drive means for driving said armature against said spring means in response to energization thereof so that said print wire is moved from said non-print position to said print position and causing said spring means to return said armature to said non-print position in response to deenergization thereof, the print wires of said printer heads forming an array of matrix on a front end of said printer head assembly, a heat sink in thermal contact with said electromagnetic drive means of each said printer heads, characterized by comprising an elastic rear panel spaced a distance from said stopper plate; and in that said heat sink extends beyond said stopper plate to said rear panel to define an air chamber between said stopper plate and said elastic rear panel. - A matrix printer head assembly as claimed in claim 4, wherein said air chamber is open to the outside through an opening formed on a bottom portion of said printer head assembly.
- A matrix printer head assembly as claimed in claim 4 or 5, wherein a dimension of said air chamber between said stopper plate and said rear panel is in the range between 3 mm and 10 mm.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP97225/88 | 1988-04-19 | ||
JP9722588A JPH01267049A (en) | 1988-04-19 | 1988-04-19 | Printing head assembly |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0338514A2 EP0338514A2 (en) | 1989-10-25 |
EP0338514A3 EP0338514A3 (en) | 1990-08-22 |
EP0338514B1 true EP0338514B1 (en) | 1993-07-07 |
Family
ID=14186690
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890106942 Expired - Lifetime EP0338514B1 (en) | 1988-04-19 | 1989-04-18 | Low-noise printer head assembly |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0338514B1 (en) |
JP (1) | JPH01267049A (en) |
DE (1) | DE68907435T2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE9001868U1 (en) * | 1990-02-16 | 1991-06-20 | Siemens Nixdorf Informationssysteme AG, 4790 Paderborn | Encapsulation for a dot matrix print head |
DE69328734T2 (en) * | 1992-06-23 | 2000-09-07 | Fujitsu Ltd | Print head with print wires |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3918567A (en) * | 1973-03-28 | 1975-11-11 | Edward D Kittredge | Process printing |
US4401026A (en) * | 1977-09-14 | 1983-08-30 | Exxon Reserach And Engineering Co. | Free flight hammer for impact printer |
SE425067B (en) * | 1981-01-19 | 1982-08-30 | Facit Ab | PRESSURE HAMMER FOR PRINTERS AND PRINTERS |
JPS58132567A (en) * | 1982-02-02 | 1983-08-06 | Toshiba Corp | Print head |
JPS6211654A (en) * | 1985-07-09 | 1987-01-20 | Canon Inc | Wire dot head |
JPS62256661A (en) * | 1986-04-30 | 1987-11-09 | Seiko Epson Corp | Wire head apparatus of dot printer |
-
1988
- 1988-04-19 JP JP9722588A patent/JPH01267049A/en active Pending
-
1989
- 1989-04-18 DE DE1989607435 patent/DE68907435T2/en not_active Expired - Fee Related
- 1989-04-18 EP EP19890106942 patent/EP0338514B1/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
EP0338514A3 (en) | 1990-08-22 |
DE68907435T2 (en) | 1993-10-14 |
EP0338514A2 (en) | 1989-10-25 |
JPH01267049A (en) | 1989-10-24 |
DE68907435D1 (en) | 1993-08-12 |
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