JPH061039A - Impact dot printer - Google Patents

Abstract

PURPOSE:To constitute an impact dot printer reduced in noise by partially changing the cross-sectional area of the printing paper discharge route above the printing head or platen of the impact dot printer. CONSTITUTION:Noise generated from a printing head 8 and a platen 6 is partly absorbed by the sound absorbing material 7 provided on the under surface of a first printer cover 1 and unabsorbed noise passes through the printing paper discharge route formed between printing paper 4 and first and second printer covers 1, 2 to go outside of an impact dot printer 100 from a paper discharge port 15. However, when there is a part changing in cross-sectional area in a transmission route, the particle speed of a medium becomes discontinuous across the part and sound wave is reflected. Since the reflection of the sonic wave becomes large as cross-sectional area change quantity becomes larger and the protruding quantity of a sound arresting member 10 to the printing paper discharge route is larger than that of a sound arresting member 2a and the cross-sectional area change quantity of the member 1b is larger than that of the member 2a, large sound arresting effect is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact dot printer.

[0002]

2. Description of the Related Art Conventionally, an impact dot printer drives a print wire built in a print head to apply an impact force to a print sheet via an ink ribbon to perform printing, and noise is generated when the print wire collides. However, this noise leaks to the outside of the impact dot printer from the ejecting portion of the printing paper, increasing the noise level of the impact dot printer. As a noise countermeasure of this impact dot printer,
The one disclosed in Japanese Utility Model Laid-Open No. 64-48263 is known. The configuration will be described with reference to FIGS. 6 and 7. Figure 6
FIG. 7 is a perspective view of the printer cover of the impact dot printer as seen obliquely from above, and FIG.
It is sectional drawing cut | disconnected by and seen from the arrow D direction. The printing paper discharge unit is covered by the second printer cover 501 and the first printer cover 502 to form a printing paper discharge path. The second printer cover 501 is arranged so as to face the sheet guide 503, and the second printer cover 501 is provided with a plate-shaped muffling member 504 and a paper guiding member 505 that project into the printing paper discharge path. This muffling member 50
According to No. 4, the cross-sectional area of the printing paper discharge path is partially changed, and the sound wave transmitted through the printing paper discharge path is reflected at that portion to reduce the noise level.

[0003]

However, in such a structure, the printing paper 51 is placed along the upper surface of the sheet guide 503.
When 0 is discharged, if the print paper has a weak stiffness, it floats from the sheet guide 503 and comes into contact with the noise reduction member 504 or the paper guide member 505. When the printing paper with weak stiffness comes into contact, the guiding of the printing paper 510 by the paper guiding member 505 becomes insufficient, the printing paper 510 stays at the contact portion, and the printing paper 510 is not discharged. Therefore, it is necessary to provide a certain amount of space above the sheet guide 503 so that the printing paper 510 does not come into contact with the silencing member 504 or the paper guiding member 505. Due to this space, the sound deadening effect of the sound deadening member 504 is lowered, and there is a problem that a desired noise level cannot be obtained. Further, a print head and a platen are arranged below the second printer cover 502, and when the print paper 510 is discharged, the end surface of the print paper 510 is discharged toward the second printer cover 502. Therefore, if a muffling member is provided below the second printer cover 502, the printing paper 510 is likely to come into contact with the muffling member and become caught in the muffling member, resulting in a decrease in sheet ejection performance. For this reason, there is also a problem that a noise reduction member cannot be provided under the second printer cover and noise cannot be reduced in the vicinity of a sound source such as a print head or a platen, so that effective noise reduction cannot be achieved.

The present invention has been made to solve the above problems, and an object thereof is to provide a low noise impact dot printer.

[0005]

SUMMARY OF THE INVENTION The present invention provides an impact dot printer having a print head and a platen with a cover for covering a printing paper discharge section, and a printing paper discharge path between the cover and the printing paper discharge section. In the impact dot printer in which the cross-sectional area of the print paper discharge path is partially changed in the middle of the print paper discharge path, the print head or the cross-sectional area of the print paper discharge path above the platen is also partially changed. It is characterized by

[0006]

1 is a perspective view of an impact dot printer 100 showing an embodiment of the present invention. FIG. 2 is a cross-sectional view of the impact dot printer 100 in FIG. 1 taken along the line AA and seen from the direction of arrow B. An embodiment of the present invention will be described with reference to FIGS.

The impact dot printer 100 forms an exterior by a case 3, and the upper surface of the case 3 is covered with a first printer cover 1 and a second printer cover 2. One end of the first printer cover 1 is an end 3a of the case 3.
Rotatably engages with the other end of the first printer cover 1,
It is rotatably engaged with the second printer cover 2. Below the first printer cover 1 and the second printer cover 2,
A discharge unit for the printing paper 4 is formed. The printing paper 4 is fed by a paper feed port 14 provided between the case 3 and the sheet guide 12.
The paper is fed from the tractor 5 and fed by the tractor 5. The print sheet conveyed by the tractor 5 is rolled up on the platen 6 and then discharged, and then conveyed along the upper surface of the sheet guide 12 through a sheet discharge port 15 provided between the second printer cover 2 and the sheet guide 12. Impact dot printer 10
It is discharged to the outside of 0. A print head 8 is arranged to face the platen 6, and the print head 8 has a plurality of print wires built therein. The print head 8 is mounted on a carriage 9, which has a first guide shaft 10 and a second guide shaft 1.
You can move by being guided by 1. When the carriage 9 moves, the print wire built in the print head 8 is driven at an appropriate timing to form dots on the print paper 14 via the ink ribbon 16 to perform printing. A printing paper discharge path is formed below the first printer cover 1 and the second printer cover 2. During this printing paper discharge path,
A plurality of plate-shaped muffling members 1 a, 2 a protruding from the first printer cover 1 and the second printer cover 2 are provided. The muffling member 1a provided on the first printer cover 1 is arranged close to the printing paper 4 along the discharge path of the printing paper 4, and the second printer cover 2
The amount of protrusion of the sound deadening member 1a into the print sheet discharge path becomes smaller as it approaches the side. Paper guide member 1d
Are provided so as to connect between the silencing members 1a, and the paper guiding member 1d is also provided along the discharge path of the printing paper 4 with the printing paper 4
And the amount of protrusion is reduced as the position approaches the second printer cover 2 side. As a result, the angle θ when the printing paper 4 delivered by the platen 6 comes into contact with the paper guiding member 1d becomes an acute angle. As shown in FIG. 3, when the printing paper 4 contacts the paper guiding member 1d, the printing paper 4 reacts with a reaction force f in a direction perpendicular to the surface of the paper guiding member 1d.
Receive. Then, the print paper 4 has fa = f × sin θ.
The force fa for pushing back the printing paper 4 is received. This allows
The smaller the contact angle θ between the printing paper 4 and the paper guiding member 1d, the smaller the force fa that pushes back the printing paper 4. Therefore,
The printing paper 4 is smoothly guided by the paper guiding member 1d, and since the distance between the platen 6 and the paper guiding member 1d is small, the printing paper 4 is not easily deformed, and even the printing paper having a weak stiffness is stably discharged. To be paper. FIG. 4 is a bottom view of the first printer cover 1 and the second printer cover 2 as seen from below, and the plurality of paper guiding members 1d and 2d are arranged at appropriate intervals. Inclined portion 1b of the first printer cover 1
Is a transparent member and is provided at a position on the left side (in FIG. 2) of the print head 8 and the platen 6 from above. There is. As a result, the visibility of the print result immediately after being printed by the print head 8 is improved. A paper cutter 1c is provided near the engaging portion of the first printer cover 1 with the second printer cover 2, and when the printing paper 4 is cut, the second printer cover 2 is engaged with the first printer cover 1. Part to rotate in the direction of arrow E until the upper surface of the second printer cover 2 contacts the upper surface of the first printer cover 1. Next, the printing paper 4 is brought into contact with the paper cutter 1C, and the printing paper 4 is pulled upward, whereby the printing paper 4 is cut at the contact portion with the paper cutter 1C. Further, a sound absorbing material 7 is provided above the print head of the first printer cover 1 so as to have a sound absorbing function.

When the printing paper 4 is conveyed over the upper surface of the sheet guide 12, the noise canceling member 2a provided on the second printer cover 2 is separated from the platen 6 which sends out the printing paper 4, so that the printing is performed. Since the paper 4 is easily deformed and may float from the upper surface of the sheet guide 12,
The protrusions are provided in the printing paper discharge path at appropriate intervals. Therefore, the spacing between the printing paper 4 and the noise reduction member 1a
Is set to be larger than the distance between the print sheet 4 and the printing paper 4.
A sheet guide 12 located below the second printer cover 2
Has a higher surface that supports the printing paper 4 as it approaches the paper exit 15. This is because the printing paper 4 is the paper exit 15
Since the end 4a of the printing paper 4 floats up when it is ejected from the printer, it is for making it easier to grasp the end 4a of the printing paper 4 by hand. The operability when doing is improved. The protrusion amount of the muffling member 2a provided on the second printer cover 2 into the print sheet discharge path is reduced along the support surface of the print sheet 4 of the sheet guide 12 toward the discharge port 15 side. The spacing between the support surface of the printing paper 4 of the sheet guide 12 and the silencing member 2a is substantially uniform. As a result, the printing paper 4 does not come into contact with the noise reduction member 2a and get stuck and stay there.

The noise generated from the impact dot printer 100 is generated when the print wire built in the print head 8 collides with the platen 6 through the ink ribbon 16 and the print paper and when the print wire is generated inside the print head 8. Noise generated when the driving member collides in the print head 8 is mainly. Therefore, the impact dot printer 100
Most of the noise is generated from the position where the print head 8 and the platen 6 are located. Therefore, in order to reduce noise, it is effective to mute the sound near the print head 8 and the platen 6 and attenuate the sound waves emitted from the openings of the impact dot printer 100. In the present embodiment, part of the noise generated from the print head 8 and the platen 6 is generated by the sound absorbing material 7 provided on the lower surface of the first printer cover 1.
Energy is absorbed by, and most of the rest passes through the print paper discharge path formed between the print paper 4 and the first printer cover 1 and the second printer cover 2, and from the paper discharge port 15, Although it is radiated to the outside of the impact dot printer 100, in the present embodiment, a plurality of silencing members 1a are provided above the sound sources of the print head 8 and the platen 6 so as to be close to the printing paper 4, so that it is effective. Can mute. If there is a portion of the sound wave whose cross-sectional area changes in its transmission path, the particle velocity of the medium becomes discontinuous at that portion and the sound wave is reflected. The larger the cross-sectional area change amount, the greater the reflection of the sound waves. The sound deadening member 1a has a larger projection amount into the printing paper discharge path than the sound deadening member 2a, and thus the cross-sectional area change amount is large. A muffling effect is obtained. By repeating the reflection of the sound waves by the plurality of sound deadening members 1a, 2a provided on the first printer cover 1 and the second printer cover 2, the energy of the sound waves is attenuated, and the impact dot printer is discharged from the paper discharge port 15. 10
The sound wave energy emitted to the outside of 0 becomes less,
The noise level of the impact dot printer 100 can be reduced.

FIG. 5 shows the noise spectrum when the silencing members 1a and 2a are provided on the first printer cover 1 and the second printer cover 2 of this embodiment and when they are not provided. Noise generated from the print head 8 and the platen 6 is 1K
In the present embodiment, it is 1 KHz, since the frequency band above 8 Hz is the main one.
A large sound wave attenuation is obtained at the above frequencies. Further, since the sound that is offensive to the ear is a sound wave of 1 KHz or more, it is possible to obtain a larger effect than the actual attenuation of the noise level in terms of hearing.

[0011]

As described above, according to the present invention, the print head of an impact dot printer, or
Since the cross-sectional area of the printing paper discharge path above the platen is partially changed, a low-noise impact dot printer can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of an impact dot printer showing an embodiment of the present invention.

FIG. 2 is a sectional view of an impact dot printer showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a force received by the printing paper according to the embodiment of the present invention.

FIG. 4 is a bottom view of the printer cover according to the embodiment of the present invention.

FIG. 5 is a noise spectrum diagram showing an impact dot printer showing an example of the present invention and a comparative example.

FIG. 6 is a perspective view of a conventional printer cover.

FIG. 7 is a cross-sectional view of a conventional printer cover.

[Explanation of symbols]

 1 First Printer Cover 2 Second Printer Cover 3 Case 4 Printing Paper 5 Tractor 6 Platen 7 Sound Absorbing Material 8 Print Head 9 Carriage 10 First Guide Shaft 11 Second Guide Shaft 12 Sheet Guide 13 Ribbon Cassette 14 Paper Feed Port 15 Paper Ejection Mouth 16 ink ribbon

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Shirotori 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (72) Inventor Motoyuki Shinmura 3-3-5 Yamato, Suwa-shi, Nagano Seiko -In Epson Corporation (72) Inventor Katsuhiko Nishizawa 3-3-5 Yamato, Suwa City, Nagano Seiko-In Epson Corporation

Claims (1)

[Claims] 1. An impact dot printer having a print head and a platen is provided with a cover for covering a printing paper discharge section, and a printing paper discharge path is formed between the cover and the printing paper discharge section. In an impact dot printer in which the cross-sectional area of the discharge path is partially changed in the middle of the print paper discharge path, it is possible to partially change the cross-sectional area of the print head or the print paper discharge path above the platen. Characteristic impact dot printer.