Typewriting machines – Including adjustment for optimum printing plane – By adjustment of platen relative to carriage
Reexamination Certificate
1998-06-17
2001-01-09
Hilten, John S. (Department: 2854)
Typewriting machines
Including adjustment for optimum printing plane
By adjustment of platen relative to carriage
C400S055000, C400S648000, C400S649000
Reexamination Certificate
active
06171001
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printer for printing on single paper such as a slip, more specifically to an improvement of an adjusting means for a head gap which is provided in a given distance between a platen and a printing head and a securing means of the head gap adjusting means for maintaining the head gap.
2. Description of the Prior Art
Slip printers for printing on slip paper are conventionally constructed such that slip paper inserted through a side portion or a front portion of the printer is received by a printing device, and the printing device performs printing operation. The printing device is equipped with a platen and a printing head which is disposed above and opposing the platen. Slip paper is inserted into a given opening, namely a head gap provided between the platen and the printing head. The printing head performs printing on the slip paper supported on the platen. In order to obtain stable printed images, distance of the head gap must be uniform over the entire width of the platen. Therefore, the manufacturer normally adjusts head gaps before shipment of printers.
As a structure for adjusting head gap, for example, Japanese Unexamined Utility Model Publication (Kokai) No. 61-35846 discloses a structure, in which a platen can be moved up and down by rotating screws screwed on both ends of the platen. The screws can be rotated by operation from above, and after completion of the adjustment; the platen is secured by tightening securing screws, which penetrate a frame from the side thereof. Furthermore, Japanese Unexamined Utility Model Publication (Kokai) No. 1-76247 discloses a structure installed with an adjusting roller. The adjusting roller has a spiral inclined portion on its peripheral portion. The spiral inclined portion is inserted into a slit-shaped aperture formed on the both ends of a platen so as to move the platen up and down by virtue of the inclined portion when the adjusting roller is rotated. In this case, a plurality of claw portions formed on the outer surface of the adjusting roller engage with a securing claw portion so as to restrict rotation of the adjusting roller, whereby the adjusted position of the platen is fixed.
SUMMARY OF THE INVENTION
In the former case of the prior arts disclosed in the above publications, the head gap adjusting operation by way of moving up and down the platen is performed by rotating the adjusting screw from above thereof. However, the securing operation for keeping the gap must be performed by way of tightening the securing screws from the side. Therefore, the adjusting steps, which are adjusting the head gap and securing the platen can not be smoothly performed, whereby the operation efficiency is inferior. Moreover, the securing screw inserted through the frame is tightened to the platen, so that strain occurs in the frame due to the tightening force, affecting the platen, whereby the adjusted head gap may change.
On the other hand in the later case, in order to rotate the adjusting roller, an operation tool such as a driver or the like must be used from the reverse side of the apparatus. And therefore, the adjusting operation with measuring head gap is troublesome, whereby the operation efficiency is inferior.
Therefore, an object of the present invention is to provide a printer in which head gap adjusting operation by way of moving a platen up and down and securing the platen can be easily performed.
In accordance with the invention, there is provided a printer comprising a frame, a platen mounted on the frame via a head gap adjusting means, a printing head disposed opposing the platen with a given gap provided therebetween, and a securing means of the head gap adjusting means for fixing the gap. Both the head gap adjusting means and the securing means are provided on said frame operatably from above.
Generally, printers are normally used on a working table, etc. As printers are precision apparatus, they should not be inclined or reversed. In addition, as printers have a certain weight each, it is troublesome to move them. According to the invention, the head gap adjusting means and the securing means of the head gap adjusting means are installed in the frame operatably from above the printer. Therefore, a printer is needless to move and the operation of adjusting head gap can be carried out in sequential handling which are easy and smooth, whereby operation efficiency is remarkably enhanced.
The head gap adjusting means and the securing means thereof can be constructed as follows. That is, the head gap adjusting means can comprise a rotatable cam rotatably mounted on the frame, a fixed cam fixed to a lower surface of the platen and vertically movable according to rotation of the rotatable cam, and a rotatable member rotatably mounted on the frame so as to be operable from above and engaging with the rotatable cam for rotation. The securing means can may be a securing member for unrotatablly securing the rotatable member directly to only the frame by operation from above.
In accordance with the above construction, by rotating the rotatable member from above, the rotatable cam rotates, whereby the platen vertically moves with the fixed cam, and thus adjustment of head gap is performed. Furthermore, by operating the securing member from above so as to secure the rotatable member, the rotatable cam is secured and the platen is secured at its adjusted position. In the invention, as the securing member is directly secured to only the frame, strain that occurred by the securing member does not easily affect the platen. As a result, the adjusted head gap is kept for long term in high precision.
The securing means can comprise an elastic member for elastically engaging to the rotatable member, thereby restricting rotation thereof In this construction, the rotatable member is ordinarily restricted by the securing means. Therefore, the step of securing the rotatable member can be omitted, whereby operations of adjusting head gap can be further facilitated.
These and other objects and advantages of the invention will become more apparent by referring to the following description and appended drawings.
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patent: 61-35846 (1986-03-01), None
patent: 1-76247 (1989-05-01), None
Chau Minh H.
Hilten John S.
Scully Scott Murphy & Presser
Star Micronics Co. Ltd.
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