Data processing: measuring – calibrating – or testing – Measurement system – Weight
Reexamination Certificate
1999-02-12
2003-01-07
Wachsman, Hal (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Weight
C702S101000, C101S483000
Reexamination Certificate
active
06505142
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a drawing apparatus for performing drawing on a recording material such as a plate mounted on a drum and a method of attaching balance weights for adjusting a balanced state at the time of rotating the drum.
2. Description of the Background Art
A drawing apparatus for performing drawing upon irradiation of various types of photosensitive materials with light has been used. In a drum-type drawing apparatus, a photosensitive material is attached to a recording drum which is rotatable in a primary scanning direction, and a recording head comprising a laser diode and the like is moved in a secondary scanning direction parallel to a rotary shaft of the recording drum, to perform drawing on the photosensitive material.
FIG. 37
is a schematic perspective view of a recording drum of a conventional drawing apparatus. A recording drum shown in
FIG. 37
is so constructed that a plate
2
made of aluminum can be mounted thereon as a photosensitive material. A fixing clamp
4
for fixing one end of the plate
2
and a movable clamp
5
for fixing the other end of the plate
2
are provided on an outer peripheral surface of the recording drum
1
. The movable clamp
5
is formed so as to be movable on the outer peripheral surface of the recording drum
1
depending on the size of the plate
2
. The recording drum
1
to which the plate
2
is attached is rotated at relatively low speed around the rotary shaft
3
, so that drawing is performed on the surface of the plate
2
.
In recent years, it has been needed to improve the efficiency of drawing processing on the plate
2
. Therefore, it has been examined whether the recording drum
1
to which the plate
2
is attached is rotated at high speed to perform a drawing operation.
However, the plate
2
made of aluminum is heavier than a film material or the like, and is attached in an offset state to a part of the outer peripheral surface of the recording drum
1
. When the recording drum
1
is rotated at high speed, therefore, a centrifugal force developed by the plate
2
causes an unbalance force to be exerted on the rotary shaft of the recording drum
1
. The fixing clamp
4
and the movable clamp
5
are provided on the outer peripheral surface of the recording drum
1
. The fixing clamp
4
and the movable clamp
5
respectively have corresponding masses. When the recording drum
1
is rotated at high speed, similarly to the plate
2
, therefore, centrifugal forces developed by the fixing clamp
4
and the movable clamp
5
cause an unbalance force.
When the unbalance force
5
caused by the plate
2
, the fixing clamp
4
and the movable clamp
5
is exerted on the recording drum
1
, forced vibration may occur in bearings for supporting the rotary shaft
3
of the recording drum
1
when the recording drum
1
is rotated at high speed, so that the recording drum may develop a fault. The production of such an unbalance force presents no problem when the recording drum
1
is rotated at low speed, as in the conventional example, while presenting a large problem as the recording drum
1
is rotated at high speed in order to make the drawing operation efficient.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a drawing apparatus in which no forced vibration occurs by an unbalance between centrifugal forces at the time of rotation and a method of attaching balance weights.
A drawing apparatus according to the present invention is a drawing apparatus for drawing an image on a recording material, comprising a cylindrical drum having a rotary shaft and an outer peripheral surface, driving means for rotating the drum around the rotary shaft, a fixing member provided on the outer peripheral surface of the drum for fixing the recording material to the outer peripheral surface of the drum, a plurality of balance weights provided so as to be movable and fixable along a circumference whose center coincides with the rotary shaft of the drum, and position calculation means for calculating, on the basis of information relating to the recording material and the fixing member, the positions of the plurality of balance weights for canceling an unbalance force caused by centrifugal forces developed by the fixing member and the recording material at the time of rotating the drum.
In the drawing apparatus, the recording material is mounted on the outer peripheral surface of the cylindrical drum by the fixing member, and is rotated by the driving means. An image is drawn onto the recording material which is rotated as the drum is rotated. The fixing member and the recording material which are provided on the outer peripheral surface of the cylindrical drum respectively develop centrifugal forces in different directions at the time of rotating the drum. Therefore, the unbalance force caused by the centrifugal forces developed by the recording material and the fixing member is exerted on the rotary shaft of the drum.
On the other hand, the plurality of balance weights are provided along the circumference whose center coincides with the rotary shaft of the drum. Each of the balance weights develops the centrifugal force by the rotation of the drum. The plurality of balance weights are arranged such that a composite force of the centrifugal forces developed by the balance weights is balanced with the unbalanced force caused by the recording material and the fixing member. Even when the drum is rotated, therefore, the unbalance force is prevented from being exerted on the rotary shaft. Therefore, it is possible to prevent the drum from developing a fault by forced vibration occurring in the rotary shaft of the drum. The plurality of balance weights are provided so as to be movable and fixable along the circumference whose center coincides with the rotary shaft of the drum. Even when the weight and the size of the recording material are changed, therefore, it is possible to cancel the unbalance force caused by the recording material and the fixing member by changing the positions of the plurality of balance weights.
The position calculation means calculates the positions of the balance weights on the basis of the information relating to the recording material and the fixing member. Even when a different type of recording material is used, therefore, it is possible to calculate the most suitable position of the balance weight depending on the type.
The cylindrical drum may further have two end surfaces disposed on opposite sides thereof, and the plurality of balance weights may comprise at least two balance weights provided on each of both the end surfaces of the drum so as to be movable and fixable along the circumference.
In this case, at least two balance weights are provided on each of both the end surfaces of the drum. Even when the weight and the size of the recording material are changed, therefore, it is possible to cancel the unbalance force caused by the recording material and the fixing member by changing the positions of the balance weights.
An annular groove whose center coincides with the rotary shaft may be formed on each of both the end surfaces of the drum, and the plurality of balance weights may be provided so as to be movable and fixable along the annular groove.
In this case, it is easy to move and position the plurality of balance weights by providing the annular grooves.
Each of the plurality of balance weights may include a magnet which is attractable to each of both the end surfaces of the drum.
The balance weight includes a magnet, thereby making it possible to easily move and fix the balance weights on both the end surfaces of the drum without using a special structure.
The drawing apparatus may further comprise movement means for moving the plurality of balance weights to the positions calculated by the position calculation means.
In this case, the movement means can move the plurality of balance weights. Therefore, it is possible to rotate the drum at high speed without causing forced vibration in the rotary shaf
Inoue Masao
Kawada Toru
Koyagi Yasuyuki
Nagamine Junichi
Tamura Toshio
Arent Fox Kintner & Plotkin & Kahn, PLLC
Dainippon Screen Mfg. Co,. Ltd.
Wachsman Hal
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