Typewriting machines – Sheet or web – Including friction-feed means
Reexamination Certificate
2001-01-04
2004-02-24
Hirshfeld, Andrew H. (Department: 2854)
Typewriting machines
Sheet or web
Including friction-feed means
C074S409000, C074S440000
Reexamination Certificate
active
06695505
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-4995, filed Jan. 13, 2000; the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a backlash correction device and a backlash correction method for preventing the backlash of gears by exerting an urging force to a mobile body moving in forward and backward directions, to one direction.
2. Description of the Related Art
Various types of devices for transmitting a moving force from a driving source to a mobile body through a moving force transmission means having gears allow urging means, such as a spring, to act on the mobile body in one movement direction so as to prevent the erroneous movement of the mobile body due to the backlash of the gears. The specific example of this conventional backlash correction device will be described with reference to
FIGS. 1
to
4
.
FIG. 1
is a plane view of a paper feed device of a printer or the like to which a backlash correction device is applied. An elevator
1
is vertically, movably provided at a main body base (not shown) and vertically moved by the driving force of an elevator M
1
. A paper feed base
2
, which is a mobile body, is laterally, slidably provided at the elevator
1
by being guided by a guide rail
3
. The elevator
1
is provided with a lateral movement motor M
2
serving as a driving source and driving force transmission means
4
for transmitting the driving force of this lateral movement motor M
2
to the paper feed base
2
. The driving force transmission means
4
consists of the first gear G
1
fixed to the shaft of the lateral movement motor M
2
, the second gear G
2
engaged with the first gear G
1
, the third gear G
3
engaged with the second gear G
2
, the fourth gear G
4
engaged with the third gear G
3
and a rack gear G
5
engaged with the fourth gear G
4
and fixed to the paper feed base
2
.
An extension spring
5
serving as urging means, is provided between the paper feed base
2
and the elevator
1
. The paper feed base
2
is urged by the spring force of the extension spring
5
to one direction (which is a left direction in
FIG. 1
) of the forward and backward movement directions of the base
2
. In
FIG. 1
, reference symbol S1 denotes a lateral HP (home position) sensor detecting the home position of the paper feed base
2
. The lateral correction position of the paper feed base
2
is adjusted based on the home position detected by the lateral HP (home position) sensor S1. Reference symbol S
2
denotes a paper sensor detecting whether or not paper is present on the paper feed base.
Next, the function of the backlash correction device constituted as stated above will be described. Since the positional relationship among the gears G
1
to G
5
is relatively determined, description will be given while assuming that each motor-side gears is Ga and each paper feed base-side gear is Gb. As shown in, for example,
FIG. 2
, the gears Ga and Gb are applied with the spring force f
1
of the extension spring
5
and always engaged with each other on their one engagement faces
6
a
and
7
a
. In this state, if the paper feed base
2
is moved in an opposite direction to the urging direction of the extension spring
5
, the lateral movement motor M
2
is driven from the state of FIG.
3
(A) to the movement direction of the paper feed base
2
by a predetermined movement quantity. Since the driving force is transmitted in a direction resisting the spring force f
1
of the extension spring
5
as shown in FIG.
3
(B), the lateral movement motor-side gear Ga and the paper feed base-side gear are engaged with each other on their one engagement faces
6
a
and
7
a
and a rotation force is thereby transmitted to the paper feed base
2
. Therefore, when the paper feed base
2
is stopped, the lateral movement motor-side gear Ga and the paper feed base-side gear Gb are, as shown in FIG.
3
(C), engaged with each other on their one engagement faces
6
a
and
7
a
and no backlash naturally occurs.
On the other hand, if the paper feed base
2
is moved in the same direction as the urging force of the extension spring
5
, the lateral movement motor M
2
is driven from the state of FIG.
4
(A) by a predetermined movement quantity in the movement direction of the paper feed base
2
. Since this driving force is transmitted in a direction which does not resist the spring force of the extension spring
5
as shown in FIG.
4
(B), the lateral movement motor-side gear Ga and the paper feed base-side gear Gb are engaged with each other on their other engagement faces
6
b
and
7
b
and a rotation force is thereby transmitted to the paper feed base
2
. When the paper feed base
2
is stopped, the lateral movement motor-side gear Ga and the paper feed base-side gear Gb are changed to a state in which they are engaged with each other on their one engagement faces
6
a
and
7
a
, thereby preventing the occurrence of backlash.
Namely, according to the conventional case, if the paper feed base
2
is moved in the same direction as the urging direction of the extension spring
5
, the paper feed base
2
is forced to be moved by the spring force of the extension spring
5
after the movement of the paper feed base
2
is stopped and the engagement state of the gears Ga and Gb is returned to an original state, thereby preventing the occurrence of backlash.
However, the movement load of the paper feed base
2
varies according to the quantity of the loaded paper. Therefore, if the movement load increases, the spring force f
1
of the extension spring
5
cannot force the paper feed base
2
to be moved as shown in FIG.
4
(C), with the result that backlash occurs.
Here, it is considered that an extension spring
5
having a stronger spring force is used while supposing a maximum load so as to prevent such backlash from occurring. However, if an extension spring
5
having a too strong spring force is used, it is required to change the lateral movement motor M
2
to one having a strong driving force accordingly. If so, a heavy load is always exerted on the respective gears G
1
to G
5
and the strength, durability and the like of the gears G
1
to G
5
should be disadvantageously taken into account.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a backlash correction device capable of preventing the occurrence of a movement quantity error caused by the backlash of gears without increasing the urging force of urging means.
A backlash correction device according to the present invention is characterized in that a moving force from a driving source is transmitted to a mobile body through moving force transmission means having at least a gear and the mobile body is urged to one of forward and backward movement directions of the mobile body by the urging force of urging means, thereby preventing the occurrence of a movement quantity error caused by the backlash of the gear, and characterized in that (1) if the mobile body is moved in an opposite direction to an urging direction of the urging means, the driving source is controlled to be driven in a movement direction of the mobile body by a predetermined movement quantity; and (2) if the mobile body is moved in a same direction as the urging direction of the urging means, (2-1) the driving source is controlled to be driven in a movement direction of the mobile body by a movement quantity which is the sum of the predetermined movement quantity and a correction quantity equal to or greater than a maximum backlash quantity and (2-2) then driven in an opposite direction by the correction quantity.
In this backlash correction device, (1) if the mobile body is moved in an opposite direction to an urging direction of the urging means, the driving source is driven in a movement direction of the mobile body by a predetermined movement quantity. In the transmission of the driving force, the gears are engaged wi
Iimura Naoyuki
Yoneoka Hideharu
Berkowitz Marvin C.
Hirshfeld Andrew H.
Nath Gary M.
Nath & Associates PLLC
Nguyen Houi-An D.
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