Facsimile and static presentation processing – Static presentation processing – Emulation or plural modes
Reexamination Certificate
1999-10-01
2003-09-09
Evans, Arthur G. (Department: 2622)
Facsimile and static presentation processing
Static presentation processing
Emulation or plural modes
C358S001500
Reexamination Certificate
active
06618159
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of switching print modes of a printing device that as a plurality of different print modes for printing at different speeds.
2. Description of the Related Art
There has been known a print device including a hammer bank that is reciprocally transported to form an image on a recording medium, such as a recording sheet. Dot line printers and shuttle printers are representative examples of such print devices. Several types of shuttle mechanisms are known for reciprocally transporting the hammer bank. For example, one type of mechanism is provided with a cam or a link mechanism for converting rotational drive of a drive motor into linear movement. Another type of mechanism reverses the transport direction of the hammer bank by changing rotational direction of a drive motor. There is also known a direct drive type mechanism including a linear motor. The direct drive type mechanism requires no transmission mechanism for transmitting drive of the linear motor to the hammer bank.
FIG. 1
shows an example of a printing unit of a print device. In
FIG. 1
, the printing unit
1
includes a shuttle mechanism
2
, a hammer bank
3
, a sensor
4
, and a shuttle drive mechanism. The shuttle mechanism
2
includes a guide shaft
11
, direct drive bearings
12
, a linear motor
20
, and an inversion mechanism
30
. The shuttle drive mechanism includes a controller
50
, a shuttle control circuit
60
, and a shuttle drive circuit
70
. The guide shaft
11
extends leftward and rightward as viewed in FIG.
1
. The direct drive bearings
12
are reciprocally movably mounted on the guide shaft
11
. The hammer bank
3
is supported on the direct drive bearings
12
, and so is reciprocally movable with the direct drive bearings
12
. Although not shown in the drawings, the hammer bank
3
is provided with a plurality of printing hammers for forming a dot pattern on a recording medium based on print data received from an external device. The linear motor
20
is provided with a coil
21
and magnets (not shown), and is driven in a well known manner. Although not shown in the drawings, the coil
21
includes a reversing coil and a constant velocity coil. The inversion mechanism
30
has a pair of timing pulleys
32
and a timing belt
31
wound around the timing pulleys
32
. The coil
21
is connected to the direct drive bearings
12
via the inversion mechanism
30
. With this configuration, the drive force of the linear motor
20
is transmitted to the direct drive bearings
12
so as to reciprocally transport the direct drive bearings
12
. The coil
21
is also reciprocally transported in synchronization with the direct drive bearings
12
, but always in a direction opposite to the direction in which the direct drive bearings
12
are transported. In this way, the coil
21
serves as a counter balance. That is, when the direct drive bearings
12
with the hammer bank
3
mounted thereon are reciprocally transported, such a reciprocal movement of the coil
21
, which has a fixed weight, achieves leftward and rightward weight balance of the print device, thereby reducing vibration generated on the print device due to the transport of the direct drive bearings
12
.
The sensor
4
is provided near a movable portion, which in the present example is on the hammer bank side, for detecting a position of the hammer bank
3
. The shuttle drive circuit
70
energizes the coil
21
by supplying an driving current, and the shuttle control circuit
60
controls the amount of driving current supplied to the coil
21
. Based on positional information supplied by detection by the sensor
4
, the controller
50
controls the shuttle control circuit
60
and the shuttle drive circuit
70
to move the hammer bank
3
in a predetermined shuttle speed pattern which is graphically shown in FIG.
3
. The controller
50
also receives a variety of signals from an external device (not shown).
FIG. 2
shows a sheet transport mechanism
80
provided to the printing unit
1
. A platen
81
is rotatably supported on a printer frame (now shown). A pair of left and right pin tractors
82
are provided for transporting a sheet S on the platen
81
in a direction perpendicular to the reciprocal movement direction of the hammer bank
3
. The platen
81
and the pin tractor
82
are driven by a sheet feed motor
83
. An ink ribbon
84
is provided for supplying ink.
As shown in
FIG. 3
, a region of the reciprocal movement of the hammer bank
3
(reciprocal movement of the hammer bank
3
will be referred to as “shuttle” hereinafter) includes a constant velocity region and reversing regions. In the constant velocity region, the constant velocity coil is energized so the shuttle moves at a constant speed. On the other hand, in the reversing regions, the reversing coil is energized, so the shuttle accelerates or decelerates. When the shuttle enters the reversing region from the constant velocity region, the shuttle gradually decelerates, and the velocity of the shuttle reaches zero at a reversing position P
0
. Then, the movement direction of the shuttle is reversed. The shuttle gradually accelerates in the opposite direction until the shuttle again enters the constant velocity region.
Depending on the type of character to be printed, some printing devices switch print modes with different print speeds. For example, a high speed print mode is used for printing normal characters at a high print speed. The high print speed in the high speed print mode is achieved by sacrificing quality of printed characters, which is determined by print dot density. On the other hand, a high quality print mode (i.e., a low speed print mode) is used for printing high-quality characters, such as bar codes images and OCR images. In the high quality mode, print speed is sacrificed for increased print dot density.
Conventionally, there have been two different methods for changing print speeds during printing operations upon switching print modes. According to a first method, the printing operations and the shuttle are both temporarily stopped. Then, the shuttle is restarted. Once a target shuttle speed is attained, printing operations are restarted. On the other hand, according to a second method, shuttle is continued while printing operations are temporarily stopped. Then, the value of the driving current supplied to the coil
21
is gradually changed, thereby gradually changing the shuttle speed. Once the target shuttle speed is obtained, then printing operations are restarted.
It should be noted that the series of operations for gradually changing the shuttle speed until a target speed is attained are called initialization operations.
Different accelerations and decelerations of the shuttle in the reversing regions may be used depend on the print speed. Also, the reciprocal movement distance of the shuttle may also be varied depending on print speed to enhance stability of control. When the reciprocal movement distance is changed, there is need to temporarily stop the shuttle, move the hammer bank
3
to an objective reversing position, and then restart the shuttle.
Also, in order to improve speed of printing operations, there has been proposed a printing device with a different configuration. For example, a printing device
1
′ shown in
FIG. 4
is substantially the same as the printing device
1
, but the shuttle movement is controlled using the constant velocity coil and springs
40
without using the reversing coil. The springs
40
are provided at both ends of the guide shaft
11
and at both ends of the coil
21
for urging the hammer bank
3
and the coil
21
.
Next, control of the shuttle movement in the printing device
1
′ will be described. In the constant velocity region, an driving current is supplied to the constant velocity coil, thereby attaining shuttle of a constant velocity. When the hammer bank
3
enters the reversing region, application of the driving current to the constant velocity coil is stopped. The shuttle gradually de
Mamiya Hideaki
Matsumoto Yoshikane
Tobita Satoru
Evans Arthur G.
Hitachi Koki Co,. Ltd.
Whitham Curtis & Christofferson, PC
LandOfFree
Method of switching print modes of printing device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of switching print modes of printing device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of switching print modes of printing device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3059569