JP2536697B2 - Paper transfer mechanism of thermal transfer printing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper conveying mechanism in a thermal transfer printing apparatus having a structure in which a platen and a pinch roller are brought into contact with and separated from each other, and a driving force of the pinch roller is obtained from a gear provided coaxially with the platen.

[0002]

2. Description of the Related Art FIGS. 4 and 5 are a side view and a plan view of a main part of a paper transport mechanism of a conventional thermal transfer printing apparatus disclosed in, for example, Japanese Patent Laid-Open No. 63-309482. In the figure, 1
Is a platen, 2 is a pair of first pulleys rotatably provided on both ends of the platen shaft separately from the platen 1, and 3 is hooked on the first pulley 2 at a speed substantially equal to the peripheral speed of the platen 1. The pair of running timing belts 4, 5 are a second pulley and a third pulley for extending the timing belt 3. Reference numeral 6 is a recording paper, and 7 is a paper clamper which is provided on a bridge 8 which is installed between the timing belt 3 and in parallel with the platen 1 and which grips the end portion of the recording paper 6 and runs in synchronization with the timing belt 3. Reference numeral 9 is an ink sheet, 10 is an ink sheet take-up roll, 11 is a thermal head, 12 is a pinch roller, and the pinch roller 12 and the platen 1 can be brought into contact with and separated from each other. Reference numeral 13 denotes a pinch roller gear which is provided coaxially at both ends of the pinch roller 12 and transmits the rotational driving force of the pinch roller 12. Reference numeral 14 denotes platen gears provided at both ends of the platen shaft and rotating in the same manner as the platen 1. The pinch roller gear 13 and the platen gear 14 mesh with and separate from each other when the pinch roller 12 and the platen 1 come into contact with each other, and when they mesh with each other, a rotational driving force from a drive source (not shown) connected to the platen shaft. Thus, the recording paper 6 is conveyed while being stretched by sandwiching the platen 1 and the pinch roller 12.

Reference numeral 21 is a first sensor, and 22 is a second sensor. The first sensor 21 detects the paper clamper 7 and separates the pinch roller 12 and the thermal head 11 from the platen 1. From the opening of the pinch roller 12 to the paper clamper 7
After a predetermined traveling of the timing belt 3 through which the pin passes, the pinch roller 12 and the thermal head 11 are sequentially brought into contact with the platen 1. Then, when the second sensor 22 detects the leading edge of the recording paper 6, printing is started.

In the paper transport mechanism constructed as described above,
When the recording paper 6 is supplied and gripped by the paper clamper 7 at the time of printing start, and when the ink sheet 9 is fed to the next color at the time of color printing, the thermal head 11 and the pinch roller 12 are separated from the platen 1 and the paper is fed. After passing through the clamper 7, the thermal head 11 and the pinch roller 12 are brought into contact with the platen 1 via the recording paper 6. And recording paper 6
The pinch roller gear 13 and the platen gear 14 are meshed with each other for the conveyance.

[0005]

In the conventional paper transport mechanism as described above, the platen gear 14 rotates but the pinch roller gear 13 does not rotate when the platen 1 and the pinch roller 12 are separated. Therefore, when the pinch roller gear 13 and the platen gear 14 are meshed with each other, the positional relationship between the tooth tips and the valleys of the mutually opposing gears is random. In general, "gear width dimension of gear">>"gap width dimension of gear", so smooth meshing should be performed without any trouble. However, although it is a matter of probability, a situation occurs in which the tooth tips of the gears ride on each other. When this occurs, the teeth continue to ride for a while and the teeth continue to rotate for a while, and when the pitch deviates, the riding is suddenly released and normal meshing is restored.

For this reason, the recording paper 6 is loaded on the platen 1 and the pinch roller in a state where the tooth tips of the respective gears ride on each other.
The nipping frictional force due to 12 is weakened, and the recording paper 6 is affected by the traveling speed of the paper clamper 7 to cause printing deviation. When returning to normal meshing during printing, the recording paper 6
However, there is a problem in that a horizontal streak is generated on the printing screen due to the instantaneous movement of the image and the print quality is deteriorated.

Further, the platen gear 14 and the pinch roller gear
13 are provided at both ends of the platen 1,
It is extremely difficult to accurately align and fix the lineups of the tooth tips and the valleys of the gears on both ends of the shaft, and in reality there is a lineup shift. This line-up deviation is similar to the case where the "gear tip width dimension of the gear" is increased, and the probability that the tooth tops of the gears ride on each other is increased.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a paper transport mechanism in which the platen gear 14 and the pinch roller gear 13 are always normally meshed with each other so that the printing quality does not deteriorate. To aim.

[0009]

A paper conveying mechanism of a thermal transfer printing apparatus according to the present invention is stretched on a pair of first pulleys 2 provided at both ends of a platen 1 and is substantially equal to the peripheral speed of the platen 1. A pair of timing belts 3 traveling at speed
And a paper clamper 7 that is provided on a bridge 8 that is installed at parts of the timing belt 3 that oppose each other and that pulls and runs the recording paper 6, and a pinch roller 12 that can be brought into contact with and separated from the platen 1 that makes the recording paper 6 adhere to the platen 1. And a pair of platen gear 14 and pinch roller gear 13 which are attached to the shaft of the pinch roller 12 and the shaft of the platen 1 so as to contact each other, and the platen gear 14 and the pinch roller gear 13 are in contact with each other. It is provided with a means for rotating in a forward or reverse direction by a predetermined amount.

[0010]

In the automatic paper feeding mechanism according to the present invention, the pinch roller gear and the platen gear are paired to reduce the probability that the tooth tips will ride on each other at the time of meshing contact of the gear, thereby reducing the platen gear and the pinch roller. A means for rotating the gear teeth in a forward or reverse direction with the gears in contact with each other releases the riding of the tooth tips.

[0011]

【Example】

Example 1. FIG. 1 is a perspective view of a paper carrying mechanism of a thermal transfer printing apparatus showing an embodiment of the present invention, and FIG. 2 is a side view of a main part. In the figure, 1 to 14, 21, and 22 are the same as those described in the above-mentioned conventional example. But pinch roller gears
The platen gear 13 and the platen gear 14 are configured as one set. Reference numeral 15 is a lever that pivotally supports the pinch roller 12 and the pinch roller gear 13, and is fixed to the support shaft 16 so that the pinch roller 12 and the pinch roller gear 13 are brought into contact with and separated from the platen 1 and the platen gear 14 by the rotation of the support shaft 16. .

Next, the operation will be described. The first sensor 21 detects the paper clamper 7, the pinch roller 12 and the thermal head 11 are separated from the platen 1, and the paper clamper 7 is sent to the second sensor 22 where the pinch roller 12 and the thermal head 11 are sent. Is brought into contact with the platen 1. Platen 1 and paper clamper 7 without printing
By a predetermined amount in the direction of the arrow, and then the platen 1 and the paper clamper 7 are reversed together with the ink sheet 9 to a position beyond the second sensor 22. The platen 1 and the paper clamper 7 are again fed in the direction of the arrow, and when the leading edge of the recording paper 6 is detected by the second sensor 22, printing is started.

As described above, the pinch roller gear 13 and the platen gear 14 are constituted by one set, and after the pinch roller gear 13 and the platen gear 14 are brought into contact with each other, a predetermined amount of rotation and reverse rotation are performed, so that the tooth tips of the gears are brought into contact with each other. It reduces the probability of getting together,
Even if the tooth tops of the gears run over each other, they are released by a predetermined amount of rotation and reverse rotation, and the pinch roller gear 13 and the platen gear 14 are always brought into a sure meshed state at the time of printing.

[0014]

As described above, in the present invention, the pinch roller gear and the platen gear are paired,
The probability that the tooth tops ride on each other at the time of meshing contact of the gears is reduced, and the means for rotating the platen gear and the pinch roller gear in the forward and reverse directions by a predetermined amount releases the riding of the tooth tops. Therefore, the gears are surely meshed with each other, and the feeding of the recording paper by the pinch roller is always normal to prevent the deterioration of the printing quality.

[Brief description of drawings]

FIG. 1 is a perspective view of a paper carrying mechanism of a thermal transfer printing apparatus showing an embodiment of the present invention.

FIG. 2 is a side view of an essential part of a paper transport mechanism showing an embodiment of the present invention.

FIG. 3 is a flowchart of the forward / reverse rotation means of the paper transport mechanism according to the embodiment of the present invention.

FIG. 4 is a side view of a main part of a paper transport mechanism of a conventional thermal transfer printing apparatus.

FIG. 5 is a plan view of a main part of a conventional paper transport mechanism.

[Explanation of symbols]

 1 platen 2 first pulley 6 recording paper 7 paper clamper 8 bridge 11 thermal head 12 pinch roller 13 pinch roller gear 14 platen gear 15 lever

Claims (1)

(57) [Claims] 1. A platen 1, a thermal head 11 which is provided so as to be able to come into contact with and separate from the platen 1, and a pair of first pulleys 2 which are provided at both ends of the platen 1. A pair of timing belts 3 running at substantially equal speeds, a plurality of pulleys for stretching the timing belts 3, and a bridge 8 provided on a portion of the timing belt 3 that opposes each other. A paper clamper 7 for pulling and running the paper 6,
A pinch roller 12 which is provided so as to be able to come into contact with and separate from the platen 1 to bring the recording paper 6 into close contact with the platen 1, and a pair of shafts of the pinch roller 12 and the shaft of the platen 1 which are provided so as to come into contact with each other. Platen gear 14
And a pinch roller gear (13), and a means for rotating the platen gear (14) and the pinch roller gear (13) in a forward and reverse directions by a predetermined amount in a state of being in contact with each other.