JPS646032B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a serial printer in which a platen is movable toward and away from a print head and is provided with a paper presser.

Generally, in the case of a serial printer, a print head is attached to a carrier that can be moved parallel to the platen, and printing paper is placed between the print head and the platen to perform a predetermined printing operation. It's summery. By the way, the above-mentioned printing paper comes in various thicknesses, and there is also notebook-like paper such as those used for bank transfers, but if the distance between the print head and the platen is constant, Only thick printing paper (standard printing paper) can be used, and if you use anything other than standard printing paper, you may not be able to get clear prints or the printing paper may become smudged. was.
Therefore, in the past, the print head was made movable toward and away from the platen, and a paper thickness detector was installed to detect the thickness of the print paper. After adjusting the position of the printing head according to the result, a predetermined printing operation is performed. However, with this method, a predetermined detection time and print head movement time are required from the paper thickness detection to the start of the printing operation, so there is a limit to shortening the printing operation interval. Therefore, there was a drawback that it was not possible to shorten the printing operation interval, that is, to further increase the printing speed. Further, since a paper thickness detector is provided, the structure becomes complicated, resulting in a disadvantage that the device becomes large and expensive.

This invention was made in consideration of the above-mentioned circumstances, and has a simple structure that allows the distance between the print head and the printing surface to be kept constant at all times, and also makes it possible to increase the printing speed. The purpose of the present invention is to provide a serial printer that can be lowered in price.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the main parts of a serial printer, in which numeral 1 is a platen disposed horizontally, and numeral 2 is a carrier disposed above the platen 1. As shown in FIG.

The carrier 2 is slidably held by guide shafts 3 and 4 (only one guide shaft 3 is shown), and is provided so as to be movable parallel to the platen 1. A print head 5 is provided on the carrier 2 so as to face the platen 1. Further, a feed roller 6 is arranged near the platen 1, and the printing paper 29 is fed by the feed roller 6 and a pinch roller 7 that approaches and separates from the feed roller 6. The platen 1 is mounted in a supporting member 8 having a U-shaped cross section with an open upper part so as to be able to move in parallel in directions toward and away from the print head 5 (upward and downward directions). That is, the platen 1 is provided with protrusions 9 and 10 at the lower ends of both sides, and
Elongated holes 11 and 12 extending upward and downward are provided in both side plates of the support member 8, and the protrusions 9 and 10 are fitted into the holes 11 and 12, respectively. and,
A compression spring 13 is interposed between the platen 1 and the bottom plate of the support member 8, and the platen 1 is always biased toward the printing head 5. Also,
A flat paper presser 14 is located near the printing head 5.
One end of is located. Bent pieces 15 and 16 are provided at the other end and middle part of the paper presser 14, respectively, and are bent upward at a right angle in the figure. The bent piece 15 of the paper presser 14 is rotatably attached to a mounting plate 18 along with a base end of a support arm 23, which will be described later, by a rotation shaft 17 serving as a support shaft. The bent piece 16 has a long hole 16, and a pin 21 of a plunger 20, which will be described later, is inserted into this long hole 19.
are mated. Further, the mounting plate 18 is attached to the center of the carrier base 30,
This mounting plate 18 has a solenoid 22 which is a driving source.
is attached. The solenoid 22 causes the plunger 20 to protrude downward, and is configured to move the plunger 20 upward when energized. The solenoid 22 is designed to switch the operating position of the plunger 20 into two stages depending on the current.

On the other hand, the pinch roller 7 is connected to the support arm 2.
It is supported at the tip of 3. The support arm 23 is always urged counterclockwise in the drawing by a deployment spring 24 wound around the rotation shaft 17.

In the figure, 25 is a tension spring that always urges the support arm 23 in a clockwise direction, 26 is a locking member that pulls the plunger 20 back to a predetermined position by the spring force of the compression spring 27, and 28 is a locking member that holds the printing paper 29 horizontally. It is a paper guide that guides you in the direction.

Next, the operation of the serial printer having the above configuration will be explained. First, Figure 1 shows the stationary state.
At this time, the plunger 20 is in the lowered position, holding the paper presser 14 and the pinch roller 7 at positions spaced apart from the platen 1 and the feed roller 6, respectively. In this state, the printing paper 29 is passed over the platen 1 from the left side in FIG. 1 along the paper guide 28 and inserted between the feed roller 6 and the pinch roller 7. Therefore, when the solenoid 22 is excited with a large current, the plunger 20 is strongly attracted upward, and the paper presser 14 is largely rotated counterclockwise. At this time, the support arm 23 also deploys the spring 2.
4, it rotates counterclockwise against the spring force of the tension spring 25. Then, as shown in FIG. 2, the pinch roller 7 comes into contact with the feed roller 6 via the printing paper 29, and then the paper presser 14 resists the spring forces of the compression spring 27, expansion spring 24, and tension spring 25. It rotates and stops at the position shown in Fig. 3.
At this time, since the pinch roller 7 does not move, the difference in the amount of movement between the pinch roller 7 and the paper presser 14 is absorbed by the compression of the expansion spring 24. At this time, the paper presser 14 descends to press the platen 1 from above the printing paper 29, and the platen 1 is lowered against the compression spring 13. Then, as shown in FIG. 3, the stopper 20a of the drive shaft 20 comes into contact with the drive shaft leading-out end surface of the solenoid 22, and moves the paper presser 14 by a certain amount. At this time, since the amount of movement of the paper presser 14 is constant, the change in paper thickness a of the printing paper is absorbed by the amount of descent of the platen 1, as shown in FIG. Print head 5
The distance L between the printing surface and the printing surface is always constant. Therefore, if a printing operation is performed in this state, clear printing can always be performed. In this way, after completing the predetermined printing operation, the solenoid 22
When a small current is applied to the plunger 20, the plunger 20 is lowered by the force of the spring 27 to the position shown in FIG. With this, the paper presser 14 is
Although the pinch roller 7 is rotated clockwise about 7 and separated from the printing paper 29, the pinch roller 7 is held in a contact position with the feed roller 6 by the expansion spring 24. Therefore, by driving the feed roller 6 to rotate at a constant angle, the printing paper 29 is fed by one line, and a large current is applied to the solenoid 22 again to print on the next line. and,
When the solenoid 22 is de-energized, the plunger 2
0, the paper presser 14, arm 23 and pinch roller 7 return to the positions shown in FIG.

As described above, in this device, the change in the paper thickness of the printing paper can be absorbed by lowering the platen 1, and by lowering the paper presser 14 by a certain amount, the printing head 5 and the printing surface Since the gap between the paper and the paper can always be kept constant, clear printing can always be performed on notebook-like items such as deposit cards, regardless of the thickness of the printing paper. Furthermore, since no special means for detecting the thickness of the printing paper 29 is required, the time required to detect the paper thickness of the printing paper and moving the printing head, which is required in the conventional method, is no longer required, and the printing interval can be shortened. Speed can be increased. In addition, with a simple configuration in which the platen 1 is movable and the paper presser 14 is moved by a certain amount, the desired purpose can be achieved without increasing the size of the entire device, and the cost can be reduced. You can also try it out.

As explained above, according to the present invention, with a simple configuration, it is possible to always maintain a constant distance between the print head and the printing surface even if the paper thickness of the printing paper changes, and the printing speed is It is possible to provide a serial printer that can speed up the process and also reduce the cost.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a side view showing the configuration of main parts of a serial printer, Figs. 2 and 3 are side views for explaining the operation, and Fig. 4 is a main part. It is a side sectional view which expands and shows a part. 1... Platen, 2... Carrier, 5... Print head, 6... Feed roller, 7... Pinch roller, 14... Paper presser, 22... Solenoid (drive source), 24... Deployment spring.

Claims (1)

[Claims] 1. A print head, a platen that is movable toward and away from the print head and is always biased toward the print head by a spring force, and a carrier that reciprocates the print head in parallel with the platen. A guide shaft that slidably holds the carrier, a support shaft provided parallel to the guide shaft, and a plate-shaped plate that is rotatably supported by the support shaft and whose one end is positioned to press the platen. a plunger connected to the other end of the paper presser; a solenoid that drives the plunger when a large current flows to rotate the paper presser toward the platen; and a solenoid that rotates the paper presser toward the platen. a support arm that is freely supported; a pinch roller that is rotatably supported by the support arm and moves toward and away from a feed roller disposed near the platen; and a pinch roller that moves the support arm in a direction that moves the pinch roller away from the feed roller. A tension spring biases the support arm, a deployment spring biases the support arm in a direction that presses the pinch roller against the feed roller against the spring force of the tension spring, and a small current flows through the solenoid to cause the plunger to move. A serial printer comprising: a locking member that is pulled back to a predetermined position by a spring force to separate only the paper presser from the platen.