JPS587369A - Impact type dot printer - Google Patents

Abstract

PURPOSE:To keep the clearance between a printing head and a recording paper at constant value by a method wherein a collision member, moving into fore- and-back directions together with the printing head with respect to the recording paper, is provided, and the collision member is removed after the head is fixed upon the collision thereof. CONSTITUTION:The printing head is energized by an energizing means such as a tension spring 5 or the like so as to be retreated from the recording paper (printed medium) 27. The collision member 6 is moved toward the recording paper together with the printing head by a driving means consisting of a wire 19, pulleys 8, 14, 16 and a driving source pulling the wire 19 and when this collision member 6 is collided against the printing medium of the recording paper, the printing head is fixed at the position by a locking means such as a lock lever 11, a lock pin 18 and the like, thereafter, the collision member 6 is separated from the recording paper 27 by a retreating means such as a lock control lever 13 and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet two-dot printer, and particularly to an impact-type dot printer that maintains a constant gap between a print medium and a print head to obtain proper print density.

Conventionally, various impact type dot printers have been proposed that are equipped with adjustment means for keeping the gap between the print medium and the print head constant. These adjustment means can be roughly divided into two types: those that move the platen back and forth to press the print medium against the reference surface, and those that move the print head back and forth to follow the thickness of the print medium. The disadvantage is that the mechanism for movement is complicated and large-scale), but the latter is now increasingly being used.

On the other hand, there are contact and non-contact types of adjustment means for the latter, but the non-contact type mainly uses light, irradiating the print medium with light and detecting the amount of reflected light; The disadvantage is that the amount of reflected light changes depending on the material, dirt, etc. In addition, the contact type has an abutment member that moves back and forth together with the print head, and presses it against the print medium so that the position of the print head competes with the thickness of the medium. There is one that retracts the print medium by a certain amount, but the former requires the abutment member to be separated from the print medium when feeding the print medium,
The disadvantage is that the abutment member must be retracted during forwarding, but the latter requires a means for detecting that the print head has abutted against the print medium and a drive for retracting the print head by a fixed amount no matter where it is located. This method requires additional means, and has the disadvantage that the configuration is complicated and expensive.

The present invention has been made in view of the above-mentioned drawbacks, and includes an abutment member that moves together with the print head in the front and back direction with respect to the print medium, and when the abutment member abuts against the print medium, the print head The abutment member is fixed at its stop position and moved away from the print medium, thereby maintaining a constant gap between the print head, print, and medium without contact.

The present invention will be explained below with reference to the drawings.

FIGS. 1 to 3 are plan views showing essential parts of an embodiment of the present invention, and each sequentially shows the operation when entering a printing operation.

In the same figure, a print head 1 for printing dots by selectively protruding a print wire is supported on a sliding plate 2, and this sliding plate 2 is mounted on a key 1'') holder 3. Four guide rollers 4 a + 4 b + 4 c and 4 d are slidably supported in a direction perpendicular to the direction of movement of the carriage 3 (arrow A), and the tension spring 5
It is always urged to slide in the direction of arrow B. Further, on this sliding plate 2, an abutting member 6 with a roller attached to its tip is rotatably supported around a shaft 7, and a pulley is attached to the tip of the arm-shaped portion that protrudes rearward. 8 is rotatably attached. The abutment member 6 is regulated in the position shown in FIG. 1 by a stopper 9 which abuts against the side surface of the abutment member 6 during the pause period of the printing operation.

The carriage 3 further supports a lock lever Jl that rotates around a shaft 10, a lock control arm 13 (5-shaped) that can rotate around a shaft 12, and a pulley 14. A tension system ring 15 is hung between the abutment member 6, and the lock control arm 13 has a pulley 16 at one end thereof and is biased by a tension system spring 17 to rotate counterclockwise. is in contact with the lock lever 11.

Among the above three tension springs 5, 15.17, the tension spring is the strongest, and therefore the lock lever 11
is pushed to a position away from the lock pin 18 on the sliding plate 2 against the tension spring 5. A wire 19 is still passed through the three grooves 1) 8, 14 and 16 as shown in the figure, and one end of this wire 19 is fixed on the carriage 3, and the wires 20, 2
The position of the pulley 21 is fixed, but the boo 920 is attached to the tip of the arm 23 which is rotatable around the shaft 22. It is attached and its position can be moved. The arm 23 is held in a position where it hits the stopper 25 by a tension spring 24, and is rotated as shown by the chain line in FIG. 1 by a driving source (not shown) such as a magnet. Guide shaft 26a.

26b guides and supports the carriage 3 so as to be movable in parallel with the print medium 27 and the platen 28 supporting it from behind.

Next, the operation of the above configuration will be explained. During the pause period of the printing operation, the drive source that moves the pulley 20 to the left does not work, and the print head 1 is in a position separated from the print medium 27 as shown in FIG. It is maintained. When entering the printing operation mode, the drive source operates to rotate the arm 22 counterclockwise, move the pulley 20 to the left, and remove the wire 1.
9 in the direction of the arrow shown. Since both ends of the wire 19 are fixed to the carriage 3 through the above-mentioned thread, the pulley 8 and the pulley 16 tend to move in opposite directions due to the tension of the tension ring 17. If you make it stronger than the tensile spring 5, the pulley 16
The pulley 8 moves in the direction of arrow C in FIG. 2 while maintaining its position, and the slide plate 2 integrated therewith slides toward the printing medium 27 against the tension system ring 5. As a result, the abutment member 6 has reached a position where a predetermined appropriate gap is formed between the abutment member 6 and the print medium 27 for printing. After the abutting member 6 abuts against the print medium 27, the sliding plate 2 does not slide any further toward the print medium 27 even if the wire 19 is pulled in the direction of the arrow. Instead, if you continue to pull the wire 19, the sea I
J 1 b? Pushed toward the rear of the carriage 3 by the tension in the ear 19, the lock control arm 13 rotates clockwise. And as shown in Figure 3, Rock Reno-11
is rotated to the right by the tension system ring 15 simultaneously with the rotation of the lock control arm 13, and engages the lock pin 18' to fix the sliding plate 2 in this position. Furthermore, wire 1
9 is pulled, the lock control arm 13 rotates until it abuts the rear end of the abutment member 6 and pushes it to the right. The abutting member 6 thereby rotates counterclockwise and separates from the print medium 27.

In this way, the print head 1 is maintained at a position with an appropriate gap from the print medium 27, and the abutment member 6 is placed in a non-contact state with the print medium 27. It should be noted that the wire 19 is pulled during the printing operation, but when the print body stops again, it is returned to its original position and the slider 2 and lock control Leno Z-
13 are tensile Sugering 5 and Tensile Syspring 1, respectively.
7 to return to the position shown in FIG.

As described above in the embodiments, the present invention uses a biasing means such as a tension spring 5 to bias the print head to retreat from the print medium, and the wire 19, pulley 8, etc.
16.14 and a drive source that pulls the wire 19, the abutment member is moved toward the print medium together with the print head, and when the abutment member abuts against the print medium, the lock lever 1 is moved. The print head is fixed at that position by a radlock means such as a lock bin 18, and the abutment member is separated from the print medium by an abutment member retraction means such as a lock control lever 13.

Therefore, according to the present invention, since the abutment member for keeping the gap with the print medium constant is separated from the print medium during printing, there is no need to move the abutment member away from the print medium at each line advance. As a result, printing time can be shortened, and this can be achieved with a simple and inexpensive configuration.

[Brief explanation of drawings]

FIG. 1 is a plan view showing essential parts of an embodiment of the present invention, and FIGS. 2 and 3 are explanatory views of the operation of the embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Print head, 2... Sliding plate, 3... Carriage, 6... Abutment member, 8.14.16... Pulley, 11... Lock lever +, 13... Lock control Luno f-11g...Lock bin, 19...Wire,
27...Print medium. 1g+figure

Claims (1)

[Claims] In an impact dot printer that maintains a constant gap between the print head and the print medium, the print head is supported on a carriage so that it can move back and forth in the direction of the print medium, and the print head is always urged to retreat from the print medium. a biasing means, a driving means for advancing the print head toward the print medium against the biasing means when entering a printing operation, an abutment member that moves toward the print medium together with the print head, and the abutment. An impact type dot printer comprising a print head locking means and an abutment member retracting means for fixing the print head at that position and separating the abutment member from the print medium by abutting the abutment member against the print medium.