JPH01120358A - Printing head - Google Patents

Abstract

PURPOSE:To always perform sharp printing regardless of the temp. of a coil, by mounting a leaf spring type return spring made of a bimetal to a printing head. CONSTITUTION:When the temp. of a printing head is raised by repeating printing operation, a return spring 7 made of a bimetal deformed by bimetal action so that the leaf spring part 7b of the return spring 7 moves in the direction shown by an arrow A at the leading end thereof. Therefore, the pressing force to an armature 1 is reduced. When a current is supplied to a coil 6 in this state, attraction force is generated in a yoke 5 but becomes smaller than that at low temp. because of the high resistance value of the coil 6. However, since the force of the return spring 7 to the armature is small, the armature 1 rapidly starts motion in the same way at the time of low temp. to make it possible to perform printing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a print head for a dot matrix printer that prints by selectively impacting a recording medium with a print wire.

[Conventional technology]

For printing with conventional dot matrix printers.

The armature has a yoke, an armature, and a coil, and is equipped with a plurality of electromagnetic actuators arranged in an annular shape.By applying current to the coil (energizing), the armature is attracted to the yoke, and the tip of the armature is The printer is configured to print by means of a print wire coupled to the print wire. For such printing, when C is not printed, the supply of current to the coil is stopped, and the armature is moved by the return force of the same number of return springs as the armatures that are in contact with each armature and the repulsive force from the printing surface. to be reinstated. Printing is performed by repeating these operations, but since Joule heat is generated in the coil by energizing the coil, it is inevitable that the overall temperature of the coil, yoke, and print head will rise.

[Problem that the invention seeks to solve]

As described above, in the conventional print head, the temperature of the coil increases as the printing operation is repeated many times. As the temperature of the coil increases, the resistance value of the coil increases and the suction force acting on the armature decreases.
Since the initial force of the return spring acting on the armature, which is set to cancel out the attraction force of the coil, is constant, the armature starts to operate poorly.
This method has the disadvantage that the speed at which the printing wire collides with the platen becomes slow, reducing printing energy and resulting in unclear printing. Furthermore, since the return springs are completely independent of each other for a plurality of armatures, the number of parts is large, and therefore a large number of assembly steps are required.

The purpose of the present invention is to improve the conventional printing as described above.

To provide a printing method that can always print clearly by eliminating the drawbacks of the printing method.

[Means for solving problems]

The printing of the present invention includes a closing frame having a cylindrical guide plate holding part and a disc-shaped yoke holding part provided on the outside of the guide plate holding part; A plurality of yokes are arranged radially on the upper surface of the outer periphery and have their "U" shaped bottoms fixed, and a plurality of yokes are provided corresponding to the yokes and contact the upper surface of the outer columnar part. a plurality of armatures that are vertically rotatable with the end portions as fulcrums; a plurality of coils wound around each n inner columnar portion of the yoke; and a plurality of coils held by the guide plate holding portion. a guide plate; a plurality of printing wires coupled to the inner ends of each of the plurality of armatures and whose reciprocating motion is guided by the guide plate; and a plurality of printing wires disposed above the armature so that the armature a stopper plate having a resting point that comes into contact and rests when returned;
A hold spring is provided between the stopper plate and the armature and is held on the lower surface of the stopper plate by the tips of a plurality of spring parts corresponding to the armature; Tips of a plurality of outer leaf spring portions disposed between the frame and the plurality of outer leaf spring portions contact the lower surface of the corresponding armature with a predetermined pressure, and the base of the inner end portion contacts the outer wall of the guide plate holding portion of the frame. a return spring held on an upper surface, the return spring is formed of bimetal, and when the temperature of the coil rises, the leaf spring portion deforms outward by a predetermined amount in response to the rise in temperature. is configured to do so.

〔Example〕

Next, embodiments of the present invention will be described with reference to all the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention, showing the state at low temperature, and FIG. 2 is a sectional view showing the state of the embodiment of FIG. 1 at high temperature.

In FIG. 1, the armature 1 has its tip connected to the end of the printing wire 2, and its rear end connected to the outer columnar part 5 of the yoke 5 by the tips of the plurality of spring parts of the hold spring 4.
It is pressed against the upper surface of a to form a fulcrum. The hold spring 4 is held at its inner periphery which is directly connected to the lower surface of the stopper plate 3 in an annular shape, and has the same number of leaf spring-shaped arms as the armature 1 provided radially corresponding to the armature 1. have. Inner columnar part 5 of yoke 5
The coil 6 is wound around b, and the yoke 5 is entirely formed into a U-shape by the outer columnar portion 5a, the bottom portion 5c, and the inner columnar portion 5b, and the armature is disposed on the yoke 5. forms a magnetic circuit.

The return spring 7 made of bimetal is
Corresponding to the armature 1, the base 7ai may be independent, but the base 7ai is connected to form an annular shape, and the same number of plate springs 7bi as the armature 1 are formed radially outside the base 7a. It can also be made into one part. The base 7a of the return spring is fixed on a return spring base 12a provided at the center of the frame 12, and the tip of the leaf spring 7b presses against the lower surface of the tip of the armature I. In this way, the base of the return spring is annular, and the armature is formed radially on the outside of the base, and several reciprocating spring parts are installed, thereby reducing the number of parts and the number of assembly steps. be able to.

The cylindrical center of the frame 120 holds guides 8 to 11 that support the printing wire 2 and guide the entire printing operation, and the upper surface of the disc-shaped outer cylinder holds the yoke 5. are doing.

The shape of the bimetallic return spring 7 at room temperature is such that its tips are close to each other toward the center as shown in FIG. 1, but as the temperature of the coil 6 increases, the shape changes as shown in FIG. As shown in , the tip of the plate spring portion 7b is deformed in the direction of expanding in the direction of the arrow.

Next, the operation and effect of the printing having the above-described configuration will be explained. When the temperature of the print head is close to room temperature, the tip of the leaf spring portion 7b of the return spring 7 contacts the lower surface of the stationary armature 1 and applies a constant pressure during non-printing. When current is supplied to the coil 6 in this state, the attraction force of the coke 5 increases, so the armature 1 is attracted to the yoke 5 and begins to rotate as the entire tip, which is pressed by the hold spring 4, serves as a fulcrum. As the armature 1 moves, the printing wire 2 fixed to its inner tip moves downward to perform printing. At this time, the plate spring portion 7b of the return spring 7 is pressed by the armature 1 and is bent. When the printing operation between the wire 2 and the armature L is performed, the coil 6
The current supply to the yoke 5 is stopped, and the armachier 1 moves in the direction away from the attracting surface of the yoke 5 due to the return force due to the deflection of the return spring 7 and the repulsive force from the printing surface, and the upper surface of the armachier 1 (return spring 7 and (the surface opposite to the contacting surface) contacts the stopper plate 3 and returns to the original stationary state.

When the temperature of the print head increases due to repeated printing operations, the bimetallic return spring 7 causes the tip of the plate spring portion 7b of the return spring 7 to move in the direction indicated by the arrow in FIG. 2 due to the bimetal action. transform to Therefore, the pressing force on the armature l becomes smaller. When a current is supplied to the coil 6 in this state, an attractive force is generated on the yoke 5, but since the resistance value of the coil 6 is high, the attractive force is smaller than when the temperature is low.

However, since the force of the return spring 7 on the armature 1 is small, the armature 1 can quickly start moving and perform the printing operation as in the case of a low temperature. The operation after the printing operation is exactly the same as when the temperature is low.

When the temperature of the print head drops to around room temperature, the return spring returns to the state described in the initial explanation.

〔Effect of the invention〕

As explained above, the print head of the present invention is equipped with a bimetallic plate-spring type return spring.
Even if the coil resistance increases due to temperature rise and the suction force of the yoke decreases, the return spring deforms and offsets the decrease in suction force, so the printing speed of the armature is set to the same speed as at low temperatures. Therefore, there is an effect that clear printing can always be performed regardless of the temperature of the coil.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention in a low temperature state, and FIG. 2 is a sectional view showing the embodiment of FIG. 1 in a high temperature state. 1... Armature, 2... Printing wire, 3... Stopper plate, 4...
Hold spring, 5...Yoke, 5a...
...Outer columnar part, 5b...Inner columnar part, 5
c...Bottom, 6...Coil, 7...
... Return spring, 7a ... Base, 7
b...Plate spring part, 8, 9, 10.11-...
...Guide, 12...°°°Frame, 12 a °
°・°°Return Spring Pace. Agent Patent Attorney Oto Uchihara

Claims (2)

[Claims] (1) A frame having a cylindrical guide plate holding part and a disc-shaped yoke holding part provided outside the guide plate holding part; A plurality of yokes having fixed "U" shaped bottoms, and a plurality of yokes which are provided corresponding to the yokes and are in contact with the upper surface of the outer columnar part and are freely rotatable in the vertical direction using the outer ends as fulcrums. an armature, a plurality of coils wound around each of the inner columnar parts of the yoke, a plurality of guide plates held by the guide plate holding section, and an inner end of each of the plurality of armatures. a plurality of printing wires coupled to the guide plate and guided in reciprocating motion by the guide plate; a stopper plate disposed above the armature and having a stationary point that contacts and stops the armature when the armature returns; The tips of a plurality of spring parts provided corresponding to the armature between the stopper plate and the armature press the upper surface of the corresponding outer end of the armature to press the inner end of the inner inner annular portion. a hold spring held on the lower surface of the stopper plate; and a plurality of leaf spring portions disposed on the inner side of the coil between the armature and the frame, and the tips of the plurality of leaf spring portions on the outer side thereof are on the lower surface of the corresponding armature. a return spring that is in contact with a predetermined pressure and whose inner end base is held on the upper surface of the outer wall of the guide plate holding portion of the frame, and the return spring is formed of bimetal and the temperature of the coil is The print head is characterized in that when the temperature rises, the leaf spring portion deforms outward by a predetermined amount in response to the rise in temperature. (2) The print head according to item (1), wherein the bases of adjacent return springs are connected to each other to form an annular shape, and a plurality of leaf spring portions are formed radially from the annular base in correspondence with the armature.