JPH04341865A - Impact dot head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact dot head.

0002

[Prior Art] A back stopper according to the prior art is used for the purpose of absorbing impact energy when the lever returns, and when the lever returns to the standby position or is on standby, the backstopper is used as a damper member made of rubber or the like. If the lever gets stuck, the adhesive force between the lever and the damper member becomes large, which acts as a reaction force when the lever is driven, causing problems such as missing dots. Therefore, a structure in which a metal or resin member is interposed between the lever and the damper member is common. It was a target. In the backstopper having the above-mentioned configuration, as shown in FIG. 5, the amount of rebound and the amount of depression of the lever upon return of the lever change depending on the temperature due to the temperature characteristics of the damper member. At low temperatures, the damper effect that absorbs the kinetic energy of the lever decreases, the amount of rebound increases, and the lever behavior becomes unstable during continuous drive, causing printing defects such as uneven printing dots and shading. . In addition, at high temperatures, the amount of sinking of the damper member increases, which applies excessive stress to the metal or resin member between the lever and the damper member, and repeated stress causes fatigue failure.
There is a problem in that the durability of the impact dot head is reduced. There is a method that attempts to improve this problem only in a specific temperature range. For example, there are ways to solve problems at low temperatures, such as making the damper member thicker or using a material that has a higher damping effect at low temperatures, but the amount of sinking at high temperatures is proportional to the thickness of the damper member, and the material Although it is effective at low temperatures, at high temperatures the problem of decreased durability due to fatigue failure of the metal or resin member between the lever and damper member due to the large amount of sinking of the damper member becomes worse. . On the other hand, as a way to solve the problem at high temperatures, it can be improved by increasing the thickness of the metal or resin member between the lever and the damper member, or by reducing the thickness of the damper member, but at low temperatures the damper member's damper The problem of a large amount of rebound caused by a decrease in effectiveness is further exacerbated by the fact that the next drive overlaps during the rebound in continuous printing, making the behavior unstable. As another method, even if the damping effect of the damper member decreases at low temperatures,
There is a method of reducing the driving frequency by 20% to 30% of the maximum so that the lever is activated after the lever behavior has stabilized, but this has the problem of significantly reducing the speed.

0003

The problem to be solved by the present invention is that it is not possible to ensure print quality and durability at high speed in the temperature range in which impact dot heads are used.

0004

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a lever having a plurality of cores and armatures facing each core, a return spring for returning the lever to the standby position, and a return spring for returning the lever to the standby position. The impact dot head has a back stopper for holding, and is characterized in that a temperature control member is disposed in a part of the back stopper.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an impact dot head according to a first embodiment of the present invention.

In the figure, a plurality of cores 1a are arranged substantially circumferentially on a frame 1, a magnet coil 2 is wound around the core 1a, and both ends of the winding of the magnet coil 2 are provided on the frame 1. It passes through the hole or slit and is soldered to the board 18. The armature 6a fixes the lever 6b, and the other end of the lever 6b is connected to the printing wire 6.
c is fixed to constitute a lever set 6. The lever set 6 is arranged to face the core 1a, and is held rotatably by the armature 6a by the side yoke 3, fulcrum spacer 4, yoke 5, and fulcrum shaft 9, and is further held by a return spring 11 at the lever 6b. back stopper 1
5 is held in a pressed state. Return spring 1
1 is held by a spring holder 10 so that it can be expanded and contracted by rotating the lever set 6. The spring holder 10 is positioned by the frame 1 and the nose 17. A wire guide 13 is arranged in the nose 17,
By guiding the printing wire 6c through the rotational movement of the lever set 6, the printing wire 6c is made to move linearly.

The fixing spring 16 is arranged on the back side of the lever holder 14, and is hooked onto a protrusion provided on the nose 17, so that the nose 17, the spring holder 10, the frame 1,
The side yoke 3, fulcrum spacer 4, fulcrum shaft 9, and lever holder 14 are pressed and fixed.

FIG. 2 shows an enlarged view of the back stopper 15. The back stopper 15 is composed of a metal member 15a, a damper member 15b, a temperature control member 15c, and a height adjustment member 15d, which are laminated from the side that the lever 6b comes into contact with.For example, the metal member 15a is made of SK material, SUS material, etc. The damper member 15b is made of a material having a thickness of 0.03 to 0.1 mm, and the damper member 15b is made of fluororubber or the like and has a thickness of 0.3 to 1 mm.
It is formed with a thickness of 0 mm. The temperature control member 15c is made of an intermetallic compound semiconductor or the like that utilizes the Peltier effect, and can be switched between heat absorption and heat radiation depending on the current direction. A temperature detection element K such as a thermistor for detecting the temperature of the backstopper 15 is embedded in the lever holder 14 in this vicinity.

Next, the operation will be explained. Magnet coil 2
By energizing, a magnetic flux is generated passing through the core 1a, the armature 6a, the side yoke 3, and the frame 1, and the magnetic flux exerts an attractive force on the armature 6a, causing the lever set 6 to compress the return spring 11 around the fulcrum shaft 9. while rotating,
The printing wire 6c is moved linearly by the wire guide 13, and the other end of the printing wire 6c collides with a ribbon (not shown) and a printing medium to form dots on the printing medium.

After the dots are formed, the lever set 6 returns to the standby position due to the repulsive force upon collision of the print wire 6c and the restoring force of the return spring 11, and the lever 6b collides with the back stopper 15, deforming the metal member 15a and further damaging the damper member. The kinetic energy of the lever 6b is absorbed by the deformation of the lever 15b. The deformation of the metal member 15b and the damper member 15a at this time is sinking, and the kinetic energy of the lever 6b that is not absorbed becomes a rebound, but the lever 6b is returned to the standby position by the return spring 11 and one printing process is completed. . In this printing process, in the conventional structure, the characteristics of the damper member 6b change as the temperature changes, and at low temperatures it becomes difficult to deform and absorb the kinetic energy of the lever 6b, resulting in a large rebound amount and the behavior of the lever 6b. Becomes unstable. On the other hand, at high temperatures, the damper member 6b is easily deformed and the amount of sinking becomes large, the metal member is deformed greatly and the stress becomes large, and fatigue failure occurs due to repetition of this process.

However, the impact dot head according to the embodiment of the present invention has a temperature control member 15c on the backstopper 15.
is arranged, and the temperature is controlled as shown in FIG. 3 based on the signal from the temperature detection element K. If the temperature of the temperature detection element K is lower than t1, the voltage V1 is applied in the direction in which the temperature control member 15c radiates heat.
If the temperature is higher than t2, a voltage V2 is applied in a direction in which the temperature control member 15c absorbs heat, and the temperature of the damper member 15b is controlled to be within the range from t1 to t2.

Therefore, in the impact dot head of the present invention, the temperature of the damper member 15b can be kept within the set range regardless of the temperature of the impact dot head, and the damper effect of the damper member 15b can be kept constant, and the amount of rebound and sinking can be kept constant. This makes it possible to realize an impact dot head with stable printing operation, high speed in a wide temperature range, and excellent printing quality and durability.

When the impact dot head shown in FIG. 1 was used to actually measure the relationship between rebound amount and sinkage amount with respect to temperature during continuous printing at 2 KHz, as shown in FIG. 4, the rebound amount that stabilized behavior during continuous printing was found is 0
．． The result was that the amount of sinkage that ensured durability was 0.05 mm or less. Therefore, when setting the set temperatures t1 and t2 of the temperature control shown in Fig. 3 as t1 = 17 degrees C and t2 = 50 degrees C and confirming the effect, the rebound amount when the temperature of the impact dot head was 0 degrees C was 0.13 mm. , the amount of sinking at 80 degrees C is 0
．． 04, the maximum printing speed of the conventional impact dot head was reduced by 20% at temperatures below 12 degrees Celsius, but the maximum speed is maintained up to 0 degrees Celsius, and printing quality is also eliminated with no unevenness or shading. A remarkable effect was obtained. Furthermore, in terms of durability, the impact dot head according to the embodiment of the present invention had a remarkable effect in that the life span of about 250 million printing cycles was extended to more than 400 million printing cycles.

[0014]

As described above, in the impact dot head of the present invention, a temperature control member for controlling the temperature of the damper member is disposed on the back stopper that the rear part of the lever contacts. It is possible to control the amount of rebound and sinking to be constant without depending on the temperature characteristics of the damper member, ensuring stable printing operation regardless of the temperature of the impact dot head. , it is possible to realize an impact dot head that is high speed, has excellent print quality and durability in a wide temperature range.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a detailed view of the back stopper portion of the embodiment of the present invention.

FIG. 3 is a diagram showing an example of controlling a temperature control member according to temperature according to the present invention.

FIG. 4 is a diagram illustrating the characteristics of a damper member according to temperature in a conventional example.

FIG. 5 is a diagram illustrating the behavior of a lever depending on temperature in a conventional example.

[Explanation of symbols]

1 Frame 1a Core 2 Magnet coil 3 Side yoke 4 Fulcrum spacer 5 York 6 Lever set 6a Amateur 6b Lever 6c Printing wire 9 Fulcrum shaft 10 Spring holder 11 Return spring 13 Wire guide 14 Lever holder 15 Back stopper 15a Metal parts 15b Damper member 15c Temperature control member 15d Height adjustment member 16 Fixed spring 17 Nose 18　　　　Substrate K Temperature detection element

Claims (2)

[Claims] 1. An impact dot head comprising: a lever having a plurality of cores and an armature facing each core; a return spring for returning the lever to a standby position; and a back stopper for holding the lever in the standby position. An impact dot head characterized by having a temperature control member installed in a part of the stopper. 2. The impact dot head according to claim 1, wherein the temperature control member is an intermetallic compound semiconductor utilizing the Peltier effect.