JPH03219963A - Printing head - Google Patents

Abstract

PURPOSE:To enable a large number of components to be obtained from a sheet of plate by using an elastic member applying a fixing force to printing head components and a fixing screw having a step on its shank for regulating the deflection of the elastic member. CONSTITUTION:A fixing spring 18 consisting of three plate spring parts is formed into a shape shown by a dot line 18' in a free state. A fixing screw 19 is so constructed as to have a step on a part 19a. After respective head components are overlapped with each other, the fixing spring 18 is engaged with a rear heat release part 16, and fixing screws 19 penetrate fixing spring hole parts 18a to be fixed by fixing nuts 20 being pressed on the step parts 19a. The length l of the shank of the fixing screw 19 is set to a proper value. The fixing screw 19 is rotated until the fixing nuts 20 abut against the step parts 19a to be fixed. In this manner, a head clamping force F can be controlled to be an optimum value without controlling a fixing screw clamping torque.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a print head for a dot printer.

<Prior art> The method of connecting each element of a conventional print head is described in Japanese Patent Publication No. 61
There is one published in Publication No. -41314. In this method, as shown in FIG. 4, a member for driving the printing wire is overlapped and coupled to the head nose using an integral coupling member having a plurality of spring parts.

<Problems to be Solved by the Invention> However, in the conventional coupling method between each element of the print head, it is difficult to adjust the spring force, and when the spring force is insufficient, the long length of the print wire of the print head Each member that makes up the print head rotates around the direction,
As a result, the sliding resistance for each printing wire changes, resulting in a difference in output between each dot, causing printing shading. Furthermore, when the spring force is increased, maintenance problems arise, such as difficulty in assembly and disassembly. Furthermore, because the fixing member of the conventional method needs to have a long arm to hold each member of the print head, the number of sheets that can be removed from a single plate by the press is significantly limited, and material is wasted. This was one of the major causes of cost increases.

Furthermore, in the method of connecting each element of the print head by tightening screws, it is difficult to control the force of tightening the screws, which has been a major problem in practical use.

<Means for Solving the Problems> In order to solve the above problems, the print head of the present invention uses an impact method in which a printing wire is driven toward the recording paper by an electromagnet to form characters and figures on the recording paper with dots. The print head is characterized by using an elastic member that applies a fixing force to the constituent members of the print head, and a fixing screw having a step on the shaft portion to define the amount of deflection of the elastic member.

Moreover, it is characterized by having a spacer for regulating the amount of deflection of the elastic member.

<Operation> The elastic member of the print head configured as described above is bent by the stepped fixing screw, and applies a fixing force to each component of the print head.

Furthermore, since the fixing force can be adjusted by adjusting the amount of deflection of the elastic member using a spacer, it is possible to accommodate dimensional variations in each member that makes up the print head.
By holding the print head with an appropriate amount of load, each member constituting the print head does not rotate, and printing shading can be suppressed.

<Examples> Examples of the present invention will be described below with reference to the drawings. First, the overall structure and operation of the print head will be explained. The printing wire 1 is supported by a wire guide 4 held by a nose guide 3 fitted to a nose 2,
The leading end faces the printing paper, and the other end is fixed to the operating lever 6 by brazing.

A drive coil 8 is provided on the frame 7, and together with a plunger 9 integrated with the actuating lever 6, and a yoke plate AIO and a yoke plate B11 in contact with the frame 7, a closed loop magnetic circuit is formed.

The operating lever 6 is rotatably supported by a fulcrum shaft 12 held by a fulcrum spacer 14, and the other end 6a engages with the printing wire 1 and is further guided by a backstop 15 to set the operating stroke. ing. A protrusion 16a of the rear heat sink 16 engages with the frame 7, and releases heat generated by the drive coil 8 to the outside. 13 is the board,
A felt ring 17 is impregnated with oil to prevent wear between the fulcrum shaft 12 and the operating lever 6. The members fixing each of the above components to the nose 2 are the fixing spring 18, the fixing screw 19, and the fixing nut 2, which are the features of the present invention.
It is 0. In the printing operation, when the drive coil 8 is energized for an appropriate period of time, the plunger 9 is attracted by the suction part 7a, the operating lever 0 rotates, and the printing wire 1 is projected. The protruding printing wire 1 collides with the platen 23 via the ink ribbon 21 and the printing paper 22 to form a dot on the printing paper 22. After colliding with the platen 23, the return spring 5 returns it to the standby position, and the printing operation is completed.

Next, the fixing spring 18, fixing screw 19, and fixing nut 20 related to the present invention will be explained in detail. Fixed spring 1
As shown in FIG. 2, the reference numeral 8 is composed of three leaf spring parts, and in the free state, it has the shape shown by the dotted line 18' in FIG. , the fixing screw 19 is 19. as shown in FIG.
It has a structure with a step in part a, and after stacking each component of the head, the fixing spring 18 is engaged with the rear heat sink 16, and the fixing screw 19 is passed through the fixing spring hole part 18a.
Stepped portion 19. Fix by pressing the fixing nut 20 onto a.

At this time, the gap S between the rear heat sink 16 and the fixed spring 18 is
When s>O, the tightening force F is determined only by the spring force of the fixed spring. Here, the fixed spring 18 is bent by δ in the direction of arrow A shown in FIG. 1, and if the spring constant of the fixed spring is k, the tightening force F becomes F=δk.

By the way, if the tightening force F is too small, it will cause rattling of the various parts that make up the print head, print shading and poor response caused by rotation around the longitudinal direction of the printing wire, and if it is too large, it will cause printing problems. This may cause deformation of each member constituting the head.

In the conventional fixing method using fixing screws without steps, in order to control the force F during tightening, it is necessary to equalize the friction coefficient of each threaded part and the force when tightening, which is difficult for practical use. There was a big problem.

However, in the present invention, the shaft length l of the fixing screw 19 is set to an appropriate value, and the fixing screw 19 is rotated so that the stepped portion 19a
Since the fixing nut 20 is tightened and fixed, the force F can be controlled to the HA value when tightening the head without controlling the torque when tightening the fixing screw. Therefore,
Prevents rattling and rotation of each component that makes up the print head,
Print shading caused by rotation can be suppressed and responsiveness can be improved.

In addition, in order to achieve strong tightening force that eliminates rattling of each member of the head, with the conventional fixing method using only springs, tightening requires force on the force plate during assembly and disassembly. This would not have been possible without a special jig, but with the method of the present invention using springs and screws, the same tightening force can be achieved in a short time using only a screwdriver, improving maintainability. I can do it.

By the way, in order to accurately manage the tightening force at each screw position, it is necessary to keep the displacement δ of the fixed spring constant. Assuming that the height from the seat surface of the fixing nut 20 to the upper end of the fixing spring 18 is hl, and the length of the shank of the fixing screw is 1, the displacement δ is:
It is rained with δ=hl-1. , hl vary depending on the dimensional error of each component, which causes the displacement δ to vary. To fix this variation, fix the spacer 25 with the thickness h2 with the screw 1.
9 and the fixed spring 18 for calibration.

At this time, the displacement δ is expressed as δ=hl-1+h2. Several types of h2 are prepared and used depending on the value of hl.

In this way, by using the spacer, there is no need to prepare a large number of fixing screws with a length of 1, and it is also possible to easily accommodate dimensional variations in each member constituting the print head.

In addition, if the tightening force of the print head varies due to an error in the spring dimensions of each spring part in the two fixed springs, each member of the head may be attached at an angle with respect to the axial direction. This causes problems such as printing shading and poor response. Conventional fixing methods using fixed springs have dealt with this problem by managing the dimensions of each spring part through sorting after pressing, but this has led to major problems such as a drop in yield. However, according to the fixing method of the present invention, by using a spacer according to the dimensions of each spring, the difference in spring force between each spring part can be easily adjusted, and the yield and printing quality can be improved. .

By the way, in this embodiment, the fixing nut 20 has been described as a member to be engaged with the fixing screw 19, but the same effect can be expected even if the nose 2 is provided with a threaded part, and the number of parts can also be reduced. It becomes possible. Also, spacer 25
The installation location is not limited to between the fixing spring 18 and the fixing screw 19, for example, between the nose 2 and the fixing nut 20.
It goes without saying that the same effect can be achieved even if it is installed between the two.

<Effects of the Invention> According to the print head of the present invention described above, the elastic member only needs to have the function of applying force to clamp the operating member, the electromagnetic means, and the holding member to the nose. There is no need to have a long arm to hold the parts, and therefore a large number of parts can be removed from a single plate, leading to cost reductions.

In addition, in order to achieve strong tightening force to eliminate rattling of each member of the head, with the conventional fixing method using only springs, the force on the force plate is required for tightening during assembly and disassembly. This would not have been possible without a jig, but according to the method of the present invention using a spring and a screw, the same tightening force can be achieved using only a screwdriver, making it possible to improve maintainability.

In addition, compared to the conventional fixing method using screws that do not have a stepped part, since the screw is rotated and fixed by pressing it against the stepped part, there is no need to manage the tightening torque of the screw, and it is easy to assemble. It is possible to save labor and simplify the process.

Further, by changing the length of the shaft portion of the stepped screw, the force for fixing the constituent members of the print head can be adjusted, so that each member does not rotate and printing shading can be suppressed.

Furthermore, since the fixing force can be adjusted by adjusting the amount of deflection of the elastic member using a spacer, it is possible to accommodate dimensional variations in each member that makes up the print head.
It is possible to reduce costs by improving yield.

Figure 4 shows the conventional printing head. Wire 2...Nose 6...Operating lever 18... Fixed spring 19...Fixing screw 20...Fixing nut 25...Spacer FIG.

that's all

Claims (2)

[Claims] (1) In an impact-type print head for forming characters and figures on the recording paper using dots by driving the printing wire toward the recording paper using an electromagnet, an elastic member that applies a fixing force to the constituent members of the print head; A print head characterized in that a fixing screw having a step on the shaft portion is used to define the amount of deflection of the elastic member. (2) The print head according to claim 1, further comprising a spacer for regulating the amount of deflection of the elastic member.