JPH07329367A - Small printer - Google Patents

Abstract

(57) [Summary] [Structure] In a printer of a type in which a plurality of types 102 are arranged on the outer periphery and a type ring 101 made of an elastic material is pressed by a hammer 130 from the inside to print, the hammer is driven by the reaction force of the pressing. It is configured such that 130 flexes. Further, the print carry cam 40 is configured to directly drive the hammer 130 without an intermediary. [Effect] Even if there is a dimensional change in the mechanism part, the first convex part or the second convex part of the hammer bends due to the reaction force of the pressure applied to the type wheel at the time of printing and absorbs this, so the pressing force of the type is stable. To do.
Further, since the hammer is directly driven by the print carry cam, the transmission efficiency of the driving torque is good, so that the output torque of the DC motor which is the driving source of the printer can be minimized. Further, since the torque transmission part and the sliding part of each part of the printing mechanism are not worn or deteriorated, the reliability of the printing quality can be guaranteed for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a type printer having a type ring made of an elastic material such as rubber, and more particularly to a printing mechanism thereof. Most of this type of printers are installed in electronic desk calculators.

[0002]

2. Description of the Related Art A conventional small-sized printer of this type disclosed in Japanese Examined Patent Publication No. 3-58776 has an end face cam 34 when a print carry cam 340 rotates as shown in FIG.
The hammer 330 is rotated in the direction of arrow J through the limiter spring 370 and the transmission lever 360 by the cam lead of 0A, and the convex portion 330A of the hammer 330 engages with the back surface portion of the type wheel 301 to cause the type wheel 301 to protrude from the inner side, 311
Is pressed against the platen 11 via the printing paper 10 to print,
After printing, the hammer 330 is rotated by the hammer return spring 380 to the counter arrow J and returned to the initial position. At this time, the convex portion 3 of the hammer 330 is caused by the dimensional variation of the mechanical parts.
Even if the distance between 30A and the platen 11 changes, the limiter spring 370 absorbs this and a certain pressing force is applied to the type.

[0003]

However, since the pressing force is transmitted from the print carry cam to the type wheel by the limiter spring, the transmission lever, and the hammer, the transmission efficiency of the pressing force is high. It was very bad. Therefore, the motor, which is the drive source of the printer, is forced to have a torque higher than necessary, resulting in an expensive printer. Further, since each driving component of the small printer has to transmit the above-mentioned high torque, the sliding portion or the transmitting portion of the pressing force is worn away with the elapse of the driving time, resulting in poor long-term reliability. .

[0004]

SUMMARY OF THE INVENTION The structure of the present invention for solving the above-mentioned problems is a type wheel formed of an elastic body having a plurality of types of characters arranged on the outer circumference, and a hammer which is rotated or linearly moved by a hammer driving member. In a printer that presses the recording paper from the inside to press the recording paper against the platen for printing, a hammer driving member that includes a first engaging portion and that is rotated or rotated, and a second protrusion that is inserted into the first engaging portion of the hammer driving member. And a hammer provided with a first convex portion that engages with the type letter and presses the type letter, and the hammer is elastically deformable to change the relative position between the first convex portion and the second convex portion. It is characterized in that a flexible portion is provided.

Further, the hammer is characterized in that the flexible portion is a spring member and is entirely made of resin.

[0006]

According to the above construction of the present invention, since the second convex portion is fitted and inserted into the first engaging portion, the reciprocating operation of the hammer rotation or movement is restricted by the hammer driving member. However, since the flexible portion is arranged between the second convex portion and the first convex portion, the amount by which the hammer pushes out the printed characters can be adjusted by the flexible portion.

[0007]

First Embodiment FIG. 1 shows a first embodiment of a printing mechanism according to the present invention. In the present embodiment, the printing mechanism used in a small type printer is taken into consideration. 11 is a platen for guiding the recording paper 10, 101 is a type wheel wound around a holding frame 121, and 13 is a type wheel.
0 is a hammer that presses the selected type A111 from behind. The hammer 130 has a shape having a first convex portion 131 that presses the type A111, an arm portion 133 having an arm shape, and a concave portion 135. Further, a cylindrical second convex portion 134 is arranged at the tip of the arm portion 133, and is loosely fitted to the groove-shaped cam lead portion 40A of the print carry cam 40.

Hammer 130, holding frame 121, type wheel 10
1. The print carry cam 40 is mounted on the carriage 30. As shown in FIG. 2, a plurality of characters 102 are radially formed on the outer periphery of the character wheel 101 at substantially equal intervals, and a back projection 103 is formed on the inner peripheral side corresponding to each character 102. Generally, the design shape of the typeface 102 is largely different depending on various typefaces, and therefore the surface area of the typeface is also different. The thickness M of the back projection 103 is different for each type. That is, the thickness M of the back projection 103 is set so as to be directly proportional to the area of the printed surface. Adjacent type 10
2, the rear projection 103, and the thin portion 104 are integrally formed of an elastic material such as rubber or elastomer, and form the type wheel 101.

The holding frame 121 is formed in a cage shape as shown in FIG. 3, and is integrated with the boss portion 122 and the disc portion 123. In addition, as shown in FIG.
It is radially formed corresponding to the number of divisions of 1, that is, the number of print characters 102, and abuts on the inner circumference of the thin portion 104 to print the print character ring 101.
Hold. Since the inner diameter of the thin portion 104 is set to be slightly smaller than the outer shape of the holding frame 121, when the type wheel 101 is wound around the holder 121, a slight tension acts on the entire type wheel 101 to cause the holder 121 to move. The thin portion 104 is in close contact.

Further, a predetermined gap 140 is provided so that each holding frame 121 and the adjacent rear projections 103 do not come into contact with each other. The boss portion 12 located at the center of the holding frame 121
As shown in FIG. 2, a deformed hole 2 is formed in 2, and the type wheel shaft 20 penetrates through this hole with a very small gap to form a spline connection.

The operation of character selection and printing will be described below. First, when the type wheel shaft 20 rotates, the holding frame 121 rotates in synchronization with this, and the type mechanism A111 is selected by stopping rotation when the desired type character A111 faces the recording paper 10 by a selection mechanism (not shown). .

Similarly to the relationship between the holding frame 121 and the type wheel shaft 20, the printing carry cam 40 has an irregular hole, and the printing shaft 50 forms a spline connection.
When 0 rotates in the direction of arrow D, the print carry cam 40 also rotates in the same direction in synchronization with it. The hammer 130 is rotatably supported on the carriage 30 that moves in the digit direction. As described above, the second convex portion 134 arranged on the arm portion 133 of the hammer 130 has the groove shape of the print carry cam 40. Since it is loosely fitted in the cam lead portion 40A, when the print shaft 50 rotates in the direction of arrow D, the hammer 130 synchronously rotates in the direction of arrow E.

When the hammer 130 rotates, the first convex portion 131 integrally formed at the tip moves toward the type wheel 101, and as shown in FIG. 4, the first convex portion 131 has the selected type letter A111. Is pushed out from the back surface and pressed against the printing paper 10. Ink is previously applied to the surface of the type A111 by an ink roller 150 (see FIG. 2) which is an inking means, and when the type A111 is pressed on the recording paper 10, the ink is transferred to the recording paper. Make the print. When the print shaft 50 further rotates in the direction of arrow D after printing is completed,
Guided by the cam lead 40A, the hammer 130 rotates in the direction of the counter arrow E and returns to the original state (state of FIG. 1). After that, the carry is carried and the process of paper feeding is started.

FIG. 4 shows a state in which the hammer 130 presses a character, and the chain double-dashed line of the arm 133 is the print carry cam 40.
7 shows a free shape of the arm 133 when the drive torque is not received from FIG. The two-dot chain line of the type A111 portion shows the free shape of the type A111 when the pressing force does not act, and G shows the compression amount of the type during printing.

As can be seen from the above, in the hammer 130, the first convex portion 131 presses the back surface of the type A111 in a state where the arm portion 133 having an arm shape is bent. At this time, even if the distance L (see FIG. 1) from the first convex portion to the platen changes due to dimensional change of the component parts, this is absorbed by the bending of the arm portion 133, and the hammer 130 is changed to the type A111. A constant and stable pressing force can be transmitted. As described above, since the thickness M of the back protrusion of the type A111 is proportional to the surface area of each type, the compression amount G of each type is G.
Is constant, and stable print quality can be obtained.

Since a small printer is generally composed of a plurality of parts, the distance L between the first convex portion 131 of the hammer and the platen 11 is likely to change. For example, if the above-mentioned distance L is too long, the hammer 130 cannot sufficiently press the printed characters on the recording paper, and the characters are printed in a missing state.
On the other hand, when the distance L is too short, the amount of press of the characters increases more than necessary, the blurring of characters and the ink bleeding become remarkable, and stable printing quality cannot be obtained.

Further, in this case, the print characters B112 and C113 (see FIG. 2) on both sides of the print character A111 come too close to the recording paper 10, and printing stains are generated by printing some unnecessary characters. The state of poor print quality due to these phenomena is shown in FIG. In FIG. 5 (a), a printed character 201 (corresponding to the type A111) is printed above and below the type B112,
Characters 202 and 203 corresponding to the respective print characters C113
A part of the is transferred and the print is dirty. When the distance L is properly secured, it is possible to obtain clear print quality without print stains or defects as shown in FIG. 5 (b).

Also in the conventional structure (see FIG. 10), it has been considered that the limiter spring 370 absorbs even if the distance L from the hammer to the platen changes, and a constant pressing force acts on the type 311. However, the print carry cam 340
In order to transmit the pressing force from the type wheel 301 to the type wheel 301, the structure is such that it passes through the limiter spring 370, the transmission lever 360, the hammer 330 and three parts, so that the power transmission efficiency is poor.

Further, a hammer return spring 380, which is a tension spring, is provided for returning the hammer 330, and acts as a load for reducing the pressing force to be transmitted during printing. Therefore, specifically, the limiter spring 370
It was inevitable to set the acting force to about 400 gf, which is about 1.6 times more than the required pressing force for printing (about 250 gf in terms of the printing press portion in the experiment by the author).

As a result, since a large force is applied to each part of the driving parts during the operation of the small printer, the pressure transmitting part and the sliding part of each driving part are abraded with the lapse of the operation time, and the above-mentioned distance is caused. There is a problem in that L fluctuates beyond the limit that can be absorbed by the limiter spring 370 and the print quality deteriorates. That is, there is a problem in long-term reliability of the small printer.

In the first embodiment, the printing mechanism is devised in order to prevent the deterioration of the printing quality as described above. The pressing force is transmitted from the print carry cam to the type wheel 101 through only one part of the hammer 130, and the variation of the distance L causes the arm portion 133 of the hammer to bend and be absorbed. In addition, since the cam lead portion 40A of the print carry cam 40 is formed in a groove shape for returning the hammer 130, the arm portion 133 of the hammer 130 is rotated and returned in the direction opposite to the arrow E, which causes a load during printing. It does not deploy parts like mechanism limiter springs. Therefore, the efficiency of power transmission is very good and the hammer 1
The force required to bend the arm portion 133 of 30 may be almost equal to the required pressing force for printing (250 gf as an experimental value by the author).

As a result, when the small size printer according to the present invention is operated, no excessive load is applied to the pressure transmitting portion or the sliding portion of each driving component, so that no abrasion occurs, so that the print quality can be obtained even if it is used for a long period of time. There is no deterioration. That is, the printer has high long-term reliability.

The output torque value required for the motor that is the drive source of the small printer is determined by the required torque value during printing. In the conventional mechanism, printing cannot be performed unless a force that exceeds the acting force of the limiter spring 370 is generated. However, in the printing mechanism according to the present invention, the efficiency of power transmission is very good as described above, and therefore, almost no characters can be printed. Only the force required to press is required.

That is, the output torque of the motor may be the minimum required for printing. According to the comparative measurement result of the author, the output torque of the motor of the invention example 1 is about 30 as compared with the conventional example.
% Reduced. Incidentally, in the first embodiment, the hammer 1
30 is injection-molded material with polyacetal, the arm 133
Has a minimum width H of 2.5 mm and a thickness of 0.9 mm.
The maximum deflection amount of 33 when printing is set to 0.5 mm. Further, since the arm 133 and the recess 135 are designed to be connected by a large radius so that stress is not concentrated, the arm 133 will not be broken or deformed even if the above-mentioned bending is repeatedly applied.

FIG. 6 shows a second embodiment of the present invention. The feature is that the base portion 131A of the first convex portion 131 of the hammer 130 is thin and elastic, and the arm portion 133 is designed wide and is a rigid body. The operation of selecting and printing the type letter is the same as that in the first embodiment, and the hammer 130 is rotated by the rotation of the print carry cam 40, and the back surface of the type letter A111 is pushed out for printing. In the case of the second embodiment, it is possible to obtain the same effect as that of the first embodiment by bending and absorbing the fluctuation of the distance L at the base portion.

FIG. 7 shows a third embodiment of the present invention. Hammer 1
Reference numeral 30 is formed by firmly contacting each of a hammer pressing body 139 for pushing out a printed character, a hammer elastic body 137, and a cam loose fitting body 136. The hammer pressing body 139 and the cam loose fitting body 136 are rigid bodies, and the hammer elastic body 137 is made of a metal spring material. The cam loose fitting 136 has a second convex portion that loosely fits in the cam lead 40A of the print carry cam 40.

Compared with the first embodiment, the hammer pressing body 139 has the hammer elastic body 1 on the first convex portion 131 of the first embodiment.
The one in which 37 and the cam loose fit body 136 are in solid contact corresponds to the arm 133 of the first embodiment. The operation of selecting characters and printing is the same as in the first embodiment, and the hammer 1 is rotated by the rotation of the print carry cam 40.
30 rotates to push out the back surface of the type A111 to print.
In the case of the third embodiment, the hammer elastic body 135 bends and absorbs the variation of the distance L, and the same effect as that of the first embodiment can be obtained. In this case, since the hammer elastic body 137 is made of metal, it is possible to prevent the deformation due to the creep phenomenon even if the stress is high. Therefore, it is effective when the large-sized typeface having a large surface area or the typeface material is hard.

FIG. 8 shows a fourth embodiment of the present invention. Hammer 1
Hammer elastic portion 130A, which is a part of arm portion 133 of 30, is thin and has elasticity, and the tip portion thereof is second convex portion 134, which is loosely fitted to cam lead 40A of print carry cam 40. ing. When the print carry cam 40 rotates in the direction of the arrow N after the printing wheel is selected, the second convex portion 134 loosely fits into the cam lead 40A of the print carry cam 40 as described above. The hammer 130 is an arrow P
It is driven linearly in the direction to push out the back surface of the type A111 and print.

After the printing, when the print carry cam 40 rotates in the direction opposite to the arrow N direction, the hammer 130 causes the cam lead 40A to move.
Is guided to move in the direction opposite to the arrow P direction and returns to the original position. The change in the distance L is absorbed by the hammer elastic portion 130A bending and absorbing the same effect as in the first embodiment.

FIG. 9 shows the fifth embodiment of the present invention, in which the hammer 130 is linearly driven as in FIG. 8, and the printing operation is also the same. In the case of the present embodiment, the hammer elastic portion 130A is in a part of the first convex portion, and the arm portion 133 has rigidity. The change in the distance L is absorbed by the hammer elastic portion 130A bending and absorbing the same effect as in the first embodiment.

[0031]

As described above, according to the present invention, even if the distance between the first convex portion of the hammer and the platen varies, the variation is absorbed by the bending of the first convex portion or the second convex portion of the hammer. Thus, it is possible to always apply a constant pressing force to the type wheel.
Therefore, it is possible to obtain clear print quality without print stains and chipping. Also, because the power transmission efficiency is very good,
The output torque of the motor, which is the drive source of the small printer, may be the minimum required for printing.

In other words, each component of the printing mechanism for transmitting torque is not overloaded, and even if it is operated for a long time, the torque transmitting portion and the sliding portion of each component will not be worn or deteriorated. Therefore, the first of the hammer
The distance from the convex portion to the platen does not fluctuate, a stable pressing force can be constantly applied to the type wheel during printing, and a compact printer with high long-term reliability can be provided.

Further, since the output torque of the motor may be the minimum required, it is possible to install an inexpensive one. In a small printer, the motor occupies a large way in terms of cost, so that its economical effect is great.

Furthermore, the printing mechanism according to the present invention is very simple, and since the shape of the hammer has no protrusions that hinder the operation of the type ring and the type ring body,
Further, it has a very high degree of freedom in designing a small size printer or a small size printer which requires a large number of type wheels.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a printing mechanism according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of the printing mechanism according to the first embodiment of the present invention.

FIG. 3 is a perspective view of the printing mechanism according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a printing process in the printing mechanism according to the first embodiment of the present invention.

FIG. 5 is a diagram for explaining the contents of improvement in print quality according to the present invention.

FIG. 6 is a plan sectional view of a printing mechanism showing a second embodiment of the present invention.

FIG. 7 is a plan sectional view of a printing mechanism showing a third embodiment of the present invention.

FIG. 8 is a side sectional view of a printing mechanism showing a fourth embodiment of the present invention.

FIG. 9 is a side sectional view of a printing mechanism showing a fifth embodiment of the present invention.

FIG. 10 is a diagram showing a conventional printing mechanism.

[Explanation of symbols]

 10 Recording Paper 11 Platen 20 Type Wheel 30 Carriage 40 Printing Carry Cam 101 Type Wheel 111 Type A 130 Hammer 131 First Convex Part 133 Arm Part 134 Second Convex Part

Claims (2)

[Claims] 1. A printer for printing by pressing a recording paper onto a platen by pushing out the printing characters from the inside by a printing wheel having a plurality of printing characters on the outer circumference and made of an elastic body, and a hammer rotated or linearly driven by a hammer driving member. In, a hammer driving member that includes a first engaging portion and that is rotated or rotated, and a second engaging portion that is fitted and inserted into the first engaging portion of the hammer driving member.
A hammer having a convex portion and a first convex portion that engages with the type letter and presses the type letter is provided, and the hammer has a relative position between the first convex portion and the second convex portion. A small printer having a flexible portion that is elastically deformed to be changed. 2. The small printer according to claim 1, wherein the flexible portion of the hammer is a spring member, and the hammer is entirely made of resin.