JPH04129760A - Typographic printer - Google Patents

Abstract

PURPOSE:To prevent noise emanated from a backward rotation-checking mechanism from diffusing directly to the outside of a type drum by placing the position of the backward rotation-checking mechanism on the inside of the type drum. CONSTITUTION:Contact surfaces 3-h of ratchet teeth 3-f formed on an internal wall of a type drum 3 are constructed so that a very small gap becomes existent between the said contact surface and a front end of a first claw 34-a of a backward rotation- checking claw 34 when selection is made for printing. In a very short period of time when a drum gear 2 and the type drum 3 are made overshot, the backward rotation- checking claw 34 is made to thrust in the direction B, being energized by a spring 35, and is made to enter an area where the claw engages with the contact surface 3-h of the ratchet tooth 3-f. In a very moment right after that, the drum gear 2 and the type drum 3 are about to bounce, but the bounce is checked as the contact surface 3-h of the ratchet tooth 3-f of the type drum 3 runs against a first claw 34-a of the backward rotation-checking claw 34. A backward rotation-checking mechanism consisting of the backward rotation-checking claw 34 and the ratchet tooth 3-f is housed in the type drum 3, and thereby noise source is confined in the type drum 3, preventing diffusion of the noise to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a small type printer using a type drum (or type wheel).

Conventional technology] Conventionally, this type of type printer was disclosed in Japanese Patent Application Laid-Open No. 6116486.
Lache, as disclosed in 5.

The teeth and the reversal pawl were installed on the outside of the step motor that drove the type drum, and were used to stabilize the stop position of the step motor. The tip of the reverse stopper pawl was located on the underside of the type drum or step motor, and engaged with the ratchet teeth of the step motor.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, noise (collision sound) between the ratchet teeth and the reverse stopper is generated when the type drum rotates. Since it is installed completely outside, it is not possible to block out the noise. In addition, the tip of the reverse stopper claw is located on the lower side of the type drum, step, or ram, and the stop position at the time of selection is stabilized at the bottom of the type drum, ste, or ram. Since the center bearing of the motor always has a clasp, the clasp will affect areas other than the area where the anti-reverse pawl acts, especially on the printing surface side (platen side), which directly affects printing quality. ), the accuracy of the stop position of the type drum had deteriorated.

The present invention has been made to solve these numerous drawbacks, and its first purpose is to provide a low-noise type printer by suppressing the noise generated by the reverse stop mechanism. The second object is to improve the accuracy of the stopping position of the type drum on the printing surface side, that is, on the platen side, and to provide a type printer with high quality characters.

[Means for Solving the Problems] In the type printer of the present invention, a reversing prevention mechanism for stabilizing the stop position of the type drum is installed inside the type drum, and a reversing prevention pawl formed on the inner wall of the type drum. It is characterized by consisting of a reversal stopper nail that is swingably installed inside the type tram, and a spring that biases the reversal stopper pawl in the direction of the ratchet teeth.

Further, the tip of the reversing pawl is characterized in that it engages with the teeth on the inner wall of the type tram on the side closer to the printing surface of the printer.

[Function] According to the above structure of the present invention, since the position where the reverse stop mechanism exists is inside the type tram, the noise generated by the reverse stop mechanism is not directly radiated to the outside of the type tram.

Furthermore, the accuracy of the stopping position of the type drum on the printing surface 01ll, that is, on the platen side, is improved because the bearing is not affected by backlash or the like.

[Example] Fig. 1 is a left side view of the area around the reverse stop mechanism of a type printer related to an embodiment of the present invention, Figure 2 is a plan view of the entire type printer, and Figure 3 is a right side view of the area around the selection mechanism. 4 is a left sectional view of the printing mechanism and its surroundings, and FIGS. 5(a) and 5(b) are diagrams showing the behavior of the type drum when it is selected.

1 is a frame. In FIG. 2, 2 is a drum gear, and a key groove 2-a is provided on the outer periphery.

3 has a type tram, key 3-a, paper feed drive tooth 3-
b1 hole 3-el In addition, ratchet teeth 3-f on the inner wall,
Or it is integrally molded. 4 has a type sheet with type 4-a arranged in a staggered manner on the front side and type 4-a on the back side.
A protrusion 4-b is provided corresponding to the letter type tram 3, and the protrusion 4-b is inserted into the hole 3-e to be wound around the type tram 3.

In FIG. 4, 5 and 6 are printing yokes forming yokes of the printing electromagnet, 7 is a printing iron core fixed to the printing yoke 6, and 8
is a printing coil arranged at a ratio of one for every two digits of the type 4-a, 9 is a hammer that is slidably set inside the printing coil 8, and 10 is located inside the printing coil 8 and is approximately the same as the hammer 9. It is a print suction plate that moves integrally and is attracted to the print core 7 by an attractive force when the print coil 8 is energized. One end of the printing yoke 5 passes through the first bearing 31 (see FIG. 3),
The other end passes through the second bearing 32. The first bearing 3 supports the drum gear 2 , and the second bearing 32 supports the type drum 3 . The key 3-a of the type drum 3 engages with the keyway 2-a of the drum gear 2 and rotates together. The printing yoke 5 is permanently fixed to the frame 1 at both ends.

The second bearing 32 has holes 32 in three locations as shown in FIG.
-3 is open. In one place of these holes 32-a,
The reversing shaft 33 or the reversing pawl 34, which is pivotally supported so as to be swingable about the shaft, is inserted and press-fitted. The reverse stopper pawl 34 has a main first pawl 34-a and a spare second pawl 34-b integrally formed at the tip thereof, and the above-mentioned type drum 3
A torsion fill type spring 35 biases the ratchet tooth 3-f toward the tooth surface formed on the inner wall of the ratchet tooth 3-f. The ratchet teeth 3-f of the type drum 3 are alternately assigned a cam surface 3-g and a percussion surface 3-h at a division pitch equal to the number of character bosses of the type drum 3. Further, this division pitch is also equal to the division pitch of the ratchet 2-c of the drum gear 2, which will be described later. Note that these ratchet teeth 3-f
The reverse stopper pawl 34 and the spring 35 constitute a reverse stop mechanism for stably stopping the type drum 3 when the [E] selection is selected.

As shown in FIGS. 2 and 3, the power of the DC motor 11 is transmitted to the drum drive gear 13 via a transmission mechanism 12 (details not shown). A detector 14 is installed on the drum drive gear 13.
or connected to generate timing pulses. This timing pulse is constituted by a pulse corresponding to the type pontoon on the type tram. The tram drive gear 13 meshes with the gear portion 2-b of the drum gear 2 and drives the drum gear 2 and the type tram 3. The tram gear 2 is a ratchet that is divided in the circumferential direction corresponding to the typefaces.

2-c is formed. Reference numeral 15 denotes a selection claw, which is pivotally supported at both ends of the shaft by the frame 1.

17 is a selection electromagnet. 16 is the selection electromagnet 17 with 3
It is a suction plate that is suctioned when N is applied (see Figure 2).

One end of the suction plate I6 engages with the selection claw 15, and the selection claw 1
5 by a predetermined angle. The selection electromagnet 17, the suction plate 16, the selection pawl 15, and the drum gear 2 described above constitute a selection mechanism.

An ink roll cup 19 is attached to the frame 1, as shown in FIGS. 1 and 4.

The ink roll cover 19 is an ink roll L 2 Q
Hold it so that it can rotate freely. Inklovka”-19,
It is biased toward the type drum 3 by a wire wire 26 attached to the frame 1.

Reference numeral 23 denotes a paper feed gear, which passes through the paper feed comb 21 and is pivotally supported by the platen 22 (see FIG. 2).

The paper press roller 25 has both ends inserted into a paper press shaft (not shown) supported by the frame 1, and presses the printed paper (not shown) against the paper feed comb 21 by the spring force of the paper press shaft 26. (See Figure 4 p, p).

Next, the operation of the mechanism configured as above will be explained. When the motor 11 is energized and rotated, this driving force passes through the transmission mechanism 12 and the drum drive gear 13, and moves the drum gear 2 and type drum 3 in the direction of the arrows in FIGS. 1, 3, and 4. Rotate. When the type drum 3 rotates, the type 4-a is sequentially positioned opposite the platen 22. When a desired type character 4-a on the type sheet 4 faces the platen 22, the selection electromagnet 17 is driven to attract the suction plate 16, and the selection claw 15 engages with the ratchet portion 2-c of the drum gear 2. At the same time, the drum gear 2, the type tram 3, and the type notebook 4 rotating integrally therewith are stopped. While the type tram 3 is stopped, the printing coil 8 of the desired digit is energized to attract the print suction plate 10, and the hammer 9 is operated to press the type 4-a onto the platen 22 via the printing paper (not shown). Print (see Figure 4). When the printing coil 8 is de-energized and the selection electromagnet 17 is also de-energized, the selection pawl 15 returns to the standby state and rotates the drum gear again. The same operation is repeated for each desired type character, and just before the type drum 3 completes one rotation, the paper feed drive tooth 3-b (see Fig. 2) and the paper feed gear 23 are in a positional relationship where they can mesh with each other. (details omitted). As the type drum 3 rotates, the paper feed drive tooth 3-b and the paper feed gear 23 mesh with each other, and the paper feed gear 23 rotates by a predetermined amount to feed the paper by one line. Immediately before the end of this paper feeding process, the positional relationship between a reset signal generation protrusion (not shown) formed on the upper digit side end surface of the type drum 3 and a reset sensor (not shown) is engaged. This is possible, and a reset signal is generated (details omitted). After detecting this reset signal, the motor 11 is stopped and one line printing cycle is completed.

By the way, as can be understood from the above explanation, the drum gear 2 and the type drum 3 are mechanically stopped by the selection claw 15 at the time of selection. At this time, the drum gear 2 and type drum 3, which have large inertia and have been rotating in the direction of arrow A in the figure, are moved by the selection claw 1 as shown in FIG. 5(a).
5, it is abruptly stopped, and immediately after the elasticity of each part causes it to open neatly δ, the elastic key is released and bounces significantly β. In order to operate the hammer 9 by energizing the printing coil 8 in the stop area C of the type drum 3, if the bounce β of the type drum 3 does not converge quickly, the hammer 9
Even while hitting the type 4-a, the type drum 3, that is, the type 4-a
Or it may vibrate in the direction of rotation. In this case, type 4-a
Because the type 4-a shifts while it is in contact with the printing paper,
This causes extremely troublesome print quality defects such as print misalignment (also called coasting).

However, in this embodiment, as shown in FIG.
-h is set to have an extremely small gap with the tip of the first claw 34-a of the reverse stopper claw 34 in the selected state.

Within a short period of time when the tram gear 2 and the type tram 3 are rotating δ, the reversing pawl 34 falls in the direction of arrow B in FIG. 1 due to the biasing force of the spring 35, and the contact surface of the ratchet tooth 34-f 3-h and enters the engagement area. Next m
During this period, the drum gear 2 and the type drum 3 try to bounce β, but the contact surface 3-h of the ratchet tooth 3-f of the type drum 3 hits the first pawl 34-a of the reversing pawl 34, Bounds are regulated. Then, compared to the selection behavior of the type tram 3 with or without the reverse stop mechanism (Figure 5 (a)), the bound β converges in a much shorter time as shown in Figure 5 (b).
), hit hammer 9 or type 4-a (previously, type tram 3
That is, it is possible to stabilize the vibration of the printed characters 4-a. Note that this embodiment is characterized in that the above-mentioned reversal prevention mechanism directly acts on the type drum 3, which minimizes the factors of warp and deflection that would prevent the type drum 3 from stably stopping. I can do it.

Also, the selected state, ie tram gear 2! When the selection pawl 15 is stopped, the ratchet tooth 3-f of the type drum 3
In order to improve the accuracy of the stopping position of the type drum 3, it is essential that the contact surface 3-h of the rotary contact surface 3-h and the first pawl 34-a of the reverse stop pawl 34 be in a positional relationship with almost no play. . However, dimensional variations in related parts cannot be avoided. Here, in this embodiment, three holes 32a are provided in the second bearing 32 for press-fitting and fixing the reverse stop shaft 33. Although each of these three holes 32-a is at the same distance from the center of the type drum 3, the pitch angle θ2 between the holes is very small relative to the division pitch angle θ1 of the ratchet teeth 3-f of the type drum 3. It is a change of angle. If the accuracy of the related parts changes, by selecting an appropriate hole from among the three holes 32-a into which the reverse stop shaft 33 will be press-fitted,
The center of rotation of the reverse stopper claw 34 and the ratchet of the type drum 3)
The relative positional deviation with the tooth 3-f can be optimized.

That is, in the selected state, the ratchet teeth 3- of the type drum 3
The contact surface 3-h of r and the first pawl 34-a of the anti-reverse pawl 34
The play between the
It can be adjusted to the smallest possible size.

As can be seen in Figures 1 and 2, the above-mentioned non-return mechanism is characterized in that it operates on the platen 22, that is, the side closest to the print surface, and this has the greatest effect on the actual print quality. The accuracy of the stopping position of the type drum on the platen 22 side is improved because the bearing is not affected by backlash or the like.

Furthermore, when the type drum 3 rotates, noise due to collision between the ratchet teeth 3-f and the reverse stopper pawl 34 is unavoidable. However, in this embodiment, as described above, the reverse rotation prevention mechanism including the reverse rotation prevention pawl 34 and the ratchet teeth 3 - f is housed inside the type drum 3 . Therefore, since the noise source is within the type drum 3, noise radiation is blocked.

By the way, in the above explanation, the ratchet m3-f and the type drum 3 are integrally formed, but they may be manufactured separately and then fixed together. Also, the reversal prevention mechanism is the type drum 3.
As long as it is inside the cylinder, it may be installed anywhere in the axial direction, and in either case, it does not deviate from the technical idea of the present invention.

[Effects of the Invention] As described above, according to the present invention, since the position where the reverse stop mechanism is located is inside the type drum, the noise generated by the reverse stop mechanism is not directly radiated to the outside of the type drum. , noise radiation is blocked, and the user operating the printer approximately above the printer can hardly hear the noise. Furthermore, the accuracy of the stopping position of the type drum on the printing surface side, that is, on the platen side, is improved because the bearing is not affected by backlash or the like.

Therefore, it is possible to provide a type printer with low noise and high print quality, which is extremely effective.

[Brief explanation of the drawing]

Fig. 1 is a left side view of the reverse stop mechanism and surroundings of a type printer related to an embodiment of the present invention, Fig. 2 is a plan view of the entire type printer, Fig. 3 is a right side view of the selection mechanism and its surroundings, and Fig. 4 The figure is a left sectional view of the printing mechanism, and FIGS. 5(a) and 5(b) are diagrams showing the behavior of the type tram during selection. 3... Type drum 3-f... Ratchet teeth 4
...Reverse stopper claw 5...More than spring

Claims (1)

[Scope of Claims] 1) A printer of a type that prints by selectively stopping a type drum with type arranged on its outer periphery, which includes a reversal prevention mechanism for stabilizing the stop position of the type drum; A type printer characterized in that a stop mechanism is installed inside the type drum. 2) The reverse stop mechanism includes ratchet teeth formed on the inner wall of the type drum, a reverse stop pawl that is swingably installed inside the type drum, and the reverse stop pawl is attached in the direction of the ratchet teeth. It is characterized by consisting of a spring that forces the
A type printer according to claim 1. 3) The typeface according to claim 1, wherein in the reverse rotation prevention mechanism, a tip of the reverse rotation prevention pawl engages with the ratchet teeth on the inner wall of the type drum on a side closer to the printing surface of the printer. formula printer.