JPS62183357A - Printer - Google Patents

Abstract

PURPOSE:To prevent a slur due to the rotating force of a hammer in a printing operation, by a method wherein a projection on a drive click provided on a selective ratchet is selectively engaged with and disengaged from a cutout of a drive shaft, and a lock groove on a type wheel is engaged with a selective click of the selective ratchet. CONSTITUTION:In a type selection, when a selection ratchet 6 is brought to a halt by a selective click 25, a drive click 20 is rotated integrally with a drive shaft 2 and a type wheel 5 to come into collision with either of engaging portions 16, 17 on the selective ratchet 6 according to the rotating direction, which results in disengagement of a cutout portion 3 on the drive shaft 2 from a projection 21 on the drive click 20 and therefore discontinued transmission of the rotating force of the drive shaft 2 to a type wheel 5. Simultaneously, a lock groove 8 provided on the type wheel 5 is also engaged with the tip of the selective click 25, which positively hold the tipe wheel 5 on a desired type selection position. Thus, the type wheel 5 never rotates even if the rotating force of a hammer 47 acts on the type wheel 5 during the subsequent printing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a printer, and particularly to a printer that rotates a type wheel in both forward and reverse directions during, for example, two-color printing.

(Prior Art) Conventionally, a plurality of type wheels having typefaces on the circumferential side are arranged in rows, for example, 18 rows, on a rotating shaft arranged parallel to a platen around which recording paper is wound, and the rotation of each type wheel is controlled. Printers that perform desired printing through individual control have been proposed. Figure 16 is an explanatory diagram showing the main parts of this type of conventional printer,
This is disclosed in Japanese Patent No. 1798.

In FIG. 16, 101 is a rotating shaft, and 102 is a type wheel attached to this rotating shaft 101.

The type wheel 102 has a bearing 102a into which the rotating shaft 101 is inserted, a type body 102b on the circumferential side, and a selection ratchet 102c surrounding the bearing 102a. Reference numeral 103 is a driving claw that transmits the rotational force of the rotating shaft 101 to the type wheel 102, and the bearing 10
2a and the selection ratchet 102c, the first arm 1 has a shaft portion 103a inserted into a circular recess 102e formed between the selection ratchet 102c and the selection ratchet 102c, and has a claw portion 103b at the tip and has a short length and rigidity.
03c, and a second arm 103 having elasticity with a long length dimension.
It consists of d. This driving claw 103 has its claw portion 1
03b is inserted into a cavity 102d formed in the bearing 102a and engaged with the bearing IQ2a, and the claw part 103b is inserted into the notch 101a formed in the rotating shaft 101, that is, the axis of the rotating shaft 101. It can be engaged with a notch 101a having a surface 101b extending in the center direction and a surface 101c inclined with respect to this surface 101b. Note that 104 is a selection pawl that can be engaged with the selection ratchet 102c, and is rotatable about a shaft 105.

In this printer, as shown in FIG.
1a, the rotating shaft 101 rotates in the direction of arrow R, so that the rotational force of the rotating shaft 101 is applied to the drive claw 1.
03 to the type wheel 102, the type wheel 102 rotates, and the selection claw 104 moves in the direction of the arrow S.
By rotating in the direction and engaging the selection ratchet 102c, rotation of the selection ratchet 102c, that is, the type wheel 102, is stopped, and the desired type body 102b reaches the printing position. Further, even when the type wheel 102 is locked, the rotating shaft 101 continues to rotate further, for example, to select another type wheel. Due to the relative sliding of the facing surfaces of the drive claw 103, the drive claw 103 expands against the elasticity of the second arm 103d, thereby cutting off the transmission of the rotational force of the rotating shaft 1 to the type wheel 102. .

(Problems to be Solved by the Invention) By the way, in the conventional printer configured as described above, the rotational force is transmitted from the rotary shaft 101 to the type wheel 102 by using the notch in the rotary shaft 1. This depends on the frictional force between the surface 101c of the portion 101a and the opposing surface of the drive claw 103b, and therefore, when the drive claw 103 stops suddenly during high-speed rotation, or at the end of startup, the drive claw 103 is There is a concern that the driving claw 103 may come off the rotating shaft 101, and furthermore, there is a fear that the drive claw 103 may come off the rotating shaft 101 if some external load is applied to the type wheel 102. In addition, in order to eliminate such concerns, drive claw 1
The spring force of the second arm 103d of 03 must be set large.However, if the force of the drive claw 103 is increased in this way, the drive claws for each of all the type wheels including the type wheel not shown in the figure must be set large. As the spring force increases, the torque that drives the rotating shaft 101 increases when the type wheel is stopped, which increases the manufacturing cost and reduces power consumption due to the increase in the size of the motor that drives the rotating shaft 101. This will lead to an increase in running costs, etc.

Therefore, in order to eliminate such drawbacks, the applicant has proposed the first
We first proposed a printer as shown in Figure 7 (patent application 1986-
No. 4851). In the figure, 106 is the type wheel 1
02 so as to be rotatable relative to the type wheel 1.
A selection ratchet 107 that rotates integrally with the type wheel 102 is arranged between the type wheel 102 and the selection ratchet 106, and transfers the rotational force of the rotating shaft 101 to the type wheel 102.
The drive pawl 107 is a drive pawl that transmits information to the type wheel 10.
It has a hole 107a that is rotatably inserted into the shaft 102f provided in the rotating shaft 101, and a notch 1 of the rotating shaft 101.
A first arm 107c that has a projection 107b that can be engaged with the 01a and has rigidity, and a second arm 107 that has elasticity.
It consists of d.

Further, the selection ratchet 106 has a portion with which the tip of the first arm 107c of the drive pawl 107 movably engages, that is, a guide recess 106a for rotating the drive pawl 107 around the shaft 102f, and also has a guide recess 106a around the shaft 102f. Teeth 10 on the side
6b exists. Furthermore, 108 is a selection ratchet 1
06 is a selection claw arranged facing outward from the other first
Components corresponding to those in FIG. 6 are given the same reference numerals.

In the printer of this prior application, as shown in FIG. 17(a), the rotating shaft 101 moves in the direction of the arrow 109 in the figure with the protrusion 107b of the driving claw 107 engaged with the notch 101a of the rotating shaft 101. By rotating, this rotating shaft 101
The rotational force is transmitted to the type wheel 102 via the drive pawl 107', and the type wheel 102 rotates, and the selection pawl 108 is driven by an electromagnetic clutch (not shown), etc. The selection ratchet 106 is locked by engaging the tip of the lever with the teeth 106b of the selection ratchet 106. When the rotation shaft 101 continues to rotate further with the selection ratchet 106 locked, the tip of the first arm 107C of the drive pawl 107 moves outward along the guide recess 106a of the selection ratchet 06. As a result, the protrusion 107 of the first arm 107C
b is disengaged from the notch 101a of the rotating shaft 101,
Transmission of the rotational force of the rotating shaft 101 to the type wheel 103 is released.

In this way, according to the prior application, the selection ratchet 106
is provided separately from the type wheel 102, and the selection ratchet 106 is provided with a guide recess 106a for rotating the driving pawl 107. , and the rotational force of the rotating shaft 101 can be transmitted to the type wheel 102 without being affected by the frictional force between the rotating shaft 101 and the protrusion 107b. Although there are advantages in that the force can be controlled to a minimum and the torque for driving the rotary shaft 101 is thereby reduced, it is not without problems.

That is, since the selection ratchet 106, which is separate from the selection ratchet 106, is attached to the type wheel 102 so as to be relatively rotatable, when the rotational force of a hammer (not shown) acts on the type wheel 102 where a type is selected during printing operation, The rotational force may slightly rotate the type wheel 102 in the locked state, which causes problems such as printing misalignment. In particular, for example, in two-color printers in which different colors of ink are applied to the type bodies of a type wheel and the type wheel is rotated in either the forward or reverse direction depending on the selected color, the type wheel Since the direction of rotation of the hammer is always constant regardless of the direction of rotation of the hammer, it has been difficult to reliably lock the type wheel in which type is selected in either the forward or reverse direction.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a printer that can securely fix a type wheel in a printing position even when the type wheel rotates in either the forward or reverse direction.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a drive shaft that has a notch on the circumferential side and is rotatable in either forward or reverse directions, and It is rotatably mounted on the board, has typeface on the circumference side,
and a type wheel having a locking groove on its inner circumferential side, a drive pawl held by the type wheel and having a protrusion capable of engaging with a notch of the drive shaft, and a drive pawl that is rotated to the type wheel via the drive pawl. a selection ratchet which is movably mounted and has a pair of engaging parts that can engage with the drive pawl and has teeth on the circumferential side; and a selection ratchet that engages with the teeth to selectively rotate the selection ratchet. When the rotary force of the hammer acts on the circumferential surface of the type wheel where type is selected, the selection pawl engages with the lock groove of the type wheel, thereby locking the type wheel. It is characterized by being locked in the type selection position.

(Function) That is, according to the above means, when the selection pawl locks the selection ratchet when selecting type, the drive pawl, which rotates integrally with the drive shaft and the type wheel, rotates the selection ratchet according to the direction of rotation. It collides with one of the engaging parts and expands outward during the subsequent rotation of the drive shaft, thereby releasing the engagement between the notch of the drive shaft and the protrusion of the drive pawl, thereby driving the drive shaft. Transmission of the rotational force of the shaft to the type wheel is cut off. At this time, when the locking groove provided on the type wheel is also engaged with the tip of the selection pawl, the type wheel is securely locked at the desired type selection position, and the hammer is rotated during the subsequent printing operation. Even if power is applied to the type wheel, the rotational force will not cause it to rotate.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic side view of a printer according to an embodiment of the present invention. In the figure, 1 is a rotating shaft, and the rotating shaft 1 is rotated forward or reverse by the driving force of a motor (not shown) via a gear train, which will be described later. 2 is integrated with the rotating shaft 1. This is a drive shaft that rotates at a constant angle, and two notches 3 and 4 are formed on the circumferential surface of the drive shaft at opposing positions 180 degrees apart in the axial direction.

5 is a type wheel attached to the drive shaft 2, and 6, indicated by a two-dot chain line, is a selection ratchet also attached to the drive shaft 2.

FIG. 2 is a plan view of the type wheel 5, and FIG. 3 is a front view of the selection ratchet 6. As shown in Figure 2,
On the outer peripheral surface of the type wheel 5, for example, rO, 1, 2...
...9. Two groups of typefaces 7.7' are provided, with +, +, 8 is a bearing 9 in which the drive shaft 2 is inserted in the center.
has been erected.

A gap 1o is formed in a part of the bearing 9, and an engagement shaft 11 and a support shaft 12 are connected to the type wheel 5 on the outer periphery of the bearing 9.
They are planted so as to face each other about 180 degrees across the center of the two.

On the other hand, as shown in FIG.
and one locking protrusion 14, and a hole 15 into which the bearing 9 of the type wheel 5 is inserted is bored in the center. A pair of release pins 16 and 17 are erected on the outer periphery of the hole 15 at a predetermined interval, and are designed to correspond to the engagement shaft 11 and the support shaft 12 of the type wheel 5, and to sufficiently accommodate the release pins 16 and 17. Oval engagement holes 18° and 19 are bored to the extent possible.

Returning to FIG. 1, reference numeral 20 denotes a drive pawl disposed between the type wheel 5 and the selection ratchet 6, and the driving pawl 20 transmits the rotational force of the rotary shaft 1 to the type wheel 5. This drive claw 20 has rigidity and has a notch 3 of the drive shaft 2,
The first arm part 22 has a projection 21 that can be engaged with the type wheel 5, and the second arm part 24 has a sliding part 23 that is elastic and comes into elastic contact with the engagement shaft 11 of the type wheel 5. The base of the first arm 22 is rotatably inserted into the support shaft 12 of the type wheel 5. On the other hand, as shown by two-dot chain lines in the figure, both release pins 16 and 17 of the selection ratchet 6 are located near the first arm 22 via the projection 21 of the drive pawl 20, and are also engaged with the type wheel 5. The tips of the mating shaft 11 and the support shaft 12 are located within the re-engaging holes 18 and 19 of the selection ratchet 6, respectively.

Further, 25 shown in FIG. 1 is a selection pawl that can lock the selection ratchet 60 rotations, and the selection pawl 25 is attached to the teeth 13 and the locking protrusion 14 of the selection ratchet 6, and the lock groove 8 of the type wheel 5, respectively. It has an engageable pawl 26 at its tip, a hole 28 in the center into which a rotation shaft 27 is inserted, and a cam pawl 30 that engages with a reset cam 29 at its rear end.

31 is a driving means capable of selectively transmitting the rotational force of the rotary wheel 27 to the selection pawl 25, for example, an electromagnetic clutch;
33 is a locking spring capable of holding the selection pawl 25 in a state of engagement with the selection ratchet 6; and 33 is a pressing spring that cooperates with this locking spring 32 to hold the selection pawl 25 in a state away from the selection ratchet 6. be.

FIG. 4 shows the above-mentioned type wheel 59 selection ratchet 6,
FIG. 3 is an exploded perspective view showing the relationship between the drive pawl 201, the selection pawl 25, and the electromagnetic clutch 31. FIG. As shown in the figure, the electromagnetic clutch 31 includes an electromagnetic coil 34. Holding stand 35. It is roughly constituted by a yoke 369 and a rotating body 37. The electromagnetic coil 34 has a hole 38 in its center into which the rotating shaft 27 is inserted, and a cylindrical yoke 36 held by a fan-shaped protrusion 39 on the upper part of the holder 35 supports the electromagnetic coil 34. It is attached so as to surround it, and on its side there are 90
Four notches 40 are formed at degree intervals. A hole 41 into which the rotating shaft 27 is inserted is formed in the center of the rotating body 37 made of a non-magnetic material.
The rotating body 27 has a yoke 3 on its peripheral wall.
Similarly, four protrusions 42 that engage with the notches 40 of No. 6 are formed at 90 degree intervals. The electromagnetic clutch 31 configured in this manner can rotate two selection pawls, that is, the selection pawl 25 and the second selection pawl 25' of node 1 in the figure. These first and second selection claws 25.25'
As mentioned above, has a claw portion 26.26' at the tip, a hole 28.28'' at the center, and a cam 30.30' at the rear end, and further has a shape of the protrusion 39 of the holding base 35 at the bottom. Slightly larger fan-shaped notches 43 and 43' are formed correspondingly to the above.

These first and second selection claws 25°25',
When assembling the electromagnetic clutch 31, the yoke 36 is attached to the electromagnetic coil 34 so as to surround the electromagnetic coil 34 as described above, and each protrusion 42 of the rotating body 37 is arranged so as to fit into each notch 40 of the yoke 36. be done. Further, both selection claws 25 and 25' are rotatable with respect to the rotation shaft 27, and their notches 43 and 43' are connected to the holding base 35.
The rotary body 37 is mounted so as to fit into the protrusion 39 of the rotary shaft 27, and the rotary body 37 is provided integrally with the rotary shaft 27 as described above. In this assembled state, both selection claws 25.25
'', the body portions 44, 44' are arranged so as to face both sides of the yaw:l 36.

On the other hand, the type wheel 51 selection ratchet 6 and drive pawl 20 described above are attached to the drive shaft 2 in the following manner.

That is, for example, the bearing 9 of the first type wheel 5 is inserted into the drive shaft 2, then the hole of the drive pawl 20 is inserted into the support shaft 12 of the first type wheel 5, and the protrusion 21 of the first arm portion 22 is inserted. is inserted into the cavity 10 of the bearing 9, and then, for example, the protrusion 21 is engaged with the notch 3 of the drive shaft 2. Further, the sliding portion 23 of the second arm portion 24 is connected to the first type wheel 5.
It is mounted so as to come into elastic contact with the engagement shaft 11 of.

The hole 15 of the first selection ratchet 6 is then inserted into the bearing 9 of the first type wheel 5 and its release pin 16. I
T is inside the first arm 22 and its engagement hole 18.1
9 is attached to the first type wheel 5 so as to correspond to the engagement shaft 11 and the support shaft 12, respectively.

The drive shaft 2 has a second type wheel 5'9, a selection ratchet 6' and a drive pawl 2 in the same way as the first type wheel 5', the first selection ratchet 6 and the drive pawl 20 described above.
0'' is installed. That is, the bearing 9' of the second type wheel 5'' is inserted into the drive shaft 2, and then the drive pawl 20'
is inserted into the support shaft 12' of the second type wheel 5', the protrusion 21' of the first arm 22' is inserted into the cavity 10 of the bearing 9'', and then this protrusion 21' is inserted into the drive shaft. The second arm 24' is engaged with the notch 3 of the second type wheel 5'. The hole 15' of the second selection ratchet 6' is inserted into the bearing 9 of the second type wheel 5', and its release pin (not shown) is inserted into the first arm 22.
', and the engagement holes 18' and 19' are on the inside of the engagement shaft 1.
1' and the support shaft 12', respectively.
The type wheel 5' is attached to the type wheel 5'.

and the above-mentioned first type wheel 5. First selection ratchet 6, second type wheel 5'.

The second selection ratchet 6' is connected to the first selection ratchet 6.
The phase of the tooth 13 of the second selection ratchet 6' and the tooth 1 of the second selection ratchet 6'
The teeth 13' are arranged on the drive shaft 2 so that the phases of the teeth 13' are different from each other, for example, shifted by 1/2 pitch from each other, that is, the teeth 13' are located at positions corresponding to the spaces between the teeth 13.

Although not shown, two type wheels 5. 5', selection ratchet 6, 6'.

A plurality of combinations, for example nine sets, of the drive pawl 20.20', the selection pawl 25.25', and one electromagnetic clutch 31 are arranged along the axial direction of the drive shaft 2 and the rotation shaft 27, respectively.

FIG. 5 is an explanatory diagram showing the engagement relationship between the drive shaft 2 and the drive pawls 20, 20', and FIG.
FIG. 4 is an explanatory diagram showing the engagement relationship between the selection claw 25 and the selection claw 25, 25'. The character selection operation of the character wheel 5.5' will be explained below mainly with reference to these figures.

First, as shown in FIG. 5(a), the notch 3 of the drive shaft 2
When the protrusion 21.21' of the drive pawl 20.20'' is engaged with the protrusion 21.21' of the drive pawl 20.20'', the distal end of the selection pawl 25.25' is engaged with the locking spring 32. 32”
When the drive shaft 2 and the rotation shaft 27 are rotated in the direction of the arrow A in FIGS. 5 and 6 by a motor (not shown) while the drive shaft 2 and the rotation shaft 27 are in a standby state in which the ridge is not climbed over, for example, the rotation of the drive shaft 2 As shown in FIG. 5(a), the notch 3 and the driving claw 20
．． 20" projection 21.21', a rotational force is transmitted to the drive pawl 20.20', and this rotational force is further transmitted from the first arm 22 of the drive pawl 20.20' to the selective ratchet 6.6. ' release pin 16.17.16'.

17', which causes the type wheel 5°5'
(selection ratchet) 6.6' and the drive shaft 2 rotate together in the six directions indicated by the arrows. During this time, although the rotating body 37 and the yoke 36 rotate with the rotation of the rotating shaft 27, the rotational force of the rotating shaft 27 is not transmitted to the selection claw 25.25'', so these selections cannot be made. Claw 25.25'
is maintained in the standby state shown in FIG. 6(a).

and the desired type body 7 of the first type wheel 5, for example.
Or when 7' reaches near the printing position, the electromagnetic coil 34
When energized, the body 44.44' of the selection claw 25.25'' is attracted to the side end surface of the yoke 36. Therefore, the selection claw 25.25' is as shown in FIG. 6(b).
As shown by arrow B in (c), the first selection claw 25 tries to rotate integrally with the yoke 36, but at this time
6 is located between the teeth 13 of the first selection ratchet 6, so that the distal end of the selection pawl 25 climbs over the peak of the locking spring 32 and moves in the direction of arrow B, as shown in FIG. 6(b). The pawl portion 26 and the tooth portion 13 engage with each other, thereby locking the rotation of the first selection ratchet 6. Such a condition is
It is stably held by the spring force of the locking spring 32. When the rotation of the first selection ratchet 6 is stopped by the first selection claw 25 in this way, the drive shaft 2 is rotated in the direction of the arrow A in FIG. 5(a). The tip of the first arm portion 22 of the pawl 20 is engaged with the release pin 16 provided on the first selection ratchet 6 and moves outward;
In other words, the drive claw 20 is expanded against the spring force of the second arm 24, and as a result, the protrusion 21 of the first arm 22 and the notch of the drive shaft 2 are opened as shown in FIG. 5(b). 3 is released, and the transmission of the rotational force of the drive shaft 2 to the first selection ratchet 6 and the first type wheel 5 is cut off. Note that at this time, the engagement shaft 11 provided on the first type wheel 5
and the support shaft 12 engage with the ends of the engagement holes 18 and 19 drilled in the first selection ratchet 6, as shown in FIG. 1 relative position with the selection ratchet 6 is regulated. In addition, the drive claw 2
When the second arm portion 24 of No. 0 is expanded, the sliding portion 23 at the tip thereof is bent in the direction of expansion of the second arm portion 24 and comes into elastic contact with the engagement shaft 11 of the first type wheel 5. Therefore, it slides into contact with the engagement shaft 11 with a relatively small frictional force,
In addition, this engagement shaft 11 connects to the support shaft 12 through the center of the drive shaft 2.
Since the second arm portion 24 is provided at a position opposite to the second arm portion 24, the spring constant thereof can be set to be small.
The engagement force when the 0 projection 21 is engaged with the notch 3.4 of the drive shaft 2 can be increased, and the load when these engagements are released can be made small.

On the other hand, the second selection claw 25' is 1/2 as described above.
As the pitch shifts, the pawl 26' comes into contact with the tooth 13' of the second selection ratchet 6', as shown in FIG. 6(C), and remains in this state. Therefore, the second selection ratchet 6' and the second type wheel 5' continue to rotate. Further, for example, when the electromagnetic coil 34 is de-energized in synchronization with the locking of the rotation of the first type wheel 5, the transmission of the rotational force of the rotation shaft 27 to the second selection pawl 25' is cut off. ,
The force of the locking spring 32 causes the second selection pawl 25' to move as shown in FIG.
Return to the standby state shown in a). Therefore, regardless of the rotation of the drive shaft 2, the second selection pawl 25' and the second selection ratchet 6' do not engage with each other.

When the desired type body 7 or 7' of the second type wheel 5' comes close to the printing position, the electromagnetic coil 34 is energized, and the second print wheel 5 in the standby state is thereby energized.
' is positioned in the same manner as the first type wheel 5 described above, that is, it is in the state shown in FIG. 6(b). moreover,
The type bodies provided on the type wheel (not shown) are also positioned in the same manner as described above, thereby making it possible to perform the desired printing operation.

As mentioned above, the claw part 26°26' of the selection claw 25.25'
cam pawl 30.30' of the selection pawl 25.25' engages with the teeth 13.13' of the selection ratchet 6.6', i.e. during the selection movement of the type bodies 7, 7' As shown in FIG. 6(b), is located at a position facing the stepped portion 45 provided on the reset cam 29. When the printing operation is completed, the rotation of the reset cam 29 causes the convex portion 46 provided on the reset cam 29 to move to the selection claw 25°2.
5' cam pawl 30.30", thereby all selection pawls including selection pawl 25.25'
Climb over the peak of arrow C in Figure 6 (b) and (c).
It rotates in the direction shown by and is held in the standby state again by the peak of the locking spring 32 and the pressing spring 33. When the selection pawl 25.25' is reversed in this way, the selection pawl 25.2
5' and the selection ratchet 6.6' are disengaged. In this state, when the drive shaft 2 rotates, for example, in the direction of the arrow in FIG. 5(a), the protrusion 21.2 of the drive claw 20.20'
1'' slips on the circumferential surface of the drive shaft 2, and when the notch 3 or 4 comes to a position facing the protrusion 21.21', the second arm 24.24' of the drive pawl 20.20' The spring force causes the protrusion 21.21" to engage the notch 3 or 4,
As shown in FIG. 5(a), the rotational force of the drive shaft 2 can again be transmitted to the selection ratchet type wheel 5.degree. 5'. In addition, selection claws and drive claws 9 related to other sets (not shown)
Selection ratchet.

Exactly the same operation is performed for type wheels and the like.

The series of operations described above is for the case where the drive shaft 2 is rotated in the direction of the arrow A shown in FIG. Basically, the same operation is performed when rotating in the direction indicated by the arrow. That is, as shown in FIG. 5(c), for example, when the tooth portion 13 of the selection ratchet 6 is engaged with the selection pawl 25 and the rotation of the selection ratchet 6 is stopped, the subsequent rotation of the drive shaft 2 is stopped. With rotation in the direction indicated by the middle arrow in FIG. 5(c), the approximate center of the first arm portion 22 of the drive pawl 20 is engaged with the release pin 17 provided on the selection ratchet 6 and moves outward; As a result, the protrusion 21 of the first arm portion 22 and the cutout portion 3 of the drive shaft 2
The transmission of the rotational force of the drive shaft 2 to the selection ratchet 6 and the type body wheel 5 is cut off. However, in this case, since the direction of rotation of the drive shaft 2 is opposite to the rotational force that the type wheel 5 receives due to the rotation of the hammer, which will be described later, the rotation direction shown in FIG. As shown in c), the claw portion 26 of the selection claw 25 engages with the lock groove 8 provided on the type wheel 5. Regarding this point, please refer to the printing operation described below.
This will be explained in detail in the section below.

Returning to FIG. 1 again, reference numeral 47 denotes a hammer disposed opposite to the row of type wheels 5, 48 denotes an error printing prevention plate disposed between these type wheels 5 and the hammers 47, and 49
50 is a paper guide that guides the recording paper to the printing position (not shown); 50 is a paper feed roller disposed near the paper guide 49;
Reference numeral 1 denotes a driven roller disposed opposite to the paper feed roller 50, and the upper recording paper is conveyed while being held between the paper feed roller 50 and the driven roller 51.

FIG. 7(a) is a plan view of the hammer 47, FIG. 7(b)
is a sectional view taken along the line E-E. As shown in these figures, the hammer 47 has a plurality of, for example, 18 chevron-shaped pressing portions 52 corresponding to the number of the type wheels 5, and each pressing portion 52 is separated by a notch 53. The hammer 47 is made of, for example, a relatively hard synthetic resin material, but since a void 54 is formed inside the pressing portion 52, the hammer 47 maintains its surface hardness and is easily deformed.

Moreover, since the pressing parts 52 are separated from each other by the notches 53, even if the hammer 47, type wheel 5, etc. are slightly eccentric, a uniform pressing force can be applied to each type wheel. I can do it. Note that 55 indicated by a two-dot chain line in FIG. 1 is the locus of the tip of the hammer 47, that is, the tip of the pressing portion 52.

FIG. 8 is a plan view of the erroneous printing prevention plate 48.

As shown in the same figure and in FIG. 1, the printing error prevention plate 48 is made of, for example, a bent metal sheet, and fixing ears 56 are formed on both sides of its lower end. Further, a plurality of holes 57 are bored at predetermined intervals in the longitudinal direction, and these holes 57 are formed, for example, 18, corresponding to the rows of the type wheels 5. The type bodies 7,7' of each type wheel 5 correspond to the hammers 47 through these holes 57, and as is clear from FIG. The length of the protrusion 58 (l) shown in FIG. 8 is set to be approximately equal to one type body 7.7' of the type wheel 5. Therefore, only the typeface selected for the printing position protrudes from the projection 58 of the hole 57 in the direction of the hammer 47, and the typeface located in the front-rear direction of the typeface selected for the printing position faces the hole 57. It does not protrude from the hole 57.

In addition, 59 in FIG. 1 is the first ink roll, and 60 is the second ink roll.
The first ink roll 59 is impregnated with, for example, red ink, and the second ink roll 60 is impregnated with, for example, black ink. These first and second ink rolls 59 and 60 are rotatably held by a roll holder 61, as shown in FIG. (only one of which is shown in the figure) is rotatably and slidably supported by, for example, a chassis (not shown). Further, the roll holder 61 is always urged toward the center of the drive shaft 2 by a spring member (not shown), and a first
A cam pawl 63 and a second cam pawl 64 are formed,
These first and second cam pawls 63, 64 are formed slightly offset in the axial direction of the ink roll 59.60.

The ink rolls 59, 60 and roll holder 61 configured in this manner are driven by a switching cam 65 shown in FIG. 1O. Although this switching cam 65 is not shown in FIG. 1, it is designed to rotate in synchronization with the type wheel 5, and is, for example, provided integrally on the outside of the type wheel in the outermost row. . Further, as is clear from FIG. 10, a first cam groove 66 is provided on the outer periphery of one surface of the switching cam 65, and a second cam groove 67 is provided on the outer periphery of the other surface, extending approximately half a circumference. Both cam grooves 66
．． 67 are arranged so that they do not overlap each other. and,
The first cam claw 63 of the roll holder 61 mentioned above faces the first cam groove 66 of the switching cam 65, and the roll holder 6
The second cam pawl 64 of the switching cam 65 faces the second cam groove 67 of the switching cam 65.

FIG. 11 is an explanatory diagram showing the engagement relationship between the roll holder 61 and the switching cam 65, and FIG. 12 is an explanatory diagram showing the engagement relationship between the roll holder 61 and the switching cam 65.
60 is an explanatory diagram showing the engagement relationship between the type wheel 60 and the type wheel 5. FIG. Below, we will mainly use these figures to create the ink roll 59.6.
0 inking will be explained.

First, as shown in FIG. 11(a), the roll holder 61
The first cam claw 63 of the switching cam 65 is connected to the first cam groove 6 of the switching cam 65.
6 and the second cam pawl 64 of the roll holder 61
12(a) when the cam claws 63 and 64 are both engaged with the outer peripheral surface of the switching cam 65. As shown, both ink rolls 59 and 60 are separated from the type body 7.7 of the type wheel 5. From this state, when the switching cam 65 rotates, for example, in the direction of arrow F in FIG. Although the second cam pawl 64 is still engaged with the peripheral surface other than the second cam groove 67, as shown in FIG. The ink roll 59 is pressed against the first type body 7 of the type wheel 5. This state continues until the first cam pawl 63 is in the first cam groove 66 and the second cam pawl 64 falls into the second cam groove 67, so that the first cam pawl 63 of the type wheel 5 Typeface 7
The ink of the first ink roll 59, for example, red ink, is applied to all the parts constituting the ink.

The switching cam 65 rotates until the first ink roll 59 finishes coating the final type body 7, that is, the
The switching cam 65 moves approximately 180 degrees from the state shown in Figure (a) as shown by the arrow F.
When the first cam pawl 63 is rotated in the direction shown in FIG. Instead, the second cam pawl 64 falls into the second cam groove 67, and as shown in FIG. 12(C), the first ink roll 5
9 separates from the first type 7 and enters the second ink roll 6
0 is pressed against the second type body 7'. This state is maintained for approximately half a rotation of the switching cam 65,
As a result, all parts of the type wheel 5 constituting the second type body 7' are coated with ink from the second ink roll 60, for example black ink. When the switching cam 65 rotates once from the state shown in FIG. the twelfth
As shown in Figure (a), both ink rolls 59, 60 are again separated from the type 7, 7'. This kind of behavior is
The same applies when the switching cam 65 rotates in the opposite direction to the above, and in either case, one of the ink rolls 59.6
0 is pressed against the type body 7.7', and in about half a rotation in the latter half, the other ink roll 59,60 is pressed against the type body 7.7'.

Next, the above-mentioned rotating shaft 1. Reset cam 29°hammer 4
7. A transmission system for controlling the rotation of the switching cam 65 and the like will be explained using FIGS. 13 to 15.

Fig. 13 is a timing chart showing the relationship between each operation during printing operation for one line, Fig. 14 is an explanatory diagram showing an outline of the transmission system, and Figs. 15 (a) and (b) are preparations for the transmission system. FIG.

In Fig. 13, the drive shaft 2 rotates 1.5 revolutions in either the forward or reverse direction during the printing operation for one line, and the inking operation is performed during the first approximately 172 revolutions of the drive shaft 2. A character selection operation is performed in approximately 1/2 rotation following 1, and a printing operation and a paper feeding operation are performed in the final approximately 172 rotations. Among these operations, the type selection operation is for positioning the type bodies 7, 7' of the type wheel 5 at the desired printing position, so the drive shaft 2 in this case needs to rotate slowly. During the ink eve operation for pressing the ink roll 59, 60 against the type body 7.7 of the type wheel 5 and the paper feeding operation for conveying the recording paper,
Since position control as described above is not required, the drive shaft 2 in this case needs to be rotated quickly.

Such control of the rotational direction and rotational speed is performed by a transmission system shown in FIG. 14. In the figure, reference numeral 68 denotes a drive gear that integrally includes a plurality of gears, and this drive gear 68 is rotated at a constant speed in a fixed direction, for example, in the direction of arrow H in the figure, via an intermediate gear (not shown) by a motor that rotates at a constant speed. do. 69
is a hammer gear that drives the hammer 47; 70 is a paper feed gear that drives the paper feed roller 50; 71 is a reset gear that drives the reset cam; and 72 is the rotating shaft 2.
Of these, the rotary gear 72 is always meshed with the drive gear 68 at a predetermined tooth ratio and rotates at a constant speed in the direction of the arrow ■ in the figure, and the remaining hammer gear 691 is a paper feed gear. 70 and the reset gear 71 are intermittently meshed with the drive gear 68 at a predetermined tooth ratio, and only when the drive gear 68 is at a predetermined angular position, arrows J and K in the figure, respectively.
.

Rotate in the L direction.

Further, 73 is a sun gear integral with the rotating shaft 1, 74 is three planet gears that are circumscribed and meshed with this sun gear 73, 75 is a carrier shaft that pivotally supports these planet gears 74, and 76 is a carrier shaft for supporting these planet gears 74. A carrier 77 integral with the carrier shaft 75 is a ring gear that circumscribes and meshes with the planet gear 74, and these sun gears 73. Planet gear 74, carrier 76, and ring gear 77 constitute a known planetary gear train, of which carrier 76 and ring gear 77 are on the input side, and sun gear 73 is on the output side. 78 is such a planetary gear train and the drive gear 68
a selection gear interposed between the selection gear 7 and the selection gear 7;
8 is integrally provided with three gears having different numbers of teeth, and two of the gears intermittently mesh with the drive gear 68 to rotate or stop in the direction of arrow M in the figure at a predetermined timing. That is, this selection gear 78 rotates at a low speed when the majority gear meshes with the drive gear 68, rotates at high speed when the minority gear of the selection gear 78 meshes with the drive gear 68, and further rotates at a high speed when the minority gear of the selection gear 78 meshes with the drive gear 68. and drive gear 6
It is designed to stop when it is engaged with the arcuate protrusions No. 8 (none of which are shown).

The rotational force of the selection gear 78 configured in this way is transmitted to the ring gear 77 by the remaining gears of the selection gear 78 meshing with the ring gear 77, and the rotational force is transmitted to the first ring gear 77.
It is selectively transmitted to the carrier 76 via a pawl clutch mechanism shown in FIG.

In FIG. 15, 79 is a rotation support shaft for the selection gear 78 and a rotating body 82 to be described later, and 80 is a drive shaft that rotates together with the selection gear 78. A notch 81 is formed on the circumferential surface of the drive shaft. The zero-rotating body 82 is loosely fitted to the rotation support shaft 79, and the carrier 76 of the planetary gear train described above is mounted on the circumferential surface of the zero-rotating body 82.
A support shaft 84 and an engagement shaft 85 are provided upright at a predetermined interval. 86 is a drive pawl that transmits the rotational force of the drive shaft 80, that is, the rotational force of the selection gear 78 rotated by the motor, to the rotating body 82;
The drive claw 82 includes a first arm portion 88 having a projection 87 that is rigid and can be engaged with the cutout portion 81 of the drive shaft 80;
a second arm part 90 having elasticity and a sliding part 89 that comes into elastic contact with the engagement shaft 85 of the rotating body 82;
The base of the arm portion 88 is rotatably inserted into the support shaft 84 of the rotating body 82. Reference numeral 91 indicates a selection lever that is rotatable about a shaft 92, and 93 is a solenoid having an actuator 94. This solenoid 93 moves the selection lever 91 to an engagement position opposite to the drive pawl 86, and to a corresponding drive position. It can be switched to two positions: a non-engaged position where the claw 86 is out of the rotation locus.

In the pawl clutch mechanism configured in this way, first,
As shown in FIG. 15(a), the notch 81 of the drive shaft 80
When the protrusion 87 of the drive claw 86 is engaged with the solenoid 93, the solenoid 93 is energized, and the actuator 9
4 holds the selection lever 91 in a non-engaging position with the drive claw 86, and when the selection rotation shaft 79 and the drive shaft 80 rotate in the direction of arrow M in the figure as the gear 78 rotates,
Due to the engagement between the notch 81 and the protrusion 87 of the drive claw 86, the drive shaft 80 and the rotating body 82 rotate together in the direction of arrow M in the figure. The rotational force of this rotating body 82 is transmitted to the carrier 76 that meshes with the toothed portion 83, and the carrier 76 is connected to the arrow N in the figure.
Rotate in the direction. At this time, the rotational force of the selection gear 78 that rotates in synchronization with the drive shaft 80 is transmitted to the ring gear 77, the planet gear 74, and the sun gear 73, as described above, and therefore, in this case, the rotational force of the motor is The carrier 7, which is the two input shafts of the planetary gear train, is connected via the selection gear 78 and the rotating body 82 that rotates integrally with the selection gear 78
6 and ring gear 77, and the sun gear 73, which is the output side of the planetary gear train, rotates, for example, in the direction of arrow P in FIG. can do.

On the contrary, when it is desired to rotate the rotating shaft l in the direction of the arrow Q in FIG.
The selection lever 91 rotates in the direction of arrow R in Fig. 5(a).
As shown in FIG. 15(b), the drive claw 86 is held in an engagement position where it can face the drive claw 86. In this state, when the rotating body 82 rotates together with the drive shaft 80 in the M direction in the figure, the tip of the first arm portion 88 of the drive claw 86 comes into contact with the guide portion 95 provided at the tip of the selection lever 91. As the drive shaft 80 continues to rotate, the first arm 88 is guided by the guide 95 and moves outward; that is, the drive claw 86 resists the spring force of the second arm 90. The first
The engagement between the protrusion 87 of the arm portion 88 and the cutout portion 81 of the drive portion 80 is released, and the transmission of the rotational force of the drive shaft 80 to the rotating body 82 is cut off. Therefore, in this case, the rotational force of the motor is transmitted via the selection gear 78 to the ring gear 77, which is one of the two input shafts of the planetary gear train, but is not transmitted to the carrier 76, which is the other input shaft. Sun gear 73
The rotating shaft 1 integrated therewith rotates in the direction of the arrow Q in FIG. In this embodiment, the ratio of the number of teeth is set so that forward and reverse rotations occur at the same speed ratio.

In the embodiment configured as described above, the following operations are basically performed by driving the motor.

Inking> As shown in FIG. 1, when the protrusion 21 of the drive pawl 20 is engaged with the notch 3 or 4 of the drive shaft 2, the type wheel 5 is rotated as the drive shaft 2 rotates. When the cam rotates in a predetermined direction, the switching cam 65 shown in FIG.
During rotation, the first ink roll 59 is pressed against the first type body 7 of the type wheel 5, and the second ink roll 60 is pressed against the second type body 7'. That is, for example, when performing red printing, the red ink of the first ink roll 59 is transferred to the first active part of the type wheel 5 during the first half turn of the drive shaft 2 in the direction of the arrow F in FIG. 11(a). The type wheel 5 coated with red ink on the first type body 7 is then subjected to a type selection operation, which will be described later, by approximately half a rotation of the drive shaft 2, and the desired type is selected. The font 7 is positioned at the printing position. On the other hand, when the drive shaft 2 rotates in the opposite direction to the above, in the first half rotation of the drive shaft 2,
The black ink of the second ink roll 60 is transferred to the type wheel 5.
With approximately half a subsequent rotation of the drive shaft 2, the desired type body 7' coated with black ink is selected for printing position.

<Type selection> Once the desired ink has been applied to the type body 7 or 7' in this way during the first half-turn of the drive shaft 2, each type wheel 5 is moved during the subsequent half-turn of the drive shaft 2. is stopped at the desired position and the desired typeface 7.7' is moved by the hammer 4.
The printing position opposite to 7 is selected. Since this type selection operation has been described above, detailed explanation will be omitted here.

Depending on the use, there are type wheels that do not require type selection, but type wheel 5 where type selection was not performed
This is because the engaging convex portion 14 of the selection ratchet 6 always engages with the claw portion 26 of the selection claw 25 at a predetermined position during one rotation.
At this position, the transmission of rotational force from the drive shaft 2 to the selection ratchet 6 and the type wheel 5 is cut off and stopped. At this time, the locking operation by the selection claw 25 of the selection ratchet 6 is automatically performed by the engagement convex portion 14 of the selection ratchet 6 and the claw portion 26 at the tip of the selection claw 25, so that the Thus, there is no need to energize the electromagnetic clutch 31, and its power consumption can be reduced.

The stop position of the type wheel 5 where no type selection has been made is, for example, the position shown in FIG. located in position.

As is clear from the above description, when the drive shaft 2 rotates, for example, approximately 180 degrees clockwise in the figure from the initial state shown in FIG. The type body 7' is coated, and during the subsequent rotation of the drive shaft 2 for about half a turn, that is, from 180 to 360 degrees counted from the initial state, the desired type wheel 5 is stopped and the type body 7' is selected. The type wheel is also stopped if no type selection was made at the end of its rotation. When inking and character selection are performed in about one rotation of the drive shaft 2 in this manner, the drive shaft 2 is stopped and the printing operation continues.

Further, when the drive shaft 2 rotates about one rotation in the counterclockwise direction in the figure from the initial state shown in FIG. 1, red ink is applied to the type body 7 of the type wheel 5 during the rotation, and The selection of the type on the inked type wheel 5 takes place in a similar manner.

Printing> The printed characters 7 or 7' of the selected character wheel 5 face the protruding part 58 of the hole 57 of the error printing prevention body 48, and protrude from the protruding part 58 in the direction of the hammer 47 ( As for the type wheel 5 for which no type has been selected, the blank portion without the type body 7, 7' faces the protrusion 58, as shown in FIG. On the other hand, recording paper (not shown) is
The rotation of the paper feed roller 50 and the driven roller 51 causes the paper to be conveyed along the paper guide 49 onto the erroneous printing prevention plate 48, and when the hammer 47 rotates counterclockwise in FIG. The pressing portion 52 presses the recording paper against the selected type body 7° 7' of the type wheel 5, and one line of printing is performed. In addition, as mentioned above, the hammer 47
Although the pressing portion 52 is highly flexible, its surface is hard and is separated for each digit of the type wheel 5, so that clear characters are printed on the recording paper.

During the above typesetting operation, the type wheel 5, which is stopped at the printing position, receives a rotational force in a predetermined direction when it comes into contact with the rotating hammer 47. It is designed so that it does not shift. This will be explained below with reference to FIGS. 5(b) and 5(c).

FIG. 5(b) shows that, as described above, the engagement between the notch 3 of the drive shaft 2 rotating in the direction of arrow A and the protrusion 21 of the drive pawl 20 is released, and the type wheel 5 is stopped at the type position. In other words, the type is selected. in this case,
The selection ratchet 6 has its tooth portion 13 connected to the pawl portion 2 of the selection pawl 25.
6, and the type wheel 5 has its engagement shaft 11 and support shaft 12 engaged with the ends of the engagement holes 18, 19 of the selection ratchet 6, so that the type wheel 5 is engaged with the hammer 47 in this state. Even if a rotational force in the direction of arrow A is applied from , the type wheel 5 does not rotate. That is, if the rotation directions of the drive shaft 2 and the hammer 47 are different, in other words, the hammer 4
When the direction of the rotational force applied to the type wheel 5 by 7 and the rotation direction of the drive shaft 2 are the same, the type wheel 5 is a selection ratchet whose engagement shaft 11 and support shaft 12 are locked by the selection pawl 25. By engaging with the engagement holes 18 and 19 of No. 6, rotation is restricted and held at the printing position.

If the rotation direction of the drive shaft 2 is opposite to this, that is, the fifth
As shown in Figure (c), the drive shaft 2 rotates in the direction of the arrow.
When the engagement between the notch 3 and the protrusion 21 of the drive pawl 2 is released, the pawl 26 of the selection pawl 25 passes between the teeth 13 of the selection ratchet 6 and locks the type wheel 5. It is adapted to engage with the groove 8. By locking the type wheel 5 with the selection pawl 25 in this way, even if a rotational force in the direction of the arrow A, which is opposite to the direction indicated by the arrow, is applied from the hammer 47 of the type wheel 5 in this state, the type wheel 5 will not move. If the lock groove 8 of the type wheel 5 is not locked by the selection pawl 25 in the state shown in FIG. 5(c), the type wheel 5 receives a rotational force in the direction of the arrow. Engagement hole 18.1 of selection ratchet 6
9 and the engagement shaft 11 and support shaft 12 of the type wheel 5, the rotation of the type wheel 5 is restricted, but when the type wheel 5 receives rotational force in the direction of arrow A, The engagement shaft 11 and the support shaft 12 are not restricted by the match holes 18 and 19, and the type wheel 5 is moved slightly in the direction of the arrow A, that is, the engagement shaft 11 and the support shaft 12 and the engagement hole 1
Therefore, if the rotation direction of the drive shaft 2 and the hammer 47 are the same, in other words, the direction of the rotational force received by the hammer 47 on the type wheel 5 and the direction of the rotation force of the drive shaft 2 If the direction of rotation is different, the lock groove 8 of the type wheel 5 is locked by the selection pawl 25, so that the rotation is restricted and held at the printing position.

Reset> When the printing operation is completed as described above, the drive shaft 2, which had stopped during printing, begins to rotate about half a turn in the same direction again, that is, 360 to 540 degrees when counted from the initial state.
In addition, the tooth portion 13 or the locking convex portion 14 of the selection ratchet 6
All the selection claws 25 that were locked with the reset cam 2
9 rotates it to the standby state. That is, when the reset cam 29 rotates counterclockwise in FIG.
The selection pawl 25 that is engaged with the selection pawl 25 rotates in the direction of arrow C when the cam pawl 30 rides on the convex portion 46 from the stepped portion 45 of the reset cam 29, and thereby the selection pawl 25 and the selection pawl 26 of the selection pawl 25 are rotated. The ratchet 6 is disengaged from the teeth 13. This operation is performed simultaneously for the selection pawls 25 attached to all the type wheels 5, and not only the selection pawls 25 that are engaged with the teeth 13 of the selection ratchet 6 as described above but also the selection pawls 25 that are engaged with the teeth 13 of the selection ratchet 6 as described above. The selection claws that were engaged with the mating convex portions 14 are also released from engagement, and all the selection claws 25 are held in a standby state by the reset cam 29 and the pressing spring 33. Note that the angular position of the type wheel 5 of each digit that is stopped at the printing position varies depending on the type selected; for example, the type wheel 5 with no type selected rotates approximately one rotation from the initial state. However, the type wheel 5 whose type is selected is stopped at a smaller angular position.

In this way, when the locking state of the selection ratchet 6 by the selection pawl 25 is released, the type wheel 5 and the selection ratchet 6 that had been locked at the printing position until then are moved by the drive pawl 21 through the notch in the drive shaft 2. By coming into elastic contact with the circumferential surface of the portion 3.degree.4, it rotates integrally with the drive shaft 2. When the engaging protrusion 96 provided on the outer circumference of the type wheel 5 comes into contact with the claw part 26 of the selection claw 25 in the standby state, the drive shaft 2
Since the transmission force of the rotational force to the type wheel 5 is only the spring pressure of the drive pawl 20 and is very small, the type wheel 5 and the selection ratchet 6 stop at the relevant position, and the subsequent rotation of the drive shaft 2 In this case, the protrusion 21 of the drive claw 20 slips on the circumferential surface of the drive shaft 2. Since one of the engaging protrusions 96 is provided at a desired position on each type wheel 5, specifically at a position outside the locking convex part 14 of the selection ratchet 6, the rotation angle thereof will vary at the printing position. As described above, the engagement protrusions 96 of the type wheels 5 are locked by the selection claws 25, so that the digits are aligned at a constant angular position, that is, about one rotation from the initial state.

When the engaging protrusions 96 of the type wheel 5 of all digits are engaged with the selection claw 25 in this way, the protrusion 21 of the drive claw 2 is reengaged with either one of the notches 3 and 4 of the drive shaft 2. match. In this case, as mentioned above, the rotation angle from the initial state is
While the drive shaft 2 rotates approximately 1.5 revolutions, the type wheel 59, selection ratchet 6, and drive pawl 20 rotate approximately 1 revolution. The protrusion 21 of the drive pawl 20 that has been in the position engages with the other notch 4 of the drive shaft 2 at the reset position. Then, when the drive shaft 2 continues to rotate by a certain amount, that is, approximately 1.5 revolutions counted from the initial state, each type wheel 5 and selection ratchet 6 rotate integrally with the drive shaft 2, and at this time The rotation transmission force of the drive shaft 2 to the type wheel 5 is very large due to the engagement between the protrusion 21 of the drive claw 20 and the notch 3.4 of the drive shaft. The type wheel 5 is rotated outwardly against the spring force of the pressing spring 33 by the engaging protrusion 96 of the type wheel 5, which rotates integrally with the type wheel 5, that is, the claw 26 of the selection claw 25 rides over the engaging protrusion 96, as shown in FIG. At this position, as the drive shaft 20 stops rotating, the type wheel 5 and selection ratchet 6 also stop.

Paper feed> When the printing operation is completed, the paper feed roller 50 is rotated counterclockwise in FIG. 1 in parallel with the reset operation, and the rotation of the paper feed roller 50 causes the paper feed roller to rotate. The recording paper held between the roller 50 and the driven roller 51 is conveyed by a predetermined amount.

Each operation explained above, namely inking.

One line is printed through the following operations: ``Select type'', ``Print'', ``Reset'', and ``Paper feed'', and then the desired printing is performed by repeating this process. Then, by selecting the direction of rotation of the drive shaft 2, that is, by selecting the direction of rotation of the drive shaft 2 between forward and reverse using the pawl clutch mechanism shown in FIG. 15, as described above. , you can choose between two types: red printing and black printing.

(Effects of the Invention) As explained above, according to the printer according to the present invention,
Since the protrusion of the drive pawl and the notch of the drive shaft can be selectively engaged and disengaged by either one of the pair of engaging parts provided on the selection ratchet, it is possible to select type on the type wheel rotating in forward and reverse directions. Moreover, since the type wheel with type selected can be reliably locked by the engagement between the lock groove provided on the type wheel and the selection pawl that locks the selection ratchet, the rotational force of the hammer is applied to the type selected during printing. Even if the type wheel acts on the wheel, the type wheel can be fixed in the printing position to prevent printing misalignment.

[Brief explanation of drawings]

1 to 15 relate to one embodiment of the present invention, in which FIG. 1 is a schematic side view of the printer, FIG. 2 is a front view of the type wheel, FIG. 3 is a front view of the selection ratchet, and FIG. 4 is a schematic side view of the printer. 5 is an exploded perspective view showing the relationship between the type wheel, selection ratchet, drive claw 5 selection claw, and electromagnetic clutch; FIGS. 5(a) to (0) are explanatory views showing the engagement relationship between the drive shaft and the drive claw; 6 figures + 8
) to (C) are explanatory diagrams showing the engagement relationship between the selection ratchet and the selection pawl, FIG. 7(a) is a plan view of the hammer, and FIG.
)) is a sectional view taken along the line E-E in Figure 7(a), Figure 8 is a plan view of the printing error prevention plate, Figure 9 is a perspective view of the roll holder and ink roll, and Figure 10 is a cross-sectional view of the switching cam. Perspective view, Figure 11 (
a) to (0) are explanatory diagrams showing the engagement relationship between the roll holder and the switching cam; FIGS. 12(a) to (C1 are explanatory diagrams showing the engagement relationship between the ink roll and the type wheel; FIG. The figure is a timing chart showing the relationship between each operation during the printing operation for one line, Figure 14 is an explanatory diagram showing an outline of the operation transmission system, and Figures 15 (al) and (b) are the components provided in the power transmission system. Fig. 16 is an explanatory diagram of the pawl clutch mechanism, and Fig. 17 (a) is an explanatory diagram showing the main parts of a conventional printer. Fig. 17 (b) is an explanatory diagram showing the main parts of a conventionally proposed printer. 1. ... Rotating shaft, 2 ... Drive shaft, 3, 4
...Notch, 5.5' ... Type wheel, 6.6' ... Selection ratchet, 7.7'
...Print, 8...Lock groove, 11
．． 11"...Engagement shaft, 12.12'...
... Support shaft, 13.13' ... Teeth, 14.
14'...Locking convex portion, 16.17...
・Release pin, 18°18'19.19'...
・Engagement hole, 20.20'... Drive claw, 21.2
1'...Protrusion, 22.22'...1st
Arm part, 23.23'...Sliding part, 24°24
゛...Second arm, 25.25'...
Selection claw, 26.26'...Claw part, 27...
... Rotation axis, 29 ... Reset cam, 30.
30'...Cam pawl, 31...Electromagnetic clutch, 32...Latching spring, 33...
Pressing springs, 34...' are magnetic coils, 36...
...Yoke, 45...Step drop, 46...
...Protrusion, 47...Hammer, 48...
- Erroneous printing prevention plate, 52... Pressing part, 53...
...Notch, 54...Gap, 57...
- Hole, 58... Protrusion, 59... First
ink roll, 60... second ink roll, 61... roll holder, 62... spindle, 63... first cam claw , 64...
Second cam pawl, 65...Switching cam, 66...
...First cam groove, 67... Second cam groove, 68... Drive gear, 69... Hammer gear, 72... Rotating gear, 73... Sun gear, 74... Planet gear, 75...
... Career axis, 76 ... Career, 77.
...Ring gear, 7B...Selected gear, 7
9... Rotation support shaft, 80... Drive shaft,
81... Notch, 82... Rotating body, 8
3...Tooth portion, 85...Engagement shaft, 86...
...Drive claw, 87...Protrusion, 88...
...First arm, 90...Second arm, 91
... Selection lever, 93 ... Solenoid, 95 ... Guide portion, 96 ... Engagement protrusion. t2FiI sai 3 Figure/Z t e mouth tA) 1'7 hindi-iβaki 7゜j (/'niτ go] ya' iiO figure-sai' i5 Σi1! ni kozai 15 times

Claims (1)

[Claims] A drive shaft that has a notch on the circumference and can rotate in either the forward or reverse direction, and a drive shaft that is rotatably attached to this drive shaft and has typeface on the circumference, and the inner circumference of the drive shaft. a type wheel having a locking groove in the type wheel; a drive pawl held by the type wheel and having a protrusion capable of engaging with a notch of the drive shaft; and a drive pawl rotatably attached to the type wheel via the drive pawl. a selection ratchet having a pair of engaging portions that can be engaged with the driving pawl and having teeth on the circumferential side; and a selection ratchet that can engage with the teeth to selectively lock the rotation of the selection ratchet. When the rotating force of the hammer acts on the circumferential surface of the type wheel that selects type, the selection pawl engages with the locking groove of the type wheel, so that the type wheel is brought to the type selection position. A printer characterized in that it is locked.