JPH042432B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a printer, and more particularly to a printer having an improved type selection mechanism for locking the rotation of a type wheel that rotates in both forward and reverse directions.

(Prior Art) Conventionally, a plurality of type wheels having typefaces on the circumferential side are arranged in rows, for example, 18 rows, around 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. FIG. 16 is an explanatory diagram showing the main parts of this type of conventional printer, which was disclosed in Japanese Utility Model Publication No. 55-21798.

In this FIG. 16, 101 is a rotating shaft, 10
2 is a type wheel attached to this rotating shaft 101. This type wheel 102 has a rotating shaft 101
It has a bearing 102a into which the bearing 10 is inserted.
A selection ratchet 102c is provided to surround 2a. Reference numeral 103 denotes a driving pawl that transmits the rotational force of the rotary shaft 101 to the type wheel 102, and includes a shaft portion 103a inserted into a circular recess 102e formed between the bearing 102a and the selection ratchet 102c, and a pawl portion 103b at the tip. The first arm 103c has a short length and is rigid, and the second arm 103d has a long length and is elastic. This driving claw 103 has a claw portion 103b that is connected to the bearing 102a.
The claw 103b is inserted into a gap 102d formed in the bearing 102a, and the claw 103b is inserted into a notch 1 formed in the rotating shaft 101.
01a, that is, a notch 101a having a surface 101b extending in the axial direction of the rotating shaft 101 and a surface 101c inclined with respect to this surface 101b. In addition, 104 is a selection pawl that can be engaged with the selection ratchet 102c, and the shaft 105
It can be rotated around the center.

In this printer, as shown in FIG. 16, the claw portion 103b of the drive claw 103
The rotating shaft 10 is engaged with the notch 101a of 1.
1 rotates in the direction of arrow R, the rotational force of this rotating shaft 101 is transmitted to the type wheel 102 via the drive claw 103, and this type wheel 10
2 rotates, and the selection pawl 104 rotates in the direction of arrow S and engages with the selection ratchet 102c, thereby locking the rotation of the selection ratchet 102c, that is, the type wheel 102, and selecting the desired type body 10.
2b reaches the printing position. Also, type wheel 10
2 is locked, the rotating shaft 101 continues to rotate, for example, to select another type wheel, but at this time, the opposing surface of the claw portion 103b of the drive claw 103 passes over the surface 101c of the notch 101a. Due to the relative sliding, the drive claw 103 expands against the elasticity of the second arm 103d, and thereby the rotation shaft 1
The transmission of the rotational force to the type wheel 102 is cut off.

(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. Surface 101c of portion 101a and drive claw 103
The drive claw 103 is dependent on the frictional force between the facing surface and the rotating shaft 101, and therefore, when a sudden stop occurs when rotating at high speed, or when starting, the drive claw 103 comes off from the rotating shaft 101 due to the large inertia force. There is a concern, and in order to eliminate this concern, the spring force of the second arm 103d of the drive claw 103 must be set large. However, if the force of the drive pawl 103 is increased in this way, the spring force of each of the drive pawls on all the type wheels including the type wheel not shown increases, so that the rotation axis when the type wheel is stopped increases. The torque for driving the rotary shaft 101 increases, which causes a rise in manufacturing costs due to an increase in the size of the motor that drives the rotary shaft 101, and a rise in running costs due to an increase in power consumption.

In addition, in the conventional printer described above, there is a concern that the driving pawl 103 may come off the rotating shaft 101 if an external load is applied to the type wheel. is not suitable.

Furthermore, in the conventional printer described above, only when the rotary shaft 101 rotates in the direction of arrow R in FIG. 16, when the type wheel 102 is locked, the rotational force of the rotary shaft 101 10
2, and when the rotating shaft 101 rotates in the opposite direction, that is, in the counterclockwise direction in the figure, the claw portion 10 of the drive claw 103
3b remains engaged with the surface 101b of the notch 101a, and character selection cannot be performed. Of course, the surface 10 also exists on the surface 101b of the notch 101a.
If a taper similar to 1c is provided, the rotational force of the rotating shaft 101 described above can be transmitted to the type wheel 102 or released, regardless of whether the rotating shaft 101 rotates forward or backward. Even in such a case, the above-mentioned problem, that is, the problem that the drive pawl 103 comes off the rotation shaft 101 at the time of a sudden stop during high-speed rotation or at the time of starting, remains unresolved.

Therefore, it is an object of the present invention to make it possible to select type from a type wheel that rotates in both forward and reverse directions, and to enable the rotational force of the drive shaft to be applied to the type wheel even if the spring force of the drive pawl is reduced. The object of the present invention is to provide a printer that can reliably transmit data.

(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 A type wheel rotatably attached to a shaft and having a type body on the circumferential side; a drive claw held by the type wheel and having a protrusion that can be engaged with a notch of the drive shaft; is rotatably attached to the type wheel,
a selection ratchet having a pair of locking parts that can be engaged with the driving pawl and having teeth on the circumferential side; and a drive that can engage with the teeth and selectively lock the rotation of the selection ratchet. means, when the notch of the drive shaft and the protrusion of the drive pawl are in an engaged state, the rotational force of the drive pawl is transmitted to the type wheel and the selection ratchet, respectively, via the drive pawl; When the selection ratchet is locked by the driving means, the rotating driving pawl slides into contact with one of the locking parts of the selection ratchet and deforms, thereby engaging the notch part of the drive shaft. The feature is that the driving pawl is configured to be disengaged from the protrusion.

(Function) That is, when the selection ratchet is locked during type selection, the drive pawl, which rotates integrally with the drive shaft and the type wheel, engages one of the locking portions of the selection ratchet depending on the direction of rotation. The protrusion of the drive pawl and the notch of the drive shaft are disengaged from each other by being expanded outward by the subsequent rotation of the drive shaft. Then, the transmission of the rotational force of the drive shaft to the type wheel is cut off, and the type wheel is locked at the desired type selection position.

(Example) Hereinafter, an example of the present invention will be described 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 the rotation axis,
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. Reference numeral 2 denotes a drive shaft which rotates together with the rotary shaft 1, and two notches 3 and 4 are formed on the circumferential surface of the drive shaft at 180 degrees opposite positions in the axial direction. 5
6 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 FIG. 2, on the outer circumferential surface of the type wheel 5, two groups of typefaces 7, 7 are arranged, for example, "0, 1, 2...9, +, -, ×, ÷" etc. ', and a plurality of lock grooves 8 are provided on the inner circumferential side thereof corresponding to each type body 7, 7', and a bearing 9 into which the drive shaft 2 is inserted is provided upright in the center. There is. A gap 10 is formed in a part of the bearing 9, and an engagement shaft 11 and a support shaft 12 are implanted on the outer periphery of the bearing 9 so as to be opposed to each other by approximately 180 degrees through the center of the type wheel 5. ing.

On the other hand, as shown in FIG. 3, the selection ratchet 6 is provided with a plurality of teeth 13 and one locking protrusion 14 on the outer circumferential surface corresponding to the printed characters 7, 7', and in the center thereof. A hole 15 is bored into which the bearing 9 of the type wheel 5 is inserted. A pair of release pins 1 are provided on the outer periphery of the hole 15 at a predetermined interval.
6 and 17 are erected, and the type wheel 5
The engagement hole 1 has an oval shape that can accommodate the engagement shaft 11 and the support shaft 12.
8 and 19 are drilled.

Returning to FIG. 1, reference numeral 20 denotes a driving 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 a first arm part 22 having a projection 21 that is rigid and can be engaged with the notches 3 and 4 of the drive shaft 2, and a first arm part 22 that is elastic and has an engagement shaft 11 of the type wheel 5. sliding part 2 that comes into elastic contact with
3, and the base of the first arm 22 is connected to the support shaft 12 of the type wheel 5.
is rotatably inserted into the On the other hand, as shown by two-dot chain lines in the figure, both release pins 16 and 17 of the selection ratchet 16 are located near the first arm portion 22 via the protrusion 21 of the drive pawl 20, and are also engaged with the type wheel 5. The tips of the shaft 11 and the support shaft 12 are located in both engaging holes 18 and 19 of the selection ratchet 6, respectively.

Further, reference numeral 25 shown in FIG. 1 is a selection pawl capable of locking the rotation of the selection ratchet 6, and the selection pawl 25 engages the teeth 13 of the selection ratchet 6, the locking protrusion 14, and the locking groove 8 of the type wheel 5. Each has an engageable pawl 26 at its tip, a hole 28 in the center into which a rotating shaft 27 is inserted, and a cam pawl 30 that engages with a reset cam 29 at its rear end. 31 is a claw 25 that selects the rotational force of the rotation shaft 27.
32 is a locking spring capable of holding the selection pawl 25 in a state of engagement with the selection latch 6; 33 cooperates with this locking spring 32; This is a pressure spring that holds the selection pawl 25 in a state away from the selection ratchet 6.

FIG. 4 is an exploded perspective view showing the relationship among the type wheel 5, selection latch 6, drive pawl 20, selection pawl 25, and electromagnetic clutch 31. As shown in the figure, the electromagnetic clutch 31 is roughly composed of an electromagnetic coil 34, a holding base 35, a yoke 36, and a rotating body 37. The electromagnetic coil 34 has a hole 38 in the center thereof into which the rotating shaft 27 is inserted, and is held by a fan-shaped projection 39 on the upper part of the holding table 35. A cylindrical yoke 36 is attached to surround the electromagnetic coil 34, and has four notches 40 formed at 90 degree intervals on one side thereof. 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, so that the rotating shaft 27 and the rotating body 37 rotate together,
In addition, a notch 4 of the yoke 36 is provided on the peripheral wall of the rotating body 27.
Similarly, four protrusions 42 that engage with 0 are formed at 90 degree intervals. The electromagnetic clutch 31 configured in this manner can rotate two selection pawls, that is, the first selection pawl 25 and the second selection pawl 25' in the figure. As described above, these first and second selection claws 25, 25' have claw portions 26, 26' at their tips, holes 28, 28' in the center, and cams 30, 30' at their rear ends, respectively. Furthermore, slightly larger fan-shaped notches 43 and 43' are formed in the lower part, respectively, in accordance with the shape of the protrusion 39 of the holding base 35.

These first and second selection claws 25,
25', when assembling the electromagnetic clutch 31,
As described above, the yoke 36 is attached to the electromagnetic coil 34 so as to surround the electromagnetic coil 34, and each protrusion 42 of the rotating body 37 fits into each notch 4 of the yoke 36.
0. Further, both selection claws 25, 25' are rotatable about the rotation shaft 27,
And those notches 43, 43' are 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. When assembled in this way,
Both selection claws 25, 25' body parts 44, 44' are connected to the yoke 3.
6 are arranged to face each other on both sides.

On the other hand, the above-mentioned type wheel 5, selection ratchet 6 and drive pawl 20 are connected to the drive shaft 2 in the following manner.
will be installed on the That is, for example, the first
The bearing 9 of the first type wheel 5 is inserted, and then the hole of the drive pawl 20 is inserted into the support shaft 12 of the first type wheel 5.
The protrusion 21 of the first arm portion 22 is inserted into the bearing 9
is inserted into the cavity 10 of the drive shaft 2, and then, for example, the protrusion 21 is engaged with the notch 3 of the drive shaft 2. Further, the second arm portion 24 is mounted so that its sliding portion 23 comes into elastic contact with the engagement shaft 11 of the first type wheel 5. 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 pins 16, 17 are inserted inside the first arm 22.
It is attached to the first type wheel 5 so that the engagement holes 18 and 19 correspond to the engagement shaft 11 and the support shaft 12, respectively.

The drive shaft 2 includes the above-mentioned first type wheel 5,
Similar to the first selection ratchet 6 and drive pawl 20, the second type wheel 5', selection ratchet 6' and drive pawl 20' are mounted. That is, the bearing 9' of the second type wheel 5' is inserted into the drive shaft 2, and then the hole of the drive pawl 20' is inserted into the support shaft 12' of the second type wheel 5', and the first arm The protrusion 21' of 22' is inserted into the cavity 10' of the bearing 9', and then this protrusion 21' is engaged with the notch 3 of the drive shaft 2. Further, the second arm portion 24' is mounted such that its sliding portion 23' comes into elastic contact with the engagement shaft 11' of the second type wheel 5'. The hole 15' of the second selection ratchet 6' is then inserted into the bearing 9 of the second type wheel 5' so that its release pin (not shown) is inside the first arm 22' and It is attached to the second type wheel 5' so that the engagement holes 18' and 19' correspond to the engagement shaft 11' and the support shaft 12', respectively.

Then, the above-mentioned first type wheel 5, the first
a selection ratchet 6, a second type wheel 5',
The second selection ratchet 6' is arranged such that the phase of the teeth 13 of the first selection ratchet 6 and the phase of the teeth 13' of the second selection ratchet 6' are different, for example, shifted by 1/2 pitch from each other. , that is, tooth part 1
The tooth portion 13' is arranged on the drive shaft 2 so that the tooth portion 13' is located at a position corresponding to the gap between the teeth.

Although not shown, the two type wheels 5, 5', selection ratchets 6, 6', and
A plurality of sets, for example nine sets, of the drive claws 20, 20', the selection claws 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 claws 20, 20', and FIG. 6 is an explanatory diagram showing the engagement relationship between the selection ratchets 6, 6' and the selection claws 25, 25'. It is a diagram. Hereinafter, the character selection operation of the character wheels 5, 5' will be explained mainly using these figures.

First, as shown in FIG. 5a, the protrusions 21, 21' of the drive pawls 20, 20' are engaged with the notch 3 of the drive shaft 2, and as shown in FIG. 6a, , the end portions of the selection claws 25, 25' are engaged with the locking spring 3.
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, for example, a motor (not shown) while the drive shaft 2 and the rotation shaft 27 are in a standby state where the peaks 2 and 32' are not climbed over, the drive shaft As the drive claws 20 and 2 rotate, the notches 3 and the protrusions 21 and 21' of the drive claws 20 and 20' engage with each other as shown in FIG.
0', and this rotational force is transmitted from the first arm 22 of the drive pawl 20, 20' to the release pins 16, 17, 16', 1 of the selection ratchet 6, 6'.
7', whereby the type wheels 5,
5', selection latches 6, 6', and drive shaft 2 rotate together in the direction of arrow A. During this time,
Although the rotating body 37 and the yoke 34 rotate with the rotation of the rotating shaft 27, the rotational force of the rotating shaft 27 is not transmitted to the selection claws 25, 25'. 25' is maintained in the standby state shown in FIG. 6a.

For example, when the desired type body 7 or 7' of the first type wheel 5 comes close to the printing position,
When the electromagnetic coil 34 is energized, this causes the bodies 44, 44' of the selection claws 25, 25' to move toward the yoke 36.
It is adsorbed to the side end surface of. Therefore, the selection nail 2
5 and 25' are about to rotate integrally with the yoke 36 as shown by arrows B and C in FIGS. Since it is located between the tooth portions 13 of No. 6,
As shown in FIG. The rotation of the first selection ratchet 6 is locked.
This state is stably maintained by the spring force of the locking spring 32. When the rotation of the first selection ratchet 6 is stopped by the first selection pawl 25 in this way, the fifth rotation of the drive shaft 2 continues.
As the rotation in the direction of arrow A in FIG.
In other words, the driving pawl 20 is expanded against the spring force of the second arm 24, thereby causing the driving pawl 20 to move outward as shown in FIG. 5b.
As shown in , the engagement between the protrusion 21 of the first arm 22 and the notch 3 of the drive shaft 2 is released, and the rotational force of the drive shaft 2 is transferred to the first selection ratchet 6 and the first type wheel 5. transmission is cut off. In addition, at this time, the engagement shaft 11 provided on the first type wheel 5 and the support shaft 1
2 engages with the ends of engagement holes 18, 19 drilled in the first selection ratchet 6, as shown in FIG. 5b, thereby connecting the first type wheel 5 and the first selection ratchet 6. The relative position with respect to is regulated. Further, when the second arm portion 24 of the drive claw 20 is expanded, the sliding portion 23 at the tip thereof is moved toward the second arm portion 24.
4 is bent in the direction of expansion of the first type wheel 5 and is in elastic contact with the engagement shaft 11 of the first type wheel 5, so it slides into contact with the engagement shaft 11 with a relatively small frictional force, and this engagement shaft 11 is not driven. Support shaft 1 via the center of shaft 2
Since the second arm portion 24 is provided at a position opposite to the second arm portion 24
By increasing the length of the spring constant, the spring constant can be set small, that is, the engagement force when the protrusion 21 of the drive claw 20 is engaged with the notches 3 and 4 of the drive shaft 2 can be increased, and these engagements can be released. It can reduce the load when the machine is running.

On the other hand, as shown in FIG. 6c, the second selection pawl 25' has a phase shift of 1/2 pitch as described above, so that the pawl portion 26' engages the tooth portion 13 of the second selection ratchet 6'. ′ and waits in this state. Therefore,
The second selection ratchet 6' and the second type wheel 5' continue to rotate. Also, for example, in synchronization with the rotation locking of the first type wheel 5, the electromagnetic coil 3
4, the transmission of the rotational force of the rotation shaft 27 to the second selection pawl 25' is cut off, and the second selection pawl 25' is moved to the position shown in FIG. 6 by the force of the locking spring 32. a
Returns to the standby state shown in . Therefore, regardless of the rotation of the drive shaft 2, the second selection claw 25' does not engage with the second selection ratchet 6'.

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, so that the second type wheel 5' in the standby state is moved to the above-mentioned position. It is positioned in the same manner as the type wheel 5 of No. 1, ie, in the state shown in FIG. 6b. Further, 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 portions 26 of the selection claws 25, 25',
26' are the teeth 13, 1 of the selection ratchets 6, 6'.
3', that is, during the selection operation of the type bodies 7, 7', the cam pawls 30, 30' of the selection pawls 25, 25' engage the reset cam 29, as shown in FIG. 6b. It is located at a position opposite to the stepped portion 45 provided in the. When the printing operation is completed, the rotation of the reset cam 29 causes the protrusion 46 provided on the reset cam 29 to close the selection claws 25, 25'.
As a result, all the selection pawls including the selection pawls 25 and 25' are moved over the peak of the locking spring 32 in the direction shown by arrow C in FIGS. 6b and 6c. and is held in the standby state again by the peak of the locking spring 32 and the pressing spring 33.
When the selection claws 25, 25' are reversed in this way,
The engagement between the selection pawls 25, 25' and the selection latches 6, 6' is released. In this state, when the drive shaft 2 rotates, for example, in the direction of arrow A in FIG. 5a, the drive claw 2
The protrusions 21 and 21' at 0 and 20' slip on the circumferential surface of the drive shaft 2, and the notches 3 and 4 are attached to the protrusions 21 and 2.
1', the spring force of the second arm portions 24, 24' of the drive claws 20, 20' causes the protrusion 2 to move.
1, 21' engages in the notch 3 or 4, and as shown in FIG. It should be noted that exactly the same operation is performed for the selection claws, drive claws, selection ratchets, type wheels, etc. of other sets (not shown).

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 the device is rotated in this direction. That is, as shown in FIG. 5c, for example, when the teeth 13 of the selection ratchet 6 are engaged with the selection pawl 25 and the rotation of the selection ratchet 6 is stopped, the subsequent fifth rotation of the drive shaft 2 is stopped. As the drive claw 20 rotates in the direction of arrow D in FIG. The engagement between the protrusion 21 of the first arm 22 and the notch 3 of the drive shaft 2 is released, and 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 rotational direction 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 fifth As shown in Figure c, the claw portion 26 of the selection claw 25
is adapted to engage with a locking groove 8 provided in the type wheel 5. This point will be explained in detail in the section <Printing operation> below.

Returning again to FIG. 1, 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 denotes an error printing prevention plate. A paper guide (not shown) that guides recording paper to a printing position; 50 is a paper feed roller disposed near this paper guide 49; 51 is a driven roller disposed opposite to this paper feed roller 50; The upper recording paper is conveyed while being held between the paper feed lower 50 and the driven roller 51.

FIG. 7a is a plan view of the hammer 47, FIG. 7b
is a sectional view taken along the line E-E. As shown in these figures, the hammer 47 is attached to the type wheel 5.
A plurality of, for example, 18 chevron-shaped pressing portions 5 corresponding to the number of
2, 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 deformable. Further, since the pressing parts 52 are separated from each other by the notches 53, for example, the hammer 47
Even if the type wheel 5 or the type wheel 5 is slightly eccentric, a uniform pressing force can be applied to each type wheel. 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 prevention plate 48 is made of, for example, a bent metal plate, and fixing ears 56 are formed on both sides of its lower end. Further, a plurality of holes 57 are bored in the longitudinal direction at predetermined intervals, and these holes 57 are formed, for example, 18, corresponding to each type wheel 5. The type bodies 7, 7' of each type wheel 5 are connected to the hammer 4 through these holes 57.
7, but as is clear from FIG. 1, the misprint prevention plate 48 is bent so that the central portion of the hole 57 protrudes, and the length of this protrusion 58 (as shown in FIG. l) is set to be approximately equal to one of the type bodies 7, 7' of the type wheel 5. Therefore, only the typeface selected for the printing position projects 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 of the object.

Further, 59 in FIG. 1 is the first ink roll, 6
0 is a 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,
60 is a roll holder 61 as shown in FIG.
The roll holder 6
Support shafts 62 (only one of which is shown in the figure) provided at both ends of the support shaft 1 are rotatably and slidably supported by, for example, a chassis (not shown). In addition, the roll holder 6
1 is constantly biased toward the center of the drive shaft 2 by a spring member (not shown), and furthermore, a first cam pawl 63 and a second cam pawl 64 are provided at one end of the roll holder 61. are formed, and these first and second cam claws 63, 64 are connected to the ink rolls 59, 6.
It is formed with a slight deviation in the axial direction of 0.

Ink rolls 59, 60 configured in this way
The roll holder 61 is driven by a switching cam 65 shown in FIG. Although this switching cam 65 is not shown in FIG. 1, it is adapted 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 the circumference. The cam grooves 66 and 67 are arranged so that they do not overlap with each other. Then, the above-mentioned roll holder 6
The first cam pawl 63 of the roll holder 61 faces the first cam groove 66 of the switching cam 65, and the second cam pawl 64 of the roll holder 61 faces the second cam groove 67 of the switching cam 65.
It is becoming more and more confronting.

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 ink rolls 59, 60 and the type wheel 5. Inking of the ink rolls 59 and 60 will be explained below mainly using these figures.

First, as shown in FIG. 11a, the first cam pawl 63 of the roll holder 61
is not in the cam groove 66 of the roll holder 61 and the second cam pawl 64 of the roll holder 61 is not in the second cam groove 67 of the switching cam 65, that is, both cam pawls 63, 6
4 are both engaged with the outer peripheral surface of the switching cam 65, both ink rolls 59, 60 are separated from the type bodies 7, 7' of the type wheel 5, as shown in FIG. in a state. From this state,
When the switching cam 65 rotates, for example, in the direction of arrow F in FIG.
Although the second cam pawl 6 falls into the cam groove 66 of
4 is still engaged with the peripheral surface other than the second cam groove 67, so 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 first 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 first ink roll 59 is applied to all parts constituting the
of ink, for example, red ink, is applied.

The switching cam 65 rotates until the application of the first ink roll 59 to the final type body 7 is completed.
That is, when the switching cam 65 rotates about 180 degrees in the direction of arrow F from the state shown in FIG. The ink roll 59 rides on the circumferential surface other than the first cam groove 66, and the second cam pawl 64 instead falls into the second cam groove 67, and as shown in FIG. 12c, the first ink roll 59 1
A second ink roll 60 separates from the typeface 7 of
is pressed against the second type body 7'. Such a condition is
The switching cam 65 is held for approximately half a rotation, thereby applying the ink of the second ink roll 60, e.g. black ink, to all parts of the type wheel 5 constituting the second type body 7'. be done. When the switching cam 65 rotates once from the state shown in FIG. Fig. 12a
As shown in FIG. 2, both ink rolls 59, 60 are separated from the type bodies 7, 7' again. This kind of behavior is
The same is true when the switching cam 65 rotates in the opposite direction to that described above; in either case, one of the ink rolls 59, 60 rotates in the first half of the rotation of the switching cam 65 to rotate the type bodies 7, 7. ', and in the latter half of the rotation, the other ink roll 59, 60 is pressed against the type bodies 7, 7'.

Next, the above-mentioned rotating shaft 1, reset cam 29,
A transmission system for controlling the rotation of the hammer 47, the switching cam 65, etc. 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 pawl clutch mechanisms provided in the transmission system. FIG.

In Fig. 13, the drive shaft 2 rotates 1.5 rotations in either the forward or reverse direction during the printing operation for one line, and the inking operation is performed during the first 1/2 rotation of the drive shaft 2. A character selection operation is performed in the following 1/2 rotation, and a printing operation and a paper feeding operation are performed in the final 1/2 rotation. 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. Furthermore, during the inking operation for pressing the ink rolls 59 and 60 against the type bodies 7 and 7' of the type wheel 5 and the paper feeding operation for conveying the recording paper, the above-mentioned position control is not necessary. Therefore, the drive shaft 2 in this case needs to be rotated quickly.

Such control of the rotation direction and rotation speed is carried out in the 14th
This is done by the transmission system shown in the figure. In the figure, reference numeral 68 denotes a drive gear that integrally includes a plurality of gears, and the drive gear 68 is driven by a motor rotating at a constant speed to move in a fixed direction, for example, in the direction of arrow H in the figure, via an intermediate gear (not shown). Rotate quickly. 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; 72 is a rotary gear that drives the rotating shaft 27; Of these, the rotating gear 72 is always meshed with the driving gear 68 at a predetermined tooth ratio and rotates at a constant speed in the direction of arrow I in the figure.
The remaining hammer gear 69, paper feed gear 70, and reset gear 71 are intermittently engaged with the drive gear 68 at predetermined tooth ratios, and only when the drive gear 68 is at a predetermined angular position, the respective arrows J in the figure ，
Rotates in the K and L directions.

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 supports these planet gears 74, and 76 is a carrier shaft 75. A carrier 77 integrated with the planet gear 74 is a ring gear that meshes externally with the planet gear 74, and these sun gear 73, planet gear 74, carrier 76, and ring gear 77 constitute a known planetary gear train, of which the carrier 76 and the ring gear 77 is on the input side, sun gear 7
3 is on the output side. 78 is a selection gear interposed between the planetary gear train and the drive gear 68, and this selection gear 78 has three different numbers of teeth.
By integrally comprising two gears, two of which are intermittently meshed with the drive gear 68,
It rotates or stops in the direction of arrow M in the figure at a predetermined timing. That is, the selection gear 78 rotates at a low speed when the majority gear meshes with the drive gear 68, and the minority gear of the selection gear 78 meshes with the drive gear 68.
It rotates at high speed when it meshes with the selection gear 78, and stops when the toothless portion of the selection gear 78 and the circular arc-shaped protrusion (both not shown) of the drive gear 68 engage through the toothless portion. It's becoming like that.

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 is also transmitted to the ring gear 77 through the pawl clutch mechanism shown in FIG. The signal is selectively transmitted to the carrier 76.

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. . Rotating body 82
is loosely fitted to the rotational support shaft 79, has a toothed portion 83 on its circumferential surface that meshes with the carrier 76 of the planetary gear train described above, and a support shaft 84 and an engagement shaft 85 are spaced apart from each other at a predetermined interval. It is erected. Reference numeral 86 denotes 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. 81, and a second arm 90 having elasticity and having a sliding part 89 that comes into elastic contact with the engagement shaft 85 of the rotating body 82. Cage, first arm portion 8
The base of 8 is rotatably inserted into a support shaft 84 of a 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. 15a, the drive shaft 80
The protrusion 87 of the drive claw 86 is engaged with the notch 81 of the drive claw 86, and the solenoid 93 is energized and its actuator 94 holds the selection lever 91 in a position in which it is not engaged with the drive claw 86. 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, the engagement between the notch 81 and the protrusion 87 of the drive pawl 86 causes the drive shaft 80 to rotate. The body 82 rotates as one 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.
The carrier 76 rotates in the direction of arrow N in the figure. At this time, the selection gear 78 rotates in synchronization with the drive shaft 80.
As mentioned above, Kaidou Riki has ring gear 77,
The rotational force of the motor is transmitted to the planet gear 74 and the sun gear 73. Therefore, in this case, the rotational force of the motor is
The signal is transmitted to the carrier 76 and ring gear 77, which are the two input shafts of the planetary gear train, through the selection gear 78 and the rotating body 82 that rotates integrally with the selection gear 78, and to 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.
The rotating shaft 1 integrated with the sun gear 73 can also be rotated in the direction of arrow P.

On the contrary, the axis of rotation 1 is
When it is desired to rotate the selection lever 91 in the direction shown in FIG. As shown in FIG. 15b, it 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. , followed by the drive shaft 8
0, the first arm portion 88 is guided by the guide portion 95 and moves outward, that is, the driving claw 86 is expanded against the spring force of the second arm portion 90, and this As a result, the engagement between the protrusion 87 of the first arm portion 88 and the notch 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 to the ring gear 77, which is one of the two input shafts of the planetary gear train, via the selection gear 78, but is not transmitted to the carrier 76, which is the other input shaft. Sun gear 73 and rotating shaft 1 integrated therewith
The rotating shaft 1 rotates in the direction of arrow Q in FIG. In this case, the gear ratio is set so that the gear rotates forward and reverse 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, as the drive shaft 2 rotates, the type wheel 5
When the switching cam 65 rotates in a predetermined direction, the switching cam 65 shown in FIG.
The 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, 7'. That is, for example, when printing in red, the red ink of the first ink roll 59 is transferred to the first type body 7 of the type wheel 5 during the first half turn of the drive shaft 2 in the direction of arrow F in FIG. 11a. The type wheel 5 is coated with red ink and thus the first type body 7 is coated with red ink.
Subsequently, by about half a rotation of the drive shaft 2, a type selection operation, which will be described later, is performed, and the desired type 7 is positioned at the printing position. On the other hand, when the drive shaft 2 rotates in the opposite direction, the black ink of the second ink roll 60 is applied to the second type body 7' of the type wheel 5 during the first half rotation of the drive shaft 2. coated,
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 approximately the first half turn of the drive shaft 2, each type wheel 5 is moved to the next drive shaft 2.
During about half a rotation, the print head is stopped at a desired position and the desired type body 7, 7' is selected in a printing position opposite the hammer 47. Since this type selection operation has been described above, detailed explanation will be omitted here.
Depending on the use, there are some type wheels that do not require type selection, but in the type wheel 5 in which no type is selected, the engagement convex portion 14 of the selection ratchet 6 engages the claw of the selection pawl 25 during one rotation of the type wheel 5. Since it always engages with the portion 26 at a predetermined position, the transmission of rotational force from the drive shaft 2 to the selection ratchet 6 and type wheel 5 is cut off and stopped at that position. At this time, the locking operation by the selection pawl 25 of the selection ratchet 6 is automatically performed by the engaging convex portion 14 of the selection ratchet 6 and the pawl portion 26 at the tip of the selection pawl 25. Thus, there is no need to energize the electromagnetic clutch 31, and its power consumption can be reduced.
In addition, the type wheel 5 where no type selection was made
The stopping position is, for example, the position shown in FIG.
In this position, the type bodies 7, 7' provided on the type wheel 5 are located at a position not facing the hammer 47.

As is clear from the above explanation, 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, i.e. 180 to 360 degrees counted from the initial state, the desired type wheel 5 is stopped and the type body 7' is selected. At the same time, any type wheels with no type selections at the end of their rotation are also stopped. 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 printed character wheel 5 of all the selected digits face the protruding part 58 of the hole 57 of the misprint prevention body 47, and the hammer 47 is pressed from the protruding part 58.
(For the type wheel 5 for which no type was selected, as shown in FIG. 1,
The blank part without the typefaces 7, 7' is the protruding part 58.
). On the other hand, the recording paper (not shown) is conveyed along the paper guide 49 onto the erroneous printing prevention plate 48 by the rotation of the paper feed roller 50 and the driven roller 51, and in this state, the hammer 47 is rotated counterclockwise in FIG. When the recording paper is rotated in the direction, the pressing portion 52 of the hammer 47 presses the recording paper against the selected type body 7, 7' of the type wheel 5, and printing for one line is performed.
Note that, as described above, the pressing portion 52 of the hammer 47
is highly flexible but has a hard surface and is separated for each digit of the type wheel 5, so that descriptive type is printed on the recording paper.

During the above-mentioned printing operation, the type wheel 5 that is stopped at the printing position receives a rotational force in a predetermined direction when it comes into contact with the rotating hammer 47. In this embodiment, this rotational force causes the type wheel 5 to rotate. Designed to prevent the printing position from shifting. This will be explained below with reference to FIGS. 5b and 5c.

FIG. 5b shows the notch 3 of the drive shaft 2 and the protrusion 2 of the drive pawl 20 rotating in the direction of the arrow A, as described above.
1 is released and the type wheel 5 is stopped at the type position, that is, a type is selected. In this case, the tooth portion 13 of the selection ratchet 6 engages with the pawl portion 26 of the selection pawl 25, 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. Since the type wheel 5 is engaged with the part, even if a rotational force in the direction of arrow A is applied from the hammer 47 to the type wheel 5 in this state, the type wheel 5 does not rotate. That is,
When the rotation directions of the drive shaft 2 and the hammer 47 are different,
In other words, the type wheel 5 is moved by the hammer 47.
When the direction of the rotational force received by the type wheel 5 is the same as the direction of rotation of the drive shaft 2, the type wheel 5 is engaged with the selection ratchet 6 whose engagement shaft 11 and support shaft 12 are locked by the selection pawl 25. Rotation is restricted by locking in the matching holes 18 and 19, and the printing position is held.

When the direction of rotation of the drive shaft 2 is opposite to this, that is, as shown in FIG. In the released state, the pawl 26 of the selection pawl 25 passes between the teeth 13 of the selection ratchet 6 and engages with the locking groove 8 of the type wheel 5. By locking the type wheel 5 with the selection pawl 25 in this manner, even if a rotational force in the direction of the arrow A, which is opposite to the direction of the arrow D, is applied from the hammer 47 of the type wheel 5 in this state, the type wheel 5 can be locked. 5 does not rotate. If the lock groove 8 of the type wheel 5 is not locked by the selection pawl 25 in the state shown in FIG. Although the rotation of the type wheel 5 is restricted by the engagement between the engagement holes 18 and 19 of the type wheel 5 and the engagement shaft 11 and the support shaft 12 of the type wheel 5, the type wheel 5 receives a rotational force in the direction of arrow A. In this case, the engagement shaft 1 by the engagement holes 18 and 19
1 and the support shaft 12 are not regulated, and the type wheel 5 moves slightly in the direction of the arrow A, that is, the engagement shaft 11
And, it rotates by the clearance between the support shaft 12 and the engagement holes 18 and 19. Therefore, when the rotation directions of the drive shaft 2 and the hammer 47 are the same, in other words, when the direction of the rotational force applied to the type wheel 5 by the hammer 47 is different from the rotation direction of the drive shaft 2, the type wheel 5 The lock groove 8 is the selection claw 2.
5, 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, will again begin to rotate approximately half a turn in the same direction, that is, 360 to 540 degrees when counted from the initial state. Teeth 13 of selection ratchet 6
Alternatively, all the selection claws 25 that are locked with the locking protrusion 14 are rotated by the reset cam 29 to the standby state. That is, when the reset cam 29 rotates counterclockwise in FIG.
As shown in FIG. 2, the selection pawl 25 engaged with the teeth 13 of the selection ratchet 6 rotates in the direction of arrow C as its cam pawl 30 rides on the convex portion 46 from the stepped portion 45 of the reset cam 29. As a result, the engagement between the claw portion 26 of the selection claw 25 and the tooth portion 13 of the selection ratchet 6 is released. This operation is carried out by selection claws 25 attached to all type wheels 5.
At the same time, not only the selection pawl that was engaged with the teeth 13 of the selection ratchet 6 as described above but also the selection pawl that was engaged with the engagement protrusion 14 of the selection ratchet 6 are also engaged. The state is released, and all the selection claws 25 are connected to the reset cam 29 and the pressing spring 3.
3, it is held in a standby state. It should be noted 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 for which no type was selected rotated 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 latch 6 by the selection pawl 25 is released, the type wheel 5 and the selection latch 6, which had been locked at the printing position, are moved by the drive pawl 21 into the notch of the drive shaft 2. By coming into elastic contact with the circumferential surfaces other than the parts 3 and 4, it rotates integrally with the drive shaft 2. And type wheel 5
When the engagement protrusion 96 provided on the outer periphery comes into contact with the claw portion 26 of the selection claw 25 in the standby state, the force of transmitting the rotational force of the drive shaft 2 to the type wheel 5 is reduced by the spring pressure of the drive claw 20. Since the type wheel 5 and the selection ratchet 6 stop at this position, the protrusion 21 of the drive pawl 20 slips on the circumferential surface of the drive shaft 2 during the subsequent rotation 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 protrusion 14 of the selection ratchet 6, the rotation angle of the engaging protrusion 96 varies at the printing position. As described above, the engaging protrusions 96 of the hot 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. be exposed.

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 approximately 1.5 rotations for the drive shaft 2, while the rotation angle for the type wheel 5, selection ratchet 6, and drive pawl 20 is approximately 1 rotation.
For example, the protrusion 21 of the drive pawl 20 that was engaged with one notch 3 of the drive shaft 2 in the initial state 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, when it reaches about 1.5 rotations from the initial state,
Each type wheel 5 and selection ratchet 6 rotate integrally with the drive shaft 2, and the rotational force transmitted from the drive shaft 2 to the type wheel 5 at this time is transmitted through the notch of the drive shaft of the protrusion 21 of the drive pawl 20. 3 and 4, the selection claw 25 is attached to the engagement protrusion 96 of the type wheel 5 that rotates integrally with the drive shaft 2.
The selection claw 25 is rotated outward against the spring force of the pressing spring 33, that is, the claw portion 26 of the selection claw 25 overcomes the engagement protrusion 96 and enters the initial state shown in FIG.
At this position, as the drive shaft 2 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 50 to and driven roller 5
The recording paper held between the two rollers 1 is conveyed a predetermined distance.

One line of printing is performed through each of the operations explained above, namely <Inking>, <Type Selection>, <Printing>, <Reset>, and <Paper Feed>, and by repeating this process, desired printing is achieved. will be held. 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.

In the embodiment configured in this way, the rectangular notches 3 and 4 of the drive shaft 2 press against the rectangular protrusion 21 of the drive pawl 20, that is, the rotation direction of the drive shaft 2 The rotational force of the drive shaft 2 is applied to the type wheel 5 through a plane substantially orthogonal to the
In addition, when selecting type, the release pins 16 and 17 of either one of the selection ratchets 6 in the locked state release the first arm portion of the drive pawl 20 according to the direction of rotation of the drive shaft 2. 22 outward, that is, the drive shaft 2 is almost unaffected by the frictional force between the protrusion 21 of the drive pawl 20 and the notches 3 and 4 of the drive shaft 2.
The transmission of the rotational force to the type wheel 5 can be cut off. Therefore, even during high-speed rotation, the spring force of the drive claw 20 can be reduced, the torque for driving the rotary shaft 1 can be reduced, and the motor for driving the rotary shaft 1 can be made smaller. Further, the work of mounting the drive claw 20 on the type wheel 5 becomes easier, and the assembly work becomes easier.

In the above embodiment, since the type wheel 5 rotates once while the drive shaft 2 rotates 1.5 times, two notches 3 and 4 are provided at 180 degrees opposite positions on the drive shaft 2. The number of notches can be changed as appropriate depending on the amount of rotation of the drive shaft 2 and the type wheel 5 in one line printing. For example, when the drive shaft 2 and the type wheel 5 both make one rotation, It is sufficient to provide one notch in the surface.

(Effects of the Invention) Since the printer of the present invention is configured as described above, even when the drive shaft rotates in either the forward or reverse direction, either one of the pair of locking portions provided on the selection ratchet can be rotated. This makes it possible to release the engagement between the protrusion of the drive pawl and the notch of the drive shaft, making it possible to select type on the type wheel that rotates in both forward and reverse directions, and also to reduce the spring force of the drive pawl. Even if the drive claw is not disengaged from the drive shaft, the rotational force of the drive shaft can be reliably transmitted to the type wheel.

[Brief explanation of drawings]

1 to 15 relate to an embodiment of the present invention,
Figure 1 is a schematic side view of the printer, Figure 2 is a front view of the type wheel, Figure 3 is a front view of the selection ratchet, and Figure 4 is the relationship among the type wheel, selection ratchet, drive pawl, selection pawl, and electromagnetic clutch. FIGS. 5a to 5c are explanatory views showing the engagement relationship between the drive shaft and the drive pawl, FIGS. 6a to 6c are explanatory views showing the engagement relationship between the selection ratchet and the selection pawl, Fig. 7a is a plan view of the hammer, Fig. 7b is E- of Fig. 7a.
E-line sectional view, 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, Figure 10 is a perspective view of the switching cam, and Figures 11 a to c are roll holders. 12A to 12C are explanatory diagrams showing the engagement relationship between the ink roll and the type wheel, and FIG. 13 is an explanatory diagram showing the engagement relationship between the body and the switching cam. FIG. 13 is an explanatory diagram showing the engagement relationship between the ink roll and the type wheel. 14 is an explanatory diagram showing the outline of the power transmission system, FIGS. 15a and 15b are explanatory diagrams of the clutch mechanism provided in the power transmission system, and FIG. 16 is the main parts of a conventional printer. FIG. 1... Rotating shaft, 2... Drive shaft, 3, 4... Notch, 5, 5'... Type wheel, 6, 6'... Selection ratchet, 7, 7'... Type body, 8... Lock groove, 11, 11'... Engagement shaft, 12, 12'... Support shaft, 13, 13'... Teeth, 14, 14'... Locking protrusion, 16, 17... Release pin ( locking part), 18,
18', 19, 19'...Engagement hole, 20, 20'...
...Drive claw, 21, 21'...Protrusion, 22, 22'...
...first arm portion, 23, 23'...sliding portion, 24,
24'...Second arm portion, 25, 25'...Selection claw,
26, 26'...claw portion, 27...rotation shaft, 29...
...Reset cam, 30, 30'...Cam pawl, 31
...Electromagnetic clutch, 32...Latching spring, 33...
Pressing spring, 34... Electromagnetic coil, 36... Yoke, 45... Stepped portion, 46... Convex portion, 47...
Hammer, 48... Erroneous printing prevention plate, 52... Pressing portion, 53... Notch, 54... Gap, 57...
Hole, 58... Projection, 59... First ink roll, 60... Second ink roll, 61... Roll holder, 62... Support shaft, 63... First cam pawl, 64... ...Second cam pawl, 65...Switching cam, 66...First cam groove, 67...Second cam groove, 68...Drive gear, 69...Hammer gear, 7
2...Rotating gear, 73...Sun gear, 74...Planet gear, 75...Carrier shaft, 76...Carrier, 77...Ring gear, 78...Selection gear, 79...Rotation support shaft, 80...Drive axis, 81
... Notch, 82 ... Rotating body, 83 ... Teeth, 8
5... Engagement shaft, 86... Drive claw, 87... Protrusion,
88...Selection lever, 93...Solenoid, 95
...Guide portion, 96...Engagement convex portion.

Claims (1)

[Claims] 1. A drive shaft that has a notch on the circumferential side and can rotate in either forward or reverse directions, a type wheel that is rotatably attached to this drive shaft and has a type body on its circumference, and a type wheel that has a type body on its circumference. A driving pawl that is held on the wheel and has a protrusion that can be engaged with the notch of the drive shaft, and a pair of locking parts that are rotatably attached to the type wheel and that can be engaged with the driving pawl. , a selection ratchet having teeth on the circumferential side, and a drive means capable of selectively locking the rotation of the selection ratchet by engaging with the teeth, and a cutout of the drive shaft and a drive pawl. When the protrusions are in the engaged state, the rotational force of the drive shaft is transmitted to the type wheel and the selection ratchet through the drive pawl, respectively, and when the selection ratchet is locked by the drive means. , the rotating drive pawl slides into contact with one of the locking parts of the selection ratchet and is deformed, so that the engagement between the notch of the drive shaft and the protrusion of the drive pawl is released. A printer characterized by comprising: