JPS6245072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing mechanism of a serial printer suitable for being attached to a display section of a small desktop calculator or a measuring machine.

Desktop calculators and measuring machines often display calculation results and measured values digitally on a liquid crystal display. Moreover, recently it has become possible to record these calculation results and measured values on recording paper using many small serial printers. This type of serial printer used in these devices is subject to considerable restrictions on the mounting parts, so it is desirable to make it as small as possible, but it is necessary to shift the mechanism that rotates the type wheel and the carriage that holds the type wheel. The reality is that it is difficult to miniaturize the printer because it includes many complex mechanisms such as a hammer drive mechanism for printing, and a paper feed mechanism.

In addition, recent desktop electronic calculators have various calculation functions, and for this reason, the print data can range from 0 to
In addition to the number 9, it is required to print about the same number of function symbols as these 10 numbers.
However, when numbers and function symbols are housed in the same type wheel, the diameter of the type wheel becomes large, which increases the overall size of the printer, making it unsuitable for use as a printer, especially for portable desktop computers. .

In order to solve this problem, the applicant previously proposed a serial printer in which the type wheel for function symbols and the type wheel for numbers are separated, and only the type wheel for numbers is moved in the direction of the digits. did. This application, as shown in Japanese Patent Application Laid-Open No. 52-46930, associates two type wheels with hammer bodies that each operate independently. For this reason, the mechanism becomes complicated because two hammer bodies are selectively operated by the same driving source.

By eliminating the selection mechanism of the two hammer bodies mentioned above,
The applicant of the present application has also previously filed an application for a serial printer in which two type wheels are selectively struck by a single hammer body as Japanese Patent Application Laid-Open No. 53-56514.

The above-mentioned JP-A-52-46930 and JP-A-53-
The serial printer shown in No. 56514 has a simple mechanism, small size, and light weight, making it ideal for mounting on desktop electronic computers and the like. However, it uses a pulse motor to rotate the type wheel, a relatively large electromagnetic plunger to drive the type wheel and drive the hammer body, and a relatively large electromagnetic plunger to feed the paper and release the carriage. Therefore, the cost of parts and the space occupied by the drive source tend to be relatively large.

The present invention is a novel invention that improves the above-mentioned drawbacks of the conventional printers, and its purpose is to provide a printing device in which the return operation of the carriage, which returns to the home position in the row direction by means of a spring force, is reliable.

Next, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a plan view of a printing device according to the present invention, and 1 in the figure is an iron frame plate. Side plates 1a and 1b are attached to the frame plate 1 so as to face each other. Note that 1c is a support plate that supports the upper ends of the side plates 1a and 1b. A rail 2 is spanned between the side plates 1a and 1b. 3 is a carriage, which is movable along the rail 2 from side to side, that is, in the row direction. 4 is a type wheel for printing function symbols, and 5 is a type wheel for printing numbers, which are held in the carriage 3. A rotary shaft 6 consisting of a spline shaft passes through each type ring. Each of the type wheels spline-connected to the rotary shaft 6 is rotated by the rotary shaft 6, but the rotary shaft 6 is free to move in the axial direction independently of each other within a predetermined range. Reference numeral 7 designates a tension spring, one end of which is fixed to the side plate 1a and the other end of which is fixed to the carriage 3, pulling the carriage 3 to the initial position, that is, the position shown in FIG. Reference numeral 8 denotes a moving wire or thread that moves the carriage 3 (pulls it in the direction of the arrow). Note that 9 is a guide member for guiding the tension spring 7, and 10 is a guide member for the shift wire 8, which are attached to the side plates 1a and 1b, respectively. Reference numeral 11 denotes a printing hammer, which has a notch 11a at its right end for preventing printing. 12 is a printing hammer 11
A non-circular hammer cam that drives the drive shaft 13
installed on. 14 is a recording sheet inserted between the printing hammer 11 and the type wheels 4 and 5, 3b is an ink roller, and 15 is a stopper disk.

First, before giving a detailed explanation of the drive mechanism, the printing operation will be explained.

When the rotary shaft 6 rotates and a desired function symbol comes to the printing position, the drive shaft 13 rotates and the hammer cam 12 presses the printing hammer 11. For this purpose, the printing hammer 11 presses the recording paper 14 against the type ring 4, and the function symbol is printed. Note that at this time, since the type ring 5 is located in the notch 11a, no numbers are printed.

When printing of the first digit is completed, the shift wire 8 is pulled in the direction of the arrow to shift the carriage 3 to the left by one digit. At this time, the type wheel 5 held by the carriage arm 3a shifts to the second digit, but although the type wheel 4 is pushed by the spring 14 and shifts to the left, it does not follow the movement of the carriage 3 and the printing hammer It stops at a position facing the notch 11a of No. 11, and remains at this position until one line of printing is completed and the carriage returns. (Although not shown, the type wheel 4 comes into contact with a step provided on the shaft 6.) On the other hand, when the carriage 3 shifts to the second digit and the desired number comes to the printing position, the printing operation as described above occurs. is performed, and the second digit is printed.

After such a printing operation continues, when one line of printing is completed, the winding member of the shift wire 8 becomes free. Therefore, the carriage 3 returns to the initial position shown in the first figure by the tensile force of the tension spring 7, and the printing operation for one line is completed. (If necessary, please refer to the above-mentioned Japanese Patent Application Laid-Open No. 53-56519 regarding this operating principle.
Please refer to the issue. ) Next, details of the printing mechanism will be explained.

The printing mechanism according to the present invention includes (1) a rotating shaft mechanism that rotationally drives the type wheels 4 and 5, (2) a shaft mechanism that rotates the hammer cam 12 for driving the printing hammer, and (3) feeding the recording paper. It has three shaft mechanisms: paper feed shaft mechanism,
These are organically connected using a gear mechanism and a clutch mechanism to perform various sequence operations.

(1) Rotating shaft mechanism that rotationally drives the type wheels 4 and 5 In Fig. 2, 16 is a fixed bearing, and the side plate 1b
The rotary shaft 6 is fitted into a half-moon-shaped hole 1b-1 in a manner that it cannot rotate, and the rotating shaft 6 is inserted through the center hole 16a. Reference numeral 17 denotes a reverse rotation prevention ring, which is tightly fitted to the rotating shaft 6 and rotates integrally therewith. Reference numeral 18 denotes a coil spring for preventing reverse rotation, which is wound in a direction that unwinds when the rotating shaft 6 is twisted in a predetermined rotational direction. The fixed bearing 16 and the anti-reverse ring 17 have drum portions 16b and 1 having the same diameter.
7a is provided, and these drum parts 16b and 17a
The sides are close together. A coil spring 18 is wound around these drum parts. Note that the inner diameter of the coil spring 18 is slightly smaller than the outer diameter of each drum portion. When the rotating shaft 6 is rotating in a predetermined direction, the coil spring 18 is driven in the direction in which it is unwound, so that the drum part 1
6b and 17a are separated, but if the rotating shaft 6 tries to rotate even slightly in the opposite direction, the coil spring 18 tightens the drum parts 16b and 17a, so they are connected, and the rotating shaft 6 rotates in the opposite direction. become unable.

A gear 19 is loosely fitted to the rotating shaft 6 and has a drum portion 19a. 20 is a holding cylinder, which has a hole 20a on one side through which the drum portion 19a of the gear 9 passes, and a groove 20b formed on the outer periphery. 21
is a cylindrical body having a drum portion 21a on one side, and a groove 21b formed on the circumferential surface. 22 is a coil spring, and bent end portions 22a and 22b are formed at both ends. 23 is a ratchet gear;
It has a boss portion 23a on one side, and the inside is formed hollow so that a clutch, which will be described later, can be housed therein.

When assembling the clutch portion 21A, first attach one end 22b of the coil spring 22 to the cylindrical body 21.
At the same time, approximately half of the coil spring 22 is fitted into the drum part 21a of the cylindrical body 21 (the inner diameter of the coil spring 22 is slightly larger than the outer diameter of the drum parts 19a and 21a, which have the same diameter). (It's getting smaller). Next, the drum portion 19a of the gear 19
loosely fit and protrude from the hole 20a of the holding cylinder 20,
The remaining coil spring 22 is press-fitted into the drum portion 19a, and the other end 22a of the coil spring is inserted into the groove 20b of the holding cylinder 20. That is, each member 19, 20, 21 is connected via a coil spring, and is coupled so as to rotate together in a predetermined direction (the tension direction of the coil spring). Further, when assembling the holding cylinder 20, the both ends of the coil spring 22 are rotated by a small amount with respect to a ratchet gear 23, which will be described later.
It is designed to absorb variations in the relative angles of 2a and 22b (which causes unavoidable manufacturing errors).

Then, the cylindrical body 21 of the members assembled as described above is press-fitted and firmly fitted onto the rotating shaft 6, and then the ratchet gear 23 is placed over the cylindrical body 21. On this occasion,
Each member is attached to the rotating shaft 6 by aligning the fan-shaped protrusion 21d provided on the other drum part 21c of the cylindrical body 21 with the fan-shaped hole 23c communicating with the center hole 23b at the end of the ratchet gear 23. ing.
Note that the fan-shaped protrusion 21d and the fan-shaped hole 23c described above
When engaged, the holding cylinder 20 is adjusted and rotated to achieve a predetermined mounting position as described above. Moreover, the fan-shaped protrusion 21d and the fan-shaped hole 23
The engagement relationship with c is designed to allow for some margin, and is set so that the coil spring 22 can smoothly move toward the tensioning or loosening side when the clutch is operated, which will be described later.

The coil spring 18 and the coil spring 22
are set in opposite winding directions with respect to the rotational direction of the rotating shaft 6, and when the gear 19 rotates in response to the rotation of a motor, which will be described later, the rotation is caused by the coil spring 2.
2, the transmission is transmitted to the rotating shaft 6 via the cylindrical body 21, and when the ratchet gear 23 is prevented from rotating by a locking member, which will be described later, the cylindrical body 21, which rotates together with the ratchet gear 23, also rotates. When the rotation is stopped, the coil spring 22 immediately loosens and the gear 1
Rotation transmission between the rotary shaft 9 and the cylindrical body 21 (ie, the rotating shaft 6) is cut off. When the rotating shaft 6 attempts to rotate in the opposite direction (the opposite direction to the rotation caused by the motor drive) when the rotating shaft 6 stops rotating, the aforementioned coil spring 18 immediately moves between the fixed bearing 16 and the anti-reverse rotation ring 1.
7 to prevent reverse rotation of the rotating shaft 6.

(2) Shaft mechanism for rotating the hammer cam 12 for driving the printing hammer In Fig. 3, 24 is a fixed bearing, and the side plate 1b
The drive shaft 13 is fitted into a half-moon-shaped hole 1b-2 made in the center so as not to rotate, and the drive shaft 13 is inserted through the center hole 24a. 25 is a reversal prevention wheel;
It is tightly fitted to the drive shaft 13 and rotates together with it. 26 is a coil spring for preventing reverse rotation;
It is wound in a direction that unwinds when twisted in the rotational direction of the drive shaft 13. The fixed bearing 24 and the anti-reverse ring 25 are provided with drum portions 24b and 25a having the same diameter, and the side surfaces of the drum portions 24b and 25a are in close contact with each other. A coil spring 26 is wound around these drum parts. Note that the inner diameter of the coil spring 26 is slightly smaller than the outer diameter of each drum portion. When the drive shaft 13 is rotating in a predetermined direction, the coil spring 26 is driven in the direction in which it is unwound, so the drum parts 24b and 25a are separated, but even if the drive shaft 13 is When trying to rotate in the opposite direction, coil spring 2
6 tightens the drum portions 24b and 25a, so that they are connected, and the drive shaft 13 cannot rotate in reverse. A gear 27 is loosely fitted onto the drive shaft 13, and a ratchet gear 27a is fixed or integrally formed on the side surface. 28 is a clutch plate, and drive shaft 1
Rotates with 3. The clutch plate 28 has two notches 28a and 28d in the diametrical direction on its outer periphery, a hole 28b on the side into which the tip 29a of the pin 29 is fitted and fixed, and a hole 28b on the side. It has a body portion 28c around which a helical spring 30 is wound.
Both ends of the helical spring 30 are bent outward to form the tip 3.
0a and 30b are formed. 31 is a locking plate. Two notches 31a and 31b are formed in the outer circumference of the locking plate 31 in the diametrical direction, and the drive shaft 1 is formed in the center.
3 has a circular hole 31c passing through, and further has a long hole 31d drilled along the circumference and a long hole 31e drilled in the radial direction. 32 is a ratchet claw. Holes 32a and 32 are provided at both ends of the ratchet pawl 32.
b is opened, and a claw 32c is formed in the center. 33 is a pin, and 34 is a split washer. The clutch 35 section is assembled as follows. Insert the tip 29a of the pin 29 into the hole 28b of the clutch plate 28.
After inserting and fixing the narrow diameter part 33a of the pin 33 into the long hole 31e of the locking plate 31, the narrow diameter part 3
3a is fitted and fixed into the hole 32b of the ratchet pawl 32. A helical spring 30 is attached to the body 28c of the clutch plate 28.
and hook the tip 30a onto the pin 29. Next, the circular hole 31c of the locking plate 31 is inserted into the body portion 28c.
Insert. At this time, the pin 29 is inserted through the long hole 31d of the locking plate 31 and into the hole 32a of the ratchet pawl 32, and the tip 30b of the helical spring 30 is inserted into the pin 33.
hook on the narrow diameter part 33a of the. Finally, Wariwashiya 3
4 into the tip of pin 29.

The drive shaft 13 is inserted into the center of the clutch 35 assembled in this way, and the clutch plate 28 and the drive shaft 13 are connected.
The claw 32c is engaged with a.

When the gear 27 is rotated in the direction of the arrow from this state, the ratchet gear 27a hooks and pulls the ratchet pawl 32, so the clutch plate 28 also rotates and the drive shaft 13 rotates. During rotation, when claws (not shown) are fitted into the notches 28a and 31a, the clutch plate 28 and the locking plate 31 are prevented from rotating, and the gear 2, which is constantly rotating in conjunction with the motor, is stopped.
Since the ratchet gear 27 of No. 7 presses the ratchet pawl 32, the ratchet pawl 32 is inserted into the long holes 31d and 3.
1e, the ratchet gear 27 and the ratchet pawl 32 are disengaged, and the connection between the gear 27 (i.e., the motor) and the clutch plate 28 (i.e., the drive shaft 13) is severed. . At this time, even if the drive shaft 13 tries to rotate in the reverse direction, the aforementioned reverse rotation prevention mechanism by the coil spring 26 works, and the drive shaft 13
is designed so that it cannot be rotated in the opposite direction.

(3) Paper feed shaft mechanism for feeding the recording paper In Fig. 4, 36 is a fixed bearing, and the side plate 1b
The paper feeding shaft 37 is inserted into the center hole 36a so as not to rotate. Reference numeral 38 denotes a reverse rotation prevention ring, which is tightly fitted to the paper feed shaft 37 and rotates integrally therewith. Reference numeral 39 denotes a coil spring for preventing reverse rotation, which is wound in a direction that unwinds when twisted in the direction of rotation of the paper feed shaft 37. The fixed bearing 36 and the anti-reverse wheel 38 are provided with drum parts 36b and 38a having the same diameter.
The sides of a are closely spaced. A coil spring 39 is wound around these drum parts.
Note that the inner diameter of the coil spring 39 is slightly smaller than the outer diameter of each drum portion. When the paper feed shaft 37 is rotating in a predetermined direction, the coil spring 3
9 is driven in the direction of unwinding, the drum parts 36b and 38a are separated, but if the paper feed shaft 37 tries to rotate even slightly in the opposite direction,
The coil spring 39 is connected to the drum parts 36b and 38a to tighten them, and the paper feed shaft 37
cannot be reversed.

A gear 40 is loosely fitted to the paper feed shaft 37, and a ratchet gear 40a is fixed to the side surface. 41
is a clutch plate which rotates together with the paper feed shaft 37. The clutch plate 41 has a small diameter portion 42a of the pin 42.
There is a hole 41a for inserting and fixing, and a coiled spring 4 on the side.
The main body 41b has a body portion 41b around which 3 windings are wound. Tensile spring 43
Both ends are bent outward to form tip portions 43a, 43b.
is formed. 44 is a locking plate. Locking plate 4
Five teeth 44a are provided on the outer periphery of 4, and the central part has a circular hole 44b through which the paper feed shaft 37 passes.
Furthermore, it has a long hole 44c drilled along the circumference and a long hole 44d drilled in the radial direction. 45 is a ratchet claw. Holes 45a and 45b are formed at both ends of the ratchet pawl 45, and a pawl 45c is provided in the center.
is formed. 46 is a pin, and 47 is a split washer. The clutch 48 section is then assembled as follows. The tip 42a of the pin 42 is fitted into the hole 41a of the clutch plate 41 and fixed, and the pin 46
After inserting the narrow diameter portion 46a into the elongated hole 44d of the locking plate 44, the narrow diameter portion 46a is fitted and fixed into the hole 45b of the ratchet pawl 45. Body portion 4 of clutch plate 41
A helical spring 43 is fitted to 1b, and the tip 43a is hooked to the pin 42. Next, the circular hole 44b of the locking plate 44 is inserted into the body portion 41b. At this time, pin 42
is inserted into the hole 45a of the ratchet pawl 45 through the elongated hole 44c of the locking plate 44, and the tip 43b of the helical spring 43 is hooked on the narrow diameter portion 46a of the pin 46. Finally, the split washer 47 is fitted onto the tip of the pin 42.

The paper feed shaft 37 is inserted into the center of the clutch 48 assembled in this manner, and the clutch plate 41 is connected to the paper feed shaft 37 with a strong fit, and the pawl 45c is engaged with the ratchet gear 40a. A claw 50a is provided at the tip of an arm 50 fixed to a paper feed command shaft 49 pivotally supported on the side plate 1b.
meshes with the teeth 44a of the locking plate 44 to prevent rotation of the locking plate 44. In addition, 51 is a small gear attached to the rotating shaft of a drive motor (not shown), and 52
An intermediate gear is supported on a shaft 53 attached to the side plate 1b, and its gear 52a meshes with the small gear 51, and the gear 52b meshes with the gear 40.

When the gear 40 is rotated in the direction of the arrow from this state, the ratchet gear 40a hooks and pulls the ratchet pawl 45, so the clutch plate 41 also attempts to rotate, but the pawl 50a pressed by the spring pushes against the locking plate 45.
rotation is prevented. Note that when force is applied and it tries to rotate, the ratchet pawl 45 engages the long holes 44c, 44 of the locking plate 44.
In order to escape by being pushed in the outer circumferential direction along d, the pawl 45c of the ratchet pawl 45 and the ratchet gear 40a
The gear 40 is disengaged from the shaft 37, and only the gear 40 rotates without rotating the shaft 37. Note that the arm 50 rotates in response to a paper feed command, and the claw 50a and the locking plate 4
When the paper feed shaft 37 is temporarily disengaged from the gear 44a, the paper feed shaft 37 is rotated by the gear 40, and when the predetermined paper feed is completed (when the locking plate 44 rotates 1/5 rotation), the paper feed shaft 37 is rotated by the spring. The pawl 50a and the tooth 44a mesh again, and the clutch 48 prevents the rotation of the gear 40 from being transmitted to the paper feed shaft 37.

The explanation of the three axes has been completed above, but when these three axes are assembled, the gear 40 supported on the paper feed shaft 37 and the gear 27 supported on the drive shaft 13 mesh with each other. The gear 27 and the gear 19 supported on the rotating shaft 6 mesh with each other, and the rotation of the pinion 51 is ultimately transmitted to the gear 19, so that they all rotate at the same time.

The side plate 1b is provided with a switching drive mechanism for switching clutches provided on the rotation shaft 6 and the drive shaft 13. In FIG. 5, 53 is the switching plate;
54 is a driving magnet, and 55 is a tension spring. Elongated holes 53a and 53b are formed in the longitudinal direction at both ends of the switching plate 53, and a locking piece 53c is formed in the center.
A slit 53d is formed at the bottom of 3a. The long hole 53a is supported by the rotating shaft 6, and the long hole 53b is supported by the drive shaft 13 so as to be movable in the left-right direction. When the switching plate 53 is located at one end, the locking piece 53c engages with the ratchet gear 23, and when the switching plate 53 is located at the other end,
The notch 31a (or 31b) of the locking plate 31 and the notch 28a (or 28d) of the clutch plate 28 engage with each other. An arm 54a is supported on the drive magnet 54, and when the coil 54b is energized, the arm 54a is attracted against the spring 55.

FIG. 6 is a side view of the printing mechanism seen from the side plate 1b. As is clear from this drawing, the driving magnet 54 is fixed to the side plate 1b with a screw 56, the tip 54a' of the arm 54a engages with the slit 53d of the switching plate 53, and the tension spring 55 is attached to the arm 54a and the side plate 1b. Pole 57 erected
When the magnet 54 is inactive, the locking piece 53c is engaged with the clutch plate 28 and the locking plate 31.

FIG. 7 is an exploded perspective view showing the mechanism on the side plate 1a side. In the figure, reference numeral 58 denotes a locking arm, which is supported on the rotating shaft 6 and can rotate independently of the rotation of the rotating shaft 6. A helical spring 59 always applies a rotational force in the direction of the arrow. Locking arm 5
A claw 58a is formed at the tip of 8, and a protrusion 58b is formed at the middle. 70 is a rotary encoder fixed to the rotating shaft 6. 60 is a feed pawl fixed to the drive shaft 13, which includes two engaging pawls 60a, 60b and a locking pawl 60c in the diametrical direction.
60d (partially not shown) is provided. 61
62 is a pentagonal cam body which is fixed to the paper feed shaft 37 and rotates therewith, and 62 is a winding gear which is supported on the paper feed shaft 37 and can be separated from the paper feed shaft 37 and rotate freely. The winding gear 62 has a gear 6
2a and a ratchet gear 62b are formed, and the gear 6
Some of the teeth 2a are cut out by several pitches to form a tooth-missing portion 6.
2c is formed. In addition, the ratchet gear 6
A drum portion 62d is formed between the gear 2b and the gear 62a, and a shift wire (or thread) 8 connected to the carriage 3 is wound around the drum portion 62d. A release arm 63 is rotatably supported on a shaft 64 provided on the side plate 1a. The release arm 63 has two cam valleys 63.
a, 63b and one cam ridge 63c, and a protrusion 63d below the cam ridge 63c. 65 is paper feed command axis 4
The engaging arm fixed to 9 has a slit 65a at the tip.
is formed. In addition, 66 is a guide pole installed upright on the side plate 1a, and its tip is connected to the winding gear 62.
This is a stopper member that is fitted into a slit (not shown) provided on the back surface of the winding gear to determine the initial position of the winding gear.

When these parts arranged on the side plate 1a are assembled and the carriage 3 is in the initial position, the locking arm 58 is inserted into the cam valley 63a of the release arm 63.
The protrusion 58b is fitted to move the claw 58a at the tip away from the ratchet gear 62b, and the winding gear 62
is in a free state. Also, the protrusion 6 of the release arm 63
3d is in contact with the flat surface of the cam body 61.

FIG. 8 is a side view of the printing mechanism seen from the side plate 1a side. As is clear from this drawing, the tip 67b of the L-shaped operating arm 67a of the magnet 67, which is energized when a command to wind up the printing paper is issued, is loosely fitted into the slit 65a of the engaging arm 65. ing. 68 is a terminal plate that holds a contact piece 69 that comes into contact with the rotary encoder 70.

Next, a series of printing operations in the printing mechanism according to the present invention will be explained.

As the carriage 3 is shown in FIG.
From the rightmost or initial position,
When the motor starts rotating in response to a printing command, the gears 19, 27,
All 40 rotate. Since the clutch 21A connected to the gear 19 is in a connected state, the ratchet gear 23 and the rotating shaft 6 are rotating, and therefore the rotary encoder 70 and the type wheels 4 and 5 are also rotating.

When the desired function type is in the printing position, the drive magnet 54 (FIG. 6) is energized.
The switching plate 53 is moved to the left in FIG. Therefore, the locking piece 53c of the switching plate 53 meshes with the ratchet gear 23 to stop it.
Note that FIGS. 9a and 9b are cross-sectional views showing the state before and after the switching plate 53 is switched. When the ratchet gear 23 is stopped, the clutch 21A of the rotating shaft 6 is disengaged, and the rotating shaft 6 is stopped, and only the gear 19 rotates, as described above.

On the other hand, when the switching plate 53 moves, this locking piece 5
3c is the notch 28a of the clutch 35 (Fig. 3),
31a (Fig. 9a). Therefore, the clutch 35 is in a connected state, the drive shaft 13 rotates, and during the initial rotation, the hammer cam 12 presses the printing hammer 11 (FIG. 1) to print a function symbol.

When the drive shaft 13 further rotates, the feed pawl 60 rotates in the direction of the arrow in FIG.
(or 60d) rotates the tip 63e of the release arm 63 in the direction of the arrow, that is, in the downward direction,
The protrusion 58b of the locking arm 58 is dropped into the cam valley 63b. As a result, the locking arm 58 rotates in the direction of the arrow in FIG. 7 to engage the pawl 58a with the ratchet gear 62b, thereby preventing the take-up gear 62 from reversing. From now on, until the carriage is returned to its original state, the sharp claw 60
c, 60d and the release arm 63 cannot come into contact with each other. When the feed pawl 60 continues to rotate, the pawl 60b, which is out of phase with the sharp pawl, meshes with the gear 62a, causing the take-up gear 62 to rotate. And when this rotates,
The shift wire 8 is wound around the drum portion 62d, and the carriage 3 is shifted. The above series of operations is performed by half a rotation of the drive shaft 13. During this time, the drive magnet 54 is de-energized, so the switching plate 5
3 is moved to the right in FIG. 6 by the tension spring 55, and after half a rotation of the drive shaft 13, it engages with the notches 28d and 31b (or 28a and 31a) of the clutch 35, and the engagement with the ratchet gear 23 is completed. It comes off. As a result, the clutch 21A is in a connected state and the clutch 35 is in a disengaged state, so that the rotary shaft 6 rotates and the type wheels 4 and 5 begin to rotate, while the drive shaft 13 stops.

When the desired number to be printed on the second digit comes to the printing position, the drive magnet 54 is again excited and the switching plate 53 is again moved to the left in FIG.
Therefore, the locking piece 53c of the switching plate 53 meshes with the ratchet gear 23 to stop it. When the ratchet gear 23 is stopped, the clutch 21A of the rotating shaft 6 is disengaged, the rotating shaft 6 is stopped, and the gear 19
is idling.

On the other hand, when the switching plate 53 moves, this locking piece 5
3c comes off from the notches 28d and 31b of the clutch 35. Therefore, the clutch 35 becomes connected, the drive shaft 13 rotates, and the hammer cam 12 presses the printing hammer 11 to print the desired number.

When the drive shaft 13 rotates, the feed pawl 60 rotates in the direction of the arrow in FIG.
0b) meshes with the gear 62a and rotates the take-up gear 62 by one tooth in the same manner as described above. When this rotates, the shift wire 8 moves to the drum section 62.
d, and the carriage 3 is advanced one more digit against the aforementioned tension spring 7. Feed claw 60
When the gear rotates half a turn, the claw 60a and the gear 62a are disengaged, and the single digit shift operation is completed.
During this time, the excitation of the drive magnet 54 is released, so the switching valve 53 is moved to the right in FIG. 3
1b) and disengages from the ratchet gear 23. Therefore, the clutch 21A becomes connected, the clutch 35 becomes unconnected, the rotating shaft 6 rotates, the type wheels 4 and 5 begin to rotate, and the drive shaft 13 stops to print the second digit number. The operation ends.

This printing operation is repeated several times to print the desired number of digits, and when one line of printing is completed, the magnet 67 (Fig. 8) is energized and the actuating arm 67a is moved clockwise. Rotate. Therefore, the engaging arm 65 is lifted up against the spring 71 and rotates counterclockwise, thereby rotating the paper feed command shaft 49. Therefore, the arm 50 on the side plate 1b side, which rotates integrally with the shaft 49, rotates, and the claw 50a, which had been engaged with the teeth 44a of the locking plate 44 as shown in FIG. 10, is now engaged as shown in FIG. The clutch 48 is temporarily disengaged from the teeth 44a of the stop plate 44 and becomes connected. Therefore, the paper feed shaft 37 begins to rotate and the recording paper 14
The paper is fed by a predetermined pitch.

When the paper feed shaft 37 starts rotating, the cam body 61 (Fig. 7) that rotates together with it also starts rotating, and the first
As shown in FIG. 2, the cam body 61 pushes up the protrusion 63d of the release arm 63. This action moves the protrusion 58b of the locking arm 58 from the cam valley 63b to the cam valley 63a, thereby disengaging the pawl 58a from the ratchet gear 62b. Therefore, the take-up gear 62 becomes free. Note that when the protrusion 58b of the locking arm 58 is engaged with the valley 63b of the release arm 63, both 58
8 and 63 maintain a mechanically balanced state, and maintain this state until the release arm 63 is pushed downward by the claws 60c and 60d of the feed claw 60 described above. In other words, efforts are being made to ensure carriage return. When the gear 62 becomes free, the carriage 3 is constantly pulled in the direction of the initial position by the tension spring 7, so it quickly returns to the initial position while pulling the shift wire 8. The shift wire 8 then rotates the take-up gear 62 to return it to its initial position.

As described in detail above, according to the present invention, the locking member (locking member) of the winding body (winding gear) that locks (via the string-like body) the printing head (carriage) that resists the spring force. The stop arm) is moved to and held in the release position by the driving force of the rotating paper feed shaft when one line of printing is completed, and held in this release position until the first digit of the next line is printed. Therefore, before the carriage returns to the home position in the row direction, there is no possibility that the take-up body and the locking member will engage with each other and the carriage will stop midway, thereby providing a printing device with reliable carriage return. It is possible. or,
The driving force of the paper feed shaft is used to release the winding body and the locking member, and the printing operation of the first digit of the next line engages the winding body and the locking member.
Another advantage is that a special electromagnet or the like is not required for this release/engagement.

[Brief explanation of the drawing]

Figure 1 is a plan view of the printing device, Figure 2 is an exploded perspective view of the rotating shaft mechanism that rotates the type wheel, Figure 3 is an exploded perspective view of the drive shaft mechanism that drives the printing hammer cam, and Figure 4 is an exploded perspective view of the drive shaft mechanism that drives the printing hammer cam. Figure 5 is an exploded perspective view of the paper feed drive shaft mechanism, Figure 5 is an exploded perspective view of the two-shaft mechanism for rotating the print hammer and type wheel, Figure 6 is a right side view, and Figure 7 is an exploded view of the main parts showing the mechanism on the left side. Perspective view, Figure 8 is a left side view,
9a and 9b are cross-sectional views showing the operating state of the clutch portion, FIGS. 10 and 11 are partial perspective views showing the clutch operating portion, and FIG. 12 is an exploded perspective view showing the mechanism for releasing the carriage. be. In the figure, 1 is a frame, 3 is a carriage, 4 and 5 are type wheels, 6 is a rotating shaft, 7 is a tension spring, 8 is a feed wire, 11 is a printing hammer, 13 is a drive shaft, 1
5 is a stopper disk, 17 is a reverse rotation prevention ring, 18 is a coil spring, 19 is a gear, 20 is a holding cylinder, 21 is a cylindrical body, 21A is a clutch, 22 is a coil spring, 2
3 is a ratchet gear, 25 is a reverse rotation prevention wheel, 26 is a coil spring, 27 is a gear, 28 is a clutch plate, 2
9 is a pin, 30 is a coiled spring, 31 is a locking plate, 32
is the ratchet pawl, 33 is the pin, 35 is the clutch,
37 is a paper feed shaft, 38 is a reverse rotation prevention ring, 39 is a coil spring, 40 is a gear, 41 is a clutch plate, 42 is a pin, 43 is a coiled spring, 44 is a locking plate, 45 is a ratchet pawl, 46 is a pin , 48 is clutch, 49
is the paper feed command axis, 50 is the arm, 51 is the small gear,
52 is an intermediate gear, 53 is a switching plate, 54 is a drive magnet, 55 is a tension spring, 56 is a screw, 57 is a pole, 58 is a locking arm, 59 is a helical spring, 6
0 is a feed pawl, 61 is a cam body, 62 is a winding gear, 6
3 is a release arm, 64 is a shaft, 65 is a locking arm, 66 is a guide pole, 67 is a magnet, 68 is a terminal plate,
69 is a contact piece, and 70 is a rotary encoder.

Claims (1)

[Claims] 1. In a serial printer that prints by moving the print head in the digit direction, the print head is constantly deflected by a spring toward the home position, and the string-like body connected to the print head is moved by a winding body. A cam body that rotates integrally with a paper feed shaft and a protrusion that engages with the cam body;
By providing an open arm having two cam valleys, and providing a locking member with a protrusion that engages with the two cam valleys, the winding is carried out by the driving force of the paper feed shaft that rotates when one line of printing is completed. A locking member for preventing the body from reversing is held in a released position, and a feed pawl fixed to a drive shaft that drives a printing hammer is provided with a pair of diametrically engaging pawls and a locking pawl, and The pawl engages with the winding gear to perform digit feeding, and the kick pawl acts to rotate the open arm so that the driving force associated with the printing operation of the first digit of the next line causes the above-mentioned engagement to occur. A printing device characterized in that a stop member is engaged with a winding body.