JPH0243738Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a printer, and particularly to a serial printer.

Recently, calculators have become more multi-functional and high-end.
It is desired that calculators with printers, which are smaller and lighter and can save calculation results as printed data, also be smaller and lighter. Therefore, it is desired that the printer incorporated therein be small, lightweight, and consume low power. In addition, for printers built into electronic devices used in general households, roll paper made of easily available and inexpensive 38 mm or 58 mm wide plain paper can be used, and the printed data is clear. Therefore, a matrix printing type is desired, and it is also expected to be inexpensive as it requires fewer driving sources.

Next, a serial printer according to an embodiment of the present invention will be explained in detail with reference to the drawings. First, the general configuration of the printer will be described.

[Schematic configuration]

FIG. 1 is a schematic diagram of the printer. A driving pulley 1 and a driven pulley 2 are arranged at a predetermined interval, and an endless type belt 3 is stretched between them. A worm 5 is attached to the rotating shaft of one DC motor 4 serving as a drive source, and the driving force of the motor 4 is transmitted to a main gear 8 via a first idle gear 6 and a second idle gear 7. The rotational force from the main gear 8 is transmitted to the drive pulley 1 via a spring clutch (not shown), and a print/carry gear 9 is meshed with the main gear 8. It's summery.

One end of a printing/carrying shaft 10 is connected to the printing/carrying gear 9, and this printing/carrying shaft 10 is arranged between the driving pulley 1 and the driven pulley 2, and is parallel to the type belt 3. It extends to A hammer holder 11 is attached to the print/carry shaft 10 so as to be slidable in the axial direction, and a hammer and a carry cam are built in and supported therein as will be described later. One end of a holder return spring 12 is connected to the hammer holder 11, and the other end of the spring 12 is fixed to the base. Therefore, the hammer holder 11 is moved to the home position side near the driven pulley 2 by the tensile force of the holder return spring 12. is always elastically biased.

A rack 13 is arranged near and parallel to the print/carry shaft 10, so that the carry cam built in the hammer holder 11 and the rack teeth of the rack 13 can mesh with each other as described later. A paper feed roller 14 and a flat guide plate 15 that also serves as a platen are arranged behind the rack 13.
6 is sent out from below the paper feed roller 14 and guide plate 15 and guided near the outside of the type belt 3. A selection lever 17 is operated by an electromagnetic solenoid 18 to switch and transmit the rotational force of the main gear 8 from the drive pulley 1 to the print/carry gear 9 at a predetermined timing. Reference numeral 20 denotes an ink roller that comes into contact with the type portion on the outer peripheral side of the type belt 3 to apply ink to the type surface.

The series of basic operations of this printer consists of type selection operation, printing/carrying operation, hammer holder return/paper feeding operation, and by sequentially repeating each of these operations, it is possible to print multiple lines. will be done. Each of the above-mentioned operations and related mechanisms will be explained in sequence, but first, the configuration of the type belt 3 will be explained.

[Composition of type belt]

As shown in FIG. 3, the type belt 3 has an endless shape, and a large number of type parts 21 are individually provided along the circumferential direction at predetermined pitches on the outer circumferential side, and on the inner circumferential side, a large number of type parts 21 are individually provided along the circumferential direction. A large number of belt teeth 22 are provided at a predetermined pitch. Individual type section 2
1 and the belt gear 22 are provided in pairs with each other, that is, they are both provided with the same bit, and the type portion 21 (belt tooth portion 22) and the adjacent type portion 21
(belt tooth portion 22) are connected to each other by a thin connecting portion 23. These type portion 21, belt tooth portion 22, and connecting portion 23 are molded, for example, from synthetic rubber or synthetic resin with a low degree of polymerization, and the type belt 3 as a whole has appropriate flexibility, stretchability, and elasticity. .

As shown in Fig. 3, the type belt 3 consists of two groups of type with the same type arrangement, and one group of type consists of a group of symbols (MG), a group of numbers (FG), and a group of numbers (FG). It is configured. The symbol group (MG) includes "+", "-", "x", etc. as shown in Figure 14.
There are 13 types of symbol type sections. Each digit group (FG) has 10 types of numeric characters from "0" to "9" arranged in the same arrangement. Therefore, one set of type groups has a total of 33 character type parts 21, and the entire type belt has 66 type parts 21.
is provided. By providing a plurality of frequently used numeric groups (FG) in this manner, it is possible to reduce the loss time in selecting type as much as possible.

As explained earlier, the type belt 3 is stretched between the driving pulley 1 and the driven pulley 2, and the belt teeth 22 provided on the inner circumferential side of the type belt 3 are connected to the driving pulley 1 and the driven pulley 2. They mesh with the pulley teeth 24 (see FIG. 2) of the pulley 2, so that the type belt 3 is rotated reliably without slippage. As shown in FIG. 1, the drive-side pulley 1 is rotated counterclockwise in the same figure, and the type belt 3 is rotated in the direction of arrow A, and the driven-side pulley 2 and the drive-side pulley 1 on the side facing the paper 16 are rotated. The tension side is between. For this reason, the side of the type belt 3 facing the paper 16 does not sag, and even if there is some vibration, the paper 16 does not swing significantly along the feeding direction. Therefore, the precision of the printing position when printing is high, and even if the distance between the type belt 3 and the paper 16 becomes narrower as printers become smaller, the type part 21 will not come into contact with the paper 16 unexpectedly. Next, the type selection mechanism will be explained.

[Type selection mechanism]

First, the drive mechanism for the type belt 3 will be explained. As described above, the driving force of the motor 4 is transmitted to the main gear 8 via the worm 5, the first idle gear 6, and the second idle gear 7. Furthermore, in order to transmit the driving force of the main gear 8 to the driving pulley 1 or to cut off the drive transmission, a spring clutch, which will be described later, is interposed between the main gear 8 and the driving pulley 1. . Below the main gear 8 is a code disk 25 (see Figure 2).
are arranged coaxially, and eventually rotate in synchronization with the drive pulley 1. The main gear 8 has the shape of a bevel gear and is adapted to mesh with the printing/carry gear 9.

The spring clutch can be set to a state where power can be transmitted (ON) to transmit power from the main gear 8 to the driving pulley 1, or the spring clutch can be set to a state where power cannot be transmitted (OFF) and the power can be transmitted from the main gear 8 to the driving pulley 1. The selection lever 17 is used to change the power, such as stopping the rotation of the main gear 8 and instead transmitting the driving force of the main gear 8 to the print/carry gear 9 to rotate it. This selection lever 1
When the spring clutch is turned on by the operation 7 and the driving pulley 1 is rotated in the direction of arrow B as shown in FIG. 1, the type belt 3 is transported in the direction of arrow A accordingly.

Although not shown, a conductive pattern having a predetermined shape is formed on the lower surface of the code disk 25 to detect the rotation angle of the drive pulley 1, in other words, the amount of movement of the type belt 3. Furthermore, a plurality of contact groups consisting of a set contact, a reset contact, and a common contact are in elastic contact with this conductive pattern. These contact pieces are connected to a control section (not shown) by lead wires.

A code plate tooth part 26 is provided on the upper part of the code disc 25, and a spur gear part 28 of the sensor gear 27 is provided with the code plate tooth part 26.
are interlocking. On this spur gear part 28,
As shown in FIG. 4, a disk portion 29 having a diameter equal to the diameter of the tip of the tooth is provided, and a trigger groove portion 30 is formed at one location on the circumference from the spur gear portion 28 to the disk portion 29. There is. A cam disk portion 32 having a cam protrusion 31 at one location on its outer circumference is provided below the spur gear portion 28 .

Code plate tooth portion 26 in the code disk 25
The number of teeth in the pulley tooth portion 2 of the driving pulley 1 is
The number of teeth is equal to 4. Further, the number of teeth of the spur gear portion 28 in the sensor gear 27 is equal to the total number of characters in one set of character groups (symbol group + number group + number group) on the type belt 3 . Therefore, while the sensor gear 27 rotates once, the type belt 3 rotates exactly half a rotation.

A control gear 33 is arranged next to the sensor gear 27, and its shape will be explained with reference to FIG. 5. A single gear portion 35 having one tooth portion 34 in the circumferential direction is provided at the top of the control gear 33.
A fitting hole 36 is bored in the center thereof.
A spur gear part 38 having a missing tooth part 37 near the part facing the tooth part 34 is provided below the one gear part 35, and this spur gear part 38 is connected to the sensor tooth part 22.
It is designed so that it can mesh with the spur gear portion 28 of No. 7. A locking portion 40 is provided below the spur gear portion 28 and has one locking groove 39 on the outer periphery on the side substantially opposite to the toothless portion 37 . A paper feed cam portion 41 having a slightly larger diameter than the locking portion 40 is provided below the locking portion 40, and two spiral tooth portions 42a and 42b are arranged on the outer periphery of the cam portion 41 in a crossed manner so as to face each other every half circumference. is formed. These single gear portion 35, spur gear portion 38, locking portion 40, and paper feed cam portion 41
The control gear 33 equipped with this is integrally formed by molding synthetic resin.

A reset plate 43 is disposed above the control gear 33, and by press-fitting a shaft 44 hanging from the center of the lower surface of the reset plate 43 into the fitting hole 36 of the control gear 33, the reset plate 43 is rotated together with the control gear 33. do. A protrusion 45 is provided on the upper surface of the reset plate 43 near the outer periphery.

The locking groove 39 of the locking portion 40 of the control gear 33 is configured such that a claw portion 47 of a rotating lever 46 can be fitted therein. The rotating lever 46 has a claw portion 4.
In addition to 7, a cam surface abutting part 48 is provided protrudingly, and its tip end is always in elastic contact with the cam disk part 32 of the sensor gear 27, as shown in FIG.

In order to select type, it is first necessary to detect the reference position of the type belt 3. In the case of this embodiment, immediately after the rotation lever 46 is rotated by the cam protrusion 31 of the sensor gear 27 as the sensor gear 27 rotates, in other words, the claw portion 47 of the rotation lever 46
Immediately after the type belt 3 comes off the locking groove 39 of
The reference position of the type belt 3 is configured such that the position where the type portion 21 of "6" in the second group of numbers (FG) corresponds to a hammer (described later) in the home position. In this way, when the type belt 3 is at the reference position, the distance of each type part 21 from the type part 21 corresponding to the hammer is known in advance, so after the reference position is detected, the amount of movement of the type belt 3 can be determined. For example, by counting the rotation angle of the driving pulley by pulse signals from the code disk 25, the type belt 3 can be rotated to a position where the type part 21, which is commanded by the control section, corresponds to the hammer. It should be noted that since the position of the hammer changes sequentially due to the carry, a desired character can be selected by counting the above-mentioned pulse signals in consideration of the amount of movement of the hammer. Next, print/
The carry mechanism will be explained.

[Print/carry mechanism]

A hammer holder 11 is held on the print/carry shaft 10 so as to be slidable in the axial direction thereof, and this hammer holder 11 has a shape as shown in FIG.
In other words, the print/carry axis 1 is placed at a predetermined position on both side plates.
Freely rotatable insertion holes 49, 49 are formed, and a hammer mounting portion 50 extends horizontally from the rear to the front inside the insertion holes 49, 49, which can rotate freely. A spring hanging pin 51 is protruded from the rear of one of the side plates, and a long groove 52 is cut horizontally in front of the spring hanging pin 51 facing the direction of the spring hanging pin 51. Hammer holder 11
A partition wall portion 53 is suspended from both sides of the front side, and an ejection opening 54 having a size that allows one type portion 21 to protrude is provided between the partition wall portions 53. The hammer placement section 5
A hammer 55 is placed on top of the hammer 55 such that an extrusion portion 56 provided at its tip faces the ejection opening 54. A convex portion 57 is formed on the upper surface of the rear end of the hammer 55.
is provided in a protruding manner and is slidably fitted into a guide groove 58 formed on the upper surface of the hammer holder 11. A spring hook pin 5 is attached to one side of the hammer 55.
9 is provided protrudingly, and this pin 59 is connected to the hammer holder 11.
It protrudes outward from the long groove 52 of. This spring hanging pin 59 and the spring hanging pin 51 of the hammer holder 11
A tension spring (not shown) is stretched between the
Due to its tensile force, the hammer 55 is elastically biased in a direction away from the type belt 3 (backward). Note that the type belt 3 is attached to the partition wall portion 5 of the hammer holder 11.
It is designed to pass through the inside of 3.

A carry cam 60 connected to the print/carry shaft 10 by a spline is built in below the hammer mounting portion 50 of the hammer holder 11 . This cam 60
, a hammer drive part 61 extending in one direction from the center toward the outer periphery, a carry cam part 63 having a single protrusion 62 on the outer periphery, and an elliptical rack rotation part for restoring the rack. It consists of 64. The hammer driving section 61 is adapted to come into contact with a receiving section 65 provided on the hammer 55 by rotation. FIG. 8 is a developed view of the cam surface of the carry cam portion 63. The protrusion 62 includes a circumferentially extending circumferential protrusion 62a provided over about half of the circumferential direction, and a spirally extending circumferential protrusion 62a provided over the remaining half of the circumferential direction. Spiral protrusion 62
b, and these protrusions 62a, 62b are continuous. The protrusions 62 are adapted to mesh with rack teeth 66 (see FIG. 2) provided at equal intervals on one side of the rack 13.

As shown in FIG. 9, the rack rotating portion 64 is adapted to abut against a return lever portion 67 provided at the end (home position side) of the rack 13 when rotated.

The rack 13 is arranged near the print/carry shaft 10 and parallel to it so as to be rotatable by a predetermined angle, and as the rack rotates, the rack teeth 66 mesh with the protrusion 62 of the carry cam 60, or the rack teeth 66 mesh with the protrusion 62 of the carry cam 60. It may be canceled. At the end of the rack 13 on the side where the return lever section 67 is not provided, a rotation stopper claw section 68 and a tilting notch section 69 are formed. The rotation stopper claw 68 and the tilting notch 69 are adapted to engage with the protrusion 45 of the reset plate 43, as shown in FIGS. 10 and 11.

As shown in FIG. 2, an elliptical lever push cam portion 70 is provided on one side of the print/carry gear 9.
is provided, and is always in elastic contact with the end surface of the vertical wall portion 72 of the gear clutch lever 71. Therefore, the printing/carrying gear 9 (lever pushing cam part 70)
When the gear clutch lever 71 rotates once in the direction of arrow C, the gear clutch lever 71 reciprocates once in the direction of arrow D. The gear clutch lever 71 is also provided with a reset portion 73, which is adapted to come into contact with a protrusion 45 of a reset plate 43, as shown in FIG.

The hammer holder 11 is connected to the holder return spring 12
(see Figure 1), the reference position of the type belt 3 is detected as explained in the previous section [Print character selection mechanism]. is tilted down as shown in FIG. Furthermore, although the reset plate 43 is biased to rotate in the direction of arrow E by a spring (not shown) attached to the control gear 33, the rack 13 falls down as shown in FIG. Since the pawl portion 68 locks the protrusion 45 of the reset plate 43, the reset plate 43 and the control gear 33 connected thereto are prevented from rotating.

Further, when the reference position is being detected, the toothless portion 37 of the control gear 33 faces the spur gear portion 28 of the sensor gear 27, as shown in FIG. 6A, and the two are not meshed. ing. Furthermore, at this time, the cam surface abutting portion 48 of the rotating lever 46 is connected to the sensor gear 2.
7 is in contact with the cam bottom 74 of the cam disk portion 32, and therefore the claw portion 47 of the rotating lever 46 enters the locking groove 39 of the control gear 33.

When the sensor gear 27 continues to rotate in the direction of arrow F and the cam surface abutting portion 48 of the rotary lever 46 rides on the cam protrusion 31 as shown in FIG.
At the same time, the rotating lever 46 rotates in the direction of arrow G, and the claw portion 47 of the rotating lever 46 comes out of the locking groove 39 of the control gear 33. However, as shown in FIG. 10A, since the rotation is stopped by the rotation stopper claw 68, the control gear 33 and the reset plate 43 do not rotate and remain as they are. Therefore, the 12th
As shown in Figure A, only the gear clutch lever 71 reciprocates in the direction of arrow D while the reset plate 43 remains stationary. The reference position of the type belt 3 is set immediately after the sensor gear 27 rotates and the cam surface contact portion 48 of the rotary lever 46 falls from the cam protrusion 31, so after the reference position is detected, the type is selected. will be done. It should be noted that the selection of printed characters has been explained in the previous section, [Printed Character Selection Mechanism], so the explanation will be omitted here. Due to the depression of the cam surface abutting portion 48 described above, the rotary lever 46 rotates in the direction opposite to the direction of arrow G, and the claw portion 47 again engages the control gear 33.
into the locking groove 39.

Once a print character is selected in the bottom row (home position), the print operation continues.

13A and 13B are diagrams for explaining the printing operation, in which FIG. 13A shows the state before printing, and FIG. 13B shows the state after printing. In the state before printing, as shown in FIG. 13A, the hammer 55 is pulled rearward by a tension spring, and is positioned by a stopper (not shown).
Therefore, the type belt 3 (type portion 21) is located between the partition wall portion 53 of the hammer holder 11 and the extrusion portion 56 of the hammer 55, and is slightly separated from the extrusion portion 56.
Further, the hammer driving portion 61 faces downward and does not come into contact with the receiving portion 65 of the hammer 55.

The print/carry shaft 10 rotates once in the direction of arrow C by the drive transmitted from the main gear 8, but the return operation of the rack 13 and the printing operation occur in the previous half-turn, and the carry operation continues in the second half-turn. It is starting to be done. That is, when the print/carry shaft 10 rotates in the direction of arrow C, the carry cam 60 spline-coupled thereto also rotates together. As shown in FIGS. 9A and 9B, at the beginning of the rotation of the carry cam 60 in the direction of arrow H, the return lever part 67 is rotated by the easy rotation part 64.
Kick it up in the direction of arrow I, thereby getting Rack 1.
3 is restored, and the lock tooth 66 is opened as shown in FIG.
and the protrusion 62 mesh with each other. During this first half-circle, the circumferential protrusion 62a (see Fig. 8) is engaged with the rack teeth 66, so the carry cam 60 (along with the hammer holder 11, hammer 55, etc.) is not moved, and the It's only half a turn. Halfway around the carry cam 60, the hammer drive section 61 comes into contact with the receiving section 65 of the hammer 55, as shown in FIG.
As the hammer drive unit 61 continues to rotate, the hammer 55 is pushed forward against the elasticity of the tension spring.
Selected type part 21 facing paper 16
The opening 5 is opened by pushing out the hammer 55.
4 (see FIG. 7) and is pressed against the paper 16 to perform desired printing. In addition, as shown in FIG.
3, unnecessary prints such as side prints are not made. As the carry cam 60 rotates, the hammer drive section 61 moves to the first position.
By moving the hammer 55 upward from the horizontal position as shown in FIG. During this reciprocating movement of the hammer 55, the hammer 55 is properly guided by the engagement between the hammer mounting portion 50, the convex portion 57, and the guide groove 58, and the engagement between the spring hook pin 59 and the long groove 58.

When the carry cam 60 continues to rotate, the spiral protrusion 62b (see FIG.
6, and as it rotates, the hammer holder 11, hammer 55, carry cam 60, etc. move toward the upper digit (to the left in Figure 1) by an amount equivalent to one digit against the elasticity of the hammer return spring 12. A raise is made.

Although the explanation is complicated, when the rack 13 returns as described above, the rotation stopper claw 68 of the rack 13 separates from the protrusion 45 as shown in FIG. 10B. Therefore, the control gear 33 and the reset plate 4
Only the rotation lever 46 prevents the rotation of the rotation lever 3. Then, as shown in FIG.
9 is disengaged, the control gear 33 rotates slightly in the direction of arrow J due to the biasing force of the spring, as shown in FIG. It comes into sliding contact with the outer peripheral surface of the portion 29. This state shown in FIG. 6C is called the paper feed set state.
At this time, the projection 45 of the reset plate 43 is in the position shown in FIG. 12B.

Here, the trigger groove portion 34 of the sensor gear 27 is
After the cam protrusion 31 pushes out the cam surface contact portion 48
It is designed so that when the 30th character part 21 comes, it is in a position where it meshes with the single tooth part 34 of the control gear 33. Therefore, after the paper feed is set, if a printing operation is performed even once during the transfer of the type belt 3 for 30 characters, the reset plate 43 is moved by the forward movement of the gear clutch lever 11 in the D direction as shown in FIG. 12B. is rotated in the direction of arrow K, and the protrusion 45 is pushed back to the position shown in FIG. Since the pawl portion 47 of the rotating lever 46 is in elastic contact with the outer circumferential surface of the locking portion 40 (see FIG. 5C) of the control gear 33, the reset plate 43 is pushed back as shown in FIG. 6D. The claw portion 47 of the rotating lever 46 engages the locking groove 3 of the control gear 33.
9 and the trigger groove 30 of the sensor gear 27 passes under the tooth 34, but it does not engage.
No paper feeding operation is performed. In this way, character selection, printing operation, carry operation, paper feed setting operation, and its reset operation are repeated in sequence to print one line. Next, the hammer holder return/paper feeding mechanism will be explained.

[Hammer holder return/paper feed mechanism]

As mentioned above, when one line is printed,
It is necessary to return the hammer holder 11 to the home position again and to feed the paper by an amount equivalent to one line in preparation for printing the next line.

As shown in FIG. 2, the spiral tooth portion 42 of the paper feed cam portion 41 of the control gear 33 meshes with the intermediate gear 75. As shown in FIG. A connecting shaft 76 of the intermediate gear 75 is press-fitted into a central shaft hole 77 of the paper feed roller 14 and rotated together with the paper feed roller 14 .

If no printing operation is performed even once during the transfer of the type belt 3 for 30 characters after the paper feed is set as described above, printing of that line is deemed to have been completed. Therefore, the paper feed is set, and when the 30th character comes, the sensor gear 27 is activated as shown in FIG.
One tooth 3 of the control gear 33 is located in the trigger groove 34 of the control gear 33.
4 is inserted. Subsequently, as the sensor gear 27 rotates, the spur gear part 26 of the sensor gear 27 and the spur gear part 26 of the control gear 33 mesh with each other, and the control gear 3
3 and the reset plate 43 are rotated once.

The rotational force of this control gear 33 is further applied to the intermediate gear 7
5 to the paper feed roller 14, and its rotation feeds the paper 16 by an amount corresponding to one line. During this paper feeding operation, that is, when the protrusion 45 of the reset plate 43 has rotated about half a revolution as shown in FIG. It enters under the notch 70 for use. Furthermore, reset plate 4
3 rotates in the direction of arrow E, the side of the rack 13 opposite to the rack teeth 66 is pushed up by the insertion of the protrusion 45, and the rack 13 is tilted in the direction of arrow L. When the rack 13 is folded in this way, the rack gear 66 and the protrusion 62 of the paper feed cam 60
The hammer holder 11 containing the hammer 55 and the paper feed cam 60 is returned to the home position by the tensile force of the holder return spring 12.

When the control gear 33 rotates once, the pawl 47 enters the locking groove 39 of the control gear 33 as shown in FIG. The protrusion 45 of 43 is engaged with the rotation stopper claw 68 of the folded rack 13, and is ready for printing the next row.

Figure 14 is a diagram showing the arrangement of printed characters for each digit. After the paper feed is set and before the paper feed operation starts, the 30 characters of printed characters include all types of characters in every digit. There is. Therefore, if no printing operation is performed while the type belt 3 is moved for 30 characters after the paper feed is set, it means that the printing of that line has been completed, and the next digit return and paper feed operation is started.

FIG. 15 is an exploded perspective view of the spring clutch 78 interposed between the main gear 8 and the drive pulley 1.

As shown in the figure, the spring clutch 78 includes a cylindrical drive arbor 79 and a spring fixing tube 80.
, a type position selection ratchet 81 , and a coil spring 82 .

One lower end 82a of the coil spring 82 is inserted and locked into the inner circumference of the spring fixing tube 80,
On the other hand, the other end 82b on the upper side is inserted and locked into the inner circumference of the drive pulley 2. With the coil spring 82 tightly wound around the outer periphery of the drive arbor 79, the drive arbor 79 is passed through the center hole of the spring fixing tube 80 and the center hole of the ratchet 81 into the center recess of the drive pulley 1 (not shown). ), and the central cylindrical portion 83 of the main gear 8 is press-fitted into the inner peripheral portion of the drive arbor 79 so as to rotate integrally therewith.
Further, a fan-shaped protrusion 84 formed on the inner circumference of the ratchet 81 engages with a fan-shaped recess (not shown) provided in the central recess of the drive pulley 1 (however,
A minute gap corresponding to the so-called loosening angle of the coil spring 82 is provided between the fan-shaped protrusion 84 and the fan-shaped recess in the rotation direction. The spring fixing tube 80, the ratchet 81, and the pulley 1 are tightly fitted so that they rotate together. Therefore, these three members and the main gear 8 are connected via the coil spring 82.

When the claws of the selection lever 17, which will be described later, are not fitted into the teeth of the ratchet 81, the coil spring 82 is tightened and the main gear 8 and drive pulley 1 rotate together. When the claw of the selection lever 17 is fitted into the teeth of the ratchet 81 and its rotation is prevented, the coil spring 82 is immediately turned off.
becomes loose, and the rotational force of main gear 8 is transferred to drive pulley 1.
will no longer be transmitted.

As shown in the figure, the drive pulley 1 is composed of an upper flange part 87 having the pulley teeth 24 and an upper flange 86, and a lower flange part 89 having a lower flange 88, and the two are fitted together. They are all one.

When feeding paper in a printer configured in this way,
As described above, the DC motor 4 is driven by the meshing of the code disk 25, the sensor gear 27, the control gear 33, and the intermediate gear 75, which rotate integrally with the main gear 8.
The paper is fed by power transmitted from the by the way,
When the paper 16 is a roll paper and the end of the paper is glued to the roll core, or the paper 16 is wound twice, and the paper 16 cannot be fed, the driving force of the motor 4 is reduced. spring clutch 78
It rests on the other end 82b of the coil spring 82 at. When the sudden load fluctuation is concentrated on the other end 82b of the coil spring 82, the other end 82b
The printer may bend or break, and if the printer is bent, the timing will be off, causing printing errors, and if the printer is bent, it will no longer function as a printer.

Therefore, in the present invention, in order to reduce the excessive load on the coil spring 82 during the paper feeding mode as described above, when the paper 16 cannot be fed,
The coil spring 82 and the drive arbor 79 are configured to be able to slip.

In this way, an excessive load is applied to the coil spring 82.
Specific measures for causing slip between the drive arbor 79 and the drive arbor 79 include, for example, reducing the number of turns of the coil spring 82, or making the drive arbor 79 of a material with a relatively low coefficient of wear.
There are other methods, such as forming a diameter of the drive arbor 79 and reducing the dimensional difference between the outer diameter of the drive arbor 79 and the inner diameter of the coil spring 82.

As mentioned above, the present invention includes a drive source, a main gear that rotates by power transmission from the drive source,
a spring clutch that selectively transmits the rotational force of the main gear to the type rotation body; and a spring clutch that selectively transmits the rotational force of the main gear to the type rotation body; In a printer equipped with a paper feeding mechanism that transmits type paper in a predetermined direction, the spring clutch is arranged between a drive arbor that rotates integrally with the main gear, and a predetermined distance between the drive arbor and the outer periphery of the drive arbor. a spring fixing tube that rotates integrally with the type rotating body; and a spring fixing tube that is disposed between the inner circumferential surface of the spring fixing tube and the outer circumferential surface of the drive arbor so that one end is attached to the spring fixing tube and the other end is attached to the type letter. It has coil springs respectively latched to the rotating body, a ratchet fixed to the spring fixing tube, and a selection lever fitted into the ratchet, and a tube between the type body and the spring fixing tube has a coil spring fixed to the spring fixing tube. A minute gap approximately corresponding to the loosening angle of the coil spring is formed, and when the selection lever is not fitted into the ratchet, the coil spring is tightened and the rotational force of the main gear is transferred to the type rotating body and paper feeding mechanism. On the other hand, when the selection lever is fitted into the ratchet, the coil spring is loosened so that the rotational force of the main gear is not transmitted to the type rotating body,
If an overload occurs that prevents the paper from being fed while power is being transmitted from the main gear to the paper feed mechanism, the coil spring and drive arbor may be It is characterized by the fact that it is designed to slip.

By adopting the above-mentioned configuration, during the paper feed mode, that is, when the coil spring of the spring clutch is tightening the drive arbor, if for some reason the paper is not delayed and the driving force of the motor is applied directly to the spring clutch. However, this load is absorbed by the slip between the drive arbor and the coil spring. Therefore, there is no deformation or breakage of the end portion of the coil spring, and it is possible to provide a printer with good printing quality and high reliability.

[Brief explanation of the drawing]

The figures are all for explaining the printer according to the embodiment of the present invention. Figure 1 is a schematic configuration diagram of the printer, Figure 2 is an exploded perspective view of the main parts of the invention, and Figure 3 is a plan view of the type belt. Figure 4 is a bottom view of the sensor gear, Figure 5 is a diagram for explaining the control gear, Figure A is a plan view of one gear section, and Figure B is a plan view of the spur gear section. , FIG. 6 C is a plan view of the locking part, FIG. 6 D and FIG. An explanatory diagram showing the engagement relationship between the control gear and the rotation lever, FIG. 7 is a perspective view of the hammer holder, hammer, and carry cam, FIG. 8 is a developed view of the cam surface of the carry cam part, and FIG. B is an explanatory diagram for explaining the rack return operation, FIGS. 10 A and B are explanatory diagrams for explaining the rotation stopping operation of the reset plate by the rack, and FIGS. 11 A and B are explanatory diagrams for explaining the rack tilting operation. Figure 12 A, B, and C are explanatory diagrams for explaining the engagement relationship between the gear clutch lever and the reset plate. Figures 13 A and B are sectional views of essential parts for explaining the printing operation. , FIG. 14 is an explanatory diagram showing the arrangement of letters for each digit, and FIG. 15 is an exploded perspective view of the spring clutch. 1... Drive side pulley, 3... Type belt, 4...
...DC motor, 8...Main gear, 14...Paper feed roller, 16...Paper, 33...Control gear, 4
1...Paper feed cam section, 75...Intermediate gear, 78...
... Spring clutch, 79 ... Drive arbor, 8
0... Spring fixed tube, 82... Coil spring bar.

Claims (1)

[Scope of utility model registration request] A drive source, a main gear that rotates by power transmission from the drive source, a spring clutch that selectively transmits the rotational force of the main gear to the type rotating body, and a spring clutch that connects the main gear to the type rotating body. In the printer, the printer includes a paper feeding mechanism in which power is transmitted from the main gear via the spring clutch to feed type paper in a predetermined direction in a state in which rotational force is transmitted, wherein the spring clutch is integrated with the main gear. A rotating drive arbor, a spring fixing tube disposed on the outer periphery of the drive arbor with a predetermined distance therebetween and rotating integrally with the type rotating body, and an inner peripheral surface of the spring fixing tube and an outer periphery of the drive arbor. a coil spring disposed between the surface and the spring fixing tube and the other end being locked to the type rotating body; a ratchet fixed to the spring fixing tube; and a selection lever fitted into the ratchet. and a minute gap approximately corresponding to the loosening angle of the coil spring is formed in the tube between the type body and the spring fixing tube, and when the selection lever is not fitted into the ratchet, the The coil spring is tightened to transmit the rotational force of the main gear to the type rotating body and the paper feed mechanism, while when the selection lever is fitted into the ratchet, the coil spring is loosened and transmits the rotational force of the main gear to the type rotating body and the paper feed mechanism. The structure is such that power is not transmitted to the type rotating body, and if an overload occurs that prevents the paper from being fed while power is being transmitted from the main gear to the paper feed mechanism, the overload of the coil spring will be removed. A printer characterized in that the coil spring and the drive arbor are configured to slip between the coil spring and the drive arbor in order to reduce the slippage.