JPS64223B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small printer, and more particularly to a small printer having a type wheel and a hammer mechanism built into the type wheel.

Various types of printers have been proposed as printers equipped with a type wheel, but they can be roughly divided into those with a hammer mechanism placed outside the type wheel, and those with a hammer mechanism placed inside the type wheel. There are two types.

In the type in which the hammer mechanism is placed outside the type wheel, a group of hammers is placed facing the type wheel, sandwiching the printing paper, and the electromagnets that drive these hammer groups are selectively driven, and then the hammer mechanism is moved to the printing position. The so-called flying hammer method, in which the type on the type wheel that has arrived is impacted by a hammer through the printing paper to print on the printing paper, or the platen is used to sandwich the printing paper facing the type wheel. The so-called type wheel selects and aligns the desired type by selectively driving the type wheel selection mechanism located behind the type wheel, and then presses the printing paper against the type wheel using a platen to print. There are selection methods etc.

In any of the above-mentioned systems, the hammer drive mechanism and type wheel selection mechanism in the printer require a large amount of space, and there is a limit to miniaturization.

Furthermore, the above-mentioned flying hammer type printer has the disadvantage that the hammer impacts the type drum through the printing paper, so that the sound of hitting the paper is loud. In addition, in this method, printing is performed by instantaneous impact while the type drum is rotating, so the mechanism to obtain the desired timing between the type and the hammer is complex, which can lead to printing errors. .

In addition, in printers using the latter type wheel selection method, it is necessary to provide a type wheel selection mechanism for every other type wheel to be selected, which increases the number of parts and complicates the mechanism, reducing costs. It is difficult to do.

SUMMARY OF THE INVENTION An object of the present invention is to provide a compact printer with good print quality that eliminates the above-mentioned difficulties.

In the present invention, the missing part of the type belt for paper feeding is used as the type belt fixing part, and the fixed part is provided with a dummy type part lower than the type. As a result, the amount of axial movement of the ink roller can be reduced, eliminating excess seepage of ink, allowing for clear printing and preventing ink stains. Further, even if burrs occur in the dummy type portion during molding, the amount of protrusion does not affect printing, and the dummy type belt can be used as is, so the yield rate during molding of the type belt is improved.

Hereinafter, details of the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 is an exploded perspective view of the main parts of a small printer according to an embodiment of the present invention. is formed. A bottom plate 3 connects these side plates 2, 2. A type wheel 4 is rotatably accommodated within this main body frame 1. The type ring 4 is assembled on the basis of a cylindrical base 5, and this base 5 has grooves 6 formed at predetermined intervals as shown in the appendix of FIG. Small holes 7 are formed in the groove 6 at a predetermined pitch in a so-called staggered arrangement, with one groove located between adjacent grooves.
A type belt 8 is fitted into this groove 6. The type belt 8 is made of, for example, ethylene propylene rubber, fluorine rubber, neoprene rubber, acrylic rubber, chloroprene rubber, chlorosulfonated polyethylene,
Styrene butadiene rubber, urethane rubber, NBR,
A material made of a polymer rubber material such as silicone rubber or a synthetic polymer resin such as polyurethane is formed into an annular shape or a belt shape and is fitted into the groove 6 of the base 5 so as to form an annular shape. That's fine.

Type portions 9 are three-dimensionally formed on the front side of the type belt 8, and projecting portions 10 are provided on the back surface of the type belt 8, facing the type portions 9. These protrusions 10 are slidably fitted into the small holes 7 of the base 5. Therefore, the type portions 9 of the type belt 8 are also attached in a staggered arrangement between adjacent type belts. The pitch of the protruding portions 10 of the type belt 8 is set to be slightly smaller than the pitch of the small holes 7, and the type belt 8 is fitted with the type belt 8 slightly stretched and tensioned. As a result, the type belt 8 is stably attached to the base 5, and the return operation after protruding for printing is also fast and smooth, which is preferable.

The type belts 8 having the above-mentioned structure may be constructed so that each adjacent type belt is independent, but for example, as shown in FIGS. By providing it, it may be formed three-dimensionally. A plurality of short cylindrical protrusions 12 are provided on the upper surface of one side of these flat plate parts 11 in a staggered arrangement, for example, and these protrusions 12 are fitted into the other flat plate part 11. A small hole 13 is formed correspondingly. Therefore, after fitting the type belt formed in this way into the groove 6 of the base 5, the flat plate parts 11, 11 are overlapped and the protrusion 12 is fitted into the small hole 13 as shown in FIG. If this is done, the entire type belt will be connected in a ring.

The locations where these flat plate portions 11, 11 are located are so-called missing portions of type, and in principle, no type is formed in these portions, and as will be described later, the printing paper is will be sent. In the present embodiment, dummy type characters 14 are provided protruding from this conventional type missing portion of the type belt with approximately the same height as the type characters or slightly lower. The height of the protrusion 12 is approximately the same as or slightly lower than the height of the type portion 9.

As mentioned above, the reason why the dummy type is set low is to reduce the movement of the ink roller and prevent the ink from being squeezed and deposited in large quantities when the ink roller runs over the first type from the missing part of the type. Further, when connecting the fixed portion of the type belt with adhesive, if there is a large amount of adhesive, the height may be higher than the type, and it is also possible to prevent the paper from getting dirty. Furthermore, as a manufacturing problem, burrs always occur when injection molding a type belt, but if the dummy type is molded low, even if some burrs occur in this area, they will not come into contact with the paper, so it will not be a defective product. First, the yield during molding of the type belt can be improved.

By the way, the type belt 8 of this embodiment has a structure as shown in FIG. That is, as shown in FIG. 6B, the type belt 8 has a pedestal 8a projecting from the upper surface of the type belt 8, and a character portion 8b is protruded from the pedestal 8a. When such a structure is adopted, as shown in FIG. 7, unlike the conventional structure in which the character portion 8b is provided directly on the upper surface of the type belt 8, the elongation of the characters is reduced. In other words, Figure 7B
If the character part 8b is formed directly on the upper surface of the type belt as shown in , when the type belt 8 is stretched due to the external force F from the hammer, the elongation is directly caused by the character part 8b.
As shown in FIG. 7B, the character part 8b itself is deformed, and as a result, as shown in FIG. This results in a drop.
However, if the character part 8b is provided protrudingly through the pedestal 8a, the character part 8b is not deformed and can be printed clearly as shown in FIG. 9.

Here, a disc-shaped bracket 15 is fitted to one end of the base 5 and fixed with a screw 16. A boss portion 18 protruding from one end of the gear 17 is fitted onto the other end of the base 5 and fixed with a screw 16.

A hammer assembly 19 is housed inside the type wheel configured as described above. This hammer assembly 1
9 is assembled based on a yoke 20 formed in a U-shaped cross section, and a fourth
As is clear from FIG. 5, a plurality of bobbins 21 having both sides shaped like a gourd when viewed from the front are arranged in one row. A hammer 23 is slidably fitted into the boss portion 22 above the bobbin 21, and one end of the hammer 23 is bent as shown in FIG. A striking portion 24 is formed. This striking part 24 corresponds to the adjacent type belts 8, 8, as is clear from FIG. That is, one striking section 24 is responsible for striking two type belts. However, since the protrusions 10 of the type belt are arranged in a staggered manner in the circumferential direction, as described above, only one character is printed in one operation.
With such a structure of the striking part, one plunger can correspond to two type belts, the space occupied during mounting can be reduced, and high-density mounting is possible. On the front side of the bobbin 21 is a front plate 2.
5 is fitted, and a printed board 26 is arranged on the front surface of this front plate, and the wire 31a of the coil 31 is tied to the pin 102' fixed on the boss 28 protruding from the bobbin 21 and soldered. The front printed board 26 and the pin 102' are soldered and electrically connected.

A fixed iron core 29 is caulked through the front plate 25 and fitted into the bobbin 21 by a predetermined distance, and a movable iron core 30 is slidably fitted into the bobbin 21 in opposition to the fixed iron core 29. And these iron cores 29, 30
A coil 31 is wound around it. The outer end of the movable iron core 30 and the outer end of the hammer 23 are connected by a bracket 32, and a coil spring 33 is resiliently mounted between the bracket 32 and the end surface of the bobbin 21. The hammer 23 is made of a material with small mass, such as aluminum or hard synthetic resin, in order to reduce the rise time at the initial stage of suction. The plunger 34 is constituted by a pair of members that go around the bobbin, and the hammer 23 is normally kept separated from the type belt by the coil spring 33, but when the coil 31 is energized, the movable iron core 30 is moved. It is sucked, the hammer 23 is interlocked, and one printing is performed.

By the way, the above-mentioned coil spring 33 is preferably formed as a conical coil spring as shown in FIG. As shown in Fig. 11, such a conical coil spring has a load-deflection curve that is nonlinear compared to a cylindrical coil spring, and the pitch P and coil diameter
Advantageous characteristics can be brought out by changing D ₁ and D ₂ . In other words, the rising characteristics of a suction type plunger can be improved. This is because, if the attractive force when the movable iron core l ₃ moves is P ₃ as shown in Fig. 12, then when a cylindrical coil spring is used, l ₁ as shown in Fig. 13.
A load of P ₁ is required for the deflection of the plunger, that is, a load that acts as a resistance to the plunger, which consumes the attractive force in the cylindrical coil spring and slows down the rise time. On the other hand, if a conical coil spring is used, as shown in Fig. 11, even if the moving amount of the movable core is the same l ₁ , the load at that time is P ₂ (P ₂ ≪ _{P 1} )
Therefore, the resistance for the plunger is reduced, the rise time is extremely fast, and power consumption is also reduced.

The hammer assembly 19 constructed as described above is housed in the base 5, and its support structure is constructed as follows. That is, the support plate 35 formed integrally with the yoke 20 supports the bracket 15.
A screw 37 is attached to a substantially L-shaped bracket 36 that extends outwardly through a through hole 36 formed in the center of the body frame 1 and is fixed to the outside of the side wall 2 of the body frame 1.
Fixed by Further, a support plate 38 formed by integrally bending from the other end of the yoke 20 is fixed to a disk-shaped bracket 39 with a screw 40, and a cylinder 41 integrated with the bracket 39 is attached to the gear 17. It is led outward through a through hole 42 formed in the center.

Incidentally, a boss 43 formed on the outer surface of the bracket 15 surrounding the through hole 36 is connected to a circular hole 45 connected to the side plate 2 of the main body frame 1 via a notch 44.
It is rotatably fitted into a bearing member 46 fitted therein. The aforementioned L-shaped bracket 36 is fixed to the side plate 2 by screws 47 on the outside of this bearing member 46.

On the other hand, a partially toothed gear 49 having teeth 48 over a predetermined angular range is integrally formed on the outer surface of the gear 17, and bosses 50 and 51 whose diameters gradually become smaller are integrally formed on the outer side thereof. It is installed protrudingly. A cam ring 52 is fitted into the boss 50 via a through hole 53 thereof. The cam ring 52 has a cam groove 54 concentric with the through hole 53, and a portion of the cam groove 54 has cutouts 54a and 54b formed at opposing positions. The gear 17 is positioned inside the other side plate 2 of the main body frame 1 with the cam ring 52 fitted therein. A boss 57 is fitted into a circular hole 56 connected to the side plate 2 through a notch 55, and the boss 51 is rotatably fitted into the boss 57. A flange portion 58 and a threaded portion 59 connected to the flange portion 58 are formed at the outer end of the cylinder 41 guided to the outside by this boss 57. The cylinder 41 is held down by the through hole 61a of the bracket 61 to be fixed, and is fixed by screwing a nut 62 into the threaded portion 59 from the outside of the bracket 61.

A boss 63 is provided on the outside of the side plate 2 of the main body frame 1 on the side facing the cam ring 52 at a certain distance, and a support plate 65 is fixed to the boss 63 with a screw 64. The reed switch 66 is held horizontally.

On the other hand, a support 67 is provided protruding from the outside of the side plate 2 in the vicinity of the circular hole 56.
A magnet lever 68 and a return lever 69 are rotatably supported on the same axis, and a C ring 70
is prevented from leaving.

The boss 57 is located at one end of the magnet lever 68.
A shaft 68a having a D-cut portion that fits into the cam groove 54 through a notch 57a formed on the periphery of the cam groove 54 is protruded, and a permanent magnet 71 is fixed to the other end facing outward.

A shaft 69a having a D-cut portion that similarly fits into the cam groove 54 is protruded from one end of the return lever 69, and a torsion coil spring 72 is wound around the boss portion 69b of the shaft 69a. Locked to the magnet lever 68, the magnet lever 6
8 is provided with rotational sliding properties in the clockwise direction in FIG. Further, a spring 75 is stretched between a pin 73 protruding from the lower end of the return lever 69 and a pin 74 protruding from the support plate 65. Provides rotational sliding properties. The magnet lever 68 and the return lever 69 configured as described above are interlocked with the rotation of the cam ring 52 and reciprocate from side to side over a predetermined angular range by engaging with the cam groove 54.
1 in reciprocating motion, and the reed switch 66
It also generates on/off signals in synchronization with the reciprocating motion of the permanent magnet.

On the other hand, on the platen 76 side which forms the front wall of the main body frame 1 in parallel with the type ring 4, a bearing 76 is mounted on the side plates 2, 2.
A shaft 77 is rotatably supported via a shaft 76, and a rubber roller 78 for feeding paper is fixed to this shaft 77. A gear 79 is attached to one end of this shaft 77.
and a feed spring 80 are loosely fitted. A boss 79a protruding from the outer end of the gear 79 has a groove 79b formed across it, and a feed spring 8 is inserted into the groove.
The protruding portion 81a of the fixed boss 81 is fitted. A non-circular cross-section 77a is formed at the outer end of the shaft 77, and a non-circular cross-section 82a of a ratchet wheel 82 is fitted into this non-circular cross-section to restrict its rotation. spring 8
The free end 80a of the ratchet wheel 82 is engaged with internal teeth 82b formed on the inner peripheral surface of the ratchet wheel 82. The gear 79 is meshed with the gear 48 .

A manual knob 84 is rotatably fitted to a shaft 83 that extends outward from the side plate 2 in parallel with the shaft 77.
A C ring 85 prevents it from coming off. A gear 84a formed integrally with the manual knob 84 meshes with a gear 82c formed on the outer peripheral surface of the ratchet wheel 82.

The one indicated by numeral 86 is a pulse motor that connects the main body frame 1.
The bracket 7 protrudes from the outside of the platen 76.
The output gear 86b is fixed by a screw 86a via a boss 76b provided on the outer surface of the gear 6a.
is exposed to the inside of the bracket 76a through the through hole 76c of the bracket 76a. A shaft 76d projects from the back surface of the bracket 76a, and an intermediate gear 87 that meshes with the output gear 86b is supported on this shaft.
7 and transmits the rotation of the pulse motor to the type wheel.

On the other hand, a comb-shaped paper guide 88 is arranged on the inner surface of the platen 76 . This paper guide 88 is fixed at one end by elastically deforming and inserting a tongue piece 88a having a semicircular cross section into a square hole 2a formed in the side plate 2 of the main body frame 1, and fixing the other end. The end has a small hole 76 formed on the platen 76 side by inserting a screw (not shown) into a through hole 88c formed in the protruding piece 88b.
It is fixed at e.

The one indicated by reference numeral 89 is bent into an arc shape as a whole at the upper paper guide, and is connected to the platen 76 via an L-shaped bent piece 89a formed at one end thereof.
is configured to hold the lower end thereof, and is screwed to the bottom plate 3 of the main body frame 1 through a through hole 89b formed at one end in the longitudinal direction, and a protrusion 89c formed at the other end is attached to the bracket 76a. It is fixed by being elastically deformed and inserted into a flat, concave long hole 76f formed in .

A shaft 90 is rotatably supported in front and below the platen 76 through a through hole 2b formed in the side plate 2, and a pinch roller 91 is rotatably supported on the shaft 90. A shaft 92 is horizontally suspended parallel to the shaft 90 , and one end of a torsion coil spring 93 attached to both ends of the shaft 92 contacts the shaft 90 to press the pinch roller 91 against the rubber roller 78 .

On the other hand, on the opposite side of the rubber roller 78 across the type wheel 4, an ink roller 94 is disposed so as to be supported by a rotating lever 95 via its support shaft 94a. The rotating lever 95 has a groove 95a along the axial direction in the center thereof, and the support shaft 94a is attached to the groove 95a.
It is held elastically via 5a. The upper end of the rotating lever 95a is a cylindrical portion 95b, and these cylindrical portions 95b are fitted and fixed to both ends of a support shaft 96. Both ends 96a of the support shaft 96 are connected to the side plates 2, 2.
The support shaft 96 is rotatably suspended horizontally in the through hole 2c formed in the side plate 2, and on the opposite side of the support shaft 96 that holds the ink roller 94, another support shaft 97 is connected to the through hole 2c in the side plate 2.
They are horizontally suspended in parallel via d and 2d. A torsion coil spring 98 is wound around the support shaft 96, and one end of the spring 98 is connected to a pin 96b implanted in the support shaft 96.
The other end is locked to the support shaft 97, which applies a force that presses the ink roller 94 toward the type wheel 4.

What is indicated by the reference numeral 99 is printing paper.

Next, the operation of this embodiment configured as above will be explained.

Before printing, as will be described later, A, B, C, and D phase pulse signals are sequentially applied to the pulse motor 86 at different timings, and each time a pulse signal is applied, the type wheel 4 is moved by a certain angle as shown in FIG. Rotate clockwise. In this state, when a command to print a specific character is received from the control circuit as described later, the type wheel 4 stops at a predetermined position to be printed, current flows through the coil 31 of the selected plunger 34, and the movable iron core 30 is attracted against the coil spring 33. As a result, the hammer 23 advances, the striking section 24 strikes the protrusion 10 of the selected type wheel 8, and presses the printing paper 99 against the platen 76 to perform printing. At this time, the elastic type belt 8 stretches to ensure reliable printing.

Note that during this printing, the gear 79 is in the toothless portion of the toothless gear 49, and the printing paper 99 is not fed.

When the predetermined printing operation is completed in this way and the gear 17 rotates once, the partially toothed gear 49 and the gear 79 begin to mesh, and at the same time the feed spring 80 coupled to the gear 79 is also integrated with the boss 81 as shown in FIG. Start rotating counterclockwise. At the same time, ratchet wheel 8
2 is also rotated, so the shaft 77 is also rotated, and as the shaft 77 rotates, the rubber roller 78 is also rotated counterclockwise, and the printing paper 99, which is sandwiched between the pinch roller 91, is moved upward by a predetermined distance. It is then sent out and waits for the next print command.

In addition, in the above embodiment, an example was shown in which an electromagnetic plunger was used as a driving means for the hammer, but
It may be configured as a mechanical drive mechanism using a cam or a lever, and it may be configured not only as a parallel printer but also as a serial printer. It is natural that the hammer 23 and the platen 76 are set in a vertical relationship, but if the hammer 23 is tilted upward as shown in FIG. 4 while maintaining that relationship, the paper immediately after printing will be This is preferable because the printed characters during feeding become faster and easier to see. This angle of inclination is preferably between 10° and 30°, particularly around 24°, and the diameter of the type ring in this case is between 20° and 30°.
30 mm, particularly preferably around 25 mm, and the type pitch (distance between the centers of two type characters) at this time is preferably around 4.4 mm.

Next, details of the control will be explained using time charts and block diagrams.

FIG. 16 schematically shows a block circuit that controls printing based on printing commands, in which a pulse motor control circuit 100 is connected to a reference signal oscillator (OSC) 10.
Drive pulses are generated at outputs corresponding to phases A to D, respectively, based on the signals from phase A to D. The phase relationship between the pulses generated in each phase is suitable for driving the pulse motor 102 in a two-phase excitation method, as shown in FIGS. 14d to 14g. The pulse motor 102 is driven by a two-phase excitation method via a driver 101' based on pulses appearing in each phase to rotate the type wheel 103.

The pulses appearing in the A-phase to D-phase outputs of the pulse motor control circuit 100 are one shot multi 104
This occurs after a predetermined period of time has elapsed since the printing command pulse PO (see FIG. 14a) applied to the input of is generated. That is, the one-shot multi 104 is driven by the pulse PO, and a pulse of a predetermined width as shown in FIG. Note that the pulse PO is also directly applied to the pulse motor control circuit to put it into operation.

The A-phase output of the pulse motor control circuit 100 is input to a counter 108, which counts the pulses appearing at the A-phase output. The output _Q1 of the counter 108 generates a signal when 24 pulses of the A phase output are counted, and the pulse motor control circuit 1 indicates that the printing process is completed.
Enter 00. As will be explained later, these 24 numbers correspond to the number of 12 characters on the type ring, and since the adjacent type belts on the type ring are staggered and shifted by half a pitch, the number of 12 characters corresponds to the number of 12 characters on the type ring. To scan across each digit, the type wheel must be at least twice as large, i.e.
This is because it must be rotated 24 times in steps.

This counter 108 receives a timing signal TR (Fig. 14h) which is generated when the reed switch 109 closes when the computer finishes calculation and enters the printing cycle.
is reset by the rising edge of , and the A phase output that appears thereafter is counted. timing signal TR
When the paper feeding process is completed and the printing cycle is completed, the reed switch 109 is turned off and turned off. The counter 108 may be reset at the falling edge of this timing signal. Note that the timing signal is also applied to the pulse motor control circuit 100 and serves as a control input necessary for the printing cycle.

The contents of counter 108 are directed to match circuit 110 and compared with the contents of character register 111 to determine a match. The character register 111 stores character information to be printed as a result of the calculation. The characters stored in the character register 111 are synchronized with the A-phase output pulse, and first all the information of odd number digits, then the information of even number digits, then the information of odd number digits again, and then the information of odd number digits. All information on digits and all information on even-numbered digits are read out alternately and sequentially. For example, if the content of the counter is 2, character register 11
If there is information of 2 among the odd numbered digits read from 1, the part corresponding to that digit (that is, all digits having information of 2) is sent to the serial input parallel output register 113 through the delay circuit 112. 1”,
In addition, "0" is input in parallel to each of the other digits. The output of the register 113 that stores "1" drives the corresponding solenoid (for example, in the case of 12-digit information, six solenoids are provided as described above) via the solenoid driver 114, and the number "2" is output. is printed. Note that at this time, the type belts corresponding to the odd numbered digits of the type ring are all aligned to the "2" position.

Next, all the information of even number digits is read from the character register 111, and the solenoids corresponding to the digits including "2" are similarly driven. At this time, the type wheel has moved by one step, and all the type belts corresponding to even numbered parts are "2", so that printing can be performed on the digits including "2".

Next, the counter output _Q2 becomes "3", and similarly, "3" is printed in the odd numbered digits including 3, and then "3" is printed in the even numbered digits including 3. Thereafter, printing of "4", "5", etc. is continued in the same manner.

Note that the contents appearing on the counter output _Q2 must be incremented by one every time two A-phase outputs are counted, but an even-digit counter and an odd-digit counter are provided, and the contents of both counters are changed for each A-phase output. may be alternately counted one by one and led to the matching circuit. In addition, in FIG. 16, PF indicates a paper feeding mechanism.

FIGS. 14 i to 14 k each illustrate the timing when printing "123.+". When a type is selected and printed during the type selection printing step X, the pulse motor must be held for a predetermined length in preparation for printing. This situation is illustrated in more detail in FIG.

That is, in FIG. 17, a is the matching circuit 110.
b indicates the reference pulse from the oscillator 101, c to f indicate the pulses appearing in the A phase to D phase, respectively, g indicates the pulse energized to the selected solenoid via the solenoid driver 114, and h to k indicate the amount of movement of the pulse motor, type wheel, solenoid, and type belt, respectively. After the output of the matching circuit 110 is obtained at time t ₁ , it is delayed by one reference pulse by the delay circuit 112, and then the solenoid is energized for two reference pulses from t ₂ to _{t 3} (Fig. 17g). Thereafter, the motor is held until one reference pulse _t4 , and finally the solenoid is energized from _t2 to _t3 , and the pulse motor is stopped for four pulses from _t2 to _t4 . At the same time as the pulse motor stops, the type wheel 103 stops,
A pulse signal is applied to the solenoid between times _t2 and _t3 , and the hammer is operated to perform printing. Return time t ₃ of the type belt after further printing
After ~t ₄ , the type wheel starts rotating again.

After the character selection printing process X is thus completed, the paper feeding process Y is started (FIG. 14l). At this time, an output is generated at the output _Q1 of the counter 108, a signal is given to the pulse motor control circuit 100, and the drive pulse width increases from _t5 to _t6 . That is, in the paper feeding process Y, the driving pulse width to the pulse motor is extended to increase the torque and the paper is fed. As described above, drive pulses with a short pulse width are used in the character selection and printing processes, which have a small load, and drive pulses with a long pulse width are used in the paper feeding process, which has a large load (see FIG. 15). In this way, during the paper feeding process of the type wheel, the paper is fed with high torque, so that even a small and inexpensive pulse motor can be used, which is extremely preferable.

Furthermore, after the paper feeding process Y is completed, the type drum stabilization process Z starts with 6 standard pulses, in which long drive pulses are used to ensure that various operations are completed and one printing cycle T is completed. finish.

The 1 printing cycle in Fig. 14 described above is
This will be explained using the flowchart shown in the figure. First, when a printing command is issued at 120, energization is started from the A and D phases, and the pulse motor advances one step with two reference pulses (OSC) (121). Next, in step 122, the rise of the timing signal TR is determined, and if it exists, the pulse motor is caused to advance by one step with one OSC (step 123). After that, it is determined by the matching circuit whether or not to print (124), and if there is a matching output, the solenoid is energized for two reference pulses after being delayed by one reference pulse.
During this time, the pulse motor for four reference pulses is held and printing is performed (125).

If there is no coincidence output, it is determined at 126 whether 24 shots of the A phase have been counted from the rising edge of the timing signal, and if not yet, it is determined again at 124 whether there is a coincidence. When the selection printing process is completed after counting 24 shots, the paper feeding process is started at 127. That is, with two reference pulses, the pulse motor advances one step, becomes 1/2 or 1/n slower, and the torque increases. After that, at step 128, it is determined whether the timing signal TR is falling, and if a falling edge is detected, the pulse motor is held for 6 standard pulses at the next rising edge of the A phase, and electricity is cut off, in order to stabilize the type drum. (129) One print cycle ends.

[Brief explanation of drawings]

The figure explains one embodiment of the present invention.
The figure is an exploded perspective view of the drive unit, Figure 2 is a perspective view of the type belt, Figure 3 is an enlarged perspective view of the type belt connection, Figure 4 is a vertical side view, and Figure 5 is a vertical front view of the type ring. Figures 6A and 6B are a plan view and a vertical side view of the type belt, Figures 7A and B are enlarged cross-sectional views illustrating the conventional type belt, and Figure 8 is an explanatory diagram of the state of printing by conventional type. , Fig. 9 is an explanatory diagram of the printing state of the type belt, Fig. 10 is a side view of the conical coil spring, Fig. 11 is a diagram illustrating the load-deflection characteristics of the conical coil spring, and Fig. 12 is the suction of the plunger. A diagram illustrating the relationship between force and stroke; FIG. 13 is a diagram illustrating the load-deflection characteristics of a conical coil spring; FIG. 14 is a time chart illustrating the printing cycle of the small printer according to this embodiment; Fig. 15 is a diagram explaining the relationship between pulse motor torque and drive frequency, Fig. 16 is a block diagram explaining the control circuit, and Fig. 17 is a diagram explaining the printing process of the printing cycle in more detail. , FIG. 18 is a flowchart illustrating the control operation of the small printer of this embodiment. 1...Body frame, 2...Side plate, 4...Type wheel, 5
... base, 8 ... type belt, 10 ... protrusion,
14...Dummy type, 19...Hammer assembly, 2
0...Yoke, 23...Hammer, 30...Movable iron core, 78...Rubber roller, 86...Pulse motor, 94...Ink roller, 99...Printing paper,
100...Pulse motor control circuit, 101...
Oscillator, 106, 107... Gate circuit, 108
...Counter, 111...Character register.

Claims (1)

[Claims] 1. In a small printer that has a type ring in which a type belt is wound around the circumferential surface of a cylindrical base, and a printing hammer disposed within the type ring, both ends of the type belt are connected to flat plate parts. and forming dummy type characters having a height equal to or lower than the type characters on the flat plate part, forming a protrusion at one end of the type belt and a hole to fit with the protrusion at the other end, A small printer characterized in that a hole is fitted into the protrusion of the type belt to form a type belt fixing part.