JPS6148422B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an impact type dot printer.

Conventionally, as disclosed in JP-A-53-83825, for example, a platen (rotating drum) having one or more helical protrusions on its outer circumferential surface, and There is a helical platen type dot printer that has crossbar hammers that are disposed opposite to each other along the axial direction and that strike the protrusions. However, in this helical platen type dot printer, the protrusion of the crossbar hammer is formed long in a straight line along the axial direction of the platen.
For example, in the case of a character in a dot matrix with 7 rows and 5 columns, 7 This required multiple paper feeds, which made high-speed printing difficult. Furthermore, since the platen has a structure that requires a length corresponding to the required number of printing digits, deformation or warping of the platen greatly affects printing quality.
Its manufacturing requires high precision. Moreover, since the intersection position (dot formation position) between the protrusion of the crossbar hammer and the helical protrusion of the platen moves laterally sequentially as the platen rotates, the intersection position is at the end of the platen. When the crossbar hammer is in position, the crossbar hammer is subjected to a non-negligible torsional force and its operation becomes unstable. Therefore, there is a limit to the length of the crossbar hammer, that is, the number of digits that can be printed with one crossbar hammer, and in order to print a large number of digits (per line), it is necessary to use multiple crossbar hammers. It has no choice but to be installed. Furthermore, since the platen is long, its inertia is large, and large power is required to drive its rotation.

As a modification of this helical platen type dot printer, there is a dot printer that uses a platen that has a large number of small dot-like protrusions arranged in a helical pattern instead of the continuous helical protrusions on the platen. is disclosed in Japanese Patent Application Laid-Open No. 55-2065. In this modified second conventional technique, a printing hammer with a very small striking surface is used so as not to strike adjacent small protrusions simultaneously. The printing principle is substantially the same as the first conventional technique described above, in which the printing hammer is scanned left and right in accordance with the rotation of the platen.
One scan of the printing hammer forms only one horizontal row of dots, so to form a character,
It is necessary to scan the print hammer a number of times corresponding to the number of vertical dot rows of the dot matrix character, and a small paper feed is also required during this time. Therefore, similar to the first prior art, the actual printing speed is slow. Furthermore, in this second conventional technique, multiple rows of small protrusions arranged in a helical pattern are provided, and as many printing hammers as there are required for the number of rows. It had the same drawbacks as the conventional technology.

Furthermore, Japanese Patent Application Laid-Open No. 50-91416 discloses a printer in which both a platen and a printing hammer are kept facing each other and scanned in a direction perpendicular to the feeding direction of recording paper. This third conventional technology also
The printing principle itself is an application of the above-mentioned helical platen system, and the dot formation position is determined by the intersection position of the platen (spiral wheel), the protrusion, and the bar-shaped printing hammer. Therefore, even if both the platen and the hammer are kept facing each other and scanned in a direction perpendicular to the feeding direction of the recording paper,
If the opposing relationship between the two is not maintained accurately, there is a drawback that the positions of the dots tend to be irregular. For this reason, in this example, when configuring two endless belts for scanning the carrier supporting the platen and the carriage supporting the printing hammer,
It was necessary to adopt a special connection structure to compensate for belt length errors, and to maintain the exact opposing relationship between the platen and the printing hammer.

Accordingly, the main object of the present invention is to provide an impact type dot printer having a novel configuration that does not have the above-mentioned drawbacks, and embodiments thereof will be described below with reference to the drawings.

1 to 3, a carriage 1 made of a non-magnetic lightweight material is slidably fitted and supported on guide shafts 3, 3 fixed to side plates 2, 2. As shown in FIGS. The lower end of the printing lever 4 formed of a leaf spring is attached in a cantilevered manner via pins 5, 5, and the impact surface 6 is integrally attached to the upper end (free end). is formed.
This impact surface 6 has an area slightly larger than the area of one character of the dot matrix formed in this device. The printing lever 4 is driven by an electromagnetic drive device 7.
According to this embodiment, which is driven by An outer circumferential magnetic pole 10 fixed to the rear disk portion of the magnet 9, and both magnetic poles 8, 10
This electromagnetic drive device 7 is constituted by a moving coil 11 that is inserted into the magnetic path gap between the print lever 4 and fixed to the print lever 4. The platen 12 is fitted and supported by a platen shaft 13 supported by the side plates 2, 2, with a positional relationship opposite to the impact surface 6 of the printing lever 4. This platen 12 has a plurality of (six in this embodiment) dot-shaped protrusions 14a, 14b, . . . 14 on its outer peripheral surface.
f, and each protrusion is arranged in a spiral shape. That is, each protrusion 14a, 14b...14f
are positioned with a constant phase difference (center angle of about 45° in this embodiment) along the rotational direction of the platen 12, and in the axial direction (lateral direction), the dot pitch d ₁ (center angle) of the dot matrix is (see Figure 5). It is sufficient that the platen 12 has a length sufficient to form the protrusions 14a, 14b, . . . 14f, and the length of the platen 12 has no relation to the number of printed digits. Further, the platen 12 is slidable in the axial direction with respect to the platen shaft 13, and
The platen shaft 13 is non-circular (in this embodiment, it is rectangular)
Due to the cross-sectional shape, the platen shaft 13 rotates together with the platen shaft 13.
Cylindrical bodies 15, 15 are formed protrudingly from both side surfaces of the platen 12, and these cylinder bodies 15, 15 are sandwiched in the two-pronged arms 17, 17 of the carrier 16 in a sandwich-like manner and rotated. freely held. The carrier 16 is movable in the same direction as the carriage 1 (left-right direction) because a support shaft 19 fixed to the side plates 2, 2 is fitted into a notch 18 at the rear of the carrier 16. Cylinder body 15, 15
It is impossible to rotate around it. Carriage 1
Each end of a single scanning drive rope 20 is fixed to both sides of the carrier 16, and each end of a single scanning drive rope 21 is fixed to both sides of the carrier 16. Each rope 20 and 21 is adapted to be rotated by mechanisms well known and commonly used in the art. That is, each of the ropes 20 and 21 is actually wound around a pulley drum (not shown) disposed near each side plate 2, 2, and the pulley drum is connected to one of the pulley drums by a stepping motor (not shown). (not shown), and by the operation of this stepping motor, the carriage 1 and the carrier 16 are connected to the ropes 20 and 21.
They are also intermittently scanned to the right by a constant pitch d ₂ (see FIG. 5), and continuously returned to the left to the home position.

A gear 22 is fixed to the end of the platen shaft 13 protruding from the right side plate 2. This gear 2
A pinion 23 and a gear 24 integrated therewith are rotatably supported on a shaft 25 implanted in the side plate 2, and a pinion 27 of a drive motor 26 attached to the side plate 2 is connected to the gear. 2
It meshes with 4. A slit disk 28 is fixed to the pinion 27, and the outer circumference of the slit disk 28 is inserted into the opening of the detector 29.
This detector 29 is designed to generate _a detection signal in which _one cycle is _{P 1 ,} P _{2 .} The printing operations described above are synchronized.

Next, to explain the printing operation, in FIG. 1, when the drive motor 26 operates, the pinion 2
7. The platen shaft 13 rotates via the gear 24, pinion 23, and gear 22, and the platen 12 continuously rotates counterclockwise in FIG. At the same time, the carriage 1 and the carrier 16 are intermittently scanned to the right in FIG. 1 at a pitch (character pitch) of d ₂ as shown in FIG. 5 via the stepping motor and ropes 20 and 21. At that time, dot matrix characters, images, etc. are formed as described below. Now, the carriage 1 and the carrier 16 are at the position corresponding to the n-th digit, and the protrusions 14a, 14b...14f shown in the second figure
14a is in the positional relationship shown in the fourth figure with respect to the impact surface 6 of the printing lever 4. That is, the protrusion 14a is located in the first example of the first row of the n-th digit dot matrix. As the platen 12 rotates, the protrusion 14a sequentially moves downward on the first column to the second, third, and so on to the tenth row. Projection 14
When a passes the 10th row, that is, platen 12
When rotated by about 45 degrees, the protrusion 14a in FIG.
A protrusion 14b that is located behind appears in the first row and second column, and this protrusion 14b sequentially moves downward on the second column. Furthermore, the protrusions 14c, 14d, 14e
and 14f are also 3 in order in the same way as above.
Move down row, 4th column, 5th column, and 6th column. That is, the protrusions 14a, 14b...14f
correspond to the first, second, . . . , sixth columns of the printed digits. The pulses P ₁ , P ₂ ...P ₇ shown in FIG. 4 are generated when the protrusion 14a or 14b... or 14f is at each position of the first row, second row ... seventh row in FIG. A driving voltage is selectively applied to the movable coil 11 shown in the second diagram in synchronization with the pulses P ₁ , P ₂ . . . P ₇ . As a result, the printing lever 4 is displaced to the right in FIG.
a, 14b, . . . , 14f selectively collide with each other, and dot matrix characters as shown in FIG. 5 are formed on the second illustrated recording paper 30.

In the embodiments described above, the driving source for each of the carriages 1 and 16 may be common, or may be provided separately. Furthermore, the rotation direction of the platen 12 may be reversed, and the number of protrusions provided on the outer peripheral surface of the platen 12 is not limited to six. However, in general, characters etc. are 7
Since it is often composed of a dot matrix with 5 rows and 5 columns, it is desirable that the number of protrusions is 5 or more.

6 and 7 show a plan view and a right side view of another embodiment of the platen 12. According to this embodiment, the first column of the dot matrix,
2nd row... 2 protrusions 1 each corresponding to the 6th row
4a' and 14''a, 14'b and 14''b, . . . 14'f and 14''f are formed to face each other. In the case of the platen 12 having such a structure, 1/2 rotation of the platen 12 Carrier 1 and Carrier 16
Intermittent scanning is performed.

As described above, according to the present invention, the printing head section can be constructed with a very small number of parts, and accordingly, the printing head section can be extremely light and compact, and its manufacturing cost can be reduced. Since the platen, which has dot-like protrusions on its outer circumferential surface, is configured to scan together with the print head, the length of the platen can be shortened to the necessary minimum, which facilitates its manufacture. Even if the platen is deformed or warped, the printing quality will not be affected. Moreover, the number of printed digits per line can be freely increased regardless of the length of the platen, and since the inertia of the platen is small, it can be used with low power. The platen can be operated by a motor. In particular, according to the configuration of the present invention, since the dot formation position is uniquely determined by the position of the dot-shaped protrusion on the platen, even if the position of the print lever relative to the platen is slightly deviated when the platen and the print lever are scanned, It does not affect print quality. Therefore, compared to the above-mentioned prior art, it is easier to control printing quality and, accordingly, easier to manufacture and assemble. Furthermore, since one line of printing can be performed with one head scan, a printing speed comparable to that of a known wire printer can be achieved. In addition, in the present invention, the impact surface of the printing lever is made slightly larger than the area occupied by one character made up of dot matrix, and the carriage for the printing head and the carrier for the platen are arranged for each printing digit. Since scanning is performed intermittently and the printing operation is performed in a stopped state, no disturbance occurs in the dot arrangement when forming a single character or the like.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention.
The figure is a plan view, Figure 2 is a sectional view taken along the line in Figure 1, Figure 3 is a front view of the print head seen from the line in Figure 2, Figure 4 is a diagram of the output waveform of the detector, and Figure 5. 6 and 7 are a plan view and a right side view of another embodiment of the platen. 1...Carriage, 4...Print lever, 6...
Impact surface, 7... Electromagnetic drive device, 12... Platen, 13... Platen shaft, 14a to 14f, 1
4'a to 14'f, 14''a to 14''f... dot-shaped protrusion, 16... carrier, 20, 21... scanning drive rope, 26... platen drive motor.

Claims (1)

[Scope of Claims] 1. A carriage that is slidably provided in a direction perpendicular to the feeding direction of recording paper, a printing lever that is mounted on the carriage and is driven via an electromagnetic drive device, and this printing. An impact surface is provided at the tip of the lever and has an area larger than the space for one character composed of a dot matrix, and an impact surface that is rotationally driven together with the platen shaft and is slidable with respect to the platen shaft. a platen that is provided and faces the impact surface; a plurality of dot-shaped protrusions formed on the outer peripheral surface of the platen; a scanning drive device for intermittently moving the carriage and the carrier together at pitches corresponding to the character spacing; An impact type dot printer characterized in that the dot-like protrusion is selectively driven at a timing when the dot-shaped protrusion moves one pitch of the dot matrix while the dot-shaped protrusion faces the impact surface.