JPH02196680A - Sheet feeding mechanism for printer - Google Patents

Abstract

PURPOSE:To obtain a sheet feeding mechanism for a printer having a high accuracy, a small size and low power consumption by providing a type drum having types arranged on its outer surface and to be rotatable and rockable in a digit direction, a drive gear formed integrally with the type drum on the same axis, and a driven gear to be engaged directly with the drive gear only at the time of feeding of a sheet. CONSTITUTION:A type drum 3 is moved at a lower digit side by one digit by the engagement of a cam groove 301 with a rotor 12 upon rotation of a stepping motor 2. In this stroke, the type drum 3 is disposed at a lower digit side, and the positional relationship of the digit direction between a sheet feeding drive gear 304 and a sheet feeding gear 23 is capable of being engaged. The first gear 304b of the sheet feeding drive gear 304 is engaged with the second gear 23b of the sheet feeding gear 23, the second gear 304c of the sheet feeding drive gear 304 is engaged with the third gear 23c of the sheet feeding gear 23, and the first gear 23a is engaged with the groove of a first locking cam 304a. Accordingly, the sheet feeding gear 23 is rotated to feed the sheet for a distance corresponding to one line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper feeding mechanism for a printer installed in a calculator or the like.

[Conventional technology]

In the past, many paper feeding mechanisms for printers have been proposed, and in particular there is a mechanism as shown in Japanese Patent Application Laid-Open No. 11264/1983.

[Problem to be solved by the invention]

However, although the above-mentioned conventional technology includes a type drum, a driving gear integrally formed therewith, and a driven gear that meshes with the type drum, the type drum does not swing, or the driving gear and driven gear In some cases, the mesh was not only present when paper was being fed.

For example, if the type drum does not swing, basically, when the type drum rotates once, the driven gear also moves once. Therefore, when considering a printer that can use this conventional mechanism, there is a constraint that the printer is limited to one that can form one line printing cycle with one rotation of the type drum.

Furthermore, although there is no detailed description in the past, in the case of a mechanism in which the driving gear and the driven gear mesh not only during paper feeding, the movement of the driven gear and the paper feeding movement do not correspond one-to-one; It was necessary to use some kind of clutch mechanism to obtain rotational motion only during paper feeding and transmit it to the paper feeding gear. In this case, a space is required to provide the clutch mechanism, which increases the size of the paper feeding device itself and increases the cost. In addition, since a clutch mechanism is interposed between the drive gear (type drum), which determines print timing, and the paper feed gear, which determines paper feed timing, there is a risk that accuracy will deteriorate when the timings of both are combined. be. Furthermore, since the paper feed gear receives power from the type drum via a clutch mechanism, the load increases due to a decrease in transmission efficiency, which increases power consumption.

Furthermore, the drive source for paper feed is not obtained from the type drum, but is generally separated into the type drum side and the paper feed 1 side from one drive source, and drives each side. Even in this case, since a transmission member is interposed between the two timings, there is a risk that the accuracy when the two timings are combined may deteriorate.

SUMMARY OF THE INVENTION The present invention has been made to solve these drawbacks, and an object of the present invention is to provide a paper feeding mechanism for a printer that is highly accurate, compact, and consumes low power at a low cost.

[Means for Solving the Problems] The paper feeding mechanism of the printer of the present invention includes a type drum having type characters disposed on its outer periphery and rotatable and swingable in the digit direction, and a type drum coaxially integral with the type drum. The present invention is characterized in that it is provided with a drive gear formed in the same shape as the drive gear, and a driven gear that directly meshes with the drive gear only during paper feeding.

〔Example〕

FIG. 1, FIG. 2, and FIG. 3 are an exploded perspective view, a plan sectional view, and a side sectional view of an embodiment of the present invention, respectively.

Reference numeral 1 denotes a frame, in which a hole 101 and a groove 102 are provided. Reference numeral 2 denotes a step motor, and the outer periphery thereof is provided with a groove 201 and ratchet teeth 202 corresponding to the phase of each printed character. 3
is a type drum, which includes a cam groove 301, a groove 302, and a protrusion 3.
03, paper feed drive gear 304, reset signal cam 305
is integrally molded, and a through hole 306 is provided on the outer periphery. 4 is a type sheet, which has type 401 on the front side and protrusions 402 corresponding to the type 401 on the back side;
The protrusion 402 is inserted into the through hole 306 and wound around the type drum 3. 5 and 6 are yokes that form the yoke of the electromagnet;
7 is an iron core fixed to the yoke 6, 8 is a coil arranged at a ratio of one for every two digits of the type 401, 9 is a hammer slidably set inside the coil 8, and 10 is located inside the coil 8. , is a suction plate that moves almost integrally with the hammer 9 and is attracted to the iron core 7 by an attractive force when the coil 8 is energized.

One end 501 of the yoke 5 passes through the step motor 2, and one end 502 passes through the bearing 11. The bearing 11 pivotally supports the type drum 3, and the protrusion 303 of the type drum 3 engages with the groove 201 of the step motor 2. 5th hole is hole 503.
504, it is positioned and fixed to the frame 1. The step motor 2 and the bearing 11 cannot swing in the digit direction, but the type drum 3 can swing in the digit direction. A rotor 12 is pivotally supported in a hole 101 of the frame 1, engages with a cam groove 301 of the type drum 3, and swings the type drum 3 in the direction of one digit per revolution.

13 is a first detection spring, and 14 is a second detection spring. The curved portion 131 of the first detection spring 13 rides on the reset signal cam 305 of the type drum 3, and the first detection spring 13 and the second detection spring 14 come into contact with each other, thereby generating a set signal that rotates once every two revolutions of the type drum 3. to occur. Reference numeral 15 denotes an ink roller cover, which supports the ink roller shaft 16 . The ink roller receiver 17 has a black ink roller 18 or a red ink roller 19 inserted therein, and the ink roller shaft 1
The partition wall portion 171 is loosely fitted into the groove 151 of the ink roller cover 15 to position the ink rollers 18 and 19 in the column direction. A paper feed shaft 20 passes through a paper feed rubber 21 and is pivotally supported by a platen 22 attached to the frame 1. 23 is a paper feed gear, which is coaxially supported by the platen 22 with the paper feed shaft 20, and a paper feed spring 24 attached to the frame 1.
It is pressed against the paper feed shaft 20 by.

The paper feed gear 23 and the paper feed shaft 20 engage as a one-way clutch with triangular teeth, and the paper feed gear 23 reliably drives the paper feed shaft 20 during rotation in the paper feed direction. There is. The paper press roller 25 has both ends inserted through a paper press shaft 26 supported by the frame 1, and presses the printed paper 31 against the paper feed rubber 21 by the spring force of the paper press shaft 26. Reference numeral 27 denotes a reverse stopper claw attached to the frame 1, which is activated by the ratchet teeth 202 of the step motor 2 to stop the type 401 at the printing position 28.

Reference numeral 29 denotes an ink roller frame, which swings integrally with the type drum 3 when the protrusion 291 engages with the groove 302 of the type drum 3 . An ink roller spring 30 presses the ink rollers 18 and 19 against the type drum 3 side.

The operation of the mechanism having the above configuration will be explained. In the present embodiment and example, as shown in FIG. 6, two revolutions of the type drum 3 constitute one line printing cycle, and one line printing cycle consists of five strokes from the first stroke to the fifth stroke. type drum 3
The rotation and stopping of the step motor 2 is performed by controlling the energization of the step motor 2, but a detailed explanation of this energization control method will be omitted. Further, as shown in FIGS. 7 and 13, the first tooth portion 304 of the paper feed drive gear 304 that drives the paper feed gear 23
b and the second tooth portion 304C are a small part of the circumference of the paper feed drive gear 304, so the stroke in which the first tooth portion 304b and the second tooth portion 304C side face the paper feed gear 23 side is called the third stroke. This is limited to the fifth stroke, and there is no possibility of paper feeding in other strokes.

In the first stroke, the type drum 3 moves as shown in FIG.
The hammer 9 is located closer to the step motor 2, that is, closer to the lower digit, and the positional relationship between the hammer 9 and the type 401 is as shown in FIG. When the step motor 2 is energized and rotated in the direction of the arrow, the printed characters 401 are sequentially positioned at the printing position 28 as the step motor 2 rotates. When a desired type character 401 of a desired color faces the printing position 28, the step motor 2 is controlled and the type drum 3 is stopped. At this time, in order to stop the type drum 3 accurately and quickly, the step motor 2 is
is energized to reverse the direction (in the direction of arrow B), and the reversal stopper claw 27
All you have to do is give it a lot of attention. While the type drum 3 is stopped, the coil 8 of a desired digit is energized to attract the suction plate 10, and the hammer 9
is operated to press the printed characters 401 onto the printing paper 31 to perform printing. After the coil 8 is de-energized, the step motor 2 is rotated in the direction of arrow A again. The same operation is repeated for each desired printed character 401 to complete the first step.

The second stroke is a stroke in which the type drum 3 moves from the lower digit side to the higher digit side. As the step motor 2 rotates, the cam groove 301 and the rotor 12 engage with each other, causing the type drum 3 to
moves one digit to the upper digit side.

In the third stroke, the type drum 3 is located on the upper digit side, the positional relationship between the hammer 9 and the type 401 is as shown in Figure 5, and the positional relationship between the paper feed drive gear 304 and the paper feed gear 23 is as shown in Figure 8. become. In this positional relationship, the same operation as in the first step is repeated to print desired characters. In addition, at the beginning of the third stroke, the paper feed drive gear 304 of the type drum 30 rotates to an angle where it can mesh with the paper feed gear 23, but the positional relationship between the paper feed drive gear 304 and the paper feed gear 23 in the digit direction is As shown in FIG.
The paper feeding gear 23 does not rotate, and the second gear 23a is locked by the second locking cam 304d, as shown in FIG.

Also, at this time, the reset signal cam 30 of the type drum 3
5 rotates to an angle that pushes up the curved portion 131 of the first detection spring 13, but the positional relationship between the reset signal cam 305 and the first detection spring 13 in the digit direction is such that they cannot engage, as shown in FIG. Therefore, the curved portion 131 of the first detection spring 13 is not pushed up, and therefore no reset signal is generated.

The fourth stroke is a stroke in which the type drum 3 moves from the upper digit side to the lower digit side. As the step motor 2 rotates, the cam groove 301 and the rotor 12 engage with each other, causing the type drum 3 to
is shifted one digit to the lower digit.

The fifth step is a paper feeding step. In this process, the type drum 3 is located on the lower digit side as shown in FIG.
As shown in the figure, the paper feed drive gear 304 and the paper feed gear 23
The positional relationship in the girder direction is such that they can mesh with each other. Further, the positional relationship between the reset signal cam 305 and the first detection spring 13 in the digit direction can be maintained as shown in FIG. As the type drum 3 rotates, the first tooth portion 304b of the paper feed drive gear 304 and the paper feed gear 23 as shown in FIG.
The second gear portion 23b of the paper feed drive gear 304 meshes with the third gear portion 23c of the paper feed drive gear 23, and the second gear portion 23a also meshes with the groove of the first locking cam 304a. Therefore, the paper feed gear 23 rotates to the state shown in FIG. 16, and the paper is fed by one line. Also, during this paper feeding, the reset signal cam 305 pushes up the curved portion 131 of the first detection spring 13, the first detection spring 13 and the second detection spring 14 come into contact, and a reset signal is generated. After detecting this reset signal, the step motor 2 is stopped at a predetermined position, and the printing cycle for one line is completed.

During the entire stroke, the ink rollers 18 , 19 , together with the ink roller frame 29 , oscillate together with the type drum 3 and supply ink to the type 401 .

Although one embodiment of the present invention has been described above, the first tooth portion 304b and the second ridge portion 304C in the paper feed drive gear 304 and the -th gear portion 23 in the paper feed gear 23 are further explained.
The tooth profile shapes of the a and second gear portions 23b and third gear portions 23c do not need to be a general a shape such as an involute tooth profile, but may be modified tooth shapes, such as simple triangular teeth, depending on the purpose of reducing load. , it is okay even if it is formed like a cam with a complicated curve.

Furthermore, the groove shape of the first locking cam 304a does not simply escape the first tooth portion 23a of the paper feed gear 23;
By making the shape the same as the tooth profile of the first tooth portion 304b of the paper feed drive gear 304, the load on the first tooth portion 304b can be reduced.

Further, the one-line printing cycle is not limited to two rotations, and may be formed by three or more rotations.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to feed one line of paper by multiple rotations of the type drum, and by directly engaging the paper feed drive gear (type drum) and the paper feed gear, the transmission member Furthermore, the intermittent function necessary for paper feeding can be satisfied only between the paper feeding drive gear and the paper feeding gear without using a clutch mechanism. Therefore, the device itself can be made smaller and the cost can be reduced accordingly, the timing accuracy of printing and paper feeding is increased, the reliability of the iM is improved, and the transmission efficiency is also increased, which prevents unnecessary power consumption. It has many effects.

[Brief explanation of the drawing]

1 to 16 are views showing embodiments of the present invention, FIG. 1 is a perspective view, FIG. 2 is a plan sectional view, FIG. 3 is a side sectional view, FIG. 4 is a first step, Figure 5 shows the positional relationship between the type and the hammer in the digit direction in the 5th process. Figure 5 shows the positional relationship in the digit direction between the type and the hammer in the 3rd process. Figure 6 shows the 1-line printing cycle. Figure 7 is a perspective view showing the positional relationship in the digit direction between the paper feed drive gear and the paper feed gear in the 1st and 5th strokes, and Figure 8 is the paper feed drive in the 3rd stroke. A perspective view showing the positional relationship between the gear and the paper feed gear in the digit direction, FIG. 9 is the first stroke,
A plan sectional view showing the positional relationship in the digit direction between the paper feed drive gear and the paper feed gear in the 5th stroke.
Figure 11 is a plan sectional view showing the positional relationship in the girder direction with
A diagram showing the positional relationship in the digit direction between the reset signal cam and the first detection spring in the stroke, FIG. 12 is a diagram showing the positional relationship in the digit direction between the reset signal cam and the first detection spring in the fifth stroke,
FIG. 13 and FIG. 16 are diagrams showing the meshing state of the paper feed drive gear and the paper feed gear in the rotational direction. 1...Frame 2...Step motor 3...Type drum 5.6...Yoke 8...Coil O...Suction plate 2...Rotor 4...Second detection spring 6...Ink roller shaft 7... Ink roller receiver 8...Black ink roller 9...Red ink roller 0...Paper feed shaft 21...Paper feed rubber 2...Platen 23...Paper feed gear 4...Paper feed spring 25
・・Paper press roller 6・・Paper press shaft 27・・Reverse stopper claw 9・・Ink roller frame O・・Ink roller spring 4・・Type sheet 7・・・Iron core 9・・・Hammer・Bearing 3・・・First detection Spring 5... Ink roller cover and above Applicant: Seiko Epson Co., Ltd. Representative Patent Attorney Kizobe Suzuki and 1 other person Figure 3 Figure 10 Figure 14 (a) Figure 14 (b) Figure 14 (C)

Claims (1)

[Claims] A type drum with type arranged on its outer periphery and rotatable and swingable in the digit direction, a drive gear coaxially formed integrally with the type drum, and directly meshing with the drive gear only during paper feeding. A paper feeding mechanism for a printer, characterized in that a driven gear is provided.