US3623428A

US3623428A - Flying printer

Info

Publication number: US3623428A
Application number: US820199A
Authority: US
Inventors: Issei Imahashi
Original assignee: Suwa Seikosha KK
Current assignee: Suwa Seikosha KK
Priority date: 1968-04-30
Filing date: 1969-04-29
Publication date: 1971-11-30
Anticipated expiration: 1988-11-30
Also published as: GB1240604A

Abstract

A FLYING PRINTER HAVING A TRIGGEL LEVER ADAPTED FOR ROTATIONAL AND LINEAR DISPLACEMENT, A PRINT HAMMER ADAPTED TO EFFECT PRINTING IN RESPONSE TO THE LINEAR DISPLACEMENT OF SAID TRIGGER LEVER, A CONTINUOUSLY ROTATING RATCHET WHEEL HAVING AT LEAST ONE TOOTH EXTENDING THERFROM FOR LINEARLY DISPLACING SAID TRIGGER LEVER WHEN SAID TRIGGER LEVER IS DISPOSED IN THE PATH THEREOF, AND MEANS FOR SELECTIVELY ROTATING SAID TRIGGER LEVER INTO AND OUT OF THE PATH OF SAID RATCHET WHEEL TOOTH TO EFFECT PRINTING.

Description

lSSEl IMAHASHI FLYING PRINTER Nov. 30, 1971 6 Sheets-Sheet 1 Filed Api ia. 29; 3%9

FLYING PRINTER 6 Sheets-Sheet 112 Filed Apri 1 719, 1969 NOV. 1971 ISSEI IMAHASHI 3,623,428

FLYING PRINTER Filed April 29, 1969 6 Sheets-Sheet 5 ll I 2a- Nov. 30, 1971 lSSEI IMAHASHI 3,623,428

FLYING PRINTER Filed April 29, 1969 6 Sheets-Sheet d.

Nov. 30, 1971 ISSEI IMAHASHI 3,623,428

FLYING PRINTER Filed April 29, 1969 6 Sheets-Sheet 5 United States Patent O 3,623,428 FLYING PRINTER Issei Imahashi, Suwa-shi, Japan, assignor to Kabushiki Kaisha Suwa Seikosha Filed Apr. 29, 1969, Ser. No. 820,199

Claims priority, application Japan, Apr. 30, 1968,

43/28,688, 43/28,690; May 13, 1968, 43/31,814,

Int. Cl. B41j 9/10, 9/38 U.S. Cl. 101-93 21 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates generally to a printer utilized in electronic desk calculators and other numerical readout devices. In the usual line printers, alphabetic and/ or numeric characters, such as the numerals -9 for example, are provided in columnar fashion on the periphery of a print drum. The drum is disposed so that the desired character in the first column faces the hammer associated with that column, and said hammer is activated to strike the back of the paper to effect the printing of said desired character. The drum is then rotated to position the character desired in the second column and after the hammer associated therewith operates, the process is reported for each column on said drum. After every column has printed, the paper is advanced on line and the process is repeated. In this type of printer, the printing speed is relatively slow, as the print drum must stop rotating each time the hammer strikes a character.

In another type of printer, generally referred to as a flying printer, the hammer strikes a character disposed on a continuously rotating print drum. However, the known arrangements of this type of printer have several substantial drawbacks. Specifically, shear will occur in the printing process if the contact time between the hammer and the print drum is too great, resulting in smudged printing or ripped paper. In order to overcome this defect, the contact time of the hammer with the character must be shortened, thereby increasing the operating speed of said hammer. In conventional printers of the type described, the hammer is directly operated by electromagnets, and an increase in the operating speed of the hammer requires an increase in the size and power of said electromagnets. However, an increase in the size and power of the electromagnets results in an increase in the volume of the printer and requires increased electric power consumption, and is therefore undesirable. By utilizing the electromagnets to merely effect timing of the flying printer, rather than the actual direct operation of the hammer, the above described defects can be avoided while an extremely compact flying printer is provided.

Other defects in the known flying printers sought to be corrected by the present invention are the double striking of a hammer on a single line and the difficulty in adjusting said hammers to insure clear printing.

3,623,428 Patented Nov. 30, 1971 SUMMARY OF THE INVENTION Generally speaking, in accordance with the invention, a flying printer is provided having a trigger lever adapted for rotational and linear displacement. Said trigger lever is linearly displaced when disposed in the path of a tooth of a continuously rotating ratchet wheel. When so disposed, said trigger lever displaces a print hammer to effect printing. Means is provided, preferably an electromagnet, for selectively rotatably displacing said trigger lever into and out of the path of said ratchet wheel tooth.

The flying printer according to the invention preferably includes a print drum which continuously rotates at a constant speed, said ratchet wheel being synchronously driven with said print drum. A trigger lever guide member, formed with a guide groove therein, and a pair of spaced guide pins are provided to guide said trigger lever in its rotational and linear displacement. Said trigger lever is preferably formed with a shoulder adapted to strike a trigger lever stopper immediately before said hammer completes striking the character on said print drum, thereby limiting the linear displacement of said trigger lever. The contact point between said trigger lever stopper and said trigger lever shoulder is preferably disposed above the center of gravity of said trigger lever and on the side of said trigger lever adjacent said ratchet wheel whereby said contact tends to pivot said trigger lever out of the path of said ratchet wheel tooth. Springs means may also be provided for this purpose.

The cycle of linear and rotational displacement of said trigger lever commencing with the engagement thereof by said ratchet wheel tooth is preferably slightly longer than one pitch time of the teeth of said ratchet wheel.

A flying printer according to the invention preferably includes a plurality of said trigger levers each adapted to operate a hammer lever and each in turn being provided with a separate means for effecting the rotational displacement thereof into and out of the path of at least one tooth of said ratchet wheel. Said hammer levers, trigger levers, rotatable displacement means, print drum and ratchet wheel are all preferably mounted between a pair of spaced main plates. Each of said hammer levers is preferably L-shaped and is pivotably mounted at the corner defined by the two arms thereof. A hammer is secured to the end of one arm of each of said hammer levers, said hammer levers being disposed with said hambers above the axis of said print drum with the arm thereof carrying said hammer defining the upper portion thereof. A single motor is provided to drive both the ratchet wheel and print drum.

Accordingly, it is an object of this invention to provide an extremely compact flying printer adapted to print extremely clear characters.

Another object of the invention is to provide a flying printer utilizing electromagnets to select the character to be printed, without directly operating the hammer.

A further object of the invention is to provide a flying printer adapted to prevent the double printing of a character.

Still a further object of the invention is to provide a flying printer wherein the hammer is readily accessible for adjustment and replacement.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction, combinations of elements, and arrangements of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

3 BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a schematic representation of one column of a flying printer according to the invention;

FIG. 2 is a top plan view of a flying printer according to the invention, with portions broken away;

FIG. 3 is a sectional view taken along lines 33 of FIG. 2 showing one column thereof with the electromagnet associated therewith in the deenergized state;

FIG. 4 is a sectional view taken along lines 3-3 of FIG. 2 with said electromagnet energized and said column disposed in the printing position;

FIG. 5 is a side elevational view of the flying printer of FIG. 2;

FIGG. '6 is an exploded perspective view of the trigger lever and trigger lever guide member according to the invention;

FIG. 7 is a top plan view of the trigger lever guide member according to the invention;

FIG. 8 is a sectional view taken across the rotor of the motor of the flying printer according to the invention;

FIG. 9 is a sectional view taken along lines 99 of FIG. '8;

FIG. 10 is a sectional view taken along lines 10-10 of FIG. 8;

FIG. 11 is a circuit diagram of a driving circuit for the motor of FIG. 8;

FIGS. 12A and B are wave forms present in the circuit of FIG. 11; and

FIGS. 13A, B and C are wave forms of the current in the three driving coils of the motor of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, a schematic representation of one column of a flying printer according to the invention is shown. The column includes a print hammer 1 mounted on one arm of an L-shaped hammer lever 2. Said hammer lever is pivotably mounted at the corner defined by the arms thereof on hammer lever shaft 3. Disposed immediately below hammer 1 is print drum 4 having characters spaced on the peripheral surface thereof. Said print drum and a print drum gear 5 are mounted on print drum shaft 6 for rotation therewith. Shaft 6, which defines the axis of said print drum is disposed immediately below the position assumed by hammer 1 when it strikes said print drum, whereby said hammer is disposed normal to said axis when striking said print drum. Print drum gear 5 meshingly engages intermediate pinion 7 for the rotation of said pinion and intermediate gear 8 fixed thereto. Said intermediate gear, in turn, meshingly engages with ratchet gear 9 for the rotation of ratchet wheel 10. Said ratchet wheel is shown formed with a single tooth 11 but could be formed with a plurality of circumferential teeth if desired. The gear ratio between gears and

pinions

5,7, 8 and 9 is selected so that the pitch time of tooth 11 equals the circumferential spacing of the characters on the peripheral surface of print drum 4. Thus, each rotation of tooth 11 corresponds to the advancing of one character on said print drum.

First and second trigger lever guide pins 12 and 13 are provided disposed on either side of trigger lever 14. Said trigger lever is formed with a tail portion 15 and a projection 16. Trigger lever 14 is adapted for pivotal and linear displacement and trigger lever guide member 18 is provided to guide said trigger lever during said displacement. A spring 19 is secured between lever 14 and a fixing point 20 for biasing said trigger lever out of the path of tooth 11. The end of arm 21 of hammer lever 2 is disposed to be engaged by shoulder 22 of trigger lever 14 upon the linear displacement of said trigger lever to pivot said trigger lever, whereby hammer 1 strikes print drum 4.

Timing lever 23 is disposed to engage tail 15 of trigger lever 14 and is pivotably mounted on timing lever shaft 24. Fixed to said timing lever is magnetic plate 25 adapted to cooperate with an electromagnet 26 for the pivoting of said magnetic plate and timing lever in response to the activation of said electromagnet. Spring 28 is mounted between the corner of hammer lever 2 and fixing point 29 to normally bias said hammer lever in the position shown with hammer 1 spaced from print drum 4. Interposed between said hammer and said print drum are paper 30 upon which the character is to be imprinted and inked ribbon 31.

In 'FIG. 1, only one column is illustrated by way of example. However, an actual printer would include the desired number of columns, each of which would comprise a hammer 1, a hammer lever 2, a trigger lever 14, a trigger lever spring 19, a timing lever 23, a magnetic plate 25, an electromagnetic 26, and a hammer lever spring 28. As more particularly shown in the embodiment of the flying printer according to the invention shown in FIG. 2, the parallel columns are mounted between a pair of

main plates

50 and 51. The flying printer is preferably provided with a single print drum 4, ratchet wheel 10 having a single tooth 11, first and second guide pins 12 and 13, trigger lever guide member 18, trigger lever stopper 17, and timing lever shaft 24, all of which extend between said main plates. A motor 52 is provided to drive ratchet wheel 10, which in turn drives print wheel 5 through gears and

pinions

5, 7, 8 and 9.

While hammer lever 2, trigger lever 14 and timing lever 23 are relatively thin, the electromagnets 26 are relatively bulky. In order to permit the compact mounting of the components of the flying printer according to the invention, said electromagnets are disposed in three banks, as more particularly shown in FIG. 3. The electromagnets associated with one of each three adjacent columns forming said flying printer is disposed in a single bank so that space equal to the width of three colurns is provided for each electromagnet. The angle defined between magnetic plate 25 and timing lever 23 is selected in each column according to the disposition of the electromagnet associated therewith. Thus, referring to FIG. 2, the electromagnet 26 associated with columns a and b are in one bank, the electromagnets associated with colums c and d are in a second bank, while the electromagnets associated with columns g and i are in a third bank.

Also extending between

main plates

50 and 51 are a paper feeding roller 53 and guide

frames

54 and 55 adapted to guide paper 30 through said flying printer. Said paper feeding roller advances the paper one line when print drum 4 has completed one cycle of its rotation.

Turning now to the operation of the flying printer according to the invention, reference is had to FIGS. 1, 3 and 4. When the flying printer is activated but no timing signals are applied to the electromagnets or to the paper advance mechanism, motor 52 continuously rotates ratchet wheel 10 in the direction of arrow 32, thereby also rotating print wheel 4 in the manner described above. Said print wheel rotates in the same direction as said ratchet wheel. The rotation of tooth 11 of said ratchet wheel follows a path defined by dashed line 33. In the absence of any signal energizing electromagnet 26, the column is disposed as shown in FIG. 3 with end 34 of trigger lever 14 disposed outside of the path of tooth 11 and maintained in that position by spring 19. When so disposed, trigger lever 14 is positioned by means of second trigger lever pin 13 and trigger lever guide member 18. Magnetic plate 25 is also maintained spaced from electromagnet 26 in the direction of arrow 35 by spring 19 acting through tail 15 of said trigger lever which engages timing lever 23.

In order to print a character, a pulse signal is applied to electromagnet 26 immediately before the desired character on the peripheral surface of print drum 4 passes under hammer 1. The activation of said electromagnet rotatably displaces magnetic plate 25 in the direction of arrow 36, carrying timing lever 23 therewith. Said timing lever engages the tail 15 of trigger lever 14 to rotate said trigger lever in the counter clockwise direction about trigger lever guide member 18. When so disposed, as shown in FIG. 1, end 34 of said trigger lever lies in the path of tooth 11, whereby it may be linearly displaced in the direction of arrow 37 thereby.

The linear displacement of trigger lever 14 is transmitted to arm 21 of hammer lever 2 by means of shoulder 22 of said trigger lever. Said hammer lever is in turn rotated in a counter clockwise direction causing hammer 1 to strike the print drum through inked ribbon 31 and paper 30 at the moment that the desired character is positioned under said hammer. The column is shown disposed in this position in FIG. 4.

At this point in the cycle, it is necessary to rotate hammer lever 14 in the clockwise direction to bring end 34 thereof out of the path 33 of tooth 11 before said tooth completes a single revolution. If this is not done, the trigger lever will be linearly displaced in the direction of arrow 37 a second time during the next revolution of ratchet wheel 10, resulting in the double striking of hammer 1 on a single line. Several features of the flying printed according to the invention contribute to this result. The first of these is trigger lever stopper 17 which cooperates with projection 16 on trigger lever 14, to operate as follows. At the moment that end 34 of said trigger lever is struck by tooth 11, hammer lever 2 starts its rotation. Specifically, at the moment that said trigger lever is struck by said tooth, said trigger lever starts its linear displacement in the direction of arrow 37 at a speed slightly faster than that of said tooth. At the same moment, arm 21 of hammer lever 2 starts its displacement at a speed slightly faster than that of said trigger lever. This results from the fact that the coefficient of restitution at each striking point is not equal to zero. Further, after hammer 1 strikes the desired character, hammer lever 2 returns to its original position at a faster speed than does trigger lever 14. Accordingly, in the absence of trigger lever stopper 17, arm 21 of said hammer lever would tend to again strike shoulder 22 of said trigger lever, causing said hammer lever to again rotate in the clockwise direction causing hammer 1 to again strike a character. The resulting double striking on a single line is of course undesirable. This possibility is avoided by the striking of projection 16 against trigger lever stopper 17 immediately before hammer 1 strikes the character so that trigger lever 14 rebounds in the direction of arrow 38 before the return of hammer lever 2 to its original position. In this manner, arm 21 of said hammer lever will not strike shoulder 22 during said return.

The striking of projection 16 against trigger lever stopper 17 also serves to rotate said trigger lever in the direction of arrow 39 about the center of gravity 40 of said trigger lever during the return thereof to its initial position. This effect, which serves to bring end 34 of said trigger lever out of the path of tooth 11, results from the positioning of the contact point between said projection and said trigger lever stopper at a position above center of gravity 40, and preferably on the side of said center of gravity adjacent to ratchet wheel 10. Also contributing to this rotation is spring 19 which tends to return said trigger lever to its original position with the inner surface of shoulder 22 resting against trigger lever guide member 18 and end 34 of said trigger lever out of the path of tooth 11.

Still a further feature of the arrangement according to the invention tending to avoid double striking, is the timing of the arrangement. Each cycle of operation, namely the activation of an electromagnet, the linear displacement of trigger lever 14, the striking of hammer 1 and the return of said trigger lever takes an extremely short time, of the order of 7 ms. Despite all of the above described features, it is still possible, in rare cases, that end 34 of said trigger lever might still lie within the path of tooth 11 if said trigger lever returns to its original position before tooth 11 has completed one cycle or pitch time. If this were so, undesirable double striking would result. Accordingly, the ararngement according to the invention is designed so that the time required for trigger lever 14 to complete one cycle of operation commencing with the linear displacement thereof by tooth 11 and ending with its return to its original position, is slightly longer than the pitch time of the tooth of said ratchet wheel. The timing of the overall arrangement is such that a particular column would never be activated to strike two consecutive characters on the print drum in a single cycle of said print drum.

Referring now to FIGS. 6 and 7, a detailed View of trigger lever guide member 18 is shown. Said member is formed with a plurality of grooves 41 defined by walls 42 adapted to receive said trigger levers and to guide same during the rotational and linear displacement thereof.

As shown in FIGS. 2 and 3, arms 43 of hammer levers 2, upon which hammers 1 are mounted, defines the upper level of the flying printer according to the invention. In this manner, hammer 1 is disposed immediately above the axis of print drum 4 as defined by shaft 6. This construction permits easy access to hammers 1 to permit the replacement or adjustment thereof. The latter feature is important since in order to print clear characters, the face of the hammer and the surface of the character must lie in the same plane, the striking point and the desired character must exactly coincide, and uniform pressure must be applied to the surface of the character to be printed. Further, of the components of the flying printer according to the invention, said hammers are subjected to the greatest wear due to the extremely fast striking speed, and therefore require replacement after an extended period of use. Such replacement may be accomplished without disturbing the other components of the column. Finally, this feature permits the immediate and ready detection of misprints since the operator can see each character immediately after the paper is ad vanced one line.

The detailed structure of motor 52 is shown in FIGS. 810. Said motor, which is of the direct current brushless type includes a rotor shaft 56 having

yokes

57 and 58, formed of a material having high permeability mounted thereon in spaced relation. Arranged radially about shaft 56 are pairs of

permanent magnets

59 and 65, 60 and 66, 61 and 67, 62 and 68, 63 and 69, and 64 and 70. One of each of said pairs of electromagnets, namely

magnets

59, 60, 61, 62, 63 and 64, are fixedly secured to yoke 57, while the other of said permanent magnets are fixedly secured to yoke 58. Each of said permanent magnets is fan shaped. Each of said pairs of permanent magnets are in spaced relation and disposed with opposite poles in facing relation. Thus, the south pole of magnet 62 faces the north pole of magnet 68. Further, the six poles secured to each yoke are disposed so that adjacent magnets have their opposite poles facing the air gap between said pairs of permanent magnets. Thus, permanent magnet 59 has its north pole facing the air gap and its companion permanent magnet 65, while the adjacent permanent magnets 60 and 64 both have their south poles facing said air gap and their respective companion magnets.

Disposed in the air gap between said pairs of permanent magnets are substantially trapezoidal flat driving coils 71, 72 and 73. Said driving coils are radially arranged about rotor shaft 56 but are mounted independently thereof. Said driving coils are spaced degrees apart as measured from their respective centerlines. The

sides

74 and 75 of each driving coil are spaced so that one of said sides is disposed in the space between each of two adjacent pairs of permanent magnets in substantially all positions of rotor shaft 56. Thus, in FIG. 9, side 74 of driving coil 73 is shown disposed in the space between the pair of

permanent magnets

60 and 66 while side 75 of driving coil 73 is disposed between the pair of permanent magnets 61 and 67. In the position shown, driving coil 71 is aligned with the gaps between adjacent pairs of said permanent magnets while the other of said driving coils are aligned as described above.

Also provided is a detecting means consisting of three pairs of detecting

coils

76 and 77, 7-8 and 79, and 80 and 81, as more particularly shown in FIG. 10. Said detecting coils are preferably formed in the shape of small discs with the detecting coils forming each pair being disposed in spaced relation with an air gap therebetween. Said pairs of detecting coils are disposed radially about rotor shaft 56 with an angle of 40 degrees being defined between pairs 75 (77) and 78 (79), and 80 (81), respectively. Said detecting means also includes a shield plate 82 fixedly mounted to rotor shaft 56 and extending into the gap between said pairs of detecting coils. The shield plate is formed with three cut-away regions 83 within the path of said detector coil air gaps. Said cut-away regions are spaced radially about rotor shaft 56, each of said openings defining a 40 degree sector. Shield plate 82 is preferably formed from a material of low electric resistance, such as aluminum.

Re ferring now to FIG. 11, a portion of the electric circuit for driving one driving coil 71 of motor 52 is shown by way of example. The circuit includes an oscillator formed from transistor 84 and detecting

coils

76 and 77. The output of the oscillator passes through a rectifier defined by diode 85 and is applied to an amplification and switching circuit defined by

transistors

86 and 87 adapted to apply driving current to driving coil 71.

Reference is now had to the wave form diagrams of FIGS. 12 and 13, in connection with which the operation of the br-ushless direct current motor according to the invention will be exemplified. Assuming that one of the cut-away regions of shield plate 82 is disposed at the pair of detecting

coils

76 and 77, the oscillator circuit associated with said detector coils starts to oscillate to produce the wave form shown in FIG. 12A at the collector of said transistor. This oscillating wave has a pulse width of T equal to the period during which the opening 83 in shield plate 82 is positioned opposite detecting

coils

76 and 77. The oscillating circuit is rectified by diode 85 to produce, at connecting point 88 of FIG. 11, the driving wave form shown in FIG. 12B. During the

period T transistors

86 and 87 are switched on to apply driving current to driving coil 71. The oscillator circuit stops oscillating when shield plate 82 extends into the gap between detecting

coils

76 and 77 since said shield plate is formed of a conductor. The driving current in driving coil 71 interlinks with the magnetic flux of the pairs of permanent magnets between which the

sides

74 and 75 of said coil extend. Accordingly, a rotational force is produced tending to rotate shaft 56, carrying

yokes

57 and 58, the permanent magnets, and shield plate 82 therewith. The time T shown in the wave form of FIG. 12A represents the period during which the shield plate extends into the gap between the pair of detecting coils to stop the oscillation thereof. The cycle, as far as detecting

coils

76 and 77 and driving coil 71, is repeated after the time T as represented by the rotation of the rotor by 80 degress to align the next cut-away region of the shield plate with said detecting coils.

In the embodiment of the arrangement shown in the drawings, three pairs of detecting coils and three corresponding driving coils are provided. Accordingly, the motor according to the invention would be provided with three transistorized driving circuits. Each of the three driving circuits drives a driving coil to produce three phases of driving current as shown in the wave forms of FIGS. 13A, B and C, one of which represents the current in each of said driving coils. Due to the relative position of the detecting coils, driving coils, and shield plates and the alignment of the poles of the permanent magnets, rotor 1 always rotates in the predetermined direction.

The pairs of detecting coils are arranged radially about shaft 1 so that the cut-away region of shield plate 31 is aligned with at least one of said pairs of detecting coils at every position of said rotor shaft. Thus, one of said pairs of coils oscillates at each such position to drive the driving coil associated therewith. Further, said driving coil associated with the oscillating detecting coils must be disposed so that, during the period of said oscillation, it is not aligned with only one of the pairs of permanent magnets. This arrangement is necessary to insure that the motor is self starting since if a driving coil is aligned with only one pair of permanent magnets at the rest position, no rotating force will be generated in response to the oscillation of the detecting coils to start the motor.

Although the motor in the embodiment shown in the drawings has six pairs of permanent magnets, three driving coils, three pairs of detecting coils and three cutaway regions in the shield plate, this arrangement is shown by way of example and not by way of limitation, and the motor according to the invention may be designed with various combinations of coils and openings. In general, the motor should be constructed such that where n pairs of permanent magnets are provided, it being an even number equal to six or more, n/2 driving coils, n/ 2 pairs of detecting coils, an n/2 cut-away regions of the shield plate are provided. Further, the detecting coils of the detecting means may consist of only a single oscillating coil the oscillation of which can be stopped by bringing said shield plate into juxtaposition with said coil.

As best shown in FIG. 2, driving

coils

71, 72 and 73 are fixedly mounted on a circuit board 89. In like manner, detecting

coils

76, 78 and 80 are mounted on a circuit board 90, While detecting coils 77, 79 and 81 are mounted on a circuit board 91. The foregoing construction produces an extremely compact motor capable of producing suflicient force to operate the flying printer according to the invention.

Turning now to FIGS. 2 and 5, the overall operation of the flying printer according to the invention will be described. Rotor shaft 56 of motor 52, upon which ratchet wheel 10 is mounted, carries at one end thereof a position detector having a magnet 101 mounted on the peripheral surface thereof which generates timing signals with every rotation, said timing signals being detected by a magnetic pickup head 102. The rotation of rotor shaft 56 and ratchet Wheel 10 is transmitted to print drum 4 for the rotation thereof and synchronization with said ratchet wheel. As discussed above, one rotation of ratchet wheel 10 equals the advancing of print drum 4, one character. Thus, if there are sixteen characters circumferentially spaced about print drum 4, ratchet wheel 10 will rotate sixteen times for every rotation of print drum 4. Mounted on one end of shaft 6 which carries said print drum is position detector 103, also provided with a magnet in the peripheral surface thereof to provide timing signals for detection by magnetic pickup head 104. The timing signals detected by magnetic head 102 are preferably counted by a suitable pulse counter which operates in conjunction with a coincidence circuit adapted to compare the input signals from the circuitry of the desk calculator or other device to which the printer is connected with the detected signal. When coincidence is detected, the electromagnet associated with said circuit is energized to effect printing.

The timing signals detected by magnetic head 104 are used for resetting the flying printer to permit printing of the next line. Said reset signal provides clock pulses to suitable controlling circuitry which permits both the resetting of the character counter and the energization of paper feeding electromagnet 105 which displaces hooked lever 106 to rotate ratchet 107 and paper feeding roller 53 to shift said paper by one line.

It has been found that a flying printer constructed in accordance with the invention offers substantial advantages over the prior art. Thus, although printing is performed during the continuous rotation of the print drum, the period of dwell of the hammer is shortened and clearly printed characters are obtained. The arrangement minimizes the wear on the trigger lever utilized to transmit energy to the hammer, giving such trigger lever an extremely long life. Since said trigger lever is preferably formed from a material of great stiffness, the operation of the arrangement results in a relatively low energy loss during high speed operation. Further, the arrangement avoids the defect of double striking, and provides an arrangement which is readily serviced.

Further, the arrangement according to the invention provides a device which consumes relatively little electric power, while utilizing a single motor to drive the entire mechanism including both the ratchet whee-l and print drum. The arrangement according to the invention in effect, converts the rotational kinetic energy stored in the ratchet wheel to linear energy by the unique action of the trigger levers which are pulsively actuated by the rotating tooth to provide a large amount of mechanical energy to the print hammers without requiring large electromagnets.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description are efliciently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A flying printer which comprises a continuously rotating ratchet wheel having at least one tooth extending therefrom; a print drum continuously rotating synchronously with said ratchet wheel; a trigger lever mounted for rotational and linear displacement along a path, said trigger lever path being positioned so that at one point therea-long, said trigger lever lies in the path of said ratchet wheel tooth and is linearly displaced thereby out of said ratchet wheel tooth path; print hammer means displaceably mounted in said trigger lever path for effecting printing in response to said linear displacement of said trigger lever actuated by said ratchet wheel tooth, means for selectively rotating said trigger lever from an initial position into said ratchet wheel tooth path; a fixed trigger lever stopper disposed in said linear displacement portion of said trigger lever path, said trigger lever having a portion adapted to strike said trigger lever stopper immediately before said print hammer means effects printing; spring means secured to said trigger lever and biased to rotatably and linearly displace said trigger lever back to said initial position out of the path of said ratchet wheel tooth after rebound of said trigger lever from said trigger lever stopper; and guide means in said trigger lever path for freely guiding said trigger lever along a rotational and linear portion of said trigger lever path in conjunction with said spring means after said rebound from said trigger lever stopper.

2. A flying printer as recited in claim 1, wherein said print hammer means includes a hammer lever mounted for rotational displacement at a central region thereof and a hammer mounted for printing on said hammer lever on one side of said central region and spaced therefrom, said trigger lever, upon the linear displacement thereof, engaging said hammer lever at a point disposed at the other side of said central region and spaced therefrom to rotatably displace said hammer lever to effect printing.

3. A flying printer as recited in claim 1, wherein said means for selectively rotating said trigger lever includes an electromagnet and a timing lever mounted for rota- 10 tional displacement, said timing lever being rotatably displaced in response to the energization of said electromagnet to rotatably displace said trigger lever into the path of said ratchet wheel tooth.

4. A flying printer as recited in claim 1, including a print drum adapted for continuous rotation at a constant speed, said ratchet wheel being adapted for rotation in synchronization with said print drum, said print hammer means including a print hammer for striking said print drum to effect printing.

5. A flying printer as recited in claim 1, wherein the contact point between said trigger lever portion and said trigger lever stopper is disposed above the center of gravity of said trigger lever.

6. A flying printer as recited in claim 5, wherein the contact point between said portion of said trigger lever and said trigger lever stopper is disposed on the side of said center of gravity adjacent said ratchet wheel.

7. A flying printer as recited in claim 1, wherein said guide means includes a trigger lever guide member formed with a groove therein, said trigger lever being positioned in said guide groove and rotating about the bottom surface thereof.

8. A flying printer as recited in claim 1, including a first trigger lever guide pin disposed to position said trigger lever in the path of said ratchet wheel tooth upon the rotational displacement thereof and a second trigger lever guide pin disposed to position said trigger lever at said initial position out of the path of said ratchet wheel tooth.

9. A flying printer as recited in claim 1, wherein said print hammer means includes a substantially L-shaped hammer lever rotatably mounted at the corner defined by the two arms thereof, and a print hammer mounted on one of said hammer lever arms for printing, said trigger lever being adapted to engage the other of said hammer lever arms upon the linear displacement thereof by said ratchet wheel tooth to rotatably displace said hammer lever to effect printing.

10. A flying printer as recited in claim 1, wherein said spring means is constituted to have a coeflicient of flexibility, and said trigger lever is constituted to have a mass, such that a cycle of said linear and rotational displacement of said trigger lever along its path from said initial position and back to said initial position is slightly longer than one pitch time of the tooth of said ratchet wheel.

11. A flying printer as recited in claim 1, including unitary motor means for driving both said print drum and said ratchet wheel.

12. A flying printer as recited in claim 11, including a gear train interconnecting said ratchet wheel and said print drum for transmitting the motor force of said motor means from one to the other.

13. A flying printer as recited in claim 11, wherein said motor means includes a rotor shaft, a pair of spaced yokes mounted on said shaft for rotation therewith, a plurality of pairs of permanent magnets radially arranged about said shaft between said yokes, one of each of said pairs of permanent magnets being mounted on each of said yokes with a gap therebetween; a plurality of driving coils disposed in the gap between said pairs of permanent magnets; and a detecting means responsive to the position of said rotor shaft and having at least one detecting coil associated with each driving coil for the activation of said driving coil to rotate said rotor shaft.

14. A flying printer as recited in claim 13 wherein the poles of each pair of permanent magnets defining the gap therebetween are of opposite polarity to produce a magnetic field in said gap.

15. A flying printer as recited in claim 13, wherein, at each position of said rotor shaft, the driving coils activated at said position have portions disposed in the gap defined by selected pairs of permanent magnets, all of said pairs of permanent magnets being selected to produce a force on said rotor shaft in a predetermined direction.

16. A flying printer as recited in claim 1, wherein the contact point between said trigger lever portion and said trigger lever stopper is disposed above the extension line of the path of the motion of the center of gravity of said trigger lever.

17. A flying printer as recited in claim 16 wherein the contact point between said portion of said trigger lever and said trigger lever stopper is disposed on the ratchet wheel side of the extension line of the path of the motion of the center of gravity of said trigger lever.

13. A flying printer having a continuously rotating print drum, a ratchet Wheel having at least one tooth, means for continuously rotating said ratchet wheel and print drum in synchronization with each other, and at least one printing column including a trigger lever adapted for rotational and linear displacement along a path, said trigger lever path being positioned so that at one point therealong, said trigger lever lies in the path of said ratchet wheel tooth and is linearly displaced thereby out of said ratchet wheel tooth path; a hammer lever mounted in said linear displacement portion of said trigger lever path for rotational displacement in response to said linear displacement of said trigger lever; a print hammer mounted on said hammer lever for striking said print drum to effect printing upon the rotational displacement of said hammer lever; means for selectively rotating said trigger lever from an initial position into the path of said ratchet wheel tooth; a fixed trigger lever stopper disposed in said linear displacement portion of the path of said trigger lever, said trigger lever having a portion adapted to strike said trigger lever stopper immediately before said print hammer means effects printing; spring means secured to said trigger lever and biased to rotatably and linearly displace said trigger lever back to said initial position out of the path of said ratchet wheel tooth after rebound of said trigger lever from said trigger lever stopper; and guide means for 1.2 guiding said trigger lever along a rotational and linear portion of said trigger lever path in conjunction with said spring means after said rebound from said trigger lever stopper.

19. A flying printer as recited in claim 18, wherein said hammer lever is substantially L-shaped and pivotably mounted for rotative displacement about the corner defined by the two arms thereof, said print hammer being mounted on one arm of said hammer lever, said arm being disposed above said trigger lever, ratchet wheel and print drum with said hammer positioned to strike said print drum to effect printing at a point above the longitudinal axis of said print drum.

20. A flying printer as recited claim 18, wherein said flying printer includes a plurality of printing columns disposed in side-by-side relation along said print drum and ratchet wheel.

21. A flying printer as recited in claim 20, wherein the print hammer of each of said printing columns is disposed above said print drum in position to strike said print drum at a point above the longitudinal axis thereof, the portion of each hammer lever upon which said print hammer is mounted defining the top of each of said columns.

References Cited UNITED STATES PATENTS 2,766,686 10/1956 Fomenko et al. 10193 2,897,752 8/1959 Malmros et. a1 101-93 2,949,846 8/1960 Hoffman et al. 10193 3,139,820 7/1964 Kittler l0193 3,156,180 11/1964 Barnes 10l93 3,177,803 4/1965 Antonucci 10193 3,292,531 12/1966 Mutz 10193 3,351,007 11/l967 Poland 101-93 3,504,623 4/1970 Staller 101-93 WILLIAM B. PENN, Primary Examiner