US3492926A - Device for optically and selectively printing letters - Google Patents

Description

Feb. 3, 1970 TOSHIO ASAEDA ETAL 3,492,926

DEVICE FOR OPTICALLY AND SELECTIVELY PRINTING LETTERS Filed Aug. 8, 1966 4 Sheets-Sheet 1 I234 56789 no? ryulo Feb. 3, 1970 'rosmo ASAYEDA ETAL 3,492,926

I DEVICE FOR OPTICALLY AND SELECTIVELY PRINTING,LETTERS Filed Aug. 8, 1966 4 Sheets-sheaf 2' Feb. 3,' 1970 rosmo ASAEDA ET AL 3,492,926

DEVICE FOR OPTICALLY AND SELEGTI VELY PRINTING LETTERS Filed Aug. 8, 1966 4 Sheets-Sheet 3 PULSE MOTOR DRIVING CIRCUIT PULSE I06 AMPLIFIER 52 0| 5 SELECTING GATE FULLER 107 cmcun 5 53 STORAGE- GATE S no I08 55 PULSE MOTDR omvms AND CIRCUIT MATR'X s s H8 57 56 MONO n4 113 m Mum neg UNTER CIRCUIT 58 lnsssr SIGNAL Feb. 3, 1-970 Tosmo AsAEoA ET AL 3,492,926

DEVICE FOR OPTICALLY AND SELEGTIVELY PRINTING LETTERS Filed Aug. 8, 1966' 4 Sheets-Sheet 4 FIG. 6

United States Patent 3,492,926 DEVICE FOR OPTICALLY AND SELECTIVELY PRINTING LETTERS Toshio Asaeda, 18 Tamagawa Kaminoge-cho, Setagayaku, Tokyo, Japan, and Takayuki Mizutani, Tokyo, Japan; said Mizutani assignor to said Asaeda 'Continuation in-part of application Ser. No. 390,888,

Aug. 20, 1964. This application Aug. 8, 1966, Ser.

Int. Cl. B41b 21/16, 13/00 US. Cl. 954.5 8 Claims ABSTRACT OF THE DISCLOSURE An optical printer comprises a rotatable disc shutter for passing projected images of characters from a matrix through two mask members, each of which has a slit to limit the projected images to be passed, one of the mask members being curved and supporting photosensitive paper on which images are to be printed, a mirror being positioned between the mask members to rotate in synchronism with the shutter such that each time an image passes through the slit of the shutter, the mirror is indexed and reflects a character to the slit in the curved masked member whereby the characters are printed on the photosensitive paper in a line along the latter slit, the paper being displaced after printing of a line of characters thereon.

This application is a continuation-in-part of United States patent application Ser. No. 390,888 filed Aug. 20, 1964, now abandoned.

This invention relates to a high speed printing apparatus and more particularly to the optical printer comprising character selecting means having two mirrors respectively vertically and horizontally rotatable.

Electronic computers have been increasingly applied in these days to paper Work processing in various industries, and accordingly, there is a serious need for increasing the printing speed of the electronic computer output printer. The selective printing system which has been utilized heretofore in the conventional printers is of type-bar, type-box, or sphere type. In such selective printing system, because of a considerably large mechanical inertia in the movable parts of the selecting and printing mechanism thereof, the printing speed has been limited to about 1,000 characters per minute at most. There are also other type high speed printers available, such as line printers. However, such high speed printers are large in dimension and complicated in construction, and so they can be used only for large scale electronic computers. There has been a strong need for a compact printer of which printing speed is in order of several thousand characters per minute.

An object of the invention is thus to provide a novel high speed printer to optically select and print letters which comprises two selecting mirrors or two refracting members mounted individually on separate galvanometers. The high speed printer of the invention can print at a speed of several thousand characters a minute with ease.

The invention will now be described in detail referring to the accompanying drawings illustrating preferred embodiments thereof, in which:

FIG. 1 is a diagrammatic illustration of the operative principles of a character selecting means comprising two mirrors;

FIG. 2 is a similar illustration to FIG. 1, showing operative principles of a character selecting means comprising two refracting members;

3,492,926 Patented Feb. 3, 1970 ice FIG. 3 is a graphical view showing an arrangement of a matrix of characters on an enlarged scale;

FIG. 4 is a diagrammatic illustration of the construction of a printer having two mirrors according to the invention;

FIG. 5 s a diagram of the control circuit of a printer according to the invention; and

FIG. 6 is a similar illustration to FIG. 5, showing the construction of a printer having two refracting means according to the invention.

Referring to FIG. 1, light beams from a light source 1 are condensed by a condenser lens 2 to illuminate the entire surface of a font 3. As shown in FIG. 3, the font 3 comprises 72 transparent symbols including characters and marks disposed on an opaque film, for instance in a form of 9 mm. x 10 mm. matrix of characters. A projecting lens 4 acts to project the image of the entire font 3 to a photosensitive paper 7 through a selecting mirror 5 rotatable around its vertical axis VV and another selecting mirror 6 rotatable around its horizontal axis HH. As the selecting mirror 5 is rotated around its vertical axis V-V, the image of the matrix is shifted laterally. While, as the selecting mirror 6 is rotated around its horizontal axis HH, the image of the matrix is shifted longitudinally. Therefore, by rotating the selectin'g mirrors 5 and 6 in combination by a suitable extent respectively, one can place the image of any desired character or symbol in the matrix of the font 3 at a certain point P of the photosensitive paper 7. Thus, an optical character selecting means is obtained.

FIG. 2 shows operative principles of a character selecting means utilizing two retracting members, instead of two mirrors of the preceding embodiment illustrated in FIG. 1, in which the light source 1, the condenser lens 2, and font 3, the projection lens 4, and the photosensitive paper 7 are the same as those of the preceding embodiment. The image of the font 3 is produced on the photosensitive paper 7 by the projecting lens 4 through a selecting refractive member 5 rotatable around its vertical axis VV, and another selecting refractive member 6' rotatable around its horizontal axis HH. As the selecting refractive member 5' is rotated around its vertical axis V--V, the image of the matrix is shifted laterally. While, as the selecting refractive member 6 is rotated around its horizontal axis HH, the image of the matrix is shifted longitudinally. Therefore, by rotating the selecting refractive members 5' and 6' in combination by suitable extent respectively, one can place the image of any desired character or symbol in the matrix of the font 3 at a certain point P of the photosensitive paper 7.

The selecting mirrors 5 and 6 are prepared by evaporating aluminum on 1 cm. square glass plates about 1 mm. thick, and the refractive members are made of 1 cm. square glass or plastic plates of about 5 mm. thickness. Each mirror or refractive member is secured directly to the rotary shaft of a galvanometer of the moving coil type in a rotatable manner, as shown in FIG. 4. It is not difficult to cause angular movement of the rotary shaft of the galvanometer at a rate of times per second. The moment of inertia of the selecting mirror or the selecting refractive member can be made negligibly small as compared with that of the rotary shaft. Accordingly, the mechanical characteristics of the rotary shaft of the galvanometer are not affected at all by securing selecting mirror or the selecting refractive member thereon, and hence, the printer of the invention can print characters at a rate of about 150 characters per second without any substantial difficulty.

FIG. 4 illustrates the mechanism of an optical printer of the invention, which includes two selecting mirrors 5 and 6 in conjunction with the light source 1, the condenser lens 2, and font 3, the projecting lens 4, and the photosensitive paper 7. In the case of the printing means shown in FIG. 1, the mirror 5 can be rotated around its vertical axis VV, while the mirror 6 can be rotated around the horizontal axis H-H, and accordingly, it is necessary with such a printing means to provide two kinds of galvanometers, namely one having a vertically rotatable shaft and another one having a horizontally rotatable shaft. On the other hand, in the case of theprinter shown in FIG. 4, an additional optical system 10 comprising two mirrors for twisting an optical axis by 90 degrees is provided, so that both selecting mirrors 5 and 6 of the printer can be rotated vertically by galvanometers having vertical shafts only to shift the image of the font 3 in two normal directions on the photosensitive paper 7.

The photosensitive paper 7 is retained so as to form a part of a cylindrical surface. A rotatable spacing mirror 11 is provided in such a manner that it may be rotated around the axial center line of the cylindrical surface. The spacing mirror is, for instance, made by evaporating aluminum on 20 mm. x 25 mm. glass plass plate of about 1 mm. thickness.

The image of the font 3 is projected on the photosensitive paper 7 by the projecting lens 4 through the selecting mirror 5, the reflecting system 10, the other selecting mirror 6, and the spacing mirror 11. As the spacing mirror 11 is rotated step by step, around its rotary axis, the image of the font 3 is also shifted step by step on the photosensitive paper 7, and thus proper spacing is provided. The spacing mirror 11 is associated with the rotary shaft of a pulse motor 14 through a friction clutch 12 and a reduction gear train 13. In this particular embodiment shown in the figure, as a pulse is delivered to the pulse motor 14, the spacing mirror 11 is rotated by a quarter of degree, or 0.25 degree, to shift the image of the font 3 on the photosensitive paper '7 by a certain distance, say 3 mm. The stepping speed of the pulse motor 14 can be made as fast as 500 steps a second at the maximum, and hence, it is easy to carry out 150 spacing operations a second responsive to the rotation of the shafts of galvanometers 8 and 9.

A mask 15 having a slit 16 to pass only one column of symbols in the imageof the font 3 is placed just in front of the spacing mirror 11. Another mask 17 having slit 18 extending along the cylindrical surface of the photosensitive paper 7 is placed just in front of the paper 7. The slit 18 of the mask 17 is so adapted as to pass only one symbol of the column of symbols of the font 3 which are passed by the slit 16 of the mask 15. In other words, only an image of a single symbol or character is delivered to the photosensitive paper 7 at a time.

In this particular embodiment, 60 characters can be printed on a line of writing. Upon completion of print ing a line of writing, a pulse signal is delivered to another pulse motor 23, which feeds the paper 7 by a certain distance, for instance 6 mm. per pulse in a direction shown by the arrow, A and at the same time, a separate pulse is delivered to a reset magnet 26' (FIG. 5) to reset the angular position of the spacing mirror 11 to its starting position.

A shutter 19 comprising a disk having two notches 20 and 20' along the periphery thereof is placed between the mask 15 and the selecting mirror 6. The shutter 19 is driven by a synchronous motor 21 at a proper speed, for instance 75 c.p.s. or 450 rpm. in the direction shown by the arrow B in order to match with the selecting operation of the selecting galvanometers at 150' times per second. It has been ascertained by experiments that a sharp print of characters can be obtained by selecting proper exposure, for instance with an exposure time of 1 mb. by utilizing notches 20 and 20' extending 27 degrees from the center of the disk of the shutter 19. posite sides of the shutter '19 slightly below the optical A lamp 24 and a photo-transistor 25 are placed on oppath 30. Each notch 20 or 20' is so adapted as to travel just in the path of the lamp 24 immediately after crossing the optical path 30, and a clock pulse is generated from the photo-transistor 25 right after the photosensitive paper 7 is exposed. The character selecting and spacing operation is controlled by this clock pulse thus generated.

Referring to the control circuit of the printer, shown in FIG. 5, intermittent instruction signals delivered through the line 101 are stored temporarily in a buffer storage 51. The clock pulse generated by the photo-transistor 25 responsive to passage of the shutter notch 20 in front of the lamp 24 is delivered to the pulse amplifier 52 through a line 102 to be amplified there, and then the clock pulseis further delivered to lines 103 and 104. The pulse on the line 103 opens the gate circuit 53, and one of the instruction signals stored in the buffer storage 51 is transferred to the selecting circuit 55 through the gate circuit 53 thus opened and a normally open gate circuit 54. The selecting circuit 55 converts the pulse signal thus delivered into analog currents representing a character to be printed, and upon application of the analog currents thus converted to galvanometers 8 and 9 respectively, the selecting mirrors 5 and 6 are rotated by angles corresponding to the character to be printed, and accordingly, the character to be printed is properly selected. At the same time, a pulse from the selecting circuit 55 is delivered to an AND matrix 56 in conjunction with the clock pulse delivered to the line 104, and an output pulse from the AND matrix 56 is delivered to both lines and 111.

The pulse on the line 110 is applied to the pulse motor 14 through a pulse motor driving circuit 57 to rotate the pulse motor 14 by one step for a spacing. While, the same pulse on the line 111 is applied to a counter circuit 58 to be counted there. Upon completion of the aforementioned process, the succeeding shutter notch 20 comes to a position to cross the optical path 30 for exposing the photosensitive paper 7 to the character thus selected. Thereafter, as the shutter notch 20 passes just in front of the lamp 24, the next clock pulse is generated from the phototransistor 25.

As soon as the counter circuit 58 counts to 60, a pulse is delivered to lines 113, 114, 115, and 116. The pulse on the line 113 is applied to the reset magnet 26 through a monostable multivibrator 60 to reset the spacing mirror 11 to its starting position. The pulse on the line 114 is applied to the pulse motor 23 through a pulse motor driving circuit 61 to rotate the pulse motor 23 by one step for forwarding the photosensitive paper 7 by a predetermined stroke, say by 6 mm. The pulse on the line 115 acts to reset the counter circuit 58 to zero. The pulse on the line 116 is applied to the gate circuit 54 through a multivibrator 59 to close the gate 54 until the printer becomes ready for printing a new line of writing.

If a spacing instruction signal is given to the selecting circiut 55, then no output current signal from the selecting circuit is delivered to galvanometers 8 and 9, but a pulse is delivered only to the line 109 to carry out the spacing operation alone.

Upon application of a line feed signal to the selecting circuit 55, a pulse is delivered to lines 119 and 120 to feed the photosensitive paper by a distance corresponding to the line interval of the printer.

As shown in FIG. 3, there is no transparent letter provided at the origin of the matrix of characters, and accordingly no light beam will reach the photosensitive paper 7 unless both galvanometers are actuated. During the time period when no instruction signal is stored in the buffer storage 51, neither one of the galvanometers 8 and 9 receives actuating current, and accordingly, there will be no light beam delivered to the photsensitive paper 7 even when the shutter notch 20 or 20 travels across the optical path 30. In this case, there is no pulse on lines 108 and 109. Therefore, delivery of a clock pulse on the line 104 does not cause generation of any pulse on lines 110 and 111, and no spacing operation takes place.

FIG. 6 illustrates another embodiment of the invention, which comprises a printer mechanism having two refractive members. This particular embodiment is essentially the same as the last mentioned embodiment referring to FIG. 5 except for the fact that the optical character selecting means including two mirrors in the'latter embodiment is replaced with that including two refractive members. Therefore, the control circuit of FIG. 5 can be also applied to the printer mechanism of FIG. 6. The operation of this embodiment is apparent to those skilled in the art from the preceding description, and hence, no detailed explanation is repeated hereinafter.

What we claim is:

1. An optical printer comprising a matrix of characters, a projector for projecting images of the characters on the matrix, an optical letter selecting means including two optical members placed on the optical path of said projector and being individually rotatable through respective angles to pass selected of the images of the characters, a rotatable disc shutter having at least one slit adapted to open the optical path from the projector intermittently, two mask members each of which has a slit to limit the selected images, one of said mask members being curved and supporting photosensitive paper on which images are to be printed, the curved mask member being elongated and having an axis containing the center of curvature thereof, a spacing mirror between said two mask members to project the images of selected characters passing through the slit in the other of said mask members onto said photosensitive paper through the slit in said curved mask member, and means for turning said spacing mirror stepwise in synchronism with rotation of said optical members to print selected characters in succession along the photosensitive paper through the slit in the curved mask member, the latter means including elements disposed on opposite sides of said disc shutter for sensing the passage of the slit therein.

2. An optical printer as set forth in claim 1, wherein said optical members are refractive members each comprising a transparent body having flat front and rear surfaces for deviating the optical path when inclined.

3. An optical printer as set forth in claim 2, comprising reflective means between said two refractive members to bend the optical axis of the optical path by 90 degrees.

4. An optical printer as claimed in claim 1 wherein said optical members are mirrors.

5. An optical printer as set forth in claim 1, wherein said elements disposed on opposite sides of said disc shutter comprises a lamp on one side and means on the other side of the disc shutter sensitive to the illumination of said lamp and exposed thereto, through said slit in the disc shutter, during rotation of said shutter.

6. An optical printer comprising a matrix of characters, a projector for projecting images of the characters which are on the matrix, two optical members placed on the optical path of said projector and being individually rotatable through respective angles to pass selected of the images of the characters, a rotatable disc shutter having at least one slit adapted to open the path from the projector intermittently, a clock pulse generating means including a lamp and a photo-transistor each of which is placed on opposite sides of said disc shutter, an instruction source, a buffer storage connected to said source to store temporarily instruction signals supplied intermittently therefrom said instruction source, a gate connected to said storage for being opened thereby upon delivery of a signal therefrom to pass the clock pulse therethrough, a selecting circuit for converting the pulse signals into analog current signals, a pulse motor driving circuit and a counter circuit, connected to the selecting circuit, two separate rotatable galvanometers for delivering pulses to said pulse motor driving circuit and said counter circuit, each of said galvanometers being coupled to a respective optical member to rotate the same so as to select characters on said matrix, two mask members in the optical path of the projector, a stepwise rotating spacing mirror rotatably supported between said mask members for cooperating therewith to project images of the desired characters on the matrix onto a photosensitive paper through a slit provided in one of said mask members, and a pulse motor for stepwise rotating said spacing mirror so that the selected characters are projected in succession along the photosensitive paper.

7. The optical printer as set forth in claim 6, wherein said counter circuit includes a counter means and a pulse generator which generates pulses to reset the spacing mirror to a starting position and to rotate the pulse motor to advance the photosensitive paper when counts of said counter means reach a predetermined value.

8. An optical printer as set forth in claim 6, wherein one of said masks is curved and supports the photosensitive paper, said spacing mirror being supported for rotation along an axis containing the center of curvature of the curved mask to print selected characters in succession along the photosensitive paper through said slit in the curved mask member.

References Cited UNITED STATES PATENTS JOHN M. HORAN, Primary Examiner

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