GB2286999A

GB2286999A - Ribbonless impact typewriter.

Info

Publication number: GB2286999A
Application number: GB9502379A
Authority: GB
Inventors: Shui Pui Chiu
Original assignee: Ngai Keung Metal and Plastic Manufactory Ltd
Current assignee: Ngai Keung Metal and Plastic Manufactory Ltd
Priority date: 1994-02-04
Filing date: 1995-02-06
Publication date: 1995-09-06
Also published as: GB9502379D0

Abstract

An impact typewriter is characterised by a type (or die) carrier whose types (or dies) are formed of an ink-impregnated material. As shown two cases of the pre-inked type are provided on a porous annular outer band of an exchangeable type cylinder 24. The type cylinder is mounted on a casing 23, and is indexed from character to character by a DC motor within casing. The casing 23 is slidable towards and away from the platen 13, and has a vertical slot 26 in which is engaged an eccentric pin 22 on a disc 21 driven by a further motor 14M secured to the printer frame. Upon rotation of the disc 21 in one direction, the pin is caught by a sprung hook (not shown) and the casing (and hence the selected type) is both reciprocated towards the platen (to impact print on the paper) and raised (to effect a shift to upper case characters). Upon rotation of the disc in the other sense, the pin displaces the hook instead of being engaged thereby, and lower case printing is performed. The platen 13 is mounted on a slidable carriage 48 provided with a driving comb 42. A slider (shown) has a pin projecting through a cam slot (not shown) in the machine frame. The slider is reciprocated by casing 23 being abutted against it once every printing cycle, and the pin coacts with both the comb and the edge of the cam slot to index the platen one character space per reciprocation of the slider. A first detent (in the machine frame and engaging the comb) resiliently detains the platen carriage in any selected character-typing position, and a second detent (projecting from the casing 23 to abut the platen carriage) positively locks the type carrier at the moment of printing. <IMAGE>

Description

TYPEWRITER The present invention relates to a typewriter.

According to the invention, there is provided a typewriter which comprises a body, a keyboard provided on the body, a platen supported by the bod, and a typing mechanism controlled by means of the keyboard to type on a sheet of paper placed on the platen, said typing mechanism incorporating a pre-inked typing member to effect typing.

In a preferred embodiment, the typing member has a substantially cylindrical pre-inked peripheral wall bearing thereon raised patterns in the form of reversed fonts of letters of the alphabet.

More preferably, the peripheral wall of the typing member is provided by upper and lower pre-inked bands, one of which bears raised patterns in the form of reversed fonts of uppercase letters of the alphabet and the other one bears raised patterns in the form of reversed fonts of lowercase letters of the alphabet.

In a specific arrangement, the typing mechanism is adapted to turn the typing member into an appropriate orientation with a desired letter of the alphabet thereon foremost and then to move the typing member forwards against the platen in order to type the desired letter of the alphabet on a sheet of paper placed on the platen.

Preferably, the typing mechanism includes a positioning arrangement for positively defining predetermined orientations of the typing member with the corresponding letters of the alphabet thereon foremost.

In a preferred embodiment, the positioning arrangement is provided by a ring of teeth on the typing member and by a key for engagement with respective gaps between adjacent teeth to positively define the respective predetermined orientations of the typing member.

More preferably, the engagement between the teeth and the key is effected upon forward movement of the typing member to type.

In a specific embodiment, the typing mechanism incorporates a first electric motor for turning the typing member into a said appropriate orientation and a second electric motor for moving the typing member forwards to type.

It is preferred that the second electric motor is adapted to rotate in one direction to move the typing member at one level forwards to type with one said pre-inked band and to rotate in the opposite direction to move the typing member at a different level forwards to type with the other preinked band.

More preferably, the second electric motor is adapted to rotate in said one direction to move the typing member merely forwards to type with the upper pre-inked band and to rotate in the opposite direction to move the typing member forwards as well as upwards to type with the lower pre-inked band.

Preferably, the typing mechanism includes an advancing mechanism adapted to move the platen stepwise sideways with respect to the body, said platen being otherwise freely slidable sideways.

In a preferred embodiment, the advancing mechanism is provided by a elongate toothed member fixed longitudinally to the platen and by a keying member which is engageable with respective gaps between adjacent teeth of the toothed member and movable sideways in order to move the toothed member and hence the platen sideways in steps.

More preferably, the keying member is arranaBed to engage with the respective gaps of the toothed member and to so move the platen upon forward movement of the typing member to type.

It is preferred that the operation of the keying member is associated with the forward movement of the typing member through a camming action.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front perspective view of an embodiment of a typewriter in accordance with the invention; Figure 2 is a schematic block diagram showing various parts of the typewriter of Figure 1; Figures 3A and 3B are perspective views showing the construction of a platen, a drive mechanism and a typing mechanism of the typewriter of Figure 1; Figures 4A to 4D show the construction of a typing head of the typing mechanism of Figures 3A and 3B; Figures 5A to 5E are sequential side views of the typing mechanism of Figures 3A and 3B, illustrating a complete typing action for typing an uppercase letter; Figures 6A to 6G are sequential side views of the typing mechanism of Figures 3A and 3B, illustrating a complete typing action for typing a lowercase letter;; Figures 7A and 7B show an advancing mechanism for the platen of the tpewriter of Figure 1; Figures 8A to 8D are sequential plan views of the advancing mechanism of Figures 7A and 7B, illustrating an advancing action for one step; and Figures 9A and 9B illustrate are perspective views of the typing mechanism of Figures 3A and 3B.

Referring firstly to Figures 1 and 2 of the drawings, there is shown a typewriter 10 embodying the invention, which typewriter 10 has a body 11 supporting on its front part a touch-button keyboard 12 and in its rear part a platen 13.

Inside the body 11 between the keyboard 12 and platen 13, there are provided on opposite sides a drive mechanism (printing controller) 14 and a typing mechanism (index system) 15. The operation of the typewriter 10 is controlled by a microprocessor-based electronic control circuit 16 receiving user's typing commands from the keyboard 12. The control circuit 16 controls the typing operation by means of two DC motors 14M and 15M which form an integral part of the drive and typing mechanisms 14 and 15, respectively.

Reference is now made to Figures 3A and 3B, showing the construction of the drive and typing mechanisms 14 and 15.

The drive mechanism 14 is formed by a stationary open-top box-like casing 1 supporting therein the motor 14k1 and thereon a driving shaft 18. The motor 14M has an output worm gear 19 in mesh with a gear wheel 20 mounted fast on the shaft 18, thereby driving the shaft 18. On the side facing the typing mechanism 15, the driving shaft 18 supports at its end a crank wheel 21 having a crank shaft 22 which extends into the typing mechanism 15. The typing mechanism 15 has a box-like casing 23 which supports thereon a typing head 24 by means of a horizontal disc 25.

The disc 25 has a vertical axle 25A which engages from below into the typing head 24, and is arranged to be turned by the motor 15M in a controlled manner in order to determine the precise orientation of the typing head 24.

The motor 15M is located inside the casing 23, driving the lower end of the axle 25A.

The construction of the typing head 24 is shown in detail in Figures 4A to 4D, which is formed by a thick disc-like body 24A and an external band 24B disposed around the periphery of the body 24A. The band 24B is made of an absorbent material which is impregnated with a suitable (stamping) ink. The outer cylindrical wall of the preinked band 24B is formed with two rings 37A and 37B of raised patterns in the reversed shape (mirror image) of uppercase and lowercase letters and certain commonly used punctuation marks. The top and bottom rings 37B and 37A bear the whole sets of lowercase and uppercase letters, respectively. In essence, the band 24 is equivalent to an annular pre-inked stamp. The bottom rim of the body 24A is provided around with castellation 24C.

The construction and operation of the typing mechanism 15 is shown and illustrated in Figures 5A to SE. The casing 23 has a vertical slot 26 on its side wall 23A facing the drive mechanism 14, through which slot 26 the crank shaft 22 enters into the casing 23. Externally on the casing wall 23A and to the right of the slot 26, there is located a generally V-shaped operating member 27 having first and second limbs 27A and 27B. The operating member 27 is pivoted on a fixed stud 28 on the casing wall 23A, and is resiliently biassed forward (to the left side as shown) by a compression elbow spring 29 disposed on the pivot stud 28. Under the action of the spring 29, the first operating member limb 27A lies adjacent and parallel to the vertical slot 26 and bears against the crank shaft 22, and the operating member 27 is in its rest or normal position.The first limb 27A has at its remote end an enlarged hook portion 33 which covers the upper half of the slot 26, said hook portion 33 providing a detent 33A.

Externally on the casing wall 23A, a pair of fixed front and rear round studs 30A and 30B is provided at the same level. The second operating member limb 27B is crooked and, in the normal position, extends rearwards from the pivot stud 28 initially at about 450 upwards and then horizontally. In this position, the rearmost end of the second limb 2713 bears from below against the rear round stud 30B.The drive mechanism casing 17 has, externally on its side wall 17A facing the typing mechanism 15, a pair of fixed front and rear horizontal flat studs 31A and 31B which are situated at the same level slightly above that of the round studs 30A and 3OB. All the round and flat studs lie on substantially the same vertical plane, with each flat stud 31A or 31B positioned in front of the corresponding round stud 30A or 30B at the same distance off and pointing rearwards with a chamfered edge. The elbow spring 29 has a front limb bearing against a fixture 32 on the first operating member limb 27A and a rear limb bearing against the rear round stud 30B.

The casing 23 of the typing mechanism 1 is freely vertically slidable on at least a pair of vertical posts 34 which are in turn fixed on a platform 35. The platform 35 is slidable forwards and rearwards on a floor 38 of the typewriter body 11. With this arrangement, the typing mechanism 15, including the typing head 24, is movable not only upwards and downwards but also forwards and rearwards relative to the platen 13.

The operation of the typing mechanism 15 for typing an uppercase letter will now be described. In order to type an uppercase letter, the drive mechanism 14 is controlled to rotate the crank shaft 22 anti-clockwise for one complete turn, staring from its initial rightmost angular position engaging the detent 33A of the operating member 27 (Figure SA). While the crank shaft 22 is being rotated for 90 to the topmost angular position (Figure 5B), it carries with it through a dragging action the operating member 27 and hence the whole typing mechanism 15, thereby moving the typing head 24 upwards and forwards.During this movement, the two round studs 30A and 30B are lifted to and eventually placed on the corresponding flat studs 31A and 31B which are fixed with the stationary drive mechanism 14.

Consequently, the whole typing mechanism 15 will stay in this uppermost level when and after the crank shaft 22 has reached its topmost angular position, with the bottom ring 37A of uppercase letters in alignment with the axis of the platen 13.

As the crank shaft 22 is rotated to the leftmost angular position (Figures 5C), the crank shaft 22 engages the left side of the slot 26, thereby moving the whole typing mechanism 15 at its uppermost level horizontally forwards until the typing head 24 hits the platen 13. At this moment, the pre-inked band 24B on the typing head 24 will print an uppercase letter on a sheet of paper placed on the platen 13. Further anti-clockwise rotation of the crank shaft 22 will move the whole typing mechanism 1 horizontally backwards by engaging the right side of the slot 26, with the two round studs 30A and 30B sliding backwards on the corresponding flat studs 31A and 31B.The typing mechanism 15 is simultaneously lowered until the crank shaft 22 reaches the bottom-most angular position (Figure SD) and is finally slid horizontally backwards until the crank shaft 22 returns to its initial rightmost angular position (Figure 5E/5A). This completes one typing action of the typing mechanism 15 to type an uppercase letter. Throughout this typing action, the operating member 27 remains in its normal position.

The operation of the typing mechanism 15 for typing a lowercase letter will now be described with reference to Figures 6A to 6G. In the initial position of the typing mechanism 15, the top ring 37B of lowercase letters aligns with the axis of the platen 13 (Figure 6A or Figure 5A/5E).

The drive mechanism 14 is controlled to rotate the crank shaft 22 clockwise for one complete turn in order to type a lowercase letter. As the crank shaft 22 is rotated for 1800 from its initial rightmost angular position (Figure 6A) through the bottom-most angular position (Figure 6B) to the leftmost angular position (Figure 6C), the whole typing mechanism 15 is slid horizontally forwards by the crank shaft 22, engaging the left side of the slot 26, until the typing head 24 hits the platen 13. This results in the pre-inked band 24B on the typing head 24 printing a lowercase letter on a sheet of paper placed on the platen 13. During this movement, the crank shaft 22 will disengage and subsequently re-engage the detent 33.A of the operating member 27.

The crank shaft 22 will, upon further clockwise rotation for 900 towards its topmost angular position, slip off the operating member detent 33A and then push esternally against the hooking portion 33 to pivot the operating member 27 backwards from its normal position (Figures 6C to 6D/6E). Simultaneously, the whole typing mechanism 1 is slid horizontally rearwards by the crank shaft 22 engaging the right side of the slot 26. Soon after the crank shaft 22 has left its topmost angular position, the external side of the hooking portion 33 will escape from the crank shaft 22 and accordingly at once the operating member 27 will flick forwards back to its normal position under the action of the elbow spring 29, thereby permitting the detent 33A to close back onto the crank shaft 22 (Figure 6F).

Throughout this action and further on, the whole typing mechanism 15 will be slid horizontally backwards by the crank shaft 22 engaging the right side of the slot 26 until the crank shaft 22 returns to its initial rightmost angular position (Figure 6G/6A). This completes one typing action of the typing mechanism 15 to type a lowercase letter.

Referring to Figures {A, 713 and SA to 8D of the drawings, showing therein an advancing mechanism 40 for incrementall; moving the platen 13. The platen 13 is guided to move left and right along a linear path, from one predefined typing position to the next in a stepwise manner. The platen 13 is supported on a carriage 41, underneath which there is fixed a comb member 42 having a plurality of teeth 43 with interlacing gaps 44. The comb member 42 rests on a raised floor 48 of the typewriter body 11, transversely across a back-to-front passage 45 formed in the casing floor 48. A elongate, slightly narrower, plunger 46 lies inside the passage 45, which has a front end 46A and a rear end 46B.

The front end 46A carries an upstanding pin 47, and the rear end 46B projects out of the raised casing floor 48 for bearing against the forward side wall of the typing mechanism casing 23. The plunger 46 is resiliently biassed backwards by a slanting extension spring 49 on the right side thereof against the typing mechanism casing 23 (Figure 7B). In the normal position of the typing mechanism 15 (the initial position at the beginning of each typing action as referred to above), the casing 23 is sufficiently far back for the pin 4 to be just clear of the comb member teeth 43.

The pin 47 is secured to the plunger front end 46A by means of an embedded vertical cylindrical connector 50 which has a top end lying flush with the top side of the plunger 46 and a bottom end 50A projecting beyond the plunger bottom side down into a recess 51 formed below the passage 45.

The recess 51 has a periphery of a shape resembling a right-angled triangle which has a hypotenuse on the right side (Figure 8A). This hypotenuse acts as a cam track a1A for the connector bottom end or cam follower bOA to slide along, the latter being urged against the former by the slanting spring 49.

The operation of the advancing mechanism 40 will now be described. The cam follower DO. is initial at the rear end of the cam track 51A prior to each typing action of the typing mechanism 15 (Figure 8A). When the typing mechanism 15 moves forwards at the beginning of a typing action, the plunger 46 is pushed forwards and the cam follower 5OA slides forwards along the cam track 51A, thereby moving the pin 47 from right to left (Figures 8A to 8C). During this left-to-right movement, the pin 47 moves into and down a pre-aligned gap 44A of the comb member 42, thereby simultaneously pushing the comb member 42 to the left.

The typing head 24 of the typing mechanism 15 strikes hard at the platen 13 when the pin 47 reaches the innermost end of the gap 44A. Near its forward-most end, the cam tack 51A turns to extend straightly forwards (no longer slanting) in order to ensure that the comb member gap 44A and hence the platen 13 will have moved by the pin 47 to precisely the pre-defined typing position and stay there just before the typing head 24 hits the platen 13 (the paper sheet thereon). This pre-alignment is practically preferable in order to accommodate for the slight continued forward movement of the typing head 24 from the moment of initially hitting the paper on the platen 13 and to the moment of striking hard thereat.

At the end of the typing action, the typing mechanism 15 will move backwards off the platen 13, thereby allowing the plunger 46 to also move backwards under the action of the spring 49. During this backward movement1 the assembly of the platen 13, the carriage 41 and the comb member 42 will stay in position due to the inertia of their overall weight, and the pin 47 will move straight back out of the comb member gap 44A and immediately upon release will finally jerk to the right with the cam follower 50A swiftly returning to its initial position (Figure 8D). At this moment, the pin 47 will be right at the open end of the next gap 44B. This completes one incremental advancing step of the platen 13, which is synchronised with each typing action of the typing mechanism 15.

The predefined incremental positions of the platen 13 are guaranteed by a positioning member 36 provided on the casing floor 48 (Figure 7B). The positioning member 36 is located accurately at one of the predefined platen positions, and is releasably biassed to protrude slightly above the floor surface for releasably catching the coming comb member gap 44 in order to positively define the platen positions.

The DC motor 15M is installed inside the casing 23 of the typing mechanism 15, together with the appropriate gear train, for turning the typing head 24 via the supporting disc 25 and shaft 25A (Figure 3A). Turning of the typing head 24 to position the desired letter or punctuation mark on its centrally forward-most position is controlled by the control circuit 16. For this purpose, the control circuit 16 controls the supply of DC power to the motor 15M for a certain period of time which is calculated according to the angular distance necessary for the typing head 24 to turn from the last letter or punctuation mark to the desired one.

Reference is finally made to Figures 9A and 9B of the drawings. The typing head 24 is located on top of the casing 23 of the typing mechanism 15, with its bottom rim castellation 24C slightly off the casing top wall 23B. A radially extending slot 60 is formed in the casing top wall 23B on its rear side, extending across the castellation 24C. Inside the casing 23, there is provided a vertical keying member 61 which has an upper keying end 61A passing upwardly through the radially inner end of the slot 60.

The keying end 61A stays normally behind the castellation 24C.

The keying member 61 is engaged by a elongate slider 62 provided generally inside the casing 23. The slider 62 is supported for horizontal sliding movement in a direction parallel to the back-to-front, or vice versa, movement of the casing 23 when the typing mechanism 15 is in typing operation. Front end 62A of the slider 62 projects forwards outside the casing 23 and is resiliently urged forwards against the side of the raised floor 48 of the typewriter body 11 by an extension spring 63 provided inside the casing 23. Rear end 62B of the slider 62 is connected with the internal keying member 61 such that the keying member 61 is horizontally slidable by the slider 62.

With this arrangement, the keying end 61A of the keying member 61 is resiliently biassed by the spring 63 to stay at rest behind the castellation 24C.

At the beginning of each typing action, the typing head 24 will firstly be rotated to locate the desired letter or punctuation mark at the centrally forward-most position.

Once this has been done, the typing mechanism 15 will then be moved forwards, whereby the slider 62 is pushed relatively backwards further into the casing 23 (Figure 9B). At the same time, the keying member 61 is pushed relatively backwards by the slider 62, thereby causing the top keying end 61A to enter from behind into the nearest gap between the adjacent pair of castellation teeth 24C.

This keeping action is designed to prevent any mis-alignment in positioning the desired letter or punctuation mark centrally forward-most on the typing head 24, which may be caused by the use of the motor 15M which is not a stepping motor.

At the end of the typing action, the typing mechanism casing 23 will be withdrawn backwards, and accordingly the keying member end 61A will disengage from the castellation 24C and return to stay behind, under the action of the spring 63.

The invention has been given by way of example only, and various modifications of and/or alterations to the described embodiment may be made by persons skilled in the art without departing from the scope of the invention as specified in the appended claims.

Claims

CLAIM

1. A typewriter comprising a body, a keyboard provided on the body, a platen supported by the body, and a typing mechanism controlled by means of the keyboard to type on a sheet of paper placed on the platen, said typing mechanism incorporating a pre-inked typing member to effect typing.

2. A typewriter as claimed in claim 1, wherein the typing member has a substantially cylindrical pre-inked peripheral wall bearing thereon raised patterns in the form of reversed fonts of letters of the alphabet.

3. A typewriter as claimed in claim 2, wherein the peripheral wall of the typing member is provided by upper and lower pre-inked bands, one of which bears raised patterns in the form of reversed fonts of uppercase letters of the alphabet and the other one bears raised patterns in the form of reversed fonts of lowercase letters of the alphabet.

4. A typewriter as claimed in claim 2 or claim 3, wherein the typing mechanism is adapted to turn the typing member into an appropriate orientation with a desired letter of the alphabet thereon foremost and then to move the typing member forwards against the platen in order to type the desired letter of the alphabet on a sheet of paper placed on the platen.

5. A typewriter as claimed in claim 4, wherein the typing mechanism includes a positioning arrangement for positively defining predetermined orientations of the typing member with the corresponding letters of the alphabet thereon foremost.

6. A typewriter as claimed in claim 5, wherein the positioning arrangement is provided by a ring of teeth on the typing member and by a key for engagement with respective gaps between adjacent teeth to positively define the respective predetermined orientations of the typing member.

7. A typewriter as claimed in claim 6, wherein the engagement between the teeth and the key is effected upon forward movement of the typing member to type.

8. A typewriter as claimed in any one of claim 4 to claim 7, wherein the typing mechanism incorporates a first electric motor for turning the typing member into a said appropriate orientation and a second electric motor for moving the typing member forwards to type.

9. A typewriter as claimed in claim 8 when dependent upon claim 3, wherein the second electric motor is adapted to rotate in one direction to move the typing member at one level forwards to type with one said pre-inked band and to rotate in the opposite direction to move the typing member at a different level forwards to type with the other preinked band.

10. A typewriter as claimed in claim 9, wherein the second electric motor is adapted to rotate in said one direction to move the typing member merely forwards to type with the upper pre-inked band and to rotate in the opposite direction to move the typing member forwards as well as upwards to type with the lower pre-inked band.

11. A typewriter as claimed in any one of the preceding claims, wherein the typing mechanism includes an advancing mechanism adapted to move the platen stepwise sideways with respect to the body, said platen being otherwise freely slidable sideways.

12. A typewriter as claimed in claim 11, wherein the advancing mechanism is provided by a elongate toothed member fixed longitudinally to the platen and by a keying member which is engageable with respective gaps between adjacent teeth of the toothed member and movable sideways in order to move the toothed member and hence the platen sideways in steps.

13. A typewriter as claimed in claim 12, wherein the keying member is arranged to engage with the respective gaps of the toothed member and to so move the platen upon forward movement of the typing member to type.

14. A typewriter as claimed in claim 13, wherein the operation of the keying member is associated with the forward movement of the typing member through a camming action.

15. A typewriter substantially as hereinbefore described with reference to the accompanying drawings.