Locking Arrangement For Manually Set Printing Wheels

Abstract

A set of printing wheels with circumferentially spaced types and arresting recesses, can be set to digital printing positions by manual setting means. An axial row of spring biassed arresting pawls engages a row of the arresting recesses, and yield resiliently while the printing wheels are turned during setting to a selected number. The pawls have locking recesses cooperating with a locking bar extending at right angles to the direction of movement of the pawls to the arresting position. A carriage with a platen roller is manually moved out of an end position along a path over the printing wheels. The carriage is operatively connected with the locking bar so that the locking bar is ineffective in the end position of the carriage while the printing wheels are set, and engages the locking recesses in the pawls when the carriage moves out of the end position so that the wheels cannot be displaced by the platen roller during printing.

Description

BACKGROUND OF THE INVENTION

It is known to use spring biased pawls for yieldingly arresting printing wheels in angularly displaced printing positions while the printing wheels are being set so that the correct number indication can be selected for each printing wheel. However, when a platen roller is manually moved over a paper sheet covering the effective types of the set of printing wheels, it may happen that the printing wheels are displaced out of the correct position. It has been proposed to lock the printing wheels during the operation of the carriage and printing roller, but the arrangements according to the prior art are complicated.

SUMMARY OF THE INVENTION

It is one object of the invention to provide a locking arrangement for manually set printing wheels which prevents any displacement of the set printing wheels by a platen roller passing over the printing wheels during the printing operation.

Another object of the invention is to improve arrangements according to the prior art serving a similar purpose.

Another object of the invention is to lock arresting pawls against radial movement by an axially extending locking bar.

Another object of the invention is to make the operation of the locking bar depending on the position of the manually operated carriage and platen roller.

With this objects in view, the present invention provides a locking arrangement for locking arresting pawls and thereby printing wheels by means of a locking bar which is ineffective in one end position of the carriage, and effective when the carriage moves with the platen roller along a path in which the printing wheels are located.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a printing machine to which the present invention is applied;

FIG. 2 is a fragmentary perspective view illustrating an embodiment of the invention;

FIG. 3 is a fragmentary side view, partially in section, illustrating the embodiment of FIG. 2; and

FIG. 4 is a fragmentary bottom view of the embodiment of FIGS. 2 and 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, as best seen in FIG. 1, a manual printer has a casing 1 and supports a carriage 2 having a rotary platen roller 3 for movement along a path over the printing bed 4 which has a cutout 4a, see also FIG. 3, through which a segment-shaped portion of a set 55 of printing wheels 5 projects so that the top row of types 5b is engaged by the platen roller 3. Each printing wheel 5 is integral with a gear 6 having arresting recesses 6a which respectively correspond to types 5b, and to angular printing positions of the printing wheels 5. All printing wheels and gears 5, 6 are mounted for free rotation on a shaft 40 which is supported on the supporting frame means of the printer.

As shown in FIG. 1, a cover plate 7 is provided which has longitudinal slots 8 in which setting levers 9 are guided so that rack bar portions 11 of the setting levers 9 mesh with the gear portions 6 of the type wheels 5, respectively. The setting levers 9 have head portions 10 on which buttons 10a are mounted after the assembly of the casing portion 7. The rack portions 11 are guided in a comb-shaped guide 12.

A set of arresting pawls 13 is arranged in a row and guided by guide members 20 for movement in radial direction into and out of the arresting recesses 6a of the gear portions 6. A guide rod 18 having ends mounted in the frame of the machine, passes through a slot 14 in each arresting pawl 13 so that the arresting pawls can perform a slight angular movement for better fitting into the arresting recesses 6a into which they are biased by individual springs 19 located in blind bores 16 at the rear ends of the arresting pawls 13 whose front ends 15 are tapered to conform to the shape of the arresting recesses 6a.

The individual springs 19 urge the pawls 13 to the arresting position illustrated in FIG. 3, but when the rack bars 11 of the setting means 9 are longitudinally displaced by operation of the buttons 10, each tooth of each gear 6 acts on the tapered end 15 of the respective pawl 13 to urge the respective pawl 13 out of the arresting recess 6a so that the pawls 13 yield against the action of the small springs 19, and permit the setting of the printing wheels 5 to different angular printing positions in which different types 5b are located in an operative row on top of the type wheels 5.

Each arresting pawl 13 has a triangular locking recess 17, and when the arresting pawls 13 are in the arresting position fully engaging the arresting recesses 6a, all locking recesses 17 are aligned in an axial row. A bail 21 is mounted on a shaft 22 for angular movement, and has two arms 21a between which a locking bar 23 extends directly below the row of locking recesses 17. A torsion spring 21b biasses bail 21 with locking bar 23 to an inoperative position in which locking bar 23 is not located in the row of locking recesses 17.

An angular lever 24 is mounted on pivots 26 on the supporting frame 41 and has one end 24a abutting the yoke portion of bail 21 and another end portion with a pin 27 located in a fork-shaped portion 30 at one end of another angular lever 28 which is mounted for angular movement on a stationary shaft 29 secured to the machine frame. Angular lever 28 is biased by a spring 32 in the direction of the arrow A so that the motion transmitting means 28, 24, 21 are biassed by the locking spring 32 to move to a position in which the locking bar 23 is in the locking position illustrated in chain lines in FIG. 3 in which locking bar 23 engages the slanted edges of the locking recesses 17 of pawls 13.

One end of lever 28 is connected by a wire link 33 with a feeler lever 34 which is mounted on a supporting shaft 34a for angular movement. The carriage 2 has on either side of the printing bed plate 4, a pair of rollers 35 engaging the top and bottom faces of the bed plate 4 so that the carriage 2 with the platen roller 3 can move along a path from the end position shown in FIG. 1 to another end position, and back. During such movement, the platen roller 3 moves over the top portion of the set 55 of printing wheels 5 which projects out of output 4a in bed plate 4 so that an imprint can be made on a sheet placed between platen roller 3 and the printing wheels 5.

In the initial end position of carriage 2, a roller 35' is located in the region of the feeler end 34b, as best seen in FIG. 4, so that spring 32 cannot move feeler lever 34 to the position shown in broken lines. However, when the carriage 2 is manually moved out of the end position of rest shown in FIG. 1 and FIG. 4, the respective roller 35' moves to the position 35" shown in FIG. 4 in broken lines, and consequently permits feeler lever 34 to move to the broken line position due to the action of spring 32. Since feeler lever 34 and wire link 33 are part of the motion transmitting means which also include members 28, 24, and 21, spring 32 acts through the motion transmitting means on locking bar 23 so that locking bar 23 moves into the aligned row of locking recesses 17, completely locking all pawls 13 against movement out of the respective arresting recesses 6a.

The locking is particularly effective since the pawls are mounted on guide rails 20 and on guide shafts 18 for substantially radial movement in relation to the axis of the printing wheels 5, while the locking bar 23 extends in axial direction at right angles to the direction of movement of the arresting pawls 13. If one of the printing wheels 5 and gears 6 was not accurately set to a printing position so that the tapered end 15 of the respective pawl 13 is not fully located in the arresting recess 6a, the corresponding locking recess is also slightly displaced, but the locking bar 23 engaging the slanted walls of the respective locking recess 17, forces the pawl 13 to assume the correct arresting position, and the slanted edges of the front portion 15 of the respective arresting pawl 13 urge respective gear 6 and printing wheel 5 to the correct printing position.

During operation of the apparatus, a sheet is placed on the printing bed above the set 55 of printing wheels 5 and held by paper guides 1a shown in FIGS. 1 and 3. The sheet, not shown, is located between the projecting portion of the set 55 of printing wheels 5 and the plane in which the platen roller 3 moves during movement of the carriage 2. When the carriage is in the end position of rest on the left of the printing bed 4, as shown in FIG. 1 and FIG. 4, in solid lines, feeler lever 34 is held in the solid line position shown in FIG. 4 so that the motion transmitting means 28, 24, 21 hold the locking bar 23 in the solid line position of FIG. 3 outside of the row of locking recesses 17, as shown in FIG. 3. Consequently, arresting pawls 13 are biassed only by springs 19 into the arresting position engaging the arresting recesses 6a. When the printing wheels 5 are now set by movement of the setting means 9 with rack bars 11, the gears 6 turn together with the respective type wheels 5, and all type wheels are successively set to a selected printing position for printing the number represented by the uppermost types 5b on the type wheels 5 which are located under the paper sheet.

In order to produce an imprint, it is necessary to move the carriage 2 with platen roller 3 out of the position of rest and over the printing rollers 5. Such a movement may cause displacement of individual printing wheels 5 and corresponding displacement of the arresting pawls 13 so that the numbers would not be accurately printed. When carriage 2 moves out of the end position of rest, the carriage roller 35' moves out of the solid line position to the position 35" shown in broken lines. Feeler lever 34 is released, and permits angular movement of motion transmitting lever 28 about the axis of the stationary shaft 29 due to the action of the locking spring 32. Pin 27 of motion transmitting member 24 is displaced by the fork-shaped portion 28a about the axis of shaft 26 so that end portion 24a urges bail 21 out of the solid line position shown in FIG. 3 to the broken line position so that the locking bar 23 is moved from the inoperative position shown in solid lines to the operative position shown in broken lines, and all pawls 13 are locked against any movement out of the corresponding arresting recesses 6a. Consequently, a displacement of the printing wheels out of a selected angular printing position is impossible, and a selected number is accurately printed along a straight line.

Due to the fact that during the setting operation only the small springs 19 yield when a tooth of gear 6 passes the front end 15 of the respective pawl 13, the wear on the teeth 6 and recesses 6a is small. Due to the fact that the locking bar extends at right angles to the direction of movement of the pawls 13, the pawls 13 are mechanically locked by the locking bar 23 against any yielding movement out of the arresting recesses 6a, and it is not by spring force that the arresting pawls 13 are locked against movement out of the arresting recesses 6a.

However, if an arresting recess 17 is misaligned, the force of the strong spring 32 is available for urging the locking bar 23 into the misaligned locking recess 17 so that the respective pawl 13 and printing wheel 5 are adjusted to the correct positions in which the respective selected and set type of the printing wheel 5 is placed in the correct position for printing. When the locking bar 23 fully engages all locking recesses 17, all printing wheels are in correct printing position, and it is impossible for the platen roller 3 to displace the printing wheels and printing types, particularly due to the fact that the locking bar 23 extends transverse to the direction of movement of the pawls, and that no yielding of the locking bar 23 is possible in the locking position of locking bar 23.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of locking arrangements for manually set printing wheels differing from the types described above.

While the invention has been illustrated and described as embodied in a locking arrangement for a manual printer in which a transverse locking bar locks a plurality of spring biassed arresting pawls when the printing carriage is moved out of an end position, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

Claims

I claim:

1. Locking arrangement for manually set printing wheels, comprising supporting means; carriage means including a platen roller and being supported on said supporting means for movement with said platen roller along a path between two end positions; a set of printing wheel means mounted on said supporting means for independent angular movement about an axis between a plurality of angular printing positions, and having a plurality of types and a plurality of arresting recesses associated with said angular printing positions, respectively; a set of setting means for turning said printing wheel means to selected angular printing positions, respectively, so that an axial row of selected types is located in said path of said platen roller; a set of arresting pawls arranged in an axial row opposite an axial row of arresting recesses, said pawls being movable in a substantially radial direction to and from arresting positions located in said arresting recesses, respectively, and having locking recesses forming an axial row when said pawls are located in said arresting recesses in said arresting positions; arresting spring means for biassing said pawls to said arresting positions so that said pawls resiliently yield when said type wheel means are angularly displaced by said setting means; locking means including a locking bar movable between an inoperative position spaced from said pawls, and a locking position located in said row of locking recesses, said locking bar in said locking position extending in axial direction at right angles to said radial direction so that said pawls are locked in said arresting recesses; and motion transmitting means connecting said carriage means with said locking means and holding said locking bar in said inoperative position when said carriage means is in one of said end positions so that said type wheel means can be set by said setting means, and holding said locking bar in said locking position when said carriage means moves out of said one end position so that said printing wheel means can not be angularly displaced out of selected angular printing positions by said platen roller moving along said path.

2. Locking arrangement as claimed in claim 1 wherein said locking recesses have slanted edges so that when said locking bar enters a misaligned locking recess of a pawl which is not fully in said arresting position due to a wrong angular position of the respective printing wheel means, said locking recess is aligned by said locking bar with the locking recesses of the other pawls whereby the respective pawl is placed in said arresting position for holding said printing wheel means in the respective angular printing position.

3. Locking arrangement as claimed in claim 1 wherein said motion transmitting means include locking spring means for urging said motion transmitting means to hold said locking bar in said locking position, and feeler means biassed by said locking spring means to engage a portion of said carriage means only when said carriage means is in said one end position for holding said locking bar in said inoperative position whereby when said carriage means moves out of said one end position and along said path, said portion releases said feeler means so that said locking spring means causes movement of said locking bar to said locking position.

4. Locking arrangement as claimed in claim 3 wherein said locking bar is moved by said motion transmitting means to said locking position in a direction transverse to said radial direction.

5. Locking arrangement as claimed in claim 3 wherein said carriage means includes a carriage on which said platen roller is mounted for rotation, and wherein said portion of said carriage means is a roller rotatably mounted on said carriage and rolling along said path on said supporting means.

6. Locking arrangement as claimed in claim 5 wherein said supporting means include a printing bed formed with a cutout through which said set of printing wheels partly projects,said cutout being located in said path.

7. Locking arrangement as claimed in claim 3 wherein said motion transmitting means include a bail mounted for angular movement about a bail axis on said supporting means and having two arms located at the ends of said row of pawls, said locking bar being mounted on the ends of said arms; and wherein said feeler means includes a feeler lever mounted on said supporting means for angular movement and being biassed by said locking spring means to engage said carriage portion in said one end position of said carriage means.

8. Locking arrangement as claimed in claim 7 wherein said set of pawls is located in a plane passing through said axis; and wherein said bail axis is parallel to said axis so that said locking bar moves substantially perpendicularly to said plane from said inoperative position to said locking position.

9. Locking arrangement as claimed in claim 1 wherein each printing wheel means includes a printing wheel having circumferentially spaced types, and a gear portion having teeth and said arresting recesses between said teeth.

10. Locking arrangement as claimed in claim 8 wherein said set of setting means includes a set of rack bars meshing with said gear portions of said printing wheels, respectively.