US3769907A

US3769907A - Printing device for selectively printing different groups of figures

Info

Publication number: US3769907A
Application number: US00165045A
Authority: US
Inventors: M Oishi; Y Takahashi; K Yoshizawa
Original assignee: Hattori Tokeiten KK
Current assignee: Hattori Tokeiten KK
Priority date: 1970-07-24
Filing date: 1971-07-23
Publication date: 1973-11-06
Anticipated expiration: 1990-11-06
Also published as: GB1317875A; FR2099574B1; DE2136964A1; FR2099574A1; JPS5139056B1

Abstract

A printing device for electronic computors and the like comprises a printer drive circuit including a first group of printing coils for effecting printing of lower place figures and a second group of printing coils for effecting printing of higher place figures, and a switching mechanism for selectively switching print command signals to one of the first and second printing coil groups. The printing device includes means for selectively performing either a single printing operation with the energization of the lower place figure printing coils or two consecutive printing operations consisting of a first printing operation with the energization of the lower place figure printing coils and a second printing operation with the energization of the higher place figure printing coils by actuating the switching mechanism in accordance with a drive command signal.

Description

United States Patent 1191 Oishi et al. 45 N 6, 1973 [54] PRINTING DEVICE FOR SELECTIVE/LY 3,465,866 9/1969 Gehringet al, 235/619 PRINTING DIFFERENT GROUPS OF 3,461,796 8/1969 Belson et a1. 101/93 C FIGURES 3,467,005 9/1969 Bernard 101/93 C 3,211,087 10/1965 Sapino et al. 101/93 C [75] Inventors: Masaaki Oishi, Tokyo; Yoshinaga Takarlashi, Y Keiichi Primary Examiner-Clyde l. Coughenour Yoshlzawa, Matsud0-sh1,all0f Japan Attorney-Robert E. Burns el al.

[73] Assignee: Kabushiki Kaisha Hattori Tokeiten,

Tokyo, Japan [57] ABSTRACT [22] Filed: July 23, 1971 A printing device for electronic computors and the like I comprises a printer drive circuit including a first group [2]] App! 165045 of printing coils for effecting printing oflower place figures and a second group of printing coils for effecting [30] F i A li ti P i it D t printing of higher place figures, and a switching mecha- J 1 24, 1970 J 45 64461 selectwely swtchmg PmIt command sgnals uy apan I one of the first and second printing coil groups. The. [52] CL 101/93 C 235/6L6 H 235/619 R printing device includes means for selectively perform- 51 1m. (:1 B4lj 5/44 ing either a smgle Priming Operation with energize [58] Field Of Search 101/93 0 235/61 9 tion of the lower p ace fi ure printing COlIS or We con- 235/6l 6L6 K G secutive printing operations consisting of a first printing operation with the energization of the lower place [56] References Cited figure printing coils and a second printing operation with the energization of the higher place figure printing UNITED STATES PATENTS coils by actuating the switching mechanism in accorgills etttal. 235/6L6 K dance i a drive command SignaL anaru 0.. 3,442,206 5/1969 Sugimoto 101/93 C 8 Claims, 8 Drawing Figures uwmeom mm L12 1 L1 Lcj 4 5 7 a 9 11 I10 PRINTING DEVICE FOR SELECTIVELY PRINTING DIFFERENT GROUPS OF FIGURES The present invention relates to printing devices for electronic computers and the like and, more particularly, to a printing device capable of selectively performing a single operation of printing'lower place figures and two consecutive operations of printing on one line lower place figures and higher place figures.

In one well-known printing device for electronic computers andthe like, numeral figures are successively printed in a one by one manner from the lower place figure to the higher place figure. This type of device has the advantage that the number of input terminals for receiving the electric command signals for printing is small. However, in this device, a printing wheel must be rotated once every time one place figure is printed thus requiring a long time to print a number made up of a plurality of figures.

In another type of prior art printing device, a plurality of independently operated print drums are provided. In this device, however, a printing control circuit operable to print all the place figures of a number at 7 one time is comparatively complicated and requires many output terminals.

With the recent development of the LS1 and other techniques, the printer drive control circuits are being made smaller and smaller. Thus, there is an increasing demand to make the circuit as simple as possible and therefore it is desirable to have a few output terminals as possible.

The present invention is intended to provide a printing device having a construction capable of meeting the above requirements.

In accordance with one feature of the present invention, there is provided an improved printing device for electronic computers and the like comprising a printer drive circuit including a first group of printing coils for effecting printing of the lower place figures and a second group of printing coils for effecting printing of the higher place figures, and a switching mechanism for selectively switching print command signals applied to the first and second printing coil groups.

Accordingly, an object of the present invention is to simplify the printer drive circuit construction using LSI and the like by reducing the number of output terminals of the circuit to one-half that of the conventional printer drive circuit operable to print the same number of figure places.

Another object of the present invention is to provide a printing device which uses a lever mechanism for actuating the switching mechanism and which is provided with an escapement mechanism thereby ensuring increased stability of operation.

The above and other objects, features and advantages of the present invention will become more apparent from the following description when read in conjunction with the accompanying drawings, in whichr FIG. 1 is a circuit diagram, partly in block form, showing a printer drive circuit for printing device embodying thepresent invention;

FIGS. 2a and 2b are front views showing a switching mechanism for a printing device embodying the present invention;

FIGS. 3-5 are waveforms illustrating the current flowing in a printer drive coil and the operation of the switching mechanism; and

FIGS. 6a and 6b are front views of a paper feed mechanism for the printing device according to the present invention.

Referring to FIG. 1, there is shown an embodiment of a printer drive circuit A for a l2-figure computer. The drive circuit comprises a microswitch 1 having three

terminals

2, 3, and 10. The terminal 2 is a common terminal and is normally connected to the terminal 3. Six parallel printing coils L, and L, are provided for printing the first to sixth figures and the coils are each connected at one end to the terminal 3 and at the other end through respective diodes to respective output terminals 4 to 9 of a printer drive control circuit B which supplies'print command signals to the various output terminals.

Six other parallel printing coils L and L are provided for printing the seventh to twelfth place figures and these other coils are each connected atone end to the terminal 10, which is not normally connected to the terminal 2, and at the other end through respective diodes to the respective output terminals 4 to 9. Alternatively, the printing coils may be coupled to the output terminals through a change-over switch interlocked to the microswitch l. The printer drive control circuit B also has output terminals 11 and Ila respectively connected to a function coil L, and a clutch coil L The microswitch l in FIG. 1 is shown to be in the usual switching state with the terminal 3 connected by means of a movable contact to the terminal 2. In this switching state, output signals appearing at the output terminals 4 to 9 energize the respective printing coils L to L for effecting printing of the first to sixth place figures. Thus, in this position of the microswitch, it is possible to print the first to sixth place figures of a number. When the microswitch 1 is in the other switching state with the terminal 2 connected to the terminal 10, the output signals appearing at the output terminals 4 to 9 energize the respective printing coils L to L for effecting printing of the seventh to twelfth place figures. Thus, in this position of the microswitch, it is possible to print the seventh to twelfth place figures of a number. i

FIGS. 2a and 2b show a switching mechanism for actuating the microswitch. The state of the switching mechanism shown in FIG. 2a corresponds to the usual state of the microswitch when the terminal 2 is connected to the terminal 3. The switching mechanism comprises a switch push lever 12 rotatable about a pin 13. The lever 12 is urged into a normal position against a stop pin 15 by the spring force of a contact spring 14 of the microswitch 1. A switch push lever holding claw 16 is rotatable about a pin 17 and is pulled in the clockwise direction by a tension spring 18. The holding claw 16 is provided with a hood portion 19 releasably engageable with a top extension 20 of the switch push lever 12. t

A switch change-over lever 21 is secured to a rotatable shaft 22. The shaft 22 is angularly displaced in the direction of the arrowin response to movement of a one-revolution clutch start trigger lever (not shown) when the clutch coil L is energized. The switch change-over lever 21 is continuously urged in a counter-clockwise direction by a tension spring 23 and has a limiting stop position determined by the stop pin 15.

A change-over detecting lever 24 is rotatably supported on a pin 25 extending from the tip of the switch change-over detecting lever 21. The change-over detecting lever 24 has a V-shaped end portion having

opposite faces

26 and 28. The face 26 is engageable with a projection 27 of the switch push lever holding claw 16 and the face 28 is engageable with a change-over claw 29 provided on the switch push lever 12.

A function detecting lever 31 is rotatably supported about a pin 32. It can assume two stable positions determined

b limit stoppers

33 and 34 disposed on opposite sides of the function detecting lever. When the detection coil L, is energized, the lever 31 is pivoted counter-clockwise and assumes a position in contact with the limit stopper 33, as indicated by solid lines in FIG. 2a. A pin 36 is connected to the lever 31 and is dimensioned to undergo movement relative to a guide slot 30 formed in an end portion of the change-over detecting lever 24 remote from the V-shaped end. Thus, pivotal movement of the lever 31 acts through the pin and slot connection to effect pivotal movement of the change-over detecting lever 24. In the state shown in FIG. 2a, the detection coil L, is energized and the function detecting lever 31 assumes a position in contact with the limt stopper 33. In this state, the face 28 of the lever 24 is in engagement with the change-over claw 29.

The operation of the switching mechanism for printing the seventh and higher place figures of a number will now be described with reference to FIG. 3. In FIG. 3, the ordinates represent voltage level and the abscissa represents time. When the microswitch 1 is in the normal switching state as shown in FIG. 2a with the terminal 2 connected to the terminal 3, as soon as a drive command signal PR becomes fON, current flows through the clutch coil I. to rotate the clutch start trigger lever (not shown in the drawings) to effect angular displacement of the shaft 22 in the clockwise direction.

A lead switch pulse P, is set such that it becomes ON" after the clutch shaft has angularly displaced through a predetermined angle before the clutch shaft completes one rotation. In response to the angular displacement of the shaft 22 of the one-revolution clutch start trigger lever, the switch change-over lever 21 is pivoted causing the rightward advancement of the change-over detecting lever 24.

Since at this time no function command signal is supplied to the function coil L;, the function detecting lever 31 remains in its lower position as indicated by broken lines in FIG. 2a. Moreover, since the changeover detecting lever 24 is also in the position shown by broken lines in FIG. 2a, the rightward advancement of the change-over detecting lever 24 merely brings the face 26 thereof into slight contact with the projection 27 of the switch push lever holding claw l6, and the switch push lever 12 remains in the position shown in FIG. 20. Thus, the microswitch 1 also remains in the normal switching state with the terminal 2 connected to the terminal 3.

The clutch coil L is adapted to be energized only when the drive command singal PR is ON" and the lead switch pulse P, is OFF. Thus, after the clutch shaft has rotated through the predetermined angle, the pulse P, becomes ON effecting deenergization of the clutch coil L whereby the switch change-over lever 21 is pulled back to its position in engagement with the stop pin by the tensile force of the tension spring 23. Thereafter, figure print command signals appear at the output terminals 4 to 9 in a predetermined relatively timed relationship and the printing coils L to L for the first to sixth place figures are energized to effect printing of the first to sixth place figures.

Similarly, when the function command signal appears at the output terminal 1 1 in timed correspondence with a symbol to be printed, the function coil L, is energized to effect the printing of the symbol representing the desired function. Subsequently, the lead switch pulse P, becomes OFF to deenergize the printing coils L to L.,. Then, as the clutch completes one revolution, the first printing operation comes to an end.

If the drive command signal is such that the seventh and higher place figures are to be printed, the drive command signal remains ON after the above first printing operation. In this case, since the lead switch goes OFF prior to the completion of one revolution of the clutch, the clutch coil L is energized at that instant. Then, similar to the above first operation, the change-over detecting lever 24 is advanced rightwardly in response to rotation of the shaft 22. At this time, since the drive command signal PR is ON, the function coil L, remains energized and the function detecting lever 31 is in the position indicated by solid lines in FIG. 2a and the change-over detecting lever 24 also remains in the solid line position.

Thus, the rightward advancement of the change-over detecting lever 24 causes the face 28 to engage with and push the change-over claw 29 of the switch push lever 12 to pivot the switch push lever 12 in a clockwise direction so that the contact spring 14 of the microswitch is pushed against its spring force. Once the switch push lever is pivoted in this manner, it can not return to its initial position since its top extension 20 is in releasable engagement with the hook 19 of the switch push lever holding claw 16.

In this switching state of the microswitch, the terminal 2 is connected to the terminal 10. Thus, when subsequent figure print command signals appear at the output terminals 4 to 9, the printing coils L to L corresponding to the seventh to twelfth place figures are energized to effect the printing of the seventh to twelfth place figures.

At the end of the second printing operation, the drive command signal PR becomes OFF to deenergize the function coil L;. At this time, the clutch coil L remains off. Upon deenergization of the function coil L, at the end of the printing operation, the function detecting lever 31 is moved to its lower position to effect counter-clockwise pivotal movement of the chanbe-over detecting lever 24 to the position shown in FIG. 2b. In the above manner, the first to twelfth place figures of a number are printed in two consecutive printing operations.

Now the mode of printing the first to sixth place figures when the switching mechanism is in the switching state shown in FIG. 2b will be described with reference to FIG. 4. Upon the appearance of the drive command signal, the clutch coil L is energized effecting rightward advancement of the change-over detecting lever 24 through the rotation of the shaft 22 in the same manner as described above. With the change-over detecting lever 24 in the position shown in FIG. 2b, the face 26 is in engagement with the projection 27 and the rightward movement of the lever 24 causes the projection 27 to be pushed to effect counter-clockwise pivotal movement of the switch pulse lever holding claw 16 against the spring force of the spring 18.

As a result, the top extension is disengaged from the hook 19 and the switch push lever 12 is pivoted counter-clockwise by the spring force of the contact spring 14 of the microswitch 1 back to its initial position shown in FIG. 2a. Thus the microswitch 1 is switched to its normal state wherein the terminal 2 is connected to the terminal 3. Thus, when subsequent figure print command signals appear at the output terminal 4 to 9, the printing coils L to L for the first to sixth place figures are energized to effect the printing of the first to sixth place figures. Similarly, a symbol of a function is also printed, as mentioned earlier. If the number to be printed is a sixth or lower order number, the drive command signal and function command signal become OFF at the end of the aforesaid first printing operation to deenergize both the clutch coil L,- and the function coil L,, thus completing the printing operation. i

As has been described, although the switching state of the microswitch varies in dependence upon whether the number previously printed was a sixth or lower order number or a seventh or higher order number, upon the appearance of the next drive command signal the microswitch is restored to its normal switching state with the terminal 2 connected to the terminal 3 prior to the commencement of the next printing operating for printing the first to sixth figures.

FIG. 5 shows the case of the so-called fast printing, in which a drive command signal appears immediately before the end of the previous printing operation irrespective of whether the previous printing operation is the first printing operation or the second of the two consecutive printing operations. Upon the appearance of the drive command signal PR immediately before the end of the previous operation, at which time the lead switch pulse P, is OFF, the clutch coil L is energized.

At this time, the function coil L, has already been deenergized and the function detecting lever 31 is assuming its lower position. Thus, the

terminals

2 and 3 are connected together in the same manner as above irrespective of whether the previousoperation was the first .printing operation or the second of the two consecutive printing operations and the printing of the first to sixth figures will follow. i

According to the present invention, a safety means including an escapement mechanism is provided to prevent damage to the change-over claw 29 in case a function command signal prematurelyappears. If a function .cpmmand signal appears before the change-over detecting lever 24 is sufficiently returned leftward by the spring force of the spring 23 (accompanied by counterclockwise pivotal movement of the function detecting lever 31 to effect pivotal movement of the change-over detecting lever 24 in the clockwise direction) it is likely that the change-over claw 29 will be detrimentally struck by the face 28 disposed at the end of the changeover detecting lever 24 resulting in possible damage to the change-over claw 29.

Accordingly, the change-over claw 29 is rotatably mounted on the switch push lever 12 and biased into a normal position by means of a tension spring 37. Thus, in the event the face portion 28 strikes the change-over claw 29, the change-over claw 29 will rotate downwardly against the spring force of the spring 37 until after the leftward retreatment of the change-over detecting lever 24 afterwhich it will be returned to its nor mal position by the spring 37. With this arrangement, possible damage to the change-over claw 29 can be prevented.

In the printing device according to the present invention, the seventh and higher place figures are printed in the second printing operation. Accordingly, a paper feed mechanism is provided which will not feed the printing paper sheet at the end of the first one of the two consecutive printing operations.

FIGS. 6a and 6b show one embodiment of the paper feed mechanism. The paper feed mechanism comprises a feed cam 39 secured to a clutch. shaft 40. A cam follower roller 41 is rotatably mounted on a feed transmission lever 42 for rolling camming movement over the cam face of the cam 39. The feed transmission lever 42 is formed with a guide slot 44 through which a guide pin 43 extends, the guide pin being connected to a support plate.

The feed transmission lever 42 is pulled in the rightward direction by a tension spring 45. The end of the lever 42 remote from the guide slot 43 is pivotally linked to a feed lever 47 rotatable about a support pin 46. The end of the feed lever 47 remote from the support pin 46 is pivotally linked to another feed lever 48 provided with a feed pin 49.

a A paper feed roller 50 is provided to feed the paper sheet P. The roller 50is mounted on a shaft 51 which also carries a ratched wheel 52 secured thereto. A rotatably supported click lever 53 is disposed adjacent the ratched 52 and is provided with a claw 54. The claw 54 and the feed pin 49 selectively engage with the ratched wheel 52. A coil spring 55 is stretched between the click lever 53 and the feed lever 48 biasing the feed pin 49 and the claw 54 into engagement with the ratched wheel 52. Pivoted to an intermediate portion of the feed lever 47 is a feed stop lever 56. A spring 58 urges the feed stop lever 56 downwardly and the lever 56 is provided with a claw 57 engageable with a projection 38 of the aforesaid function detecting lever 31.

The operation of the paper fee-d mechanism of the above construction will now be described. The paper feed mechanism is actuated upon completion of the printing operation. In .either of I the cases shown in FIGS. 3, 4 or 5, at the end of the printing operation the function coil L, is off and the function detecting lever 31 is assuming its lower position. Upon the appearance of a drive command signal, the cam 39 is rotated in the direction of the arrow together with the clutch shaft 40.

While the roller moves toward the left by rolling over the profiled cam face from the valley portion to the hill portion against the force of the spring 45, the feed pin 49 effectively clears a claw or tooth of the ratchet wheel 52 and engages with the next claw. The reverse rotation of the' ratchet wheel 52 is prevented by the locking action of the claw S4 of the click lever.

The aforesaid switching action and subsequent printing operation take place during one rotation of the cam 39. As soon as the roller 41 reaches the hill top of the cam face at the end of one rotation of the cam 39, it momentarily rolls down the hill top due to the action of the spring force of the spring 45. As a result, the feed pin 49 is moved rightwards while in engagement with a claw of the ratchet 52 thereby rotating the ratchet wheel 52 in the direction of the arrow an amount corresponding to one claw whereupon the click claw 54 comes into engagement with the next claw.

During this time, the function detecting lever 31 remains in the lower position as shown in FIG. 6a, so that the projection 38, which also remains in the lower position, can not engage with the claw 57 of the feed stop lever 56. Thus, the feed lever 47 can pivot according to the displacement of the roller 41 in the above manner causing the feed pin 49 to feed the ratchet 52.

On the other hand, at the end of the first one of the two consecutive printing operation, such as at the intermediate line in FIG. 3, the function coil L; is ON and the function detecting lever 31 is assuming its upper position as shown in FIG. 6b. Thus, though the cam follower roller is displaced leftwards in response to rotation of the cam 39 to cause the counter-clockwise pivotal movement of the feed lever 47, the subsequent falling of the roller 41 off the hill top of the cam face will not effect clockwise movement of the feed lever 47 since the projection 57 of the lever 47 is engaged with the projection 38 of the function detecting lever 31.

Consequently, the pin 49 is stopped at the solid line position shown in FIG. 6b and is prevented from undergoing further righward movement. Thus, the ratched 52 and the paper sheet P are not fed or advanced, and the second printing operation takes place with the same position of the printing paper as in the first printing operation. In the above manner, in spite of having two consecutive printing operations, the seventh and higher place figures are printed on the same line as the sixth and lower place figures.

We claim:

I. A printing device comprising: a printer drive circuit including a first group of printing coils energizable to effect printing of lower place figures and a second group of printing coils energizable to effect printing of a group of higher place figures; means receptive of print command signals during use of the printing device for applying the print command signals to said printer drive circuit to effect energization of said printing coils; and switching means for selectively switching the print command signals to one of said first and second groups of printing coils, said switching means comprising a switch operable in one switching mode to switch print command signals to said first group of printing coils and operable in another switching mode to switch print command signals to said second group of printing coils and including means for biasing same into said one switching mode, a pivotally mounted switch push lever pivotal between a first position and a second position wherein same shifts said switch into said another switching mode, a pivotally mounted holding lever engageable with said switch push lever to releasably hold same in said first position, and means for sequentially effecting pivotal movement of said holding lever out of holding engagement with said switch push lever and pivotal movement of said switch push lever to said second position to shift said switch into said another switching mode.

2. A printing device according to claim 1; wherein said last-mentioned means comprises a movable change-over detecting lever having an end portion alternatively engageable with said holding lever and said switch push lever, a pivotally mounted function detecting lever connected to said change-over detecting lever and pivotal between two limit positions to effect movement of said change-over detecting lever to two actuating positions, and a pivotally mounted switch changeover lever connected to said change-over detecting lever pivotal in one direction to alternatively effect (a) corresponding pivotal movement of said change-over detecting lever and engagement of said end portion with said holding lever without effecting pivotal movement thereof when said change-over detecting lever is in one of said two actuating positions and (b) corresponding pivotal movement of said change-over lever and successive engagement of said end portion with said holding lever to effect pivotal movement thereof followed by engagement of said end portion with said switch push lever to effect pivotal movement thereof to said second position when said change-over detecting lever is in the other of said two actuating positions.

3. A printing device according to claim 2; wherein said switch push lever includes a change-over claw pivotally mounted thereon engageable with said holding lever, and spring means biasing said change-over claw into position on said switch push lever with a force sufficient to permit pivotal movement of said change-over claw when same is engaged by said hold lever thereby preventing damage to said switch push lever.

4. A printing device according to claim 2; including a pin and slot connection connecting together said function detecting lever and said change-over detecting lever.

5. A printing device according to claim 2; further including feeding means for selectively feeding a printing sheet upon which said groups of figures are printed only when said change-over detecting lever is in said one of said two actuating positions.

6. A printing device according to claim 5; wherein said feeding means comprises means for feeding a printing sheet along a path of travel including a ratchet wheel and a movable pin releasably engageable with said ratchet wheel to effect stepwise feeding of said printing sheet, a linkage system interconnecting said pin with said function detecting lever, and cam means for effecting movement of said linkage system and movement of said pin to stepwise feed said printing sheet. I

7. A printing device according to claim 6; including a feed stop lever connected to said linkage system engageable with said function detecting lever to render said cam means ineffective to stepwise feed said printing sheet whenever said function detecting lever is in its limit position corresponding to said change-over depreventing damage to said switch push lever.

Claims

1. A printing device comprising: a printer drive circuit including a first group of printing coils energizable to effect printing of lower place figures and a second group of printing coils energizable to effect printing of a group of higher place figures; means receptive of print command signals during use of the printing device for applying the print command signals to said printer drive circuit to effect energization of said printing coils; and switching means for selectively switching the print command signals to one of said first and second groups of printing coils, said switching means comprising a switch operable in one switching mode to switch print command signals to said first group of printing coils and operable in another switching mode to switch print command signals to said second group of printing coils and including means for biasing same into said one switching mode, a pivotally mounted switch push lever pivotal between a first position and a second position wherein same shifts said switch into said another switching mode, a pivotally mounted holding lever engageable with said switch push lever to releasably hold same in said first position, and means for sequentially effecting pivotal movement of said holding lever out of holding engagement with said switch push lever and pivotal movement of said switch push lever to said second position to shift said switch into said another switching mode.

2. A printing device according to claim 1; wherein said last-mentioned means comprises a movable change-over detecting lever having an end portion alternatively engageable with said holding lever and said switch push lever, a pivotally mounted function detecting lever connected to said change-over detecting lever and pivotal between two limit positions to effect movement of said change-over detecting lever to two actuating positions, and a pivotally mounted switch change-over lever connected to said change-over detecting lever pivotal in one direction to alternatively effect (a) corresponding pivotal movement of said change-over detecting lever and engagement of said end portion with said holding lever without effecting pivotal movement thereof when said change-over detecting lever is in one of said two actuating positions and (b) corresponding pivotal movement of said change-over lever and successive engagement of said end portion with said holding lever to effect pivotal movement thereof followed by engagement of said end portion with said switch push lever to effect pivotal movement thereof to said second position when said change-over detecting lever is in the other of said two actuating positions.

6. A printing device according to claim 5; wherein said feeding means comprises means for feeding a printing sheet along a path of travel including a ratchet wheel and a movable pin releasably engageable with said ratchet wheel to effect stepwise feeding of said printing sheet, a linkage system interconnecting said pin with said function detecting lever, and cam means for effecting movement of said linkage system and movement of said pin to stepwise feed said printing sheet.

7. A printing device according to claim 6; including a feed stop lever connected to said linkage system engageable with said function detecting lever to render said cam means ineffective to stepwise feed said printing sheet whenever said function detecting lever is in its limit position corresponding to said change-over detecting lever being in said other of said two actuating positions.

8. A printing device according to claim 5; wherein said switch push lever includes a change-over claw pivotally mounted thereon engageable with said holding lever, and spring means biasing said change-over claw into position on said switch push lever with a force sufficient to permit pivotal movement of said change-over claw when same is engaged by said hold lever thereby preventing damage to said switch push lever.