US3283873A

US3283873A - Electronic shift and shift lock device

Info

Publication number: US3283873A
Application number: US453990A
Authority: US
Inventors: William K Robinson
Original assignee: Sperry Rand Corp
Current assignee: Sperry Corp
Priority date: 1965-05-07
Filing date: 1965-05-07
Publication date: 1966-11-08
Anticipated expiration: 1983-11-08

Description

Nov. 8, 1966 w K. ROBINSON ELECTRONIC SHIFT AND SHIFT LOCK DEVICE P iled May 7, 1965 TO ENCODER INVENTOR WILL/AM K. ROB/NSO/V BY 5 A ATTORNEY United States PatentOfifice 3,283,873 Patented Nov. 8, 1966 3,283,873 ELECTRONIC SHIFT AND SHIFT LOCK DEVICE William K. Robinson, St. Paul, Minn., assignor to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Filed May 7, 1965, Ser. No. 453,990 3 Claims. (Cl. 197-71) This invention relates to the electronic typewriter keyooard and in particular to an electronic circuit for the shift and shift lock keys which are used to cause upper case characters to be printed.

The conventional mechanical typewriter keyboard has oeen generally replaced by electromechanical keyboards. Further, in many systems such as alphanumeric display systems, telegraph, teletype and computer systems, electromechanical keyboards are used. These electromechanical keyboards do not type out characters as does the conventional typewriter but instead cause an encoder to set up an electrical code that is then sent to the printer which types the character. Thus, when a key is depressed by an operator, the electrical code is produced for that key and is sent to a printer which types the character represented by that key.

. The prior art has made little or no provision for an electronic shift and shift lock key. For example Patent Number 3,129,418 which discloses an electronic key board makes no provisions whatsoever for an electronic shift or shift lock key. In Patent Number 3,104,388 provisions are made for obtaining capital and lower case letters but these provisions include a light source, apertured discs, a plurality of photo cells and so forth. In other systems, mechanical linkage is used to hold the shift lock key down.

- The circuit of the present invention eliminates the need for mechanical linkage as well as apertured discs, light sources and so forth and provides a simple electrical circuit which will produce a code representing an upper case character whenever a shift key is depressed and, when the shift lock key is momentarily depressed, will produce a code representing upper case characters until such time as the shift key is momentarily depressed. This operation is similar to that performed on the standard typewriter keyboard.

The present invention includes a relay having three coils which cause a single-pole double-throw switch to assume either one of its two positions to produce a coded output signal representing either an upper case or a lower case character. A first one of the coils is normally energized thus holding the single-pole double-throw switch in a first one of its positions to represent a lower case character. Whenever either of the right or left shift keys is depressed, a second one of the coils is energized which cause the switch to move from its first position to its second position thus providing an output signal representing an upper case character. The second coil remains energized only so long as either the right or left shift keys is depressed. Whenever one of the shift keys is depressed; not only is the second coil energized but the first coil is deenergized. This enables the single-pole switch to move from its first position to its second position. When the shift key is released, the voltage is removed from the second coil and re-applied to the first coil which causes the single pole switch to return to its original position representing a lower case character.

Whenever the shift lock key is depressed, a second relay is energized which closes a first contact that locks the second relay in its energized position. The second relay also opens a second contact which removes the potential from the first coil in the first relay. Further it applies a potential to the third coil in the first relay thus causing the single pole switch to move from its first position representing a lower case character to its second position which represents the upper case character. Whenever either of the two shift keys are momentarily depressed, the energizing circuit to the second relay is momentarily broken thus causing the holding circuit of the second relay to be lost and, when the shift key is released, the normally closed contact on the second relay again applies a potential to the first coil of the first relay thus causing the switch to be returned to its first position which represents a lower case character.

Thus it is an object of the present invention to provide an electronic shift circuit for an electronic keyboard which produces encoded signals representing lower case characters.

It is another object of the present invention to provide an electronic shift lock circuit for an electronic typewriter keyboard in which, when the shift locked key is depressed, an encoded signal representing upper case characters is produced.

These and other more detailed and specific objects will be disclosed in the course of the following specification, reference .being had to the accompanying drawings, in which FIG. 1 is a representative view of a typewriter key attached to a microswitch having three electrical contacts and,

FIG. 2 discloses the electrical circuitry forming the novel shift and shift lock circuit which produces encoded signals representing upper case and lower case characters.

FIG. 1 shows a standard typewriter key 2 mechanically attached to microswitch 4 which includes switching circuit 1 having electrical contacts or

terminals

6, 8, and 10 attached thereto. Battery 5 is coupled between ground and contact 6. Contact 6 of microswitch 4 is normally coupled to contact 10 and no coupling normally exists between contact 6 and contact 8. However, when key 2 is depressed, the circuit connecting contact 6 and contact 10 opens and the open circuit between

contact

6 and 8 closes.

As will be seen in FIG. 2, signal generator 12 is a relay, K1, and includes single-pole double-throw switch 14 and

contacts

16 and 18 with which switch 14 is associated. Signal generator 12 also includes three

coils

20, 22, and 24. When coil 20 is energized, switch 14 is forced to contact 16. When either of coils 22 or 24 is energized, switch 14 is forced to contact 18.

The right switching circuit 4a, the left switching circuit 4b and the shift lock switching circuit 40 as shown in FIG. 2 represent the base of microswitch 4 shown in FIG. 1 with its

associated contacts

6, 8, and 10. Remembering that when the key is not depressed, contact 6 is electrically connected to contact 10, it will be seen that when a voltage or potential is applied to contract 6 of the right switching circuit 4a, this potential is coupled to contact 10 of circuit 4a to which is coupled conductor 26. Conductor 26 couples the voltage from contact 10 of the right switching circuit 4a to contact 6 of the left switching circuit 4b. Again, the contact 6 of the left switching circuit 4b is electrically connected to contact 10 of circuit 4b. Thus the voltage at contact 6 of the left switching circuit 41) is transferred to contact 10 of circuit 4b and there via conductor 28 is, coupled to contact 6 of the shift lock switching circuit 40. The voltage at contact 6 of the shift lock switching circuit 40 is coupled via line 30 to the junction of normally open contact 32 and normally closed contact 34 of relay 36, K2. Since contact 34 is normally closed, the potential at the junction of contacts 32 and 34 is connected to coil 20 of relay 12, K1. Since the other end of coil 20 is coupled to a ground potential through resistor 40, it will be understood that coil 20 is normally energized and, thus, forces switch 14 against contact 16. Therefore, the closed circuit between

conductors

42 and 44, which are connected to the encoder, is a code which represents a lower case character.

When it is desired to cause a capital or upper case character to be printed, either the right shift key or the left shift key may be depressed. Conductor 48 interconnects contact 8 of both the right switching circuit 4a and the left switching circuit 4b. When either the right shift key or the left shift key is depressed, the potential on contact 6 of the associated

switching circuit

4a or 4b is coupled to conductor 48 and the potential is removed from contact 10 of the switching circuit associated with the shift key which is depressed. Conductor 50 which is coupled to coil 22 in signal generator 12 through diode 52, is also connected to contact 8 of switching circuit 4b. Thus, when either the right shift key or the left shift key is depressed, the potential which is then coupled to line 48 is also present on line 50 which passes through diode 52 to energize coil 22 of relay 12. Also it will be seen that when either of the shift keys is depressed, the potential is removed from contact 10 of switching circuit 4b thus re moving the potential from

lines

28 and 30 which are coupled through normally closed contact 34 of relay 36 to coil of relay 12. Thus, coil 20 is de-energized while coil 22 is energized. The result is to cause switch 14 to be forced from contact 16 to contact 18. This causes a closed circuit or code to appear between

conductors

42 and 46, which are coupled to the encoder, and which represents an upper case or capital character. The encoder forms no part of the present invention and will not be discussed. It will also be seen that when the depressed shift key is released, the potential is removed from

lines

48 and 50 which de-energizes coil 22 in relay 12 while the potential is re-established on conductors 28 and which re-energizes coil 20. Thus, switch 14 is forced from contact 18 to contact 16 which once more presents a closed circuit on

lines

42 and 44 which represent to the encoder a lower case character.

When a series of capital or upper case characters are to be printed, the shift lock key is depressed momentarily. This causes the potential on contact 6 of switching circuit 40 to be connected to pin 8 of switching circuit 40 to which conductor 54 is connected. The potential on contact 8 of the circuit 4c energizes coil of relay 36, K2, through conductor 54. When relay 36 is energized, it closes normally open contact 32 and opens normally closed contact 34. When normally open contact 32 is closed, the potential on contact 6 of circuit is coupled via conductor 30 and normally open contact 32 (which is now closed) to relay 36 which forms a holding circuit for relay 36 and keeps it energized. After the depressed shift lock key is released, the potential from contact 6 of switching circuit 40 is coupled to contact 8 via conductor 30, contact 32 and conductor 54. Conductor 56 which is also coupled to contact 8 of switching circuit 40 is connected to one end of coil 24 in signal generator 12 through diode 58. Since the other end of coil 24 is connected to a ground source through resistor 40, coil 24 is energized. It will also be seen that since relay 36, K2, is energized and normally closed, contact 34 is now opened, the voltage will be removed from coil 20 thus causing it to be de-energized. Since coil 24 is energized and coil 20 is de-energized, switch 14 is forced from contact 16 to contact 18 thus causing a closed circuit on

lines

42 and 46 to be connected to the encoder to represent a capital or upper case character.

Output leads 42 and 46 will then continue to produce signals to the encoder representative of upper case or capital characters until such time as either the right shift key or the left shift key is momentarily depressed. When either of these keys is momentarily depressed, the voltage is removed from normally closed contact 10 of switching circuit 4b which removes voltage from conductor 28. It is the voltage on line 28 that is coupled through line 30 and contact 32 which holds relay 36 energized. Therefore, when the voltage at contact 10 of switching circuit 4b is removed the holding circuit for relay 36 is broken and relay 36 becomes de-energized. When this happens, contact 34 of relay 36 is again closed thus coupling coil 20 to contact 6 of switching circuit 40. When the momentarily depressed shift key is then released, the voltage is coupled once again to pin 10 of the switching circuit 40 and is coupled from there via

lines

28 and 30 and contact 34 to coil 20 which energizes thus causing switch 14 to be forced from contact 18 back to contact 16. Once again then the closed circuit on

output conductors

42 and 44 to the encoder represents lower case characters.

Thus, the keyboard electronic shift and shift lock circuit comprises first and second shift keys and a shift lock key each movable between first and second positions, a signal generator 12 for producing a first electrical code on conductors 42, 44 representing lower case characters and a second electrical code on conductors 42, 46 representing upper case characters, said signal generator 12 comprising a first relay having a conducting arm 14 movably associated with a pair of electrical contacts 16, 18, and a plurality of operating coils 20, 22 and 24 for moving said arm from one of said contacts to the other, an electrical switching circuit 4a, 4b coupled to said first and second shift keys respectively for producing a first signal on terminal 10 thereof only when both of said keys are in said first position and a second signal on contact 8 thereof only when either of said keys is in said second position, each of said switching circuits 4a, 4b comprising a single-pole double-throw switch operatively associated with each of said shift keys and having an input terminal 6 and two output terminals 8, 10 whereby a first one 10 of said output terminals is coupled to said input terminal 6 when said associated key is in said first position and the second one 8 of said output terminals is coupled to said input terminal 6 when said associated key is in said second position, means 26 coupling said first output terminal 10 of said switching circuit 4a associated with said first key to the input terminal 6 of said switching circuit 4b associated with said second key to produce said first signal on said first output terminal 10 of said switching circuit 4b associated with said second key, means 48 coupling said second output terminals 8 of said switching circuits 4a, 4!) together to produce said second signal on conductor 50 and a voltage source 5 connected to the input terminal 6 of said switching circuit 4a associated with said first key for selectively energizing the coils 20, 22, 24 of said relay 12 depending upon the position of the shift keys, a second relay 36 having an energizing coil 35, a first pair of normally open contacts 32 which close to form a relay holding circuit when said second relay 36 is energized and a second pair of normally closed contacts 34 which open when said relay 36 is energized, means 28, 30, 38 coupling said first signal to coil 20 of said signal generator 12 through said normally closed pair of con tacts 34 for causing said signal generator 12 to produce said first code on conductors 42, 44, means 50 coupling said second signal to coil 22 of said signal generator 12 for causing said signal generator to produce said second code on conductors 42, 46, a normally open switch in switching circuit 40 operatively associated with said shift lock key, said switch being closed when said shift lock key is in said second position, means 28, 54 coupling said first signal to said energizing coil 35 through said switch in switching circuit 40 whereby said first signal energizes relay 36 whenever said shift lock key is in said second position, means 30, 54 coupling said first signal to said energizing coil 35 of relay 36 through said normally open contacts 32 to form a locking circuit when-- ever relay 36 is energized, said locking circuit holding said relay 36 energized until either of said shift keys is momentarily placed in said second position to interrupt said first signal on line 28, and means 56 coupling 3,283,873 6 the energizing coil 35 of relay 36 to coil 24 of said sigwherein said relay is a first relay and said signal gennal generator for causing said signal generator to produce erator comprises: said second code on conductors 42, 46 as long as said (a) a second relay having relay 36 is energized. (1) a conducting arm movably associated with a Thus it will be seen that a very simple yet effective 5 pair of electrical contacts, and electronic shift and shift lock circuit is disclosed by the (2) a plurality of operating coils for moving said present invention which avoids the use of open blade arm from one of said contacts to the other, switches which are actuated by levers attached to keys, (b) means for coupling said first signal to one of said which need frequent adjustment and which allow paper, coils for causing said arm to engage a first one of dust and dirt to collect on the contacts. said contacts to produce said first code,

It is understood that suitable modifications may be (0) means for coupling said second signal to a second made in the structure as disclosed provided such modione of said coils for causing said arm to engage the fications come within the spirit and scope of the appended second one of said contacts to produce said second claims. Having now, therefore, fully illustrated and decode, and scribed my invention, what I claim to be new and desire ((1) means for coupling said energizing coil of said to protect by Letters Patent is: first relay to a third one of said coils for causing 1. A keyboard electronic shift and shift lock circuit said arm to engage the second one of said contacts comprising: to produce said second code as long as said first relay (a) first and second shift keys and a shift lock key each movable between first and second positions, (b) a signal generator for producing a first electrical code representing lower case characters and a second electrical code representing upper case characters,

(c) an electrical switching circuit coupled to said first and second shift keys for producing a first signal only when both of said keys are in said first position and a second signal only when either of said keys is in said second position,

(d) a relay having an energizing coil, a first pair of normally open contacts which close to form a relay holding circuit when said relay is energized and a second pair of normally closed contacts which open when said relay is energized,

(e) means coupling said first signal to said signal generator through said normally closed pair of contacts for causing said signal generator to produce said first code,

(f) means coupling said second signal to said signal generator for causing said signal generator to produce said second code,

(g) a normally open electrical switch operatively associated with said shift lock key, said switch being closed when said shift lock key is in said second position,

(h) means coupling said first signal to said relay energizing coil through said switch whereby said first is energized. 3. A keyboard shift and shift lock circuit as in claim 2 wherein said electrical switching circuit comprises:

(a) a single-pole double-throw switch operatively associated with each of said shift keys and having an input and two output terminals whereby a first one of said output terminals is coupled to said input terminal when said associated key is in said first position and the second one of said output terminals is coupled to said input terminal when said associated key is in said second position,

(b) means coupling said first output terminal of said switch associated with said first key to the input terminal of said switch associated with said second key to produce said first signal on said first output terminal of said switch associated with said second y,

(c) means coupling said second output terminals of saiccll switches together to produce said second signal, an

(d) a voltage source connected to the input terminal of said switch associated'with said first shift key for selectively energizing the coils of said first and second relays depending upon the position of the shift keys and the shift lock keys.

References Cited by the Examiner UNITED STATES PATENTS 1,976,352 10/1934 Maul 234-96 signal energizes sa1d relay whenever said shift lock 2,739,649 3/1956 Hamel et 1 34 9 X y 18 111 sa1d s d P P 2,902,092 9/1959 Hildebrandt 234-23 (1) means coupling said first signal to sa1d energizing 2,928 467 3/1960 Lindberg 234 9 X coil of said relay through said normally open con- 3 017,463 1/1962 Dinsmore-ezzl 34Q 365 X tacts to form a locking circuit whenever said relay 3,021,993 2/1962 Brewer u" 34 23 X is energized, said locking circuit holding said relay 3 104 388 9/1963 Balenger 340 345 energized until either of said shift keys is momen- 3,129,413 4 /1964 De La 1 34 345 tarily placed in said second position to interrupt said 1 1 5 11/1964 11 u fi slgfial, Q 3,194,493 7/1965 Brewer 234-124 X (1) means coupling the energ1zing coil of sa1d relay to 3,212,702 10 1 5 J h t 234 124 said signal generator for causing said signal gen erator to produce said second code as long as said relay is energized.

2. A keyboard shift and shift lock circuit as in claim 1 ROBERT E. PULFREY, Primary Examiner.

E. S. BURR, Assistant Examiner.

Claims

1. A KEYBOARD ELECTRONIC SHIFT AND SHIFT LOCK CIRCUIT COMPRISING: (A) FIRST AND SECOND SHIFT KEYS AND A SHIFT LOCK KEY EACH MOVABLE BETWEEN FIRST AND SECOND POSITIONS, (B) A SIGNAL GENERATOR FOR PRODUCING A FIRST ELECTRICAL CODE REPRESENETING LOWER CASE CHARACTERS AND A SECONE ELECTRICAL CODE REPRESENTING UPPER CASE CHARACTERS, (C) AN ELECTRICAL SWITCHING CIRCUIT COUPLED TO SAID FIRST AND SECOND SHIFT KEYS FOR PRODUCING A FIRST SIGNAL ONLY WHEN BOTH OF SAID KEYS ARE IN SAID FIRST POSITION AND A SECOND SIGNAL ONLY WHEN EITHER OF SAID KEYS IS IN SAID SECOND POSITION, (D) A RELAY HAVING AN ENERGIZING COIL, A FIRST PAIR OF NORMALLY OPEN CONTACTS WHICH CLOSE TO FORM A RELAY HOLDING CIRCUIT WHEN SAID RELAY IS ENERGIZED AND A SECOND PAIR OF NORMALLY CLOSED CONTACTS WHICH OPEN WHEN SAID RELAY IS ENERGIZED, (E) MEANS COUPLING SAID FIRST SIGNAL TO SAID SIGNAL GENERATOR THROUGH SAID NORMALLY CLOSED PAIR OF CONTACTS FOR CAUSING SAID SIGNAL GENERATOR TO PRODUCE SAID FIRST CODE, (F) MEANS COUPLING SAID SECOND SIGNAL TO SAID SIGNAL GENERATOR FOR CAUSING SAID SIGNAL GENERATOR TO PRODUCE SAID SECOND CODE, (G) A NORMALLY OPEN ELECTRICAL SWITCH OPERATIVELY ASSOCIATED WITH SAID SHIFT LOCK KEY, SAID SWITCH BEING CLOSED WHEN SAID SHIFT LOCK KEY IS IN SAID SECOND POSITION, (H) MEANS COUPLING SAID FIRST SIGNAL TO SAID RELAY ENERGIZING COIL THROUGH SAID SWITCH WHEREBY SAID FIRST SIGNAL ENERGIZES SAID RELAY WHENEVER SAID SHIFT LOCK KEY IS IN SAID SECOND POSITION, (I) MEANS COUPLING SAID FIRST SIGNAL TO SAID ENERGIZING COIL OF SAID RELAY THROUGH SAID NORMALLY OPEN CONTACTS TO FORM A LOCKING CIRCUIT WHENEVER SAID RELAY IS ENERGIZED, SAID LOCKING CIRCUIT HOLDING SAID RELAY ENERGIZED UNTIL EITHER OF SAID SHIFT KEYS IN MOMENTARILY PLACED IN SAID SECOND POSITION TO INTERRUPT SAID FIRST SIGNAL, AND (J) MEANS COUPLING THE ENERGIZATING COIL OF SAID RELAY TO SAID SIGNAL GENERATOR FOR CAUSING SAID SIGNAL GENERATOR TO PRODUCE SAID SECOND CODE AS LONG AS SAID RELAY IS ENERGIZED.