JPS6013834B2 - erasing typewriter - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an automatic erasing typewriter, that is, a character typed by a typist by mistake during typing is automatically erased by a simple operation, and a desired correct character is replaced therewith. It concerns a typewriter for typing.

[Prior art]

Reference is made to U.S. Pat. No. 3,724,633 and U.S. Pat.

The first US patent discloses a typewriter with the ability to effectively erase individual characters. A second U.S. patent discloses a self-erasing typewriter that erases characters based on character signals stored in a line memory. Two published patent publications also disclose erasing typewriters in which an erasing function can proceed between tabs and erase the underline of an underlined character. As with the above-mentioned U.S. Pat. No. 3,780,846, an automatic erasing mechanism that does not require the typist to press the key corresponding to the character to be erased can be erased by a line memo IJ linked to the electronic control circuit of the typewriter. contains the code representing the character.

If the memory location in its line memory that corresponds to the print point at which the carriage is positioned does not contain an erasable character, the typewriter will go far into erasure mode, and you will need to Operation is required. If that memory location contains a code indicating a space function, a backsbase is performed in response to the first erase key press, followed by a second backsbase, and its correspondence in line memory is If an erasable character is found at the specified position, it will be erased. The first US patent mentioned above teaches a manual erasing technique that improves keystroke efficiency over its predecessors.

This improvement required that the typist press a correction key to perform the following actions: First, a backs-base is performed to associate the print point and type carrier with the character to be erased, and then when the type carrier strikes the paper with the next keystroke, a special printing ribbon is used instead of the normal printing ribbon. Ensure that the erase ribbon is inserted between the type carrier and the paper. Therefore, if the typist presses the same key as the one that was erroneously pressed, the imprint of that key will be undone or erased from the paper. The typist can then press a desired key to change the erased character to the desired character. In self-erasing typewriters, such as the one disclosed in U.S. Pat. No. 3,780,846, the code for the characters typed is
A character can only be automatically erased if it is held in memory at a position corresponding to a print point.

When the carriage is indexed to a new line (carriage return is performed), the line memory is cleared and the automatic erase mechanism is no longer available for the previous line. [Summary of the Invention] The present invention improves the operation of an automatic erasing typewriter when the character to be erased is not included in the line memory, and provides an erasing function with minimal burden on the typist. It is intended to enable implementation.

According to the present invention, the typist uses the same operation regardless of whether the character to be erased is held in line memory or not. More specifically, according to the present invention, when the operator presses the erase key, an automatic erase operation is initiated. The characters typed in a deliberate manner are lines.
If contained in memory, it is automatically erased as taught by the second US patent mentioned above. However, if the accidentally typed character is not contained in the line memory, a signal is generated to enable manual erasure as disclosed in the first U.S. patent mentioned above. Ru. Therefore, even if the accidentally typed character is not found in the line memory after pressing the erase key, the typist only needs to type the accidentally typed character. Use of the self-erasing typewriter of the present invention also improves the performance of the typewriter in other ways.

The self-erasing typewriter described in U.S. Pat.
When a functional character is found, a second backs-base is automatically performed to search for erasable characters. In other words, if a typist wants to erase a ``space J,'' he must either erase up to the character before that ``space'' and then resume typing from that position, or he can use the backsbase key instead of the erase key. is necessary. According to the invention, when the erase key is operated, the typewriter finds a "space" in the line memory location in question;
Just doing a backsbase puts me in manual erase mode. Activating the space bar takes the typewriter out of manual erase mode without escaping, allowing you to type the desired character, and then continue typing to erase the "space". In other words, pressing the erase key displaces the print point backward by one character, causing a so-called backs base.

The movement of the printing point produces two effects. Firstly, the type carrier shell 0 printing means is displaced correspondingly to the movement of the printing point, and secondly the line memory location to be addressed is also correspondingly displaced. If the line memory contains a code for an erasable character in the memory location corresponding to the print point, then erasing media is available and a print cycle is initiated and an automatic erasing function is performed. However, in any case where the line memory contains the code for such a character, the typewriter's print cycle is prohibited and
Instead, the manual erase mode is entered, so the next time you press the key corresponding to an erasable character, the erasing medium becomes ready for use, the printing cycle begins, erasing is performed, and the escapement of the printing means is activated. It is forbidden. and,
Erase mode is canceled. If the typist presses a key other than an erasable character, the auto-erase procedure will be restarted if the key is the erase key, or erase mode will only be canceled if the key is the space bar. Embodiment FIGS. 1 and 2 show a typewriter 10 controlled by an electronic circuit.

The signals generated by the keyboard are processed electronically and the controller commands the printer to perform the appropriate functions of each element of the printer, such as positive feed for printing, character spacing, etc. escaping) to perform backs-base, tab, correction, and other normal printer functions. When the key lever 12 on the keyboard 14 is pressed to select characters for printing, the keyboard 1
4 actuates each switch associated with the key lever and transmits the resulting signal to the keyboard controller 16. That is, the keyboard controller 16 is supplied with code signals from veil codes BI-B7 representing operated key levers and generates appropriate strobe or control signals. The control signals transmit the data signals to character and speed decoding logic 18. There, the letters
Speed decoding logic 18 converts signals from keyboard controller 16 into signals representing the position of a character on the type element. That is, signals from the keyboard controller are applied to a magnet driver 20 which causes the rotation and tilting of the type element 11 to position the desired type on the type element 11 at the printing point. and a signal for controlling the speed or force with which the type element is pushed toward the printed page. The signals of the keyboard controller 16 are simultaneously read into the escape and erase logic 22 which then uses a conventional table lookup to determine the escape value assigned to each character represented at the output of the keyboard controller 16. .

These escape values or escape widths are, for example, 1
If the unit is 0.42 ribs, the standard width is 6 units per character for a 10-pitch escape, or 5 units per character for a 12-pitch escape. Moreover, each character escapes to 0 per unit.
．． 42 skin allows each character to be assigned an escape width proportional to its actual print width, known as a proportional space character. This allows the typewriter 10 to escape in response to signals from the keyboard control device and print proportionally arranged characters. Carrier 13 of typewriter 10 (second
(see figure) In other words, the position of the print point setting means is the escape register 2 which is a part of the escape/erase logic 22.
4, thereby giving the current position measured from the left end movement point of the print carrier 13.

This value is updated when the print carrier 13 moves to the left or right under control of the keyboard signals. Escape/erase logic 22 outputs the width of the character selected on the keyboard to escape counter 26.

This is necessary to control the printer's escape function. Escape counter 26 then temporarily stores the information necessary to control movement of print carrier 13 a predetermined or preselected distance. During its operation, escape counter 26 is controlled by a signal from integrator 28. This integrator consists of a lead screw 19 and an escape signal wheel 2.
1 and an input signal representing the output of the photoemitter/sensor 17, which indicates which portion of a revolution the lead screw 19 has rotated. Escape counter 26 is decremented by the pulse emitted by photo emitter/sensor 17 and wheel 21 at the end of lead screw 19 of typewriter 10. As long as escape counter 26 contains a value, photoemitter/sensitivity 17 pulses escape counter 26 via integrator 28, causing escape counter 26 to receive a pulse from the appropriate magnet driver. 30 to cause the print carriage 13 to move. Print carriage 1
The rightward movement of the escape paddy of No. 3 is caused by a signal from the magnetic driver 30 which receives input from the escape counter 26.

The escape signal, direction signal, drive signal, and erase signal all come from the magnetic driver 30, but are ultimately controlled from the keyboard 14. The escape output of the magnetic driver 30 causes the lead screw 19 to be released so that it can rotate with the emitter wheel 21 which interacts with the photoemitter/sensor 17 to produce the signals described above. The directional output of the magnetic driver 30 controls the direction of rotation of the lead screw 19 by controlling the engagement of the clutch 31 in the drive unit 33 to determine the forward or backward direction of the carrier. The drive output of the magnetic driver 30 connects the main drive motor 33 of the typewriter 10 and the lead screw 19 via a transmission or drive 33 . The erasing output of the magnetic driver 30 causes the erasing medium, or erasing tape, to collide with the paper for subsequent printing by the print element.

The erasure medium is lifted from its retreating layer so that erasure occurs when the character is the same character that previously impinged on the print ribbon at its print point. The printer control device 32
Speed decoding logic 18, escape/erasure logic 22
, an escape register 24, an escape counter 26, and a line memory 34.

The signal from the control device 16 is transmitted to the character/speed decoding logic 18
Once converted into a form usable by magnetic driver 20, the same information is stored in line memory 34. This memory 34 can store data in the order in which it is received. Line memory 34 can be read backwards to obtain previously printed characters and mechanical functions such as tap start and space commands for that particular line. Each function of typewriter 10 is controlled by a keyboard functional portion 36.

Functions included in this type of typewriter 10 include tap, space, carrier return, shift, index and erase. This typewriter 10 has a US patent number 3
Automatic erasure as disclosed in No. 780,846 is possible.

The automatic erase operation performs three functions. First, the line memory is examined for the current print point to determine whether a character code or erasable character is found at that location. When an erasable character is found, the erasing medium becomes available and is raised from the retracted position, and when a printing operation is performed, the printing element presses the erasing medium, not the printing medium, against the page-stripping paper. It turns out. If the character on the printing element that presses the erasing medium against the paper matches the character to be erased, the previously typed character to be erased will be stripped of the ink adhering to the paper by the first printing operation, or It is erased by being invisibly covered with a substance on the erasing medium. When the erasing medium is thus picked up, the characters retrieved from memory are used to select characters on the type element and a print cycle is performed. Line memories often do not contain erasable characters.

This occurs when a typist types all or part of a line and then intertexes the carriage. This has the effect of clearing the line memory so that erasable characters will not be found when the line memory is subsequently examined. Once the typist has indexed the carriage to the next line, the line memory no longer contains erasable characters;
The page contains erasable characters, so the typist may wish to perform an erasing operation. line·
Another example where no erasable characters are found when memory is examined is when a line of memory contains "spaces."

For example, if a typist accidentally activates the space bar and wants to delete the space, the space will not be an erasable character. In the aforementioned US patent, in response to an erase command, the typewriter skips the smear and erases the character in that space, which is not necessarily the behavior the typist desires. Naturally, the line
If the memory does not contain a signal representing the character to be erased, an automatic erase operation is not possible.

However, prior art typewriters allow an operation called manual erasure. In manual erasing, first select the print point corresponding to the character to be erased (ie, the backsbase function is required in curved cases), enable the erasing medium, and press the character key. In this way, the type on the type element causes the erasing medium to impinge on the paper, thereby erasing the typed character if it is the same as the character to be erased. Some typewriters are capable of an automatic erase function and can also perform manual erase operations. This involves actuating the "code" key and the erase key simultaneously to perform a manual erase function. In accordance with the present invention, the electronic control circuit of the typewriter includes logic capable of performing either automatic or manual erasure, the selection being made by the electronic control unit based on the status of the line memory.

In fact, if an automatic erasing operation at a desired print position is possible, it will be performed. On the other hand, line memory
If it contains non-erasable characters, such as a "space" code or a function code, or is empty, the electronic controller will cause manual erasure to occur. In the erasing operation, if the next keystroke is an erasable character, a manual erasing operation is performed. Otherwise, if the keystroke is an erase key, automatic erasure is restarted, and if the keystroke is neither an erasable character nor an erase key, the process simply exits from manual erasure.
In the present application, "automatic erasing" refers to erasing that is performed in response to selection of only the "erase" key, and does not include an operation by the typist to select characters to be erased.

On the other hand, "manual erasure" is an erasure function that allows a typist to select characters to be erased. Conditioning or conditioning for manual erasure is the act of setting the erasure latch so that on the next print cycle, the erasure media is lifted and inserted between the print element and the paper. Similarly, releasing from manual erase means resetting the erase latch. When the erase key is activated, functional portion 36 of keyboard 14 generates a signal that is sent to functional logic 38 for decoding.

The output of function decoding logic 38 is gated to escape erase logic 22 where it is recognized that the function is an erase operation. The escape erase logic 22 accesses the line memory 34 and retrieves the character printed at the character position immediately preceding the character position immediately to the left of the character position of the current print. If an erasable character is stored in its corresponding position in line memory 34,
The auto-erase function is executed. On the other hand, if there is no erasable character at the accessed character position in line memory, or if the line memory position is empty, then
The escape erasure logic is tailored to the typewriter's manual erasure and thus has the following keystroke behavior: manual erasure mode. If the next keystroke actuates the erase key again, the machine is released from the manual erase operation and begins the sequence of operations again to perform the automatic erase operation. on the other hand,
If the next actuated key is an erasable character, a manual erasing operation is performed. The typist can take the machine out of manual erase and return it to normal operation by activating the space bar on said next keystroke. on the other hand,
If another function key is pressed, such as the tab function, index function, carriage return or shift, that function is executed and the function is released from manual clearing and returned to its normal operating state. A control device 32, shown schematically in FIG. 1, is used to implement each of the functions described above.

The control device 32 includes magnetic drivers 20 and 3.
0 to the printing mechanism 13 and its driving device. Although this controller 32 is capable of operating at very high speeds in the current state of the art, the operation of printers requiring zero mechanical movement is much more limited. Some curved electronic typewriters currently on the market have an operating cycle consisting of four different states. The first state is a rest or standby state. When the key is actuated and the data is decoded, the typewriter moves to a second state and a print cycle begins. Once a print cycle begins, it must be completed within a certain amount of time determined by the rotation of the cycle axis. At the end of the print cycle, the typewriter enters a third zero state. In this state, escape can be performed. When the escape, or time for escape, expires, the typewriter enters a fourth state. In this state, the various control signals that have controlled the print cycle and escape are turned off and the typewriter returns to its original state. The typewriter can be made to skip any of these functions depending on various conditions. For example, a machine cycle always includes time for an escape to occur, but under certain conditions there may be times when an escape does not occur. The automatic erase function requires two cycles of the four mechanical states described above in the curved case.

In its first cycle, the typewriter moves from the rest state to the second state when the actuation of the erase key is decoded. A print cycle begins, but no printing occurs. When the printing cycle is completed and the third state is reached, the erase lasse is set, so a backs base is performed instead of an escape. At the end of this buckbase, a fourth state is entered in which the control signal is turned off and the typewriter enters a quasi-dormant state similar to the sleep state except that the erase function is only partially completed. At this time, not only is the erase latch set, but the second cycle latch is also set, indicating that an erasable character has been detected by interrogating the line memory. A repeat or second cycle of machine states then begins, in which a printing cycle is carried out with the printing elements being controlled by the signals taken from the line memory, and thus erasing. The escape cycle is skipped to the fourth state, and eventually when the second cycle ends, the auto-erase function also ends. In the device that performs such an erasing function, the same mechanical state is repeated in the present invention, but
If automatic erasure were not possible, the cycle of type striking the paper would only begin after the typist had selected the character to be erased. More specifically, the typewriter of the present invention initiates an automatic erase operation as described above in response to depression of the erase key.

In this case, after the print and escape cycles in the first cycle, the manual latch is set if the erase latch is set but no erasable character is found in the interrogated line memory location.
Once the manual latch and erase latch are set, the typewriter returns to the standby state and does not begin any operation until the next key press is detected. When the next key press is detected, the typewriter again enters the second cycle as in the case of auto-erase. During this second cycle, no printing or impact occurs, but instead the printer is ready to impact in response to a key selection by the typist, assuming that an erasable character was selected by the keystroke described above. The second cycle latch is set. Escape is also inhibited, and when this cycle ends, the final or third cycle begins because the second cycle latch is set. In this final cycle, impact and erase occur, but escape is still inhibited and all latches are reset. If the typist does not select an erasable character, the second cycle latch will not be set and therefore no impact will occur on the final cycle. However, depending on the typist's selections, some or all of the latches may be reset, as discussed below. In a preferred embodiment, random logic in the form of a programmed processor, such as a microprocessor, is used to configure the controller 32.

It should be noted that the control device 32 can also be implemented in the form of separate logic or wired circuits. However, no matter what form it takes, the signal and logic flow will be similar to the flowcharts in Figures 3 and 4. As shown in FIG. 3, the control device 32 has a keyboard input in its normal state.

When a keyboard input is detected at function 50, character and speed decoding logic 18 determines at function 51 whether the input is for a character. If so, functions 53 and 54 are executed to store the character in line memory 34 and perform a print cycle to print the character on the paper at the current print point. Print sequence 54 includes the ability to space (or escape) the print carriage so that at the end of a normal printing operation, the print point moves to the next character position to prepare for the next print sequence. In the case of a curved shape, this operation only requires repeating the four functional states described above once. On the other hand, if the character rate decoding logic 18 determines that the keyboard input is not a character, the function decoding logic 38 determines at function 52 whether the erase function was commanded.

If it is not commanded, function decoding logic 3
The part of this logic in which 8 checks whether there are other function commands is not relevant to the present invention and will therefore not be described here. However, if function decoding logic 38 recognizes an erase function, the erase lasse is set.

The logic implemented at this time is shown in FIG. As shown in FIG. 4, the erase command is gated from the function decode logic 38 to the escape erase logic 22. escape·
The amount is loaded into the counter, which is
For example, as described in Samurai Batsu Sho 54-152927, it functions to make the carrier of a printer back-based. Since escape register 24 is used to access line memory, once a backsbase operation is finished, escape register 24 is
remembers the position of the print point and thus sets the line memory to “
Access in a 'backs-based' position. The escape erase logic is applied to line memory 3 at function 63.
4 to determine whether the accessed location is empty. If not empty, escape erase logic 2
2 determines whether the signal stored in line memory 34 corresponds to an erasable character. If an erasable character is found, a second cycle, the latch is set and the auto-erase function 65 is implemented. These features are shown in U.S. Pat. No. 3,780,846, so
I will not go into details here. Briefly, the erasing medium is enabled by the magnetic drives and print commands are issued corresponding to the characters found in the line memory. On the other hand, the escape erase logic in function 63 or 64 indicates that the accessed memory location is empty or that the erasable character is
- If it is determined that the escape erase logic 22 is not found in position, the escape erase logic 22 adjusts the typewriter 10 to manual erase (ie sets the manual latch) at function 66.

The erasing medium is then ready to comply with the conditions specified below. Once this operation has been performed, the escape erase logic 22 waits at function 67 for the next keystroke.
Each of the above functions from pressing the erase key to function 66 are as follows:
This corresponds to returning four functional states on one line. Next, if the keystroke is an erasable character,
The keyboard controller 16 converts the corresponding signals into characters and characters.
Send to speed decoding logic 18.

These signals are received by function decoding logic 38 to determine whether the keystroke is an erase key. That is, function 68 is that. Similarly, function decoding logic 38 determines whether the next keystroke is a space bar. That is, function 70. However, if character/speed decoding logic 18 determines that the next keystroke is actually an erasable character, that information is gated into escape erasure logic 22. The second cycle latch is set when the machine cycle is during the second cycle in which both the print and escape functions are skipped. In the final cycle, the character/speed decoding logic 18 gives a print command to the magnet driver 20,
It rotates and tilts the type ball, or performs other similar functions, depending on the type of printing device used in the typewriter. However, the machine has function 66 first.
At this point, the manual erase is adjusted (the manual latch and the erase latch are set), so the magnet driver 30 energizes the erase magnet at this time to raise the erase medium. Therefore, in the manual erasing operation of function 75, the printed character on the type ball corresponding to the pressed character key is erased by pressing the raised erasing medium against the paper during the printing cycle (erasing is performed). )
Following this, the machine is taken out of manual erase mode, ie, the latches are reset. On the other hand, if the next character key pressed is not an erasable character and a function key is pressed,
Function decoding logic 38 determines at function 74 that a function has been selected.

This selected function is implemented by escape erasure logic 22 as well as other equipment necessary to implement the selected function. At the same time, the machine is released from manual erasure. If the operator activates the space bar rather than pressing an erasable character or function key, function decoding logic 38 determines that the next activated key is the space bar.

This information is ESKEF. Gated to erase logic 22. The effect of this action is to release the typewriter from manual erasure. Finally, if the operator activates the erase key again as the next key, the function decoding logic 38 interrupts the previously prepared circuit for the erase magnet and takes the machine out of manual erase, as shown in FIG. The sequence shown in is repeated once again from the backs base function 62.

FIG. 5 details the components of erasure escape logic 22 necessary to incorporate into one embodiment of the present invention.

As shown in FIG. 5, erase escape logic 22 has two sets of signal inputs. A first set of signal inputs from function decoding logic 38 and 18 identify key actuations corresponding to character, space, erase, and other functions and identify the addressed line corresponding to the print point. - A second set of input signals from a decoding circuit arranged to decode the contents of memory 34 are indicative of a character, function, space or empty status of that memory location. As shown in FIG. 5, these two sets of signals are sent in selected combinations to AND gates 100-102.

AND gate 100 receives an input identifying actuation of the erase key and a corresponding character decoding from line memory and provides an output for setting second cycle latch 107. At an appropriate clock time, latch 1
The set outputs of 07 are combined by another AND gate 108. The output of AND gate 108 is sent to the printer to perform an erase cycle. The printer's erase cycle includes a print cycle that enables the erase medium and impacts the paper with the print element, and a skipped escape cycle. The same output of gate 108 is also sent to a three-delay circuit 109 whose output is arranged to reset second cycle latch 107. This operation corresponds to the automatic deletion function.

That is, the AND gate 100 detects that the erase key has been pressed four times and that a character is at that location in the line memory, so that the automatic erase function is executed at the appropriate time as described above. First cycle latch is set. However, according to the invention, AND gates 101 and 102 are provided, the former receiving input from an actuated erase key and decoding of the corresponding empty location in the line memory.

AND gate 102 also receives input generated by pressing the erase key and receives function commands or spaces from the line memory. AND gate 101 or 10
Both outputs of 2 indicate that the auto-erase function cannot be implemented because no erasable character is found at that print point in the line memory. The output of OR gate 110 is AN
D Gate 1 11 is clocked at appropriate times during the machine cycle to set manual erase latch 112 . If you set the manual erase latch as explained later,
Printer erase cycles are temporarily inhibited. It should be pointed out, however, that when the line memory 34 is interrogated, the print point has already been backed or escaped, and the typewriter is therefore dependent on the next key actuation to carry out manual erasure. Setting the manual erase latch places the machine in a semi-standby state similar to the normal standby state, except for the setting condition of the manual erase latch 112. Manual erase latch set output is from AND gate 103~
106. Other inputs to AND gate 103 come from actuation of letter keys, AND
When an output is generated from gate 103, this cycle
A set input for latch 107 is provided. Therefore, A
When ND gate 103 produces an output, the printer performs an erase cycle. More specifically, the erasing medium remains lifted while impacting the type element during the print cycle. As shown in FIG. 5, the output of delay circuit 109 is arranged to also reset manual erase latch 112 so that at the end of the erase cycle, both the second cycle latch and the manual erase latch are reset. . AND gate 104 has a second input resulting from actuation of the decoded function key, and the output of AND gate 104 is coupled to the printer to perform the selected function.

This same output is combined by buffer 113 to reset the hand erase latch 112. AND gate 10
The second input to 5 is provided by the actuation of the decoded space bar, the output of the gate is sent to the printer to cause a no-print no-escape cycle, and this same output is sent to buffer 114. and sent to reset the scale erase latch 112.

Finally, AND gate 106 has a second input provided by activation of the decrypted erase key and the output of AND gate 106 is sent to reset manual erase latch 112.

Comparing the logic of FIG. 5 with the flowchart of FIG. 4 reveals this distinct logic.

It can be seen that the function performed by the logic circuit is substantially the same as that shown in FIG. AND gate 108
The clock inputs to and 1 1 1 can be replaced by other status-determining signals in the typewriter, as will be understood by those skilled in the art.

The only requirement is that once the second cycle latch is set, for example, the other elements are brought to a stable state to ensure that the signal provided to the printer for the erase cycle is provided. The clock function of the AND gate 111 is
Provided to prevent race conditions on manual erase latch 112.

If the contents of the line memory are empty or indicate a function command when the erase key is operated, the manual erase latch will be set, so if the manual erase latch is set in advance, the erase key operation will AND gate 1
Since a reset signal is generated through 06, the clock function is adjusted so that the above set operation is performed after the reset signal is performed and the manual erase latch is held in the set state. A similar function is provided by the delay circuit 10.
9, but as can be appreciated by those skilled in the art, other devices or signals may be used to delay the reset of the second cycle latch 109, such as other machine state determining signals. can. However, as stated above, the present invention preferably utilizes a programmed processor, preferably a microprocessor.

Tables 1 to 3 show program instructions (or code) used in embodiments of the invention incorporating the logic described above. Tables 1 and 2 consist of the code itself and contain a series of statements listed in the column entitled "Statements". The remainder of Tables 1 and 2 consists of the columns labeled ``Source'' and the explanations to the right of the columns labeled ``Statements,'' which are useful for understanding the functions performed by program instructions. This is an explanation. Table 3 shows the meaning of some statements in order to make the explanations in Tables 1 and 2 easier to understand. As will be apparent to those skilled in the art, Tables 1 and 2 are only some of the program instructions used to control a typewriter implemented in accordance with the present invention; Other functions not directly related to the invention are also possible, and therefore other codes exist, but they are not directly related to the invention and will not be discussed. More specifically, Table 1 is the code for when the typewriter recognizes that the erase key has been pressed.

On the other hand, Table 2 shows codes related to when the typewriter recognizes that a printable character has been pressed. These two codes are interrelated. for example,
The instruction at position L33 includes a jump to LI I, which appears in the column labeled "Source" in Table 2. Similarly, the first instruction "JB4" in Table 2 is a conditional jump to L502, which is in Table 1. Simply put, when the erase key is pressed, the carry
A bit is set to indicate the printer buffer pointer.

This action causes the printer buffer pointer to point to the memory location corresponding to the key pressed prior to actuation of the erase key. After the ID word is tested, the ID indicates that no possible characters were found.
If the word indicates, it becomes a conditional jump.
The current flight is to position L500. Instruction L50 sets the manual deletion flag. The next instruction at L503 turns on the bit that controls backs base operation and then jumps to L7. One of the functions of this instruction, L17, also seen in Table 1, is to set the keyboard buffer point to the printer buffer pointer. Next instruction L3 sets bits for no escape and no print. Instruction L33 includes a jump to LII, which can be seen in Table 2. This command is an output command that enables various control bits, after which the printer is controlled. Therefore, if the typewriter is responding to an erase key press and the buffer does not contain erasable characters, there will be no print no escape when the print axis cycle is started by instruction LII, and this code action The only event performed is to set the manual erase flag. When the manual clear flag is set and the operator presses a printable character, the code in Table 2 is entered.

The first instruction involves a jump to L502 if the hand erase flag is set (L502 is visible in Table 1).The first few statements in L502 cause the character case to be If not, the shift magnet is set if it is printed and the case printed during printing is different from the case that is supposed to match the selected character case on the keyboard. Next command, L
506 turns the erase flag on and then the instruction string starting at L17 is executed and ending at LI1 (Table 1). The first pass in this code is entered when a printable character is pressed with the manual erase flag set, and has the effect of turning on the erase flag, but otherwise starts at LII. The rotation of the print shaft is still a no-print, no-escape cycle. The next cycle of the print shaft is one in which the print element is forced toward the paper to imprint the characters typed by the operator. With the erase flag on (at L506), the print element is pressed against the erase medium to perform an erase operation. As is clear from the above, Tables 1 and 2
The code shown in the table has the effect of setting the manual erase flag if the erase key is actuated and the buffer location contains no printable characters.

This code also indicates that when a printable character is activated with the manual erase flag set, normal printing is inhibited and an erase function is performed instead. The operation will be explained with one example.

Assume that the following text is printed on the page.
ABCDEFGHIJKLMN Assume that the next keystroke is the erase key.

When the electronic control circuit recognizes an erase stroke, ie at function 52 (FIG. 3), a backs-base cycle is performed (function 62) and then the line memory is interrogated (functions 63, 64). If the memory contains erasable characters, they are automatically erased (function 65). Each character up to G is thus erased as long as the erase key is held down or continues to be pressed. After the G is erased, the next press of the erase key performs the same function except that at function 64 the electronic control circuit recognizes that there are no erasable characters in the line memory.

That is, in function 66 the typewriter conditions itself for manual erasure and in function 67 it waits for the next keystroke.
If the next keystroke is an erase key, it will be recognized by the electronic control circuitry, the previous conditioning for manual erase will be removed, and the logic will return to function 62 to begin the next backs bass. let Since all other conditions are the same, F is eliminated. Assuming that after N-G are erased, the operator wants to delete the space and continue typing, the operator presses the erase key next to F after erasing G.

As mentioned earlier, the typewriter conditions itself for manual erasure and waits for the next keystroke. If the next keystroke is a space bar action, then the function performed by the electronic control circuit is simply to take the typewriter out of manual erase and wait for the next keystroke. This release does not implement the escape function, so the next keystroke is the text that the operator would like to place next to F. The text shown above was typed, but for some reason, for example because the operator moved the platen after typing and then reset the platen to the text above, the line memory did not generate the signals representing these characters. If it does not, pressing the erase key will cause function 63 to determine that the memory is empty.

The machine then conditions itself for manual erasure and waits for the next keystroke. If the next keystroke is N, a print cycle is performed, but the machine remains conditioned for manual erasure, and the media used is an erase media rather than a print media, so N is will be deleted. Table 1, Table 2, Table 3 and below show the correspondence between each component of the invention described in the claims and the embodiments.

[Brief explanation of the drawing]

1 is a block diagram of an electronically controlled typewriter into which the present invention may be incorporated; FIG. 2 is a partially cutaway view showing the interrelationship of mechanical elements of the typewriter of FIG. 1; FIGS. 5 is a logic flow diagram showing the logic of the present invention, and FIG. 5 is a schematic diagram of a single logic circuit incorporating the present invention. 14...keyboard, 16...keyboard control device, 1
8... Character and speed decoding logic, 20... Magnet driver, 22... Escape and erasure logic, 24...
Escape register, 26...Escape counter,
28... Integrator, 30... Magnet driver, 32... Printer control device 34... Line memory, 36... Special function section, 38... Function decoding logic, 40...
Tab storage. Figure 1 Figure 2 Figure 3 Figure 4 FIG. 5

Claims (1)

[Claims] 1. Signal generating means for generating a signal indicative of an actuated key, storage means for storing a series of said signals, a printing medium and an erasing medium, if said printing medium is available. printing means for performing a print cycle to print characters at the print point and, if said erasing medium is available, for performing a print cycle to erase the characters at the print point, responsive to actuation of an erase key; ,(a)
displacing said printing point to the left by one character; (b) reading out a signal stored in a position of said storage means corresponding to said displaced printing point; (c) activating said printing means; control means for enabling an erasing medium and for causing a print cycle to occur with respect to a character corresponding to a signal read from said storage means, in response to actuation of said erasing key; inhibiting said print cycle when the signal applied does not represent an erasable character and the printing means responds to said next key actuation only if the next key actuation is that of a key representing an erasable character; An erasing typewriter characterized in that it is provided with logical means for making it possible to carry out a printing cycle.