JPH02265779A - Electronic typewriter - Google Patents

Abstract

PURPOSE:To certainly erase a character by appropriately utilizing a back delete system and a non-back delete system by erasing a printed character and the printed character stored in the first memory means corresponding to the first erasure indication means and again erasing the erased character corresponding to the second erasure indication means. CONSTITUTION:When an erasure key 11 is pushed down, it is investigated whether the content of a line buffer 23 is an NUL code and the processing of a back space 10 is executed. By this method, a character 's' can be erased from the surface of paper. When the character 's' is not completely erased, the erasure key 11 is pushed down while a code key 12 is pushed. ln this case, the content of an erasure buffer 24 is 'S' and the character 's' is allowed to impact against a paper surface 35 through an erasure ribbon 34 and stripping- off operation can be again executed. By this processing, stripping-off effect is further enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic typewriter that can erase unprinted characters.

[Prior Art] Conventionally, automatic erasure of unprinted characters in electronic typewriters has been carried out as follows. In other words, the contents of the unprinted character or its string are stored in the line buffer.
The desired characters are read out from the line buffer in accordance with an operator's erasing instructions, and are erased by utilizing the retrieving effect by impacting the corresponding characters again through the erasing ribbon. The back delete method described below is used for erasing the data.

The back delete method means that when the print head points to a non-printed character, the corresponding character is erased, and when the print head does not point to a non-printed character, that is, when it points to a space part, the corresponding character is erased. It automatically moves up to the position of the removed character and erases it.

[Problems to be Solved by the Invention] However, in the conventional method described above, once a character is erased, it is logically assumed that the character has been completely erased. On the other hand, when viewed physically, it is common for there to be some erased residue on the paper, and depending on the paper quality, these erased residues are often noticeable.

At this time, even if an erase instruction is given again, the back delete method causes the character to be erased even further, and the problem of unerased characters cannot be solved.

The present invention was made to solve the above problems, and
An object of the present invention is to provide an electronic typewriter that can surely erase characters by appropriately using a back delete method and a non-back delete method.

[Means for Solving the Problems] In order to achieve the above object, the electronic typewriter of the present invention has the following configuration. That is, in an electronic typewriter capable of erasing unprinted characters, there is provided a first storage means for storing typographical characters in association with the unprinted characters, and a first erasing instruction for instructing deletion of the orthographic characters. means, erasing means for erasing the printing method characters and the unprinted characters stored in the first storage means in accordance with the first erasure instruction means, and storing the erased characters erased by the erasing means. a second storage means for instructing erasure of the erased characters stored in the second storage means; and a second erasure instruction means for instructing erasure of the erased characters stored in the second storage means; and re-erasing means.

[Operation] In this configuration, the printing method characters and the unprinted characters stored in the first storage means are erased in response to the first erasure instruction means, and the erased characters are erased again in response to the second erasure instruction means. Operates to erase.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Description of Structure (Fig. 1)> Fig. 1 is a block diagram showing the structure of an electronic typewriter in this embodiment. In the figure, 1 is a keyboard (KB) that outputs a corresponding key signal 4 when a key is pressed.
). 2 is a control device (CNT) that controls printing and erasing processing based on key signals 4 from the keyboard 1;
3 is a printer (PRN) that performs printing and erasing based on the print signal 5 and erase signal 6 output from the control device 2;
It is. The control device 2 includes a microprocessor (MPU) 20 that controls the entire device, a ROM 21 that stores control procedures (programs) for the MPU 20, which will be described later, and an MPU.
20 is provided with a RAM 22 which is used as a work area or a buffer when processing is executed. In addition, the RAM mentioned above
22 includes a line buffer 23 that stores printed characters in correspondence with the print position on the paper each time a character input from the keyboard 1 is printed, a one-character erase buffer 24 that stores erased character codes, and a carriage. Carriage pointers 25 that associate positions with line buffers 23 are defined.

The carriage pointer 25 indicates that the carriage is one step to the right.
If the carriage moves 1/10 inch, it is incremented, and conversely, if the carriage moves 1/10 inch to the left, it is decremented.

Next, the schematic structure and operation of the printer 3 described above will be described in detail below with reference to FIG. 2.

FIG. 2 is a diagram showing the relationship between the print head and paper platen. In the figure, 30 is a carriage (CRG), 31
is a printing hammer (HM), 32 is a type daisy wheel (DW), 33 is a printing ribbon (RB), 34 is an erasing ribbon (CR), 35 is paper (PAP), 36 is a platen (PTN), and The print head consists of a hammer 31, a daisy wheel 32, a printing ribbon 33, and an erasing ribbon 34, and is movable left and right as a carriage 30.

As for the operation of the printer 3 having the above-described configuration, when a normal printing command (print signal 5) is input, the hammer 31 moves the daisy wheel 32 through the printing ribbon 33.
The printed characters are impacted in the direction of the paper. On the other hand, when erasing, the printing command is received together with the erasing command (erase signal 6), so that the printed characters are impacted through the erasing ribbon 34, and as a result, the ink (carbon) adhering to the paper surface is
is attached to the erasing ribbon 34. That is, characters are erased by peeling off.

(Figures 3 to 8)> Next, Figures 3 to 8 explain the operation of the electronic typewriter in this embodiment.
This will be explained below with reference to FIG.

In this embodiment, the character string "The Tysowriter" is input using the keyboard 1 shown in FIG. 3 and printed on the printer 3, and then the incorrectly input characters "0 and S"
This is a detailed explanation of a case in which "S" is erased again because "S" is not completely erased.

First, when the character string "The Tysowriter" is input from the keyboard 1 shown in FIG. 3 in the same way as with a normal typewriter, the internal processing shown in the flowchart shown in FIG. 5 is executed for that one input character.

That is, the character code input from the keyboard 1 is stored in the position of the line buffer 23 indicated by the carriage pointer 25 (step S1), and the one-character print command 5 is output to the printer 3 (step S2). 30 to the right by 1/10 inch (step S
3) After that, the content of the carriage pointer 23 is incremented (step S4) and the process ends.

By repeating the above operations, the above character string becomes
The data will be stored in the line buffer 23 shown in FIG. 4(a).

Further, the carriage 30 has moved to a position 1/10 inch to the right of the letter "r". Therefore, to erase the incorrect input "0", press the backspace key (BS) 1
It is necessary to press 0 seven times to move to the position of the character 0''. The flowchart shown in FIG. 6 shows the internal processing corresponding to one backspace key 10.

First, the carriage pointer 25 is decremented (step 5IO), then the carriage 3° is moved to the left by 1/10 inch (step S11), and the nu
L:)-code (OOHEX) is stored in the erase buffer 24 (step 512), and the process ends. In other words, this indicates that there are no valid characters in the erase buffer 24.

In other words, the backspace operation invalidates the non-backdelete operation.

Here, the erase buffer 24 and carriage pointer 25 shown in FIG. 4(a) are in the state after pressing the backspace key 10 seven times. Further, the carriage 30 has moved to the position of the character "0" to be erased. In this state, when the erase key (CAM) 11 is pressed, internal processing is performed according to the flowchart shown in FIG. As a result, the state shifts to the state shown in FIG. 4(b). To explain the process, first, the contents of the line buffer 23 indicated by the carriage pointer 25 are checked (step 520).
, if it is a NUL code, the process advances to step S24,
Performs the backspace 10 key processing described above. However, if the code is not a NUL code, the process advances to step S21, and the line buffer 23 pointed to by the carriage pointer 25 is
The contents (character “0”) are transferred to the erase buffer 24.

Next, the NUL code is stored in the line buffer position pointed to by the carriage pointer 25 (step 522), and then the process shown in FIG. 8 is executed.

That is, it is checked whether the content of the erase buffer 24 is a NUL code (step 530), and as a result, the content of the erase buffer 24 is a NUL code.
If it is a code, the process ends, but now the erase buffer 24
The content of is “0”, and the process proceeds to step S31.
Here, the erase buffer 24 is sent along with an erase command to the printer 3.
Sends the content “0”. Then, the character "0" is actually erased from the paper.

Next, when the erase key 11 is pressed in order to erase the letter "S", the above-mentioned internal processing is similarly executed. That is, it is checked whether the contents of the line buffer 23 are a NUL code. Then, as shown in FIG. 4(b),
The carriage pointer 25 is at n+1'', and a NUL code is stored in the line buffer 23 at position n+1''. Therefore, the backspace 10 process is executed (step 524), and upon completion, the process returns to step S20. At this stage, the content of the line buffer 23 indicated by the carriage pointer 25 is "S". Therefore, by the processing of steps S21 to S23 described above, the character "So" can be similarly deleted from the paper. This operation is back delete. FIG. 4(C) shows the result of back delete. It is something.

Here, if the character "S" is not completely erased, the operator must press the code key (CODE) on the keyboard 1.
) While pressing 12, press the erase key 11. In this case, in this embodiment, the process of the flowchart shown in FIG. 8 is executed. As can be seen from the state in FIG. 4(C) and the process in FIG. 8, the content of the erase buffer 24 is "S", and the process advances from the determination in step S30 to step S31.
The letter "S" is made to impact the paper surface 35 via the erasing ribbon 34, and the peeling operation can be performed again. This treatment further improves the peeling effect.

Incidentally, if there are still remaining characters to be erased, the operator can perform the above-mentioned operation again to completely erase the characters in the - layer.

As can be understood from the above explanation, the back delete process shown in FIG. 7 is controlled so that back delete is not performed when the print head is opposed to characters on the paper.

According to this embodiment, by incorporating both convenient back delete and non-back delete methods or functions into the same device, more complete character deletion can be achieved.

In addition, it is advantageous in terms of cost because it does not particularly improve the accuracy of the printer.

As described above, although the line buffer 23 is used in this embodiment, the same effect can be obtained by using a full page buffer.

Further, although this embodiment does not describe a detailed control method regarding the left and right movement of the carriage 30, it is well known to those skilled in the art, and the explanation in this embodiment is omitted.

Furthermore, although this embodiment adopts a method (FIG. 7) in which back-delete is executed depending on the situation, the gist of the present invention remains the same even if a method of always performing back-delete is used.

Furthermore, the gist of the present invention can be achieved even if a buffer structure is used in which the character stored in the erase buffer is expressed in 7 bits and the remaining 1 bit is added as an erase bit. That is, this 1-bit erase bit corresponds to the NUL code of this embodiment, and the erase buffer corresponds to the remaining 7 bits.

Furthermore, in this embodiment, the erasing operation in units of characters has been described, but erasing operations in units of words are also possible. In that case, it is sufficient to secure enough capacity to store words as an erase buffer.

[Effects of the Invention] According to the present invention, characters can be reliably erased by appropriately using the back delete method and the non-back delete method.

[Brief explanation of drawings]

Figure 1 shows the configuration of this embodiment, Figure 2 shows the printing mechanism, Figure 3 shows the keyboard, and Figures 4 (a) to (C) show the internal line buffer and carriage pointer. and a diagram showing each state of the erase buffer. FIGS. 5 to 8 are flowcharts showing the processing procedure in this embodiment. In the figure, l...keyboard, 2...control device, 3...
・Printer, 20...MPU, 21...ROM, 2
2... RAM, 30... Carriage, 31... Printing hammer, 32... Printing ribbon, 33... Erasing ribbon, 34... Type daisy wheel, 35... Printing paper, 36 ...It's a platen. Figure 3゜Figure 2Figure 3

Claims (1)

[Claims] (1) In an electronic typewriter that can erase already printed characters, a first typewriter that stores the already printed characters in association with the already printed characters.
storage means; first erasure instruction means for instructing erasure of the printed characters; and the already printed characters stored in the printed characters and the first storage means in response to the first erasure instruction means. an erasing means for erasing the characters; and a second erasing means for storing the erased characters erased by the erasing means.
storage means; second erasure instruction means for instructing erasure of the erased characters stored in the second storage means; and re-erasure for erasing the erased characters again in response to the second erasure instruction means. An electronic typewriter characterized in that it has means.