DISPLAY DEVICE FOR TYPEWRITERS

Abstract: The disclosed is a display control device which supplies the associated display screen with not only character information inputted by a user but with also the format information indicating the format situation around the current cursor position, so that a user can know format situation of both the region where data are being entered and moreover the blank area where no character data have yet been entered, therefore advantageously making the display screen smaller relative to the sheet and the entire structure simpler.

Description: The invention generally relates to a display device for electronic typewriters; in particular for electronic typewriters which have a small display screen, which conventionally show only input characters to check word spelling or for similar purposes. However, in such known devices, it is not possible to check where the input character will be printed on the sheet. In order to compensate for such deficiency, it has been proposed to have a second display screen to indicate the position available for the input characters, for example the display control device of JP-A-60-58511. However, this display device still has the deficiency that a wider space is required to contain two display screens, so that the overall structure is complicated and enlarged. The present invention is characterized by the features of claim 1. EP-A-0115047 discloses a typewriter having a display capable of simultaneously indicating (a) the position of characters currently being inputted on a line, and (b) the position of characters already inputted on the preceding line (or possibly on the next successive line in the case of deletion and re-insertion by way of amendment). Thus the invention, as claimed, provides a display device for printers which shows format information on the display unit as well as characters inputted from the keyboard. In reference to Fig. 1, the display device includes a display unit P2 where the format information is displayed in a manner such that, initially, the format information is shown with the predetermined indication system on the display unit. In more detail, format information including that for the right and left margins, (denoted as RM and LM, respectively, in this specification), tabulation, and hot zone are shown on the display unit P2 with their respective indications. These indications will be replaced by the input characters as these characters are input through a keyboard P1, so that input characters and format information are together displayed on the same line of the display screen. It is advantageous that there is no need for a plurality of display screens, one for indicating the format information to a user. Even on a display screen which is small compared to the printing sheet format, format conditions both around the current input position and at the blank area where no character data is entered, are apparent from the format indications. If desired, the display screen can be made to represent all or part of the width of the sheet size, though on a smaller scale. The device offers advantages when applied to a typewriter with a large display screen, in that the current input position is appreciated easily from the display in relation to the overall layout, which is particularly advantageous if the sheet is much larger than the display screen. In order that the invention may be more clearly understood, the following description is given by way of example only, with reference to the accompanying drawings in which: Fig. 1 illustrates the invention, with a display unit showing examples of format information, Fig. 2A is a diagram showing one embodiment of the invention, Fig. 2B is a diagram showing the constitution of a keyboard which can form part of the invention, Fig. 3 and Fig. 4 illustrate examples of display which the invention arranges on the display unit, and Figs. 5A and 5B are a flow chart depicting how initialization and subsequent steps proceed with respect to the invention. One embodiment is now described, referring to Fig. 2 illustrating the constitution of an electronic typewriter 10 including a device of the present invention. This electronic typewriter 10 prints characters with a printing head 20 on a sheet 40 which is arranged around a platen 30. The printing head 20 and a printing ribbon 50 are provided on a carriage 70 which is attached to slide along a guide shaft 60. The carriage 70 is activated by a carriage stepping motor 90 by means of a belt 80 so that the printing head 20 can be shifted into a desired position. The platen 30 is activated by a linefeed stepping motor 100, connected with it by means of gears 35, so as to shift the sheet 40 into a desired position. An electronic control device 110 controls the stepping motors 90 and 100, and the operation of the printing head. Data inputs and user's instructions are input via the keyboard 120 which is associated with the electronic control device 110. The characters inputted by a user are displayed on the liquid crystal display unit 130. This display unit allows up to 16 characters to appear on the screen at one time in this embodiment. The electronic control device 110 comprises CPU 200, ROM 210, RAM 220, a print control circuit 230 which is associated with the printing head 20 to control printing, and a printing position control circuit 240 which is associated with the stepping motors 90 and 100 to control the movement of the printing head with respect to the sheet 40. It further comprises a keyboard input/output circuit 250 which is associated with the keyboard 120, a display control circuit 255 which is associated with the display unit 130, and a bus line 260 connecting these facilities with each other. ROM 210 has at respective addresses a character generator 211 storing dot-matrix font patterns indicating character and symbol data to be displayed on the display unit 130, and a standard format memory 212 storing the standard format. RAM 220 has at respective predetermined addresses an input buffer 225, and a head position counter 222 which stores position data of the carriage 70, i.e., the position data of the printing head 20, wherein the position is recognized based on a number of pulses fed from CPU 200 to the stepping motor 90 via the printing position control circuit 240. Also RAM 220 has at respective addresses, an LM register 223 storing the position of the left margin, an RM register 224 storing the position of the right margin, a tab register 225 storing the tabulation position, and a hot zone register 226 storing the position of a hot zone. The keyboard 120 comprises a format setting key 300 which indicates format setting, character keys 121, a space key 122, a back space key 123, a return key 124, cursor shift keys 125a, 125b, 125c and 125d, which respectively directs upward, downward, leftward, and rightward, an LM setting key 126, an RM setting key 127, a tabulation setting key 128, and a hot zone key 129. When the electronic typewriter 10 is set in the Line by Line (L/L) mode, data entered from the keyboard 120 are stored in the input buffer 221 and simultaneously characters or symbols corresponding to the data thereof are read from the character generator 211 so as to display them on the display unit 130, and so that the depression of the carriage return key 124 lets the entered data be printed by the printing head 20 in accordance with the data stored in the input buffer 221. The display on the display unit 130 and the actual printing position on the sheet 40 are interrelated as shown in Figs. 3 and 4. In Fig. 3, format conditions such as left margin LM, right margin RM, tabulation and hot zone, of which the start is indicated with the abbreviation HZ, are noted above the sheet 40 with corresponding indications for reference. The indication ( * ) signifies the left side of the left margin LM, ( / ) the tabulation position, ( X ) the hot zone, ( + ) the right side of the right margin RM, and ( . ) others. These indications are called individual forms. Moreover the printing conditions on the sheet shown in (1), (2) and (3) in Fig. 3 are connected respectively with Figs. 4A, 4B and 4D which illustrate the corresponding display conditions. Usually the display capacity on the display unit 130 is less than that of a single line to be printed on the sheet 40. As an advantage of the present invention, the current cursor position with regard to the entire format on the sheet is easily understood, because the format indications tell a user both where the cursor is at the moment and also the condition in the blank area where no character is entered. Fig. 3 (1) shows the situation when five characters have been inputted from the left margin LM; the corresponding display on the display unit 130 is shown in Fig. 4A. The display indicates the five characters entered from the left margin LM, which is indicated distinctly by ( * ), and also indicates the tabulation set at five positions to the right thereof. In displays, the cursor denoted with C indicates the next data input position. Fig. 3 (2) illustrates the situation during character entry when the cursor is approaching the hot zone, while the Fig. 4B shows its corresponding display on the display unit 130. The tabulation is set at the next input position here. As commonly known in electronic typewriters, the cursor C of the present typewriter 10 can be moved left and right in accordance with instructions from the cursor shiftkeys 125c and 125d. If the cursor shift key 125d is depressed to instruct the cursor to move rightward when the cursor is already at the right end of the display screen 130, or if the cursor reaches the right end while key 125d is depressed the cursor C remains at the same position, i.e., at the right end thereof, while the display is scrolled leftward. If the key 125c is then depressed, the cursor moves left while the display is not scrolled. Accordingly, if the rightward cursor shift key 125d is depressed nine times and the leftward cursor shift key 125c is subsequently depressed nine times by an operator, the display on the display unit 130 shown in Fig. 4B will be changed into that as shown in Fig. 4C. Thus, such display lets the user know at a glance at the display unit how many digits exist between the cursor position C and the hot zone. However, such series of operations as to depress nine times the leftward cursor shift key 125c may be substituted with a relocate key, which is specially arranged to simplify operations. Further, Fig. 3 (3) shows that the cursor is approaching the right margin RM when characters are entered within the hot zone. The corresponding display is shown in Fig. 4D. If the leftward cursor shift key 125c and rightward cursor shift key 125d are depressed respectively six times, the display on the display unit 130 results as shown in Fig. 4E. In the display, the indications ( X ) denoting the hot zone and ( + ) denoting the right margin RM signify that the entry of three more characters will put the cursor at the right margin. These displays are accomplished by the predetermined program, which the following explains in conjunction with the flow charts shown in Figs. 5A and 5B. In the flow charts, each step is denoted with the abbreviation S. Upon switching on the electric typewriter, the process starts with the initialization at S1 so that the indications showing the initial format appear on the display unit 130 in accordance with predetermined standard format data stored in the standard format memory 212. Namely, the format data stored in the standard format memory 212 are respectively stored in the LM register 223, the RM register 224, the tab register 225, and the hot zone register 226. The character generator 211 feeds the data of symbols to be displayed on the display unit 130 so as to display them each at their right positions. S2 recognizes a key input; if S2 senses key entry, S3 then determines what kind of key entry. S3 distinguishes between entry of a character key, a key instructing display of another region, a key instructing a format change, and other kinds of keys. In case the entry is a character key 121, the corresponding character data are stored in the input buffer 221. S4 erases the format indication presently appearing at the cursor position, so as to replace it with the entered character at S5. consequently, S6 shifts the cursor one position forward and the process returns to S2. If the key entry by a user instructs display of another region, such as by operation of the upward or downward cursor shift keys 125a or 125b, or the carriage return key 124, S7 erases all current indications shown on the display unit 130. S8 changes the region of display unit 130 and displays characters contained in the new region instructed by a user. Then S9 fills the blanks, where no character is displayed by S8, with format indications. In other words, S7, S8 and S9 change the region of display when a user depresses the cursor shift keys 125a or 125b, the carriage return key 124, or such, the display showing a new region containing the cursor, which is shifted out of the previous display thereby. The process returns to S2 after these steps. Further in case the entry is by the format key 300, which instructs to set or change the format, S10 sets the electronic typewriter 1 in the format mode, wherein the margins and tabulations are set, and other format-setting process is also executed. At S11, after the carriage 70 is moved by a user into desired format positions defining the format with a space key 122 and a backspace key 123, the format-setting process is performed by a user such that the right and left margins, tabulation, decimal tabulations and such are determined by means of the format-setting keys 126, 127, 128, and 129 associated therewith. At S12, RAM 220 stores the new position data of the carriage 70 and the head position counter 222 in the corresponding registers 223, 224, 225 and 226. The new position data represent the position of carriage 70 when the keys 126, 127, 128, 129 are operated in S11. The subsequent step S13 judges if the format-setting process is finished, by first sensing a second entry by a format-setting key 300. If S13 determines that format-setting is not finished yet, the format-setting process continues. If the format-setting key 300 is depressed again, S14 cancels the format mode and the process returns to S2. Otherwise if S3 recognizes a key entry instructing other commands, S15 forwards the instructed process accordingly and the process subsequently returns to S2. As described above, this embodiment fills the blanks where no character is currently displayed, with the format indications on the display unit 130. As has been explained, the character display line in the display unit 130 is also provided with the format information. Although the device has only a single display unit 130 and moreover it is a small screen relative to the sheet 40, the format information of the current input area and moreover the other blank areas where no character data is inputted can be displayed on the screen so as to let a user know the necessary format information. The typewriter can be of a small size, because the single screen makes the structure simpler and it requires less width on the typewriter. Alternatively, this embodiment may be used like other well-known electronic typewriters, where the format-setting and the modification thereof is easily made without using any particular format-setting mode, however, this described embodiment has a special format-setting mode. As another alternative for display, the input characters may each be displayed upon entry with a different predetermined color than that of the format indications, in order that a user may distinguish the format information more easily.

Claims: A display control device for a typewriter which has input means for inputting character data and format setting data,; the device having :- format memory means (220-226) for storing data indicative of the desired positions of the text; a display unit (130) having a plurality of display positions at each of which can be displayed characters corresponding to character data inputted by the input means; and control means (255) for instructing the display unit to display symbols indicative of said desired positions according to the format setting data stored in the format memory means, within each of the display positions defined by the format setting means, to output said symbols in predetermined status before the character is inputted and to display the character at the display position denoted by said symbol when the character is inputted; characterized by the fact that the data stored by format memory means is format setting data including left margin data, tabulation data, hot zone data and right margin data. A display device for a typewriter according to claim 1, wherein the control means causes the format to be displayed by the display unit as a full line of individual symbols. A display device for a typewriter according to claim 1 or 2, further comprising initial format memory means for storing standard format setting data, and wherein the control means is adapted to cause display of said symbols, according to the standard format setting data, within each of the display positions upon switching on of the typewriter. A display control device for a typewriter according to any preceding claim, wherein the number of the display positions is smaller than that of characters to be printed on a line on a printing sheet to be used in the typewriter. An electronic typewriter having a display device according to any preceding claim.

Inventors: SASAKI, RYOICHI BROTHER KOGYO K.K.
Applicants: BROTHER KOGYO KABUSHIKI KAISHA
Application year: 1987
Main classification: G06F15
IPC codes: B41J21, G06F17, G09G5, G06F3