Abstract:
There is disclosed an electronic printing apparatus with a printing mechanism utilizing a type-font element integrally provided with plural printing types for printing characters and numerals, in which a detector identifies the kind of the typefont element, and a display unit indicates the printing style of the typefont element in response to the output signals of the detector.

Description:
This application is a continuation of application Ser. No. 474,671 filed Feb. 6, 1990, now abandoned, which is a continuation of application Ser. No. 194,185 filed May 16, 1988, now abandoned, which is a continuation of application Ser. No. 912,152 filed Sep. 24, 1986, now abandoned, which is a continuation of application Ser. No. 701,655 filed Feb. 14, 1985, now abandoned, which is a continuation of application Ser. No. 495,712 filed May 18, 1983, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electronic printing apparatus, utilizing an interchangeable typefont element, such as an electronic typewriter or a word processor, and more particularly to such an electronic printing apparatus provided with display means capable of displaying characters and numerals entered into it. 
     2. Description of the Prior Art 
     Conventional electronic printing apparatus with an interchangeable typefont element such as an electronic typewriter or word processor usually uses plural typefont elements having different typing styles. For example a word processor can use typefont heads of different print sizes such as 10 points or 12 points, an the electronic typewriter can use, in addition to the standard typefonts such as elite and pica, a typefont element with Greek letters and various symbols. 
     In such electronic printing apparatus, for example disclosed in the British Patent Specification No. 2087115 published May 19, 1982, the operator can identify the printing pitch but cannot identify the printing style of that printing pitch, for example as pica or elite, unless the printing style is confirmed by the actual printing. Therefore, in case a typefont element different from the desired one is mounted in the apparatus, waste of a printing sheet will result or the operator has to effect trial printing prior to the actual printing. 
     SUMMARY OF THE INVENTION 
     The object of the present invention, in order to avoid the above-mentioned drawbacks of conventional electronic printing apparatus, is to provide an electronic printing apparatus provided with display means for reliably advising the operator of the typing style of the typefont element mounted in said apparatus. 
     The above-mentioned object can be achieved according to the present invention by such printing apparatus provided with detector means for detecting the kind of the typefont element, wherein the display style or the display mode of said display means is changed according to the output signal of the detector means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing the outline of a control circuit for use in the electronic printing apparatus of the present invention; 
     FIG. 2A is a schematic view showing the structure of a typefont element for use in the electronic printing apparatus of the present invention; 
     FIG. 2B is a lateral view showing elements for practicing the method of detecting the typing style of the typefont element in the electronic printing apparatus of the present invention; 
     FIG. 3 is a schematic cross-sectional view of the electronic printing apparatus of the present invention; 
     FIG. 4 is a flow chart showing the function of the electronic printing apparatus of the present invention; 
     FIG. 5A and 5B are schematic views showing the function of the electronic printing apparatus of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now the present invention will be explained in detail by an embodiment thereof illustrated in the attached drawings. 
     In the following description, as an example, an electronic typewriter utilizing a so-called daisy wheel typefont wheel will be explained. 
     FIG. 1 shows the outline of the control circuit for use in the electronic printing apparatus of the present invention, wherein a keyboard 1 for entering characters, numerals and symbols to be printed is composed of a key matrix and is provided with character keys A-Z, numerals keys 0-9 and other function keys. The signals entered from said keyboard are supplied to a microprocessor (MPU) 2, which controls, through a printer driver 4, the amount of rotation of the daisy wheel typefont element provided in a printer 5 and the pressure of a printing hammer in order to achieve desired printing. The microprocessor 2 comprises a read-only memory ROM storing information for sequential control and a typing style table for converting the information relative to the species of the typefont element 9 to be entered from a typing style sensor 3 into information representing the typing style. The element 9 and sensor 3 are shown in at least one of FIGS. 2A and 2B. The microprocessor 2 also comprises a processing unit for data processing according to the information to be supplied from the read-only memory, registers for storing numerical data, adders for effecting the data processing and a control unit for effecting other controls. 
     In addition to the microprocessor 2, there is also is provided with a display control system composed of a character generator unit 6 and a display driver 7, whereby the character information entered from the keyboard 1 and transmitted by the microprocessor 2 is converted into dot information in a character generator of said character generator unit 6 and is displayed through the display driver 7 on a display unit 8 composed for example of a cathode ray tube or a liquid crystal display unit. 
     Furthermore the microprocessor 2 is connected to a sensor system provided with a typing style sensor 3 (FIG. 2B) for detecting the species of the typefont element and to cover a switch 14 (FIG. 3) for detecting the opening and closing of a cover that is opened and closed at the exchange of the typefont element as will be explained later. 
     FIGS. 2A and 2B show the daisy wheel typefont element 9 mentioned in the foregoing explanation and the method of element identification by the typing style sensor 3. 
     As shown in FIG. 2A the typefont element or unit 9 has a so-called daisy wheel structure in which a circular rim is provided with plural radial spokes made of a flexible material such as plastic material, and a printing type 9&#39; is integrally provided on the outer end of each of the spokes. On the rim of the typefont element 9 there is adhered a non-reflecting black tape 10 or the like, which is provided with cut-off portions mutually separated by an angle α representing the typing style or species of the typefont element 9. The angle α and the species of the typefont element may for example be related to each other in a manner shown in the following Table 1: 
     
                       TABLE 1______________________________________Angle (α)    Typing style______________________________________ 45°        Pica 90°        Elite135°        Greek characters180°        Italic.                   ..                   ..                   .______________________________________ 
    
     In the above-described example the angle α is selected as a multiple of 45° corresponding to each typing style, and the cut-off portions are detected, as shown in FIG. 2B, by a light emitted from a light source 3&#39; and received by a typing style sensor 3 composed for example of a CdS sensor. The above-explained table is stored, in the form of digital information, in the read-only memory of the microprocessor processor 2, whereby the microprocessor is capable of detecting the species of the typefont element 9. 
     FIG. 3 shows the structure of the cover switch 14 FIG. 3 is a schematic cross-sectional view of the electronic printing apparatus of the present invention, wherein the keyboard 1 is provided on an inclined upper face positioned at left closer to the operator. Beyond the keyboard there is provided a cover 12 which can be opened and closed for exchanging the typefont wheel 9 which is positioned facing a platen 16, and the cover switch 14 is provided inside the printing apparatus in such a manner as to be actuated by a projection 13 provided at the front end of said cover 12. In the present embodiment it is assumed that the switch 14 is closed when said cover is closed. 
     The function of the above-described embodiment will now be explained with reference to FIG. 4. 
     After the start of power supply to the apparatus, the microprocessor 2 reads, in a step S1, the angle α of the cut-off portions 10&#39; of the typefont wheel 9 and, in a step S2, identifies the species of the mounted typefont wheel 9 from the typing style table and supplies the obtained information to the character generator unit 6. 
     In a step S3 the microprocessor 2 checks the state of the cover switch 14, and, if it is turned on by the closed cover 12, enables key entry from the keyboard 1 in a step S5. In a subsequent step S6 the microprocessor 2 transmits the character information entered by the operator from the keyboard 1 to the character generator unit 6, which causes the display unit 8, which may be such as a cathode ray tube, to display the entered characters through the display drier 7 in a typing style such as pica or elite according to the typing style information previously sent from the microprocessor 2. 
     Consequently the operator can easily confirm the species of the mounted typefont element from the display on the display unit 8. 
     In case step S3 identifies the opened state of the over 12 indicating that the operator is exchanging the typefont element 9, key entry is not enabled and the program returns to the step S1 after the cover switch 14 is turned on by the closing of the cover 12 in a step S4. In the foregoing embodiment there is employed a display unit of a high resolving power such as a cathode ray tube, but in the case where a display unit is employed having a lower resolving power, not sufficient for displaying the typing style, such as a liquid crystal display unit, it is also possible to display the typing style of the mounted typefont wheel. This indication may be related to the number of dots displayed as shown in FIGS. 5A and 5B, wherein one dot on the displayed character indicates pica style while two dots on the displayed character indicated elite style. It is also possible, instead of changing the typing style displayed on the display unit, to indicate the typing style in a corner of the display unit or to display the typing style for example by indicator means provided on the keyboard. 
     Although the typefont element in the foregoing description is assumed to be of a so-called daisy wheel type, the present invention is naturally applicable also to other types of the typefont elements. 
     As explained in the foregoing, the present invention is featured by detecting means for detecting the species of the mounted typefont element and by changing the typing style or display mode on the display means to indicate the typing style of the mounted typefont element. The electronic printing apparatus of the present invention can therefore reliably inform the operator of the typing style of the mounted typefont element, thereby eliminating erroneous operation or trial printing operation which has been necessary with conventional electronic printing apparatus with interchangeable typefont elements.