GB1604577A

GB1604577A - Coded printing element and apparatus for use thereof

Info

Publication number: GB1604577A
Application number: GB23094/78A
Authority: GB
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1977-09-14
Filing date: 1978-05-26
Publication date: 1981-12-09
Also published as: DE2834662A1; CA1096802A; MX4736E; BE870431A; CH637064A5; BR7804857A; FR2403192B1; IT1099016B; CH639601A5; NL7809327A; DE2834662C2; FR2403192A1; IT7825983A0; JPS5446617A

Abstract

The printing mechanism comprises a printing element having a number of types and a coded region (26) in order to identify the design and the orientation of the printing element. A sensor scans the coding, and the output of the sensor is used to control the spacing between the characters and the force of the hammer with which the hammer strikes against the types. The printing element is constructed as a daisywheel, the individual types being held at the end of a multiplicity of radially extending spokes, thus resulting in a substantially circular arrangement. The coded region (26), which identifies the printing element (10) and its alignment, is arranged with spacing from the circular type arrangement in a substantially curved manner which lies concentrically to the circular arrangement of the types. In the printing mechanism comprising such a printing element, both the spacing between the individual characters and the striking force of the hammer are adjusted automatically in accordance with the printing element used in each case. <IMAGE>

Description

(54) CODED PRINTING ELEMENT AND APPARATUS FOR USE THEREOF (71) We, EXXON RESEARCH AND ENGINEERING COMPANY, a Corporation duly organised and existing under the laws of the State of Delaware, United States of America, of Linden, New Jersey, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: Background of the invention This invention relates to printing elements and more particularly, to printing elements of the type utilized in serial impact printers.

The printing elements in serial impact printers comprise a plurality of characters which are sequentially moved to the printing position on a copy medium. The printing element is forced into contact with a marking or inking medium which in turn contacts the copy medium by appropriate means such as a solenoid-actuated hammer. In many applications, as for example typewriters, the printing elements regardless bf their form are interchangeable so as to permit various fonts (e.g., fonts for foreign languages) to be utilized in connection with the same apparatus. In addition to changing the printing elements, the printing apparatus may be appropriately adjusted so as to change the strike force, commonly referred to as hammer strength, as well as the spacing between the various characters.In addition, the number of characters on a character element may change requiring the printing apparatus to function differently with different printing elements.

A daisy-type printing element of the kind described above is disclosed in U. S. patent 4,018,639. As shown therein, the character elements are located at the ends of a plurality of radially extending beams which are centrally supported at a hub. However, such print elements do not include any code or indicia which could be machine-sensed so as to automatically prepare the printing apparatus to appropriately respond to the particular printing elements. Instead, the printing elements require the operator to appropriately identify indicia in the printing element so that the operator may appropriately prepare the printing apparatus for the particular printing element.

U. S. patent 3,498,439 does disclose coded disc for use in connection with a character element for automatically preparing the printing apparatus to perform in predetermined modes. However, no code is carried by the character element.

U. S. patent 3,949,853 discloses the use of mechanical keying to assure that the daisy-like printing element is mounted in a predetermined orientation with respect to the drive shaft.

U.S. patent 3,651,916 - Becchi discloses a system for sensing a reference datum or home position.

Summary of the invention It is an object of this invention to provide a printing element which includes a coded area which may be sensed by the printing apparatus.

It is a further object of this invention to provide a printing apparatus which automatically responds to the coded area.

The invention disclosed herein is a printing system comprising a print element having support means, a plurality of print characters mounted on said support means in a character array adapted to be moved to and from a print position, a coded area on said support means containing information for identifying operational characteristics of the particular print element; drive means coupled to said print element for moving said characters to and from said print position; sensor means associated with said print element for sensing said information contained in said coded area; and print control means including a first memory portion for storing operational information different from said information for identifying operational characteristics for said printing system and further including code storage means coupled to said sensor means for storing said information contained in said coded area and for controlling said printing system in response to the combination of said information stored in said code storage means and said first memory portion.

In a particularly preferred embodiment of this invention, the printing element comprises a character wheel including a hub and a plurality of beams extending radially outwardly from the hub. The character elements are located at and supported by the radial outer extremities of the beams in a substantially circular array so as to permit the character to be rotated through a circular path to and from the print position. The coded area may lie outside the circular path and preferably radially inwardly therefrom.

In the preferred embodiment of the invention, the coded area comprises a series of open and closed spaces providing a binary code. The first and second spaces are always open to establish a true home position. The third space is coded to indicate whether the printing element is special or regular. The fourth, fifth and sixth spaces beyond the third space are coded to represent information for controlling spacing between character elements. The seventh space is coded so as to represent the number of characters and the eighth and ninth spaces are coded to represent the impact force applied by the hammer. A tenth space is closed and an eleventh space is always open to indicate a false home position or improper printing element orientation.

Description of the drawings Figure 1 is a plan view of a daisy-type printing element embodying the invention; Figure 2 is an enlarged view of a portion of the printing element of Figure 1; Figure 3 is a block diagram of a section of a printing apparatus which reads and stores the data encoded on the printing element of Figures 1 and 2; Figure 4 is a block diagram of a section of a printing apparatus which controls the printing of the printing apparatus in response to the data encoded on the printing elements of Figures 1 and 2; Figure 5 is a detailed schematic diagram of the components of blocks shown in Figure 3; Figure 6 is a detailed schematic diagram of the components of blocks shown in Figure 4; Figure 7 is a flow chart for a microprocessor utilized in reading and storing the data encoded on the printing elements of Figures 1 and 2; and Figures 8a and 8b are flow charts for a microprocessor for controlling the printing in response to the data encoded on the printing elements of Figures 1 and 2.

Detailed description of preferred embodiments Referring to Figure 1, a printing element comprises a daisy-like wheel 10 including a central hub 12 and a plurality of beams 14 extending radially outwardly from the hub 12.

Each of the beams 14 is termmated in a character slug 16 having a character element raised thereon for use in serial impact printing.

In accordance with the description contained in U.S. Patent No. 4,198,582 and Belgian Patent No. 868,402, the hub 12 comprises a plurality of discrete rotor elements 18 which are circumferentially spaced about the hub 12. The rotor elements 18 function in conjunction with the stator structure of a rotary stepper motor so as to drive the wheel 10 from character position to character position during serial impact printing.

The wheel 10 includes a handle 2 extending radially outwardly from the hub 12. In accordance with the description contained in Belgian Patent No. 870,432, the handle 20 includes a plurality of circumferentially spaced openings 22 which are maintained in the same relative relationship as the spaces 24 between the beams 14. The openings 22 allow the position of the wheel 10 to be determined in all wheel orientations even when the handle 20 is juxtaposed to the appropriate sensor.

The wheel 10 includes a coded area 26 comprising a series of open and closed spaces 28 which form a binary code. More particularly, the coded area 26 comprises a series of eleven open and closed spaces as best shown in Figure 2 which are located near the periphery of the hub 12 adjacent the handle 20.

The following table sets forth the code utilized in the coded area 26 at the various spaces 28: Space Code Function i open home position ii open home position iii open or closed special or regular print wheel iv open or closed spacing between characters v open or closed spacing between characters vi open or closed dead characters present or absent vii open or closed number of characters viii open or closed hammer strength ix open or closed hammer strength x closed false home position xi open false home position From the foregoing table, it will be understood that each of the spaces or positions i-xi includes binary coded information in the form of an open or closed space which provides information to the printing apparatus for control of that apparatus in responsive to the coded information.In a particularly preferred embodiment of the invention, where an open space corresponds to a binary 0 and a closed space corresponds to a binary 1, the following code is utilized: Space Code Function iii 0 special print wheel 1 regular print wheel iv and v 00 unused 01 12 pitch wheel (12 characters per inch) 10 10 pitch wheel (10 characters per inch) 11 proportional spaced wheel vi 0 "dead key" characters present on wheel 1 no "dead key" characters on wheel vii 0 92 character wheel 1 98 character wheel viii and ix 00 increase strength two increments 01 increase hammer strength one increment 10 use nominal hammer strength 11 decrease hammer strength one increment x 0 homing error (e.g., wheel mounted back wards) 1 no homing error As an aid to visually identifying the coded information, operator readable indicia 30 corresponding with the coded information at the area 26 are provided on the wheel 10. The indicia 30 which is located radially inwardly from the coded area 26 and the handle 20 may be in various forms including a hexadecimal number matching the binary word encoded at the area 26. As shown in Figures 1 and 2, the wheel 10 comprises a handle 20 and 92 character elements displaced from the handle and leaving a character void at the handle 20.

In a 98 character wheel constructed in accordance with this invention, the handle 20 is eliminated and replaced by beams having character elements at the ends thereof.

Reference will now be made to Figure 3 wherein circuitry is shown in block form which performs the homing function for the wheel 10 while storing the coded information on the wheel 10 which is located at the area 26. The system includes an on/off control 50 which automatically places the system in the homing state. When the system is placed in the homing state, pulses from a homing clock 52 are applied to a wheel advance circuit 54 which is coupled to the stator 56 of the motor which drives the wheel 10. As the wheel 10 is stepped around, a wheel code sensor 58 optically scans the radial position of the wheel 10 in which the coded area 26 is located.

A code locator circuit 60 is responsive to the output from the wheel code sensor 58 to properly locate the coded area 26. Once the code area 26 has been properly located by the locator circuit 60, the binary information at each of the spaces iii-x are loaded into code storage in response to a code storage control circuit 64 such that outputs III-X of the code storage 62 represents the information stored in the spaces iii-x.

The various outputs IV-IX of the code storage 62 are utilized to control the hammer strength and character spacing as shown in Figure 4. More particularly, a hammer control circuit 66 is responsive to outputs VII-IX of the code storage 62 and character information stored in a memory 68 which is accessed in response to character position information.

Similarly, the space between the characters which will be governed by linear movement of a carriage for the wheel 10 is controlled in response to a space control circuit 70 which is responsive to the code storage outputs IV-VI and character position information from the memory 68.

Output III is utilized to indicate that the machine can operate in its normal mode if a regular print wheel is indicated or that a special print wheel is present and the machine must be operated in a different mode to accommodate the special print wheel. Output X is utilised to indicate a homing or orientation error, i.e., the wheel 10 is in backwards.

The homing operation performed by the circuitry shown in Figure 3 will now be described in greater detail with reference to the specific components of the circuit as shown in Figure 5.

The on/off control circuit 50 comprises a one-shot multivibrator 72, a flip-flop 74 and a delay circuit 76. When the positive edge of an ON signal, which is initiated in response to the application of AC power, a cover closure or an off-on switch, is applied to the single shot 72, the flip-flop 74 is set in the home state. The output from the flip-flop 74 is then applied to the delay circuit 76 so as to initiate the homing sequence after a slight settling delay. The output from the one-shot 72 also clears the counters and registers of the wheel advance circuit 54, the code locator circuit 60 and the code storage control 64.

The output from the delay circuit 76 enables an AND gate 78 of the clock circuit 52 so as to pass clock pulses from a source 80 to the wheel advance circuit 54, the code locator circuit 60 and the code storage circuit 62. As the rotor formed by the wheel 10 advances in a predetermined direction (clockwise as viewed from Figures 1 and 2) in response to the clock pulses supplied to the counter 82 of the wheel advance circuit 54, the output from the wheel code sensor 58 is applied to a previously cleared shift register 84 of the code locator circuit 60. When eight filled spaces have been sensed by the wheel code sensor 58 in a row and the corresponding input has been applied to the register 84, an AND gate 86 is enabled which sets a flip-flop 88 having an output applied to an AND gate 90 of the storage control circuit 64.With the AND gate 90 enabled, the first open space detected by the wheel code sensor 58 will produce an output from the NOR gate 92 and enable the AND gate 90 at clock pulse time. The detection of this open space enables the AND gate 90 so as to apply pulses to the load counter 94 of the code storage control 64.

As the counter 94 is advanced in response to each subsequent clock pulse, the output of the counter 94 is decoded at a decoder 96 having outputs applied to AND gates 98 which are sequentially enabled so as to permit the sequential outputs from the wheel code sensor 58 to be stored in D-type flip-flops 100 of the code storage circuit 62 after inversion at an inverter 102. The flip-flops 100 which store the states for spaces III-X are sequentially strobed by the code storage control circuit 64 as the appropriate spaces pass the point of optical communication with the wheel code sensor 58.Once the counter 94 reaches a count of ten which is arrived at after space X has reached a point of optical communication with the wheel code sensor 58, the counter resets the home state flip-flop 74 which inhibits the clock 52 thereby locking in the states of the flip-flops 100 which represent the coded information at spaces III-X. No strobing by the decoder 96 occurs during the first two counts of the counter 94 when the spaces i and ii are in optical communication with the wheel code sensor 58.

With the homing sequence completed and the code information stored, the printing operation may begin unless a homing error has occurred. In this connection, it will be understood that if the wheel 10 is mounted backwards, the flip-flop 100 having the X output will be 0 since the tenth position which will be in optical communication with the sensor 58 will actually be the ii space which is open. Only when the wheel 10 is in the proper orientation, ie., forwards, will the X output be 1 corresponding to the closed x space. If the X output is 1, the printing operation may now begin as will now be described in detail with reference to Figure 6.

The memory 68 comprises a ROM 104 which is accessed in response to a character position inputs. The output from the ROM 104 is used by the hammer control 66 and the space control 70. The hammer control circuit 66 comprises four AND gates 106 which are selectively enabled to achieve four levels of hammer strength or inhibited when a 92 character wheel is utilized rather than a 98 character wheel. The hammer strength for the individual characters as determined by the ROM 104 is combined with the incremental hammer strength as determined by a digital multiplexer 108 which is responsive to outputs VIII and IX at an adder 110. The appropriate gate is then enabled to provide the desired hammer strength.

The gates 106 are inhibited in response to output VII of the appropriate flip-flop 100 in Figure 5. In this connection, the output VII is applied to an OR gate 112 having an output which remains high where the wheel 10 has been sensed as having 98 characters so as to continuously enable the AND gates 106. Where the output VII is low, a comparator 114 provides a high output to enable the gates 106 only as long as the character position applied to the comparator 114 corresponds to one of the 92 character elements on the 92 character wheel 10. When the character position corresponds to positions 93-98, the output of the comparator will go low so as to inhibit the hammer when the wheel 10 is in these positions.

The space control circuit 70 as shown in Figure 6 also comprises a plurality of AND gates 116 which are selectively enabled in response to the output from a digital multiplexer 118 and outputs IV and V. The outputs IV and V are capable of selecting proportional outputs for each character which is stored in the ROM 104 or a constant output corresponding to 12 pitch and 10 pitch print respectively. Output VI which is applied to a NAND gate 120 is capable of selectively inhibiting the linear movement of the wheel 10 so as to inhibit spacing when dead keys are struck. In this connection, a character position is compared with predetermined dead keys corresponding to, for example, the diacritical marks "\", "/", and " " at ,,, at comparators 122. The outputs from the comparators 122 are applied to the NAND gate 120 through an OR gate 124.As long as the VI output remains low, the output of the NAND gate 120 is necessarily high so as to enable the AND gates 116. However, when the VI output goes low and the wheel 10 is in a character position corresponding to a dead key as determined by the comparators 122, the output from the NAND gate 120 goes low so as to inhibit spacing between character strikes.

Although no circuitry utilizing the X output has been shown and described, it will be understood that this output may be utilized to sound an alarm indicating that there is a homing error.

In the embodiments of Figures 5 and 6, homing and printing has been controlled by discrete components. However, it is possible to perform the same control utilizing a microprocessor. Reference will now be made to the flow chart of Figures 7 and 8 for a description of a particular use of a microprocessor.

The initial wheel position is established as zero (200) and the count of closed spaces is also initially set at zero (202). The print wheel 10 is then advanced (204) to determine if the space juxtaposed to the optical sensor, i.e., wheel sense, (206) is open or closed. If the space is closed, loop 208 is entered and the closed count is supplemented by 1 (210).

Counting of closed spaces continues as provided by loop 208 until the count of closed spaces equals 8 (212). If, however, an open space is sensed in the wheel at any time (206) prior to the time that the count of consecutive closed spaces equals 8, loop 214 will reset the count of closed spaces to zero.

After a count of closed spaces equal to 8 (212) is achieved, the wheel continued to be advanced (216) searching for the first open space. This search for the first open space continues in loop 218 until such time as the first open space in the wheel corresponding to a binary 1 is sensed (220). The index is then set at 1 corresponding to coded space 1(222).

The wheel 10 is continually advanced (224) in loop 226 with the index increasing by one (228) as long as the index is less than 9 (230). As the wheel is advanced in loop 226, the wheel sense is input to storage. With the coded information now in storage and the wheel 10 in the home position, printing may proceed as will now be described with reference to the flow chart of Figure 8a.

During printing, the selected characters input to the hammer strength is first determined by accessing hammer strength for the particular character of a hammer table and memory (232). The stored state of space VIII is then determined (234). If the state of space VIII is 0 and the state of space IX is also 0, the hammer strength will be incremented by 2 (238). If the state of space IX is not 0, the hammer strength will be incremented by 1 (240).

Similarly, if the state of space VIII is not 0, (234), the hammer strength will be diminished by one increment or remain the same depending upon the state of space IX (244).

Where the particular character to be printed is not in a position greater than 92 (246), the previously determined hammer strength is applied to the hammer (248). If the character position is greater than 92 (246), the state of space VII is determined (250). If the state of space VII is 0 indicating a 92 character wheel, the hammer strength is set at 0 (252) to inhibit impact with the character element. On the other hand, if the state of space VII is not 0 (250), the previously determined hammer strength is output and applied to the hammer (248).

The space between characters is now determined by controlling the motion of the wheel 10 relative to the print point. Initially, the state of the space IV is determined (254). If the state is 1, the state of the space V must then be determined (256). If the state of the space V is 1, the linear motion is proportional to the characters. If the state of the space V is not 1, a motion output of 6 corresponding to 12 characters per inch result (258).

If the state of position IV is not 1 and the state of the space V is determined to be 1 (260), a motion of 5 corresponding to 10 characters per inch (262) is output.

It is now necessary to determine if the particular character is a dead key, i.e., no spacing or linear motion should be produced. Referring to Figure 8b and beginning with an index equal to 1 (264), if the dead keys index equals the particular character (266) then it must be determined if the state of space VI is zero. If the state of space VI is 0 (268) indicating that the motion of the wheel 10 is inhibited (270), there is no motion output for the wheel (272).

On the other hand, if the state of the position of VI is not equal to 0, i.e., there are no dead keys, the previously determined motion is output.

If the dead keys initial index does not correspond to the character input (266), the index is successively increased by 1(272) as long as the index is less than 4 (274) in a loop 276.

When the index reaches 4 indicating that a particular character does not correspond to a dead key, the previously determined motion is utilized as the output.

The foregoing invention may be embodied in the serial impact printer described in U.S.

Patent No. 4,149,808 and Belgian Patent No. 868,402, both of which are assigned to the assignee of this invention. In addition, details concerning the manner in which the spaces I-XI may be sensed are set forth in Belgian Patent No. 870,432 which is also assigned to the assignee of this invention.

It will be understood that different codes may be substituted to achieve different objectives. For example, it is possible to eliminate hammer strength coding. It is also possible to add coding which will indicate character substitutions and/or relocations, as for example, commas and periods as well as other characters on the wheel.

Although preferred embodiments of the invention have been shown and described, it will be understood that other embodiments which will appear to those of ordinary skill in the art do fall within the scope of the invention as set forth in the appended claims.

WHAT WE CLAIM IS: 1. A printing system comprising: a print element having support means, a plurality of print characters mounted on said support means in a character array adapted to be moved to and from a print position, a coded area on said support means containing information for identifying operational characteristics of the particular print element; drive means coupled to said print element for moving said characters to and from said print position; sensor means associated with said print element for sensing said information contained in said coded area; and print control means including a first memory portion for storing operational information different from said information for identifying operational characteristics for said printing system and further including code storage means coupled to said sensor means for storing said information contained in said coded area and for controlling said printing system in response to the combination of said information stored in said code storage means and said first memory portion.

2. A system according to claim 1 wherein said print element comprises a character wheel, said support means including a hub and a plurality of beams extending radially outwardly from said hub, said character elements being supported by the radial outer extremities of said beams in a substantially circular array so as to permit said character elements to be rotated through a circular path to and from said print position.

3. A system according to claim 2 wherein said encoded area lies outside said circular path.

4. A system according to claim 2 wherein said encoded area lies radially inwardly from said circular path.

5. A system according to claim 2 wherein said encoded area is located on said hub.

6. A system according to any of the preceding claims wherein said print system comprises means for moving a copy medium relative to said print element, said print control means controlling the increment and movement of said copy medium relative to said print element in response to the coded area sensed by the sensor means.

7. A system according to claim 6 wherein said print control means inhibits said movement for selected characters of said print element in response to the coded area sensed by the sensor means.

8. A system according to claim 7 wherein said print system comprises impact means adapted to force said print character into contact with a copy medium, said print control means controlling said force in response to the coded area sensed by the sensor means.

9. A system according to claim 8 wherein said print control means inhibits said force in response to the coded area sensed by the sensor means for certain void positions in said array.

10. A system according to claim 2 wherein said encoded area comprises a plurality of open and closed spaces arranged in an arcuate pattern concentric with said circular array.

11. The printing system of claim 10 wherein said printing element comprises a handle portion extending radially outwardly from said hub between two of said beams, said encoded area being located radially inwardly from said handle portion.

12. The printing system of claim 10 wherein said encoded area comprises at least one

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. or linear motion should be produced. Referring to Figure 8b and beginning with an index equal to 1 (264), if the dead keys index equals the particular character (266) then it must be determined if the state of space VI is zero. If the state of space VI is 0 (268) indicating that the motion of the wheel 10 is inhibited (270), there is no motion output for the wheel (272). On the other hand, if the state of the position of VI is not equal to 0, i.e., there are no dead keys, the previously determined motion is output. If the dead keys initial index does not correspond to the character input (266), the index is successively increased by 1(272) as long as the index is less than 4 (274) in a loop 276. When the index reaches 4 indicating that a particular character does not correspond to a dead key, the previously determined motion is utilized as the output. The foregoing invention may be embodied in the serial impact printer described in U.S. Patent No. 4,149,808 and Belgian Patent No. 868,402, both of which are assigned to the assignee of this invention. In addition, details concerning the manner in which the spaces I-XI may be sensed are set forth in Belgian Patent No. 870,432 which is also assigned to the assignee of this invention. It will be understood that different codes may be substituted to achieve different objectives. For example, it is possible to eliminate hammer strength coding. It is also possible to add coding which will indicate character substitutions and/or relocations, as for example, commas and periods as well as other characters on the wheel. Although preferred embodiments of the invention have been shown and described, it will be understood that other embodiments which will appear to those of ordinary skill in the art do fall within the scope of the invention as set forth in the appended claims. WHAT WE CLAIM IS:

1. A printing system comprising: a print element having support means, a plurality of print characters mounted on said support means in a character array adapted to be moved to and from a print position, a coded area on said support means containing information for identifying operational characteristics of the particular print element; drive means coupled to said print element for moving said characters to and from said print position; sensor means associated with said print element for sensing said information contained in said coded area; and print control means including a first memory portion for storing operational information different from said information for identifying operational characteristics for said printing system and further including code storage means coupled to said sensor means for storing said information contained in said coded area and for controlling said printing system in response to the combination of said information stored in said code storage means and said first memory portion.

opening extending through said hub and at least one solid space adjacent said opening for forming a binary code.

13. The printing system of any of claims 10 to 12 further comprising means for moving a copy medium relative to said print element for spacing the printed characters and impact means adapted to force said printed characters into contact with said copy medium.

14. The printing system of claim 10 wherein said encoded area comprises a series of closed and open spaces in said hub, said spaces comprising a first open space, a secon open space, a third space, a fourth space coded to represent information for controlling the movement of the character element relative to the copy medium, a fifth space coded to represent information relating to the movement of the character element relative to the copy medium, a sixth space coded to represent information relating to the movement of the character element relative to the copy medium, a seventh space coded to represent the number of characters on the wheel, an eighth space coded to represent the impact force with which the character element is struck, a ninth space coded to represent the impact force with which the character is struck, a tenth space coded to represent proper homing, and an eleventh open space.

15. A printing system according to claim 1 substantially as hereinbefore described with reference to the drawings.