Typewriting machines – Carriage or carriage-moving or movement-regulating mechanism – For varying carriage feed
Patent
1986-10-30
1987-08-25
Burr, Edgar S.
Typewriting machines
Carriage or carriage-moving or movement-regulating mechanism
For varying carriage feed
400279, 400299, 400320, 400322, B41J 1958
Patent
active
046889566
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a serial printer in which a carriage is moved by a stepping motor or servo motor parallel to a platen, and more particularly to a printing control system for such a printer to enable duplex printing.
BACKGROUND ART
Conventionally, in a serial printer which actuates a printing means after the carriage is displaced and stopped, printing can be performed based on the letter data of one line and feed data between the letters.
For example, the printing data for "I am" consists of letter data "I", space data, space data, letter data "a", space data, and letter data "m".
As shown, printing is performed after a space data command, i.e. displacement of the carriage. However, as the carriage has inertia, damped oscillation is produced after stopping instant S of the drive means, in the form of a stepping motor, of the carriage, as shown in FIG. 1. The oscillation of the carriage is damped sufficiently by waiting a long settling time T.sub.1 after the timing S. Thus, when printing is performed after waiting this long settling time, the printing position is correct. As the time T.sub.1 is long, printing is ordinarily performed after a time T.sub.0 which is shorter than the time T.sub.1 and some deviation in the printing position is ignored. Thus, the printing speed is increased.
In such a system, problems are produced in bold print which prints the same letter by space data zero shown in FIG. 3B and in shadow print which prints the same letter by very small space data shown in FIG. 4B. In bold print, as shown in FIG. 1, first printing is performed at timing A.sub.1 after the instant S during which the drive means stops, and the second printing is performed at timing A.sub.2 which is time T.sub.1 after the timing S. Thus, the print position of the second printing is accurate as the timing A.sub.2 is sufficiently long with respect to the damped oscillation of the carriage.
In the shadow print, first printing is performed at timing B.sub.1 shown in FIG. 2, after time T.sub.0 from drive means stopping instant S, and the carriage is displaced by the necessary pitch P. Then after long settling mode time T.sub.2 which is sufficiently long for the oscillation of the carriage to be damped, second printing is performed at timing B.sub.2.
In these cases of bold print and shadow print, the second print positions are obtained accurately in the proper positions.
However, the first timing A.sub.1, B.sub.1 of the first printing is the ordinary printing timing, i.e., after time T.sub.0 from S, so that, as shown in FIGS. 1 and 2, the first printing position deviates by the dimension .DELTA.P from its proper position D. Thus, the second print position is accurately in alignment with the proper position, but, nevertheless, as shown in FIG. 3C, the printed bold print is not duplexed properly and the first and second prints deviate by .DELTA.P from each other. Also, in the shadow print, as shown in FIG. 4C, the first and second prints vary by a distance P.sub.1 which is vider than the intended pitch P or by a distance narrower than the intended pitch P. Therefore, they have had this fault to lead to the printing of unbecoming letters.
SUMMARY OF THE INVENTION
The object of the present invention is to eliminate the above-mentioned disadvantage.
The printing control method for a printer in this invention includes the duplex printing of bold prints and shadow prints precisely by controlling the first printing thereof such that it is effected only after sufficient damping of the carriage oscillation has taken place.
BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 is a time chart for the printing of bold printing in a conventional printer;
FIG. 2 is a time chart for the printing of shadow printing in a conventional printer;
FIGS. 3A-3C are images of bold print;
FIGS. 4A-4C are images of shadow print;
FIG. 5 is a schematic perspective view of a printer;
FIG. 6 is a block diagram of a control circuit according to the present invention;
FIG. 7 is a control flow chart of the central process unit s
REFERENCES:
patent: 4493570 (1985-01-01), Araki
patent: 4502800 (1985-03-01), Jamieson et al.
"Bold Image Typing"; C. G. Brown; IBM Technical Disclosure Bulletin; vol. 20, No. 9, pp. 3555-3556; Feb. 1978.
Burr Edgar S.
Tokyo Juki Industrial Co. Ltd.
Wiecking David A.
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