Image forming method for dot matrix printer

• US 4,622,561 A
• Filed: 04/05/1985
• Issued: 11/11/1986
• Est. Priority Date: 04/10/1984
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Koike, Takahisa
• Primary Examiner(s): MILLER JR, GEORGE
• Application Number:
  US06/720,273
• Time in Patent Office: 585 Days
• Field of Search: 346/1.1, 346/75, 358/296, 358/300
• US Class Current: 347/41
• CPC Class Codes: G06K 15/107 Mask selection
• CPC Class Codes: G06K 2215/0094 Colour printing
• CPC Class Codes: H04N 1/128 using a scanning head arranged for linear reciprocating motion
• CPC Class Codes: H04N 1/1911 Simultaneously or substantially simultaneously scanning picture elements on more than one main scanning line, e.g. scanning in swaths
• CPC Class Codes: H04N 1/1915 with subscan displacement of the array between successive scans
• CPC Class Codes: H04N 1/50 Picture reproducers for halftone screening H04N1/52
• CPC Class Codes: H04N 2201/0414 Scanning an image in a series of overlapping zones

Abstract

An image forming method for a color dot matrix printer prevents image quality from being deteriorated at the boundary between two nearby image areas which are developed by consecutive main scans. A paper is fed in a subscan direction by an amount which is one half of the width of a plurality of deflection steps, which is covered by one main scan, thereby developing an overlapping print area. The overlapping print area is subdivided at desired one of the deflection steps either column by column or color by color, an image segment in each of the resulting subregions being printed out by one of consecutive main scans.

Claims

1. An image forming method for a ink jet printer which prints out dots in a recording medium over a plurality of steps in a subscan direction by moving recording head means in a main scan direction relative to the recording medium and, every time a main scan completes, feeds the recording medium in the subscan direction relative to the recording head means, said image forming method comprising the steps of:

(a) providing mutually overlapping print areas during at least two consecutive main scans by selecting an amount of feed which is one half the width of the print line of the recording medim in the subscan direction;

(b) subdividing an overlapping region of the print areas into a plurality of subregions; and

(c) determining by which one of main scans performed by the recording head means each of the subregions should be printed out;

whereby a boundary portion between the nearby print areas each being provided by a main scan is free from deterioration of image quality.

2. An image forming method as claimed in claim 1, wherein step (b) comprises (d) subdividing the overlapping region of the print areas column by column at a predetermined step.

3. An image forming method as claimed in claim 2, wherein step (d) comprises (e) randomly selecting the predetermined step column by column.

4. An image forming method as claimed in claim 2, wherein step (d) comprises (e) selecting the predetermined step such that the overlapping portion of the print areas includes a predetermined pattern defined by boundary portions of the respective columns which originate from the dubdivision.