JPS6311153B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to dot matrix printers, and more particularly to selectively varying dot density and print quality.

The quality or appearance of the characters depends on the smoothness of the outline of the characters as well as the high contrast (black/white) ratio between the characters and the print medium. When characters are formed on the media from a matrix of dots created by a wire matrix printing head and a ribbon, the contrast ratio is a function of dot density. The smoothness of a character's outline is a function of the overlap between dots, especially in the vertical direction.

U.S. Pat. No. 4,010,835 discloses a wire matrix printing head configured with two different printing arrays. In a first embodiment, the printing wire is arranged in two guides, one of which is movable vertically from the other which is held in a fixed position. In a second embodiment, the wires are disposed in a single wire guide that is rotatable about an axis parallel to the wires and perpendicular to the document. The print head moves horizontally from left to right across the lines of the document. Printing is performed by striking a plurality of selected wires. Each printing wire is provided with a separate actuator, and when the actuator is energized the associated printing wire is driven forward to strike the paper. Upon impact of the printing wire against the ribbon, a dot is printed at the selected location on the document. By energizing the combination of actuators corresponding to the selected character, the corresponding printing wire is pressed.

In the past, it has been common to manufacture single vertical wire row printing heads with a portion of the printing wire length bent. This bending creates long wire paths that are subject to breakage and wear. Replacing the wires in such heads is not easy. Also, arranging the wires diagonally rather than in a row array makes the print head relatively resistant to breakage.

U.S. Pat. No. 4,284,001 discloses a wire matrix printer having multiple printing heads with diagonally arranged wires. This arrangement allows the diagonal head to contain more than one character. The overlapping of the diagonal heads and dot character matrix complicates the relationship between the data points and the printed wire matrix.

U.S. Pat. No. 4,284,363 discloses a dot matrix tilted print head assembly in which the print head is rotatably mounted. The wires of the dot matrix printing head are actuated so that dots of a given center-to-center distance are printed on the recording medium while the printing head moves across the medium. To improve printing quality,
Further dots are inserted between previously printed dots by controlling the rotation of the dots.

It is an object of the present invention to selectively superimpose on the same print medium by the same character or part thereof offset in at least one direction, without the need to move the print medium or perform complex head rotations. The purpose of this technique is to change the density within the printed dot matrix characters by striking them.

A printer according to the invention includes a plurality of print heads arranged to print a position in a print line, each print head including a plurality of wires for printing dots spaced a given distance apart. The dots printed by the printing wires of the alternating printing heads (alternately along the length of the print line) are the same as the dots printed by the printing wires of the remaining printing heads (alternately along the length of the print line). It is positioned in the middle (along the direction perpendicular to the print line). A vertical displacement or offset between a pair of overstrike printing heads of half the distance of a character dot allows the printing of attractive dot matrix characters. For low dot density printing, a shift of half the distance of a character dot between two adjacent characters is not easily discernible by the human eye. The only mechanical movement required is preferably simultaneous horizontal movement of the printing heads as a group.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a system configuration including a host system 1 and a printer 2. As shown in FIG. printer 2
includes a control device 3 and an electronic logic device 4. Command and data signals are given from the host system 1 to the control device 3 via the bus 5. Command and control signals are provided from the printer controller 3 via the bus 6 to the electronic logic device (printer adapter) 4. The status signal is sent from the printer control device 3 to the bus 5.
The data is supplied to the host system 1 via. In a typical case, the host system 1 gives a series of commands and data to the printer 2 and monitors the situation. The control unit 3 receives commands, decodes them, checks for errors and generates status information. The control device 3 is
It also controls printing and spacing and includes local diagnostic equipment. Electronic logic unit 4 executes the decoded commands, monitors all print operations, activates print wires, drives motors, senses print emitters, and controls operator panel light and switching circuits. . electronic logic device 4
It also controls the tractor, ribbon drive, print head carrier, operator panel and printer sensors. Printer controller 3 and electronic logic 4 may include one or more microprocessors to interpret commands and data and regulate operation.

2 and 3 illustrate the components of the printer housed within console 10. FIG. Access panels or covers 11, 12 and 13 are provided to maintain a relatively clean environment.
Top cover 11 has a window 14 to allow an operator to observe paper path movement while the printer is operating when the cover is closed. The recording medium is paper 15. Paper 15 is obtained from a stored stack 16 and fed upwardly or downwardly across the paper path by a mechanical assembly 20 including one or more sets of tractors 90 and 91. After printing, guide 28 moves the paper to a collection stack (not shown) located below the printing mechanism and to the rear of console 10. The printer prints a print medium 1 at a printing station 32.
Printing assembly 30 arranged horizontally relative to 5
including. A printing ribbon assembly 40 is located close to the front of the printer. The printer control device 3 and its associated microprocessor are located behind the side cover 13.

Ribbon 41 is provided on one of spools 42 and 43. Each ribbon box has 4 ribbons
A disposable ribbon shoe 46 is attached to the spring mounting member 130 between the print assembly 30 and the print media 15 to maintain proper alignment of the print media 1 and to minimize ink contamination of the print media. It is preferable to include. ribbon 4
1 moves along a path in front of the printing head around columns 125, 126, 127 and 128. Two motors move ribbon 41 back and forth between spools 42 and 43. Printer control device 3
detects the ribbon jam and the end of the ribbon.
When a ribbon jam is detected, an error indicator is turned on and printing is stopped.

The printer includes an operator panel 26;
The panel includes several operator control keys, two indicator lights, a power on/off switch, an operator panel display, and a density indicator.

As shown in FIG.
0 includes four print wire groups, each group of nine print wires, and associated actuators (not shown). The four printing wire groups are designated printing heads H1, H2, H3 and H4, respectively. The nine wires of each print head include W1, W2, W3, W4, W5, W6,
Reference numerals W7, W8 and W9 are provided. Printing wires W1, W2, W3, W4 and W
5 are arranged along the first ramp from top to bottom, with adjacent print heads (printing wires) spaced 10.2 mm (0.40 inch) apart horizontally and 0.424 mm (0.0167 inch) apart vertically. ) separated. There can be any number of print heads, for example two, four or seven.

As shown in FIG. 5, a vertical or tilted matrix printer has two heads 541 arranged in a gang relationship such that each head is typically assigned a predetermined area along an entire print line. and 542. In this case, the gang relationship refers to a relationship in which a plurality of print heads (in this case, two heads 541 and 542) move in unison while maintaining a distance from each other, or a relationship in which they interlock. In low-density printing (low-density printing mode), gang heads 541 and 542 are positioned to the left of the first character to be printed and are the last in the line. It is moved incrementally from left to right until it is just to the right of the character to be printed. When the gang heads 541 and 542 are just to the right after the last character to be printed on that line, the gang heads 541 and 542 are actuated to move from right to left for printing the next line. .
Using more heads and areas increases printing speed. This is because the number of heads that are simultaneously energized over longer distances increases. In addition, in FIG. 5, HZ1 and HZ2 indicate the areas printed by the heads 541 and 542, respectively, BD indicates the boundary between the areas HZ1 and HZ2, and F
1 and F2 indicate the continuous and cut forms, respectively, and the HQZ of form F2 indicates the high density region.

FIG. 6 shows two adjacent printing heads printing one character each (thus both having low vertical density). Typically, the print heads have a horizontal separation HD1.
0.51mm (0.020 inch) vertical separation VD
1 prints dot matrix characters of 0.424 mm (0.0167 inch). The other heads are vertically displaced, and the total amount of displacement D is, in a typical case,
It is 0.212mm (0.00833 inch). This is half the dot character spacing. Figure 7 shows horizontal dot spacing
HD2 is 0.254mm (0.010 inch) and vertical dot spacing VD2 in vertical row is 0.212mm (0.00833 inch)
An example of high-density printing is shown below. If you are trying to print nice-looking characters from left to right, Gang
The heads are positioned so that the rightmost head is to the left of the first character. If the right-most head is vertically lower than the left-hand head, then the second or left-most head is vertically shifted downwards for each character position to display the same character and the same During sequential overstriking, the rightmost character, shown as "E" in FIG. 7, is formed first in the entire print line. Movement of the gang heads continues until the leftmost head is to the right of the last character at the right end of the line to be printed. The speed of printing good-looking characters in this way is 1/n of draft printing.
It is. n is the number of gang heads. In addition,
In FIGS. 6 and 7, BD indicates a boundary line.

Although gang relationships between heads are not essential, they may avoid the problem of maintaining data and position synchronization. The two printing heads arranged alternately are
The printing heads of one of them are horizontally aligned with each other so as to print dots between the dots previously printed by the other head.
The print head is controlled to print in two positions of the line in a high quality print mode (high density print mode) so that high quality dot matrix characters are printed. In draft mode (low density printing mode), the print head is controlled to produce coarse density printing.

As described above, each print line is divided into multiple regions, the print heads are assigned to the corresponding regions, the multiple print heads are placed in fixed positions vertically offset from each other, and each print head is High-density printing can then be achieved by striking the print medium in a corresponding area, and overstriking a specified position in another area with a predetermined character or a portion thereof.

The present invention provides that dots printed by a printing wire of a first printing head of a plurality of printing heads are located between dots printed by a printing wire of a second printing head of said plurality of printing heads. Since the first and second printing heads are arranged so as to be located at the same position, high-density printing can be easily performed with a simple configuration.

[Brief explanation of the drawing]

Figure 1 shows a dot matrix, which is an example of an object to which the present invention is applied. FIG. 2 is a perspective view of an example of a printer provided with a recording medium passage in relation to a print head mechanism; FIG. 3 is a front view of the printer of FIG. 2;
The figures are an explanatory diagram showing a printing block including four printing heads, each printing head having nine printing wires, FIG. 5 is a front view showing a recording medium divided into printing areas, and FIGS. 6 and 7. are explanatory diagrams showing examples of characters obtained as a result of low-density printing and high-density printing, respectively. H1, H2, H3, H4...printing head, W1,
W2, W3, W4, W5, W6, W7, W8, W
9...Printing wire, 541 and 542...Gang printing head.

Claims (1)

[Scope of Claims] 1. In a wire matrix printer in which a plurality of print heads are arranged along the longitudinal direction of a print line on a recording medium, the plurality of print heads cover the entire print line with the same number of print heads. When divided into areas, the dots allocated and arranged in each area and printed by the printing wire of every other print head are the remaining 1 dots.
The printing heads are arranged intermediately along a direction perpendicular to the printing rows of dots printed by the printing wires of alternating printing heads, each printing head having a corresponding one in the low density printing mode. 1. A wire matrix printer that prints only one area, and is controlled in a high-density printing mode to not only print one corresponding area but also to overprint other areas.