JPH01160652A - Dot printer - Google Patents

Abstract

PURPOSE:To make print sharp and uniformly stable, eliminate variable density irregularity and reduce the cost of a power supply by detecting duty per each dot of a printing pattern to be printed and driving a printing head pin depending on an excitation time after the correction corresponding to said duty. CONSTITUTION:A level detection circuit 2 detects a power supply voltage Vcc and reports it to a processor 4 through an input port 3. The processor 4 retrieves the first area 5a in a memory 5, selects an excitation time corresponding to a power supply voltage Vcc detected, then accumulates the time and calculates a printing duty by checking the dots of a character pattern to be printed from a line buffer 8. After this, the processor obtains a correction time based on a collation table and adds its correction value to the previously accumulated excitation time. Further, the processor sets an excitation time to be actually driven to a programmable timer and controls a pin excitation signal through a gate circuit 7. If an excitation time is set per dot in this way, print becomes sharp and uniformly stable and variable density disappears.

Description

[Detailed Description of the Invention] [Summary] An object of the present invention is to make dot printers used in computers and word processors capable of stably printing sharply, uniformly, and eliminating uneven shading (while also reducing the cost of power supplies). For the purpose of and a processor that drives the print head pins according to the excitation time.

[Industrial application field]

The present invention relates to a dot printer used for printing on computers and word processors, and more particularly to a dot printer in which the excitation time for driving the pinage of a print head pin is set in accordance with the duty of each dot.

[Conventional technology]

Conventionally, dot impact printers used in computers and word processors print characters and the like by driving print head pins.

FIG. 2 is a block diagram showing an example of a print head drive circuit in a conventional dot printer, and 1 at the bottom of the figure is a print head pin. The print hand pin 1 is constructed by connecting a coil 1a for driving a pinage and a flyback absorption circuit 1b in parallel, and connecting a transistor IC in series thereto.

When a pin excitation signal is input to the transistor IC, the print head pin 1 is driven by applying a power supply voltage Vcc to the coil 1a.

As shown in the upper part of the figure, the power supply voltage Vcc is determined by the level detection circuit 2 to set voltages Vl, V2 . It is checked by V3 before printing and is reported to processor 4 via input port 3. The memory 5 connected to the processor 4 includes:
A table of excitation time data suitable for each power supply voltage level is stored, and the processor 4 searches its memory 5, finds the excitation time corresponding to the detected power supply voltage Vcc, and sets it in the programmable timer 6. , gate circuit 7
The pin excitation signal is controlled by

[Problem that the invention seeks to solve]

However, in the above driving method, the detected power supply voltage Vcc is only the one immediately before printing, and the actual voltage rapidly attenuates and drops as the printing operation progresses. Of course, the excitation time is set in consideration of its decay, but the power consumption of the print head varies depending on the duty such as the character pattern to be printed, and the way the power supply voltage is dropped also differs depending on the print duty. will arise.

FIG. 3 is an explanatory diagram showing the relationship between the dot structure of a character pattern and printing duty. As shown in Figure 3, for example, when printing with 9 pins, the vertical bar portion of the character pattern “H” requires the most print head current and power supply voltage Vcc, while the horizontal bar requires the least amount of current and power supply voltage Vcc only for every other dot portion. , but almost no power supply voltage Vcc is required. Therefore, the printing duty is a numerical value as shown in the bottom row (in the case of 24 bins, the denominator of the numerical value is 24).

Conventional drive methods do not take these dot-by-dot differences into account, resulting in uneven print density and sometimes blurring, and to prevent this, it is necessary to provide a margin for the power supply voltage. There was also a waste of costs.

The present invention was devised in view of these problems, and it provides clear, uniform and stable printing, eliminates uneven shading, and
It is also an object of the present invention to provide a dot printer that can reduce the cost of power supply.

[Means for solving problems]

In the present invention, means for solving the above problems include: a level detection circuit that detects the power supply voltage level for driving the radbin to print; a memory that stores data on excitation times suitable for each power supply voltage level; A memory for storing correction data for an excitation time corresponding to a duty of a dot to be printed in a dot printer comprising a processor for selecting an excitation time corresponding to a detected power supply voltage level from the memory and controlling a radbin for printing. and a processor that detects a duty for each dot of a character pattern to be printed and drives a print head pin according to the excitation time after making corrections corresponding to the duty.

[Effect]

In the present invention, empirical correction data for the excitation time corresponding to the duty of the dots to be printed is stored in memory, and the processor selects each dot to be printed from a line buffer for developing a character pattern. The print head pin is driven by the excitation time after detecting the duty for each duty and making corrections corresponding to the duty. Conventionally, the print head pin was driven only for the excitation time corresponding to the voltage level immediately before printing was started. However, in the present invention, the duty of a character pattern or the like to be printed is calculated, and the excitation time is corrected in relation to the immediately preceding voltage level to perform printing.

〔Example〕

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

FIG. 1 is a configuration diagram showing an embodiment of the present invention, in which the print head pin 1 and its power supply voltage Vcc are substantially similar to the conventional example.
Set voltage V1. V2. A level detection circuit 2 that checks before printing by V3, an input port 3 for the detected value,
It is composed of a processor 4, a memory 5 attached to the processor 4, a programmable timer 6 connected to the processor 4, and a gate circuit 7 to which a pin excitation signal is input. A line buffer 8 that temporarily stores a character pattern read from a character generator (not shown) is connected to the processor 4, and the pin excitation signal is selected according to the character pattern in the line buffer 8, and the programmable timer It passes through the gate circuit 7 for only the excitation time set to 6.

The memory 5 includes a first area 5a that stores a table of suitable excitation time data for each power supply voltage level, and a second area 5b that stores excitation time correction data corresponding to the duty of each dot to be printed. It is equipped with

Table 1 below is an example of a comparison table of power supply voltage Vcc and print head excitation time stored in the first area 5a in the memory 5.

Table 1: Print head excitation time versus power supply voltage (Vcc) Table 2 below is an example of a comparison table of correction times corresponding to print duties stored in the second area 5b in the memory 5.

Of course, the correction time for the second table printing duty may be set as a separate memory in a separate IC.

In the printing operation in the above-mentioned apparatus, first, the level detection circuit 2 detects the power supply voltage Vcc, and reports the detected value to the processor 4 via the input port 3. processor 4
searches the first area 5a in the memory 5 and selects the excitation time corresponding to the detected power supply voltage Vcc. For example, if the power supply voltage VCC is 24V, and using the comparison table in Table 1, the suitable excitation time is 200V.
μs, which is stored and stored.

Next, the processor 4 looks at the dots of the character pattern to be printed from the line buffer 8 and calculates the print duty shown in FIG. From the comparison table in the table, the correction time is 20 μs.

Therefore, the processor 4 adds the correction value to the previously accumulated excitation time to obtain bin excitation time = 200μs + 20μs = 220μs.
The pin excitation time to be actually driven is set in the programmable timer 6, and the pin excitation signal is controlled by the gate circuit 7. By setting the excitation time for each dot in this manner, the printing will be clear, uniform, and stable, and unevenness in density will be eliminated.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to stabilize printing clearly and uniformly, eliminate uneven shading, and at the same time, it is possible to change the correction value depending on the performance of the power supply, so it is also possible to reduce the cost of the power supply. It is possible to provide a dot printer with a wide range of colors.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention, Figure 2 is a configuration diagram of a conventional example. FIG. 3 is an explanatory diagram of printing duty. 1; Print head pin, 2; Level detection circuit 2. 4; processor; 5; Memory, 5b; memory area for storing correction time; 6; Programmable timer, 8; Line buffer.

Claims (1)

[Claims] A level detection circuit (2) that detects a power supply voltage level that drives the print head pin (1), a memory (5) that stores data on an excitation time suitable for each power supply voltage level, In the dot printer, the dot printer is equipped with a processor (4) that selects an excitation time corresponding to the power supply voltage level from the memory (5) and controls the print head pin (1), the excitation time corresponding to the duty of the dot to be printed. The print head pin (1) is driven by the excitation time after detecting the duty for each dot of the character pattern to be printed and making the correction corresponding to the duty. A dot printer characterized by comprising a processor (4).