JP2932606B2 - Printing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a dot matrix type printing apparatus, and more particularly, to thinning out a part of continuous dots in a basic dot pattern, and appropriately setting the remaining dots. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus capable of printing at a speed higher than a response frequency of a print head by performing printing at a proper printing timing while minimizing deterioration of print quality.

(Prior Art) Conventionally, in a dot matrix type printing apparatus, the printing speed of continuous dots is determined by the response frequency of the print head, and thus the printing speed of the printing apparatus is determined by the printing speed of continuous dots. Therefore, when increasing the printing speed as a printing device, it is common to print at 1.5 times or 2 times the basic printing speed by thinning out continuous dots in the horizontal direction in the printing dot pattern. Had been done.

(Problems to be Solved by the Invention) However, when the printing speed is increased by simply thinning out the continuous dots in the horizontal direction as described above, since many dots constituting the printing dot pattern are reduced, the printing is performed. There was a problem that the quality was greatly reduced.

Therefore, in the present invention, every third dot among the continuous dots in the horizontal direction in the basic dot pattern is thinned out, and when printing is performed using the dot pattern, the printing timing of the continuous dots is appropriately shifted from the basic printing timing. It is a technical problem to be solved to increase the printing speed without significantly deteriorating the printing quality by printing.

(Means for Solving the Problems) The technical means for solving the above problems include a printing head,
Moving means for moving the printing head relative to the printing medium in the row direction; driving means for driving the print head; storage means for storing a predetermined basic dot pattern; After reading a basic dot pattern corresponding to data from the storage means and creating a dot pattern for printing from the basic dot pattern,
A printing apparatus having print control means for printing on the print medium by controlling the moving means and the drive means in accordance with the dot pattern for printing is searched for the basic dot pattern for each dot row. A dot pattern changing means for creating a printing dot pattern by thinning out every third dot of the continuous dots when there is a continuous dot in the horizontal direction;
And a print timing generating means for generating a second print timing having a cycle shifted by a half cycle from the cycle of the first print timing, and a printing dot pattern created by the dot pattern changing means. At the time of printing, a configuration is provided which includes a print timing selecting means for printing at a second print timing which is shifted by a half cycle from the first print timing at which one of the continuous dots should be originally printed. is there.

(Operation) According to the printing apparatus having the above-described configuration, the dot pattern changing unit searches the basic dot pattern corresponding to the input data from the outside for each dot row, and when there is a continuous dot in the horizontal direction, the A dot pattern is created by thinning out every third dot of consecutive dots. Then, when printing the dot pattern, the print timing selecting means
Uniform dot printing is realized by printing one dot of the continuous dots at the second printing timing which is shifted by a half cycle from the first printing timing which should originally be printed, and prevents a significant decrease in printing quality. I do.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an electrical configuration of a printing apparatus according to the present invention.

The printing device 1 is of a serial impact dot matrix type, and is configured with a printing mechanism unit 3 and an electronic control unit 5 as main components.

The printing mechanism 3 includes a print head 7 mounted on a carriage (not shown), a stepping motor (hereinafter, referred to as a CR motor) 9 for driving the carriage, and a stepping motor (hereinafter, referred to as a CR motor) for driving a platen (not shown). LF
Motor 11). Since the mechanical configuration of the printing mechanism 3 is well known, the details are omitted.

The print head 7 includes a plurality of dot wires (not shown) and a plurality of solenoids 13 that drive each dot wire in the printing direction. Each solenoid 13 is energized and controlled by a print head drive circuit 42 in the electronic control unit 5. Is done.

The electronic control unit 5 includes a CPU 32, a ROM 34, a RAM 36, a font ROM
38 and an input / output circuit 40, which are connected to each other by a common bus 30. The input / output circuit 40 is connected to a print head control circuit 42, a CR motor drive circuit 44, an LF motor drive circuit 46, and a thinning circuit 50 to be described later.

Further, the electronic control unit 5 includes a thinning circuit 50 connected to the data bus 30a in the common bus 30 and a control line (not shown), and a thinning circuit connected to the address bus 30b and a control line (not shown). Data bus through 50
An image buffer 52 connected to 30c is provided.

The font ROM 38 stores basic dot patterns corresponding to various characters and figures. For example, if the basic dot pattern is a “24 × 24” matrix, 3
The font ROM 38 is composed of one character (figure) dot pattern data consisting of one line of data in 24 bytes and one character in bytes.
Is stored in a predetermined area.

The print head control circuit 42 includes a print head drive control circuit 54
And an energizing circuit 56, each energizing circuit 56 having a solenoid.
13 comprises a power transistor 56a for supplying a drive current to the drive transistor 13 and a NOR gate 56b connected to the base terminal of the power transistor 56a. The print head drive control circuit 54, based on the timing signal Sti from the input / output circuit 40, sends a print control signal from the image buffer 52 to a print step described later from the image buffer 52 every time the print head 7 moves in the print direction in synchronization with the rotation of the CR motor 9. The dot pattern data is read, and a dot recording signal Sd (logic L) is output to the NOR gate 56b according to the dot pattern data for printing.

The energization circuit 56 is configured to supply an energization command signal EN (logic L) input from the input / output circuit 40 to one input terminal T1 of the NOR gate 56b.
The solenoid 13 is selectively energized for a predetermined time for each step of moving the print head 7 in the printing direction based on the dot recording signal Sd (logic L) input from the image buffer 52 to the other input terminal T2. Dots are printed, and characters and figures are printed in a dot matrix of a predetermined size by conducting a predetermined number of times of energization accompanying this moving step. The CR motor drive circuit 44 outputs a pulse signal output from the input / output circuit 40.
Power is supplied to each phase of the CR motor 9 in a predetermined sequence in synchronization with Spc. The LF motor drive circuit 46 also drives the LF motor 11 based on the pulse signal Sp1 output from the input / output circuit 40.

Next, the thinning circuit 50 will be described with reference to FIG.

The thinning circuit 50 shown in FIG. 2 is a circuit for thinning out every third dot when there is a horizontally continuous dot in the dot pattern data read from the font ROM 38.

As shown in FIG. 2, the thinning circuit 50 includes a well-known shift register 70, a D-type flip-flop 71, and a logic element 7.
The circuit units 50a to 50h composed of 2,73
The number of gate arrays provided is the same as the number of 30a (for example, 8). In each of the circuit units 50a to 50h, the data (Do
~ D7), if three consecutive dot data are inputted, the dot data for the third dot is skipped from the AND gate 72 to the image buffer 52. Is output to

Next, a print control circuit in the print head drive control circuit 54 will be described with reference to FIG.

This print control circuit is provided with the same number of circuits as the NOR gate 56b so as to output a drive pulse signal of logic L (the dot recording signal Sd) to each of the NOR gates 56b.

As shown in FIG. 3, the print control circuit inputs the print dot pattern data read from the image buffer 52, and outputs a print clock signal (PRC) from the CPU 32.
LK), and stores a shift register 81 for storing and shifting the printing dot pattern data, AND gates 82, 83, 84 and a NOT gate 85 connected to the shift register 81, and AND gates 82 and 84 And a drive pulse generator 87 connected to the selector 86, and a drive pulse connected to the output terminal of the AND gate 83. It is configured using a generating circuit 88 and an AND gate 89 connected to the output terminals of the driving pulse generating circuits 87 and 88, respectively.

The selector circuit 86 selects a signal from the AND gate 82 when the direction signal from the CPU 32 is logic H, the CR motor 9 is rotated forward, and the carriage moves from left to right, while the signal from the CPU 32 is selected. When the direction signal is logic L, the signal from the AND gate 84 is selected.

The drive pulse generating circuit 87 outputs a print timing signal A from the CPU 32 for printing at a basic print timing (for example, at a 1/180 inch pitch, which corresponds to the first print timing described in the claims). When done
Based on a signal from the AND gate 82 or a signal from the AND gate 84, a pulse signal of logic L for driving the solenoid 13 is output. On the other hand, the drive pulse generating circuit 88 outputs a print timing signal B from the CPU 32 for printing at a print timing shifted by a half cycle from the basic print timing (corresponding to the second print timing described in the claims). When this is done, a pulse signal of logic L for driving the solenoid 13 is output based on the signal from the AND gate 83.

When an AND gate 89 connected to the output terminals of the drive pulse generation circuits 87 and 88 receives the pulse signal of logic L from one of the drive pulse generation circuits 87 and 88, the AND gate 89 inputs the signal and outputs a logic signal. An L drive pulse signal is output. The signal (dot recording signal Sd) output from the AND gate 89 is applied to the input terminal of the NOR gate 55b shown in FIG.

4 and 5 are timing charts of the print control circuit shown in FIG.

FIG. 4 shows a timing chart when dots are printed in the process of moving the carriage from left to right (positive direction). FIG. 5 is a timing chart for printing dots in the process of moving the carriage from right to left (reverse direction).

In FIG. 4, after the printing dot pattern data (hereinafter referred to as printing data) D1 and D2 are input in a continuous state from the image buffer 52 to the shift register 81, non-printing data is input. When the print data D3 and D4 are input in a continuous state, the shift register 81 stores the print data D1 and D2 in synchronization with the print clock signal PRCLK from the CPU 32, and further stores the print data D3 and D4.
And shifts as the print clock signal PRCLK is input, and the signals output from the shift 1 terminal, shift 2 terminal, and shift 3 terminal are sequentially shifted as shown in the figure. In this case, the direction signal is logic H, and the selector circuit 86 selects a circuit so that the output signal of the AND gate 82 is input to the drive pulse generation circuit 87, and outputs the logic signal from the AND gate 82. It is connected so as to be applied to the drive pulse generation circuit 87. On the other hand, a logic signal from the AND gate 83 is input to the drive pulse generation circuit 88. When the direction signal is logic H, that is, when the moving direction of the carriage is the forward direction, the output signal of the AND gate 84 is cut off by the selector circuit 86.

The print timing signal A and the print timing signal B output from the CPU 32 are logic L pulse signals as shown in FIG. 4, and when the carriage moves in the forward direction, the drive pulse generation circuit 87 Print timing signal A
The gate 89 and the AND gate 82
The output signal is transmitted. The drive pulse generating circuit 88 transmits the output signal of the AND gate 83 to the AND gate 89 in synchronization with the fall of the print timing signal B. When a logical L signal is output from one or both of the driving pulse generating circuits 87 and 88, the AND gate 89 outputs a logical L driving pulse signal (dot recording signal Sd) to the NOR gate 56b. is there.

FIG. 5 is a timing chart of the print control circuit when the carriage moves in the reverse direction.

From the image buffer 52 to the shift register 81, after the print data D4 and D3 are input in a continuous state, non-print data is input, and thereafter, the print data D2 and Dl
Are input in a continuous state, the shift register 81
The print data D4 and D3 are stored in synchronization with the print clock signal PRCLK from the CPU 32, the print data D2 and Dl are further stored, and the shift is performed as the print clock signal PRCLK is input. The signals output from the terminal and the shift 3 terminal are sequentially shifted as shown in the figure.

When the moving direction of the carriage is the reverse direction, the direction signal is logic L, and the selector circuit 86 selects a circuit to input the output signal of the AND gate 84 to the drive pulse generation circuit 87, The connection is made so that the logic signal from the AND gate 84 is applied to the drive pulse generation circuit 87. On the other hand, a logic signal from the AND gate 83 is input to the drive pulse generation circuit 88.

The drive pulse generation circuit 87 transmits the output signal of the AND gate 84 to the gate 89 in synchronization with the fall of the print timing signal A. The drive pulse generating circuit 88 transmits the output signal of the AND gate 83 to the gate 89 in synchronization with the fall of the print timing signal B. When a logical L signal is output from one or both of the driving pulse generating circuits 87 and 88, the gate 89 outputs a logical L driving pulse to the NOR gate 56b.

FIG. 6 shows that when the carriage moves in the forward direction and there is a continuous dot in the horizontal direction in the dot pattern data read from the font ROM 38, every third dot is skipped by the thinning circuit 50. After being pulled,
FIG. 4 is an operation explanatory diagram showing that dot printing is appropriately performed at print timing A and print timing B by passing print dot data stored in an image buffer 52 through a print control circuit shown in FIG.

The left drawing of FIG. 6 shows a dot pattern in which black dots are thinned out by the thinning circuit 50 from the dot pattern read from the font ROM 38, and white circles show dots to be printed. The right drawing shows that the leading dot of the continuous dot is printed in synchronization with the printing timing A and the subsequent dot is printed in synchronization with the printing timing B so that the dot interval to be printed is uniform. Things. By performing such control, printing can be performed at a speed higher than the printing speed at the time of continuous printing at the basic printing timing. When the moving direction of the carriage is reverse, the leading dot of the continuous dot is Since the printing is performed in synchronization with the printing timing B and the subsequent dots are printed in synchronization with the printing timing A, the printing timing A is also used in bidirectional printing.
And the dot printed at the print timing B do not change in position.

(Effects of the Invention) As described above, according to the present invention, when a basic dot pattern corresponding to input data from the outside is searched for every dot row, and there is a continuous dot in the horizontal direction, the continuous dot is detected. After thinning out every third dot of the dots, one of the continuous dots is printed at a second printing timing which is shifted by a half cycle from the first printing timing which should be originally printed, so that the printing quality is improved. There is an effect that printing can be performed at a speed higher than the printing speed at the time of continuous printing at the basic printing timing without dropping.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, FIG. 2 is a circuit diagram of a thinning circuit, FIG. 3 is a circuit diagram of a print control circuit, and FIGS. FIG. 6 is a timing chart of the print control circuit, and FIG. 1: printing device, 3: printing mechanism, 5: electronic control unit, 7: print head, 32: CPU, 38: font ROM, 50: thinning circuit, 52: image buffer, 54: print head drive control circuit

Claims (1)

(57) [Claims] 1. A print head, moving means for moving the print head in a row direction relative to a print medium, drive means for driving the print head, and a predetermined basic dot pattern stored therein. A storage means, and a basic dot pattern corresponding to externally input data is read from the storage means, a printing dot pattern is created from the basic dot pattern, and then the moving means is moved in accordance with the printing dot pattern. And printing control means for printing on the printing medium by controlling the driving means, in the case where there is a continuous dot in the horizontal direction by searching the basic dot pattern for each dot row, A dot pattern changing means for creating a dot pattern for printing by thinning out every third dot of the continuous dots; A first print timing as ring,
A print timing generating means for generating a second print timing having a cycle shifted by a half cycle from the cycle of the first print timing; and when printing the print dot pattern created by the dot pattern changing means, A printing timing selecting means for printing at a second printing timing which is shifted by a half cycle from the first printing timing at which one of the continuous dots is to be originally printed.