JP3044134B2 - Printing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to printing in a line direction (hereinafter referred to as "line printing") while moving a print head along a printing line (hereinafter referred to as "line"), and a recording medium such as paper. Alternatively, the present invention relates to a printing apparatus for performing predetermined printing on a recording medium by sequentially repeating line feeding for moving a print head in a direction perpendicular to the line direction (hereinafter, referred to as a line feeding direction).

[0002]

2. Description of the Related Art Conventionally, in a printing apparatus using a print head of an impact type, a thermal type, or an ink jet type, for example, a parameter such as an energizing voltage, an energizing current or an energizing time to the print head is changed. The print density of the print head is adjusted to obtain a desired print density.

[0003] Since a general printing apparatus obtains drive power from an outlet shared with various other electric devices, the voltage value of a power supply for driving the print head frequently fluctuates. Such a fluctuation of the power supply voltage sometimes becomes lower than a predetermined voltage value, so that printing with a desired density cannot be performed by the print head. Therefore, a technique is known which focuses on the fact that the print density changes due to the above-described change in the parameter value, and automatically compensates for the decrease in the print density due to the decrease in the power supply voltage. That is, the printing apparatus is provided with a detecting means for detecting the drop of the power supply voltage, and when the detecting means detects the voltage drop, the energizing time to the print head is made longer than usual to obtain a desired print density. is there. In some cases, instead of making the print head energizing time longer than usual, the energizing current to the print head per unit time is made longer than usual.

However, while being moved along the line,
A print head that is driven based on predetermined print data input according to the movement position and performs printing in the line direction;
In a printing apparatus using a so-called serial type print head, in order to make the energization time to the print head longer than usual, a means for generating a drive pulse having a pulse width commensurate with the increased energization time may be used. However, new complicated means and control such as a control means for moving the print head in the line direction at a speed corresponding to the longer energization time are required, so that the cost increases and the printing apparatus becomes expensive. Also, if the current supplied to the print head per unit time is to be larger than usual, the power supply of the printing device must be replaced with a large-capacity power supply, or a control means for controlling the current supplied is required. However, the cost increases and the printing apparatus becomes expensive. Furthermore, if it is possible to print with a longer energizing time than normal or an energizing current that is longer than normal in addition to the normal energizing time, the print head will have a plurality of different energizing times and Since it will be driven by the energizing current,
High durability is required for the print head.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a printing apparatus which can obtain a desired printing density simply and inexpensively even when a voltage for driving a printing head falls below a predetermined voltage value. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION The present invention provides a print head, print head transport means for moving the print head in a line direction, and temporarily storing at least one line of print data to be printed by the print head. A print buffer, print data sending means for sending the print data from the print buffer to the print head, print head driving means for driving the print head based on the print data sent by the print data sending means, A transport mechanism that relatively moves the print head or a recording medium on which printing is performed by the print head in the line feed direction, and a transport control unit that controls driving of the transport mechanism,
Print data updating means for updating print data in the print buffer; and print control means for activating the print head transport means, print data sending means, print head driving means, transport control means, and print data update means. In a printing device, one line of print data is stored in the print buffer.
Buffer determination means for determining whether or not data has been stored.
One before Symbol printing voltage for driving the head is provided a voltage drop detecting means for detecting that falls below a predetermined voltage value, said buffer determination means the print buffer provided with
If it is determined that print data for the line has been stored,
The print head is driven by a voltage drop detection unit.
Not detecting that the voltage has dropped below the specified voltage value
On the condition that the print control means sends the print data
Means, print head driving means, and conveyance control means are activated.
The print head prints one line,
When the voltage drop is detected by the voltage drop detecting means when the character head has completed printing for one line, the execution of the transport control means and print data updating means is temporarily suspended, and the print head transport means, Activating the data sending means and the print head driving means to duplicately print the same line with the same print data, and activating the transfer control means and the print data updating means which are in the execution pending state after the overlap printing. And

[0007]

According to the above configuration , the print head can be arranged in one line.
When the voltage for driving the print head when in partial printing is finished is ruled lower than the predetermined voltage value, and a recording medium or the print head line feed, such as paper by the conveyance mechanism, it is stored in the print buffer Since the same line is duplicated and printed with the same print data without updating the print data, a desired print density can be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an electrical block diagram of a wire dot printer according to an embodiment of the present invention. The wire dot printer has a CPU (central processing unit) 1 serving as a control unit main body. A ROM in which a program for the CPU 1 to control each unit is stored in advance.
(Read only memory) 2, RAM (random access memory) 3 in which various storage units for storing various data processed by the CPU 1 are formed, and drive control of the print head 4a is performed. A head controller 4, a head feeding means 5 for moving the print head 4a in the line direction, a paper conveyance means 6 as a conveyance mechanism for moving a recording medium such as a paper to be printed by the print head 4a in the line feed direction, the printing A power supply voltage detecting means 7 for detecting a voltage value V of a power supply for driving the head 4a, a communication interface 8 for receiving various data such as print data relating to printing from an external host device, etc.
It is interconnected with the CPU 1 via a bus line 9 such as a data bus and a control bus.

The head controller 4 is connected to a print head 4a having wires in which a plurality of pins are arranged at predetermined intervals in a line feed direction.

FIG. 2 is a memory map showing a storage section formed in the RAM 3, a print buffer 3a for temporarily storing at least one line to be printed by the print head 4a, and a power supply by the power supply voltage detecting means 7. The flag F1 is set to “1” when detecting that the voltage value V has dropped below the predetermined voltage value, and is reset to “0” when detecting that the power supply voltage value V is equal to or higher than the predetermined voltage value. A print head feed direction flag that stores a flag F2 that is set to "0" when the feed direction of the print head 4a with respect to the line direction is the forward direction and is set to "1" when the feed direction is the reverse direction. Area 3
c is formed.

FIG. 3 is an electric circuit diagram showing an example of the power supply voltage detecting means 7 and includes Zener diodes 10a and 10b.
And non-invert buffer gates 11a and 11b. Here, as shown in FIG. 4, the PFa signal output from the non-inverting buffer gate 11a is such that the voltage (power supply voltage) V input to the Zener diode 10a is equal to or greater than the Zener voltage value Va.
When the power supply voltage V input to the Zener diode 10a falls below the Zener voltage Va, the signal is output at the "L" level. Similarly, the PFb signal output from the non-inverting buffer gate 11b is set to “H” or “L” depending on the magnitude relationship between the power supply voltage V input to the zener diode 10b and the zener voltage Vb. Output at the level. In the present embodiment, the same west to the voltage value V ₀ of the Zener voltage value Va of the Zener diode 10a the print head 4a is printing inoperative, the zener diode 10b
The print head 4a of the Zener voltage value Vb of so that the same as the print guarantee voltage value V ₁ is the lowest voltage value obtained the desired print density at normal printing process, selects the Zener diode 10a and 10b ing.

FIG. 5 is a flowchart showing control of setting and resetting of the flag F1 performed by the CPU 1 in accordance with the PFa signal and the PFb signal output from the power supply voltage detecting means 7. First, a step (hereinafter, ST)
1), the non-invert buffer gate 11
Whether the power supply voltage value V is equal to or higher than the voltage value V ₀ at which the print head 4a cannot perform the printing operation by checking whether the PFa signal output from the “a” is “H” level or “L” level. It is determined whether or not. At this time, if the PFa signal is at the “L” level, the error processing is performed in ST2, and then this processing ends. In the above ST1,
When the PFa signal is at the “H” level, in ST3,
The PFb signal output from the non-invert buffer gate 11b is at "H" level or "L" level.
Look whether the level, the power supply voltage value V is determined whether a print guarantee voltage value V ₁ or more. At this time, if the PFb signal is at the "L" level, the flag F1 is set to "1" in ST4, and this processing ends. If the PFb signal is at the "H" level in ST3, the flag F1 is set to "O" in ST5, and this process ends.

FIG. 6 and FIG. 7 are diagrams for realizing the present invention.
FIG. 3 is a flowchart illustrating print control performed by the CPU 1. First, in ST6, it is determined whether or not print data is stored in the print buffer 3a. If not, the process waits until the print data is stored. Next, in ST7, it is determined whether or not the value V of the power supply voltage is equal to or higher than the voltage value V ₀ at which the printing operation is disabled, by determining whether the level of the PFa signal is “H” or “L”. Is determined by At this time, if the level of the PFa signal is “L”, ST
After performing error processing in step 8, this processing ends. If the level of the PFa signal is "H" in step ST7, the flag F2 in the print head feed direction flag area 3c is checked in step ST9, and the printing to be performed is forward printing (F2 = "0"). ) Or reverse printing (F2
= “1”).

At this time, if the flag F2 has been reset to "0", at ST10 the print buffer 3 is reset.
a in the forward direction to the head controller 4 and the head feed means 5
The print head 4a is moved in the forward direction to perform forward printing. Then, it is determined whether or not the forward printing is completed in ST11, and when the forward printing is completed, in ST12,
It is determined whether or not the forward printing is successfully performed, based on whether or not the flag F1 of the voltage drop flag area 3b is set to "1".

[0015] At this time, if the flag F1 has been set to "1", guaranteed power supply voltage V is printed voltage value V ₁
In step ST13, the print data stored in the print buffer 3a is sent to the head controller 4 in the reverse direction, and it is determined that the forward printing has not been properly performed. The print head 4a is moved in the reverse direction by the head feeding means 5 to perform reverse printing. Then, in ST14, it is determined whether or not the backward printing is completed.
In step 15, the print data stored in the print buffer 3a is updated, and in step ST16, the recording medium such as paper is fed by one line in the line feed direction by the paper transport means 6. If the flag F1 is not set to "1" in ST12, it is determined that the forward printing that has just been performed has been performed satisfactorily. In ST17, the print head feed direction flag area 3c is determined. The flag F2 is set to "1", and the process proceeds to ST15.

If the flag F2 of the print head feed direction flag area 3c is set to "1" in ST9, the print buffer 3a is set in ST18.
Is sent to the head controller 4 in the reverse direction, and the head feed means 5 moves the print head 4a in the reverse direction to perform reverse printing. In step ST19, it is determined whether or not the backward printing is completed. When the backward printing is completed, in step ST20, whether or not the backward printing is successfully performed is determined by checking the flag F1 of the voltage drop flag area 3b. The determination is made based on whether or not “1” is set.

At this time, if the flag F1 is set to "1", it is determined that the backward printing that has just been performed has not been performed satisfactorily, and in ST21, it is stored in the print buffer 3a. The print data is sent to the head controller 4 in the forward direction, and the print head 4a is moved in the forward direction by the head feed means 5,
Perform forward printing. In step ST22, it is determined whether or not the forward printing is completed.
Move to the processing of 15. In step ST20, the flag F1 is set.
Is not set to "1", it is determined that the reverse printing that has just been performed has been performed satisfactorily, and the flag F2 of the print head feed direction flag area 3c is reset to "0" in ST23. Then, the process proceeds to ST15.

In the embodiment having the above configuration, when print data relating to printing is transmitted from an external host device via the communication interface 8, the print data is stored in the print buffer 3a. When the voltage value V of the power supply for driving the print head 4a is equal to or higher than the voltage value V ₀ at which the printing operation is disabled, the forward printing or the reverse printing is performed according to the value of the flag F2 of the print head feed direction flag memory 3c. Dynamic printing is performed. Further, if the power supply voltage value V is lower than the print guarantee voltage value V ₁ when the forward printing or the backward printing is performed, a paper line feed by the paper conveying means 6 or The same line is repeatedly printed based on the same print data just printed, without updating the print data stored in the print buffer 3a.

Therefore, in this wire dot printer,
When the voltage value V of the power source for driving a print head 4a is lower than the print guarantee voltage value V _1, since the overlap printing the same line with the same print data, it is possible to obtain a desired print density. Then, complicated means and control for extending the energizing time to the print head 4a, or large-sized and large-capacity power supply for increasing the energizing current per unit time to the print head 4a and control for controlling the current value This can be achieved simply and inexpensively without the need for any means. In addition, since the print head performs printing with the same energizing time and energizing current value as in normal printing, it is possible to implement printing with a not so high durability.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the print head 4
The reciprocating printing method of performing line printing while reciprocating a along the line is shown. However, each time one line is printed, the printer returns to the home position and starts printing only from this home position. It may be applied to things. In the above-described embodiment, the transport mechanism for feeding the recording medium, that is, the recording medium, in the line feed direction by the sheet transport means 6 has been described. However, instead of the sheet transport means 6, the print head is moved in the line feed direction. May be applied. Further, in the above embodiment, the impact type is shown,
The present invention can also be implemented in a serial printer using a thermal or inkjet type serial print head. In addition, it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0021]

According to the present invention, the print head is used for one line.
When the voltage for driving the Printout head when printing is finished is ruled lower than the predetermined voltage value, and then, is overlapped printing the same line with the same printing data, one line's
The voltage value has dropped below the specified voltage value during printing of the minute
To reduce the efficiency of print control such as checking whether or not
It obtained inexpensively in a simple printing device capable of obtaining a Do processing print density Nozomu Tokoro also without the.

[Brief description of the drawings]

FIG. 1 is an electrical block diagram of a wire dot printer according to an embodiment of the present invention.

FIG. 2 is a diagram showing a print buffer 3a, a voltage drop flag area 3b, and a print head feed direction flag area 3c formed in a RAM 3 shown in FIG.

FIG. 3 is an electric circuit diagram showing an example of a power supply voltage detecting means 7 shown in FIG.

FIG. 4 is a diagram for explaining a method of detecting a power supply voltage in the power supply voltage detection means 7 shown in FIG.

FIG. 5 is a flowchart showing control of setting and resetting of a flag F1 performed by the CPU 1 shown in FIG. 1 to implement the present invention.

FIG. 6 is a flowchart (1) showing print control performed by the CPU 1 shown in FIG. 1 to implement the present invention.

FIG. 7 is a flowchart (2) showing print control performed by the CPU 1 shown in FIG. 1 to realize the present invention.

[Explanation of symbols]

1 CPU (print data transmission means, transport control means, print data update means, print control means) 2 ROM (print data transmission means, transport control means, print data update means, print control means) 3a print buffer 3b voltage drop flag area (Voltage drop detecting means) 4 Head controller (print head driving means) 4a Print head 5 Head feed means (print head transport means) 6 Paper transport means (transport mechanism) 7 Power supply voltage detecting means (voltage drop detecting means)

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ identification code FI B41J 19/18 B41J 3/12 P (58) Investigated field (Int.Cl. ⁷ , DB name) B41J 29/46 B41J 2 / 01 B41J 2/30 B41J 2/485 B41J 2/51 B41J 19/18

Claims (1)

(57) [Claims] A print head for moving the print head in a line direction; a print buffer for temporarily storing print data for at least one line printed by the print head; Print data sending means for sending the print data from the print buffer to the print head, print head driving means for driving the print head based on the print data sent by the print data sending means, and printing by the print head or the print head. Transport mechanism for relatively moving the recording medium in the line feed direction, transport control means for controlling the driving of the transport mechanism, print data updating means for updating print data in the print buffer, and printing Head transport means, print data sending means, print head driving means,
A printing device comprising: transport control means; and print control means for activating print data updating means.
Determines whether one line of print data has been stored in the
Provided a voltage drop detecting means for detecting that the voltage for driving the pre-Symbol printhead provided with a separate buffer determination means becomes lower than a predetermined voltage value, said buffer determination means
Stores print data for one line in the print buffer
If it is determined that the voltage has been detected,
The voltage for driving the print head drops below the specified voltage value
The print control procedure on the condition that no
The stage is the print data sending means, print head driving means,
Activate the conveyance control means and send one line to the print head.
The print head prints one line.
Upon detecting a drop in voltage by the previous SL voltage drop detecting means when the finished, while temporarily hold the execution of the transfer control means and print data updating means, the print head transport means, the printing data transmitting means and the print head drive Activate the means and duplicate the same line with the same print data,
A printing apparatus characterized in that, after the overlap printing, the conveyance control means and the print data updating means which are in the execution pending state are activated.