JPS5812763A - Recorder - Google Patents

Abstract

PURPOSE:To obtain a recorder capable of printing each letter at a fixed density in spite of a variation in the voltage of power source by using a system in which a quasi-load is given to the power source and electrifying time during printing is determined in the process in which spacing portion is provided when printing each letter. CONSTITUTION:The voltage of power source 6 is measured by a detector 7 by using a stepping motor 5 as a load during the moding of space, and the detected voltage value is digitally given to CPU 2. In the CPU 2, the detected value is stored in RAM 3, and in reference to dot patterns corresponding to printing codes stored in ROM 8, which is sent from a host computer 1 and acts as a character generator, the heating time of the head 9 is determined for every cycle by CPU 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing device that prints at a constant print density despite fluctuations in power supply voltage. The present invention relates to a printing device that corrects the accuracy of one character.

The print density of thermal type printers changes depending on the amount of heat generated by the dots. Therefore, in order to obtain uniform print density, it is necessary to keep the heating density per dot of the thermal head used constant. That is, the amount of heat generated per dot in the thermal head 'kW (mJ),
Resistance value kR (Ω).

Applied voltage kV (v), heating time? I-t (ms
ee) There is a point. For example, the resistance value of the head per dot is set to 11Ω, and the optimum heat generation value for each dot is set to 2.1Ω.
(mJ), it is necessary to satisfy the relationship shown in FIG. 1 between the voltage applied to the head and the heat generation time.

'By adding a circuit tray that reduces the electromotive force and lengthens the heat generation time to a thermal printer that uses dry battery noise as a power source, it is possible to keep the print density constant over a relatively long period of time. In order to control the print modesty to be completely constant, the applicant first measured the voltage applied to the head every time one line was printed, and calculated the optimum heat generation time for each measured voltage according to the graph shown in Fig. 1. We proposed a thermal printer that achieves uniform print density by fully controlling the voltage application time. That is, after one line of print code is sent from the host computer to the printer section of the thermal printer, a pseudo load having an impedance equal to the impedance of the thermal head is connected to the power source for -i m m s. Measure the source voltage under load 2, then,
The heat generation time is determined and printed in one line k consecutively Dj6. , for this thermal printer, one character f
When achieving the increment function of printing on σ, if the electromotive force of the battery decreases between the time when one character is printed and the time when the next character or the next character is printed, the heat generation time that has already been determined will be exceeded. Since printing is performed, the printing and N degree become thin. In addition, if a dry battery is placed under no load, the electromotive force will recover due to its self-recovery action, so 1
When printing is performed at intervals for each character, it may not be possible to keep the print density constant.

The present invention has the above disadvantages. The main purpose of the present invention is to solve each character (
In the process of creating spaces when printing (characters include printed information such as symbols, batons, etc.), a pseudo load is applied to all power supplies to determine the entire energizing time during printing, regardless of fluctuations in power supply voltage. First, we are proposing a printing device that can print each character at a constant density.

Note that the present invention is applicable not only to multi-needle electrostatic printers, multi-needle discharge breakdown printers, and multi-needle nozzle inkjet printers in which a plurality of printing elements connected in parallel are connected in series to a power supply, but also when a single printing element is connected in series to a power supply. The present invention can also be applied to a printing device for printing elements, but will be described in detail below based on an implementation applied to a thermal printer.

As shown in FIG. 2, reference number 1 is a host computer (HO8T) connected to the thermal printer, and receives a print command CPUPBr3 via a signal line Slk.

The excitation information of the pulse motor stored in the RAM section 3 according to the print command from the CPU Br3 storage computer 1 is changed to the next excitation information,
A signal is applied to the driver part 4 via the signal line S2', and the two phases of the motor part 5 are excited to create a space between the digits corresponding to one dot (the diagonal lines in the pulse motor drive half in Fig. 3). (see section). In this state, a pseudo load is applied to the power supply consisting of the dry battery 6, so CPUPBr3
At the same time, the battery voltage detection unit 7 (in this embodiment, a Bbit AD converter is used) is commanded to detect the battery voltage of the dry battery 6.

The battery voltage detection unit 7 determines the time period (2 to 3 m5ec in this embodiment) for the motor to stabilize in that phase after exciting the motor.
), then detect the voltage by averaging two or more sample values. The detected voltage value is digitized and provided to CPUPBr3 via signal line S3.

In the following, the case where the detected value is 5V will be described as column 6-. The CPU section 2 stores the detected value of 5 V in the RAM.
Store in section 3. Further, the CPU section 2 determines the heat generation time of the head for each cycle by referring to the dot pattern corresponding to the print code sent to the host computer 1 and stored in the ROM section 8 which acts as a character generator.

For example, when printing "C" in the first digit of the printing digit, the print code "'43#" is stored in the RAM section 6 as an ASCII code, so the code "43"
Based on this, the CPU section 2 refers to the dot pattern of the first cycle stored in the ROM section 7, that is, the dot pattern of "3E" in the case of a 1x7 head configuration with left-aligned printing for 'c'. At the same time, the number of dots that generate heat is determined in the same way.Then, the numerical value of the number of dots that generate heat is given to the CPU section 2, and the table of FIG. In the case of 3.OV
get.

Furthermore, the CPU section 2 is configured such that the voltage applied to the head is 3. O.V.
In order to determine the heat generation time when the head applied voltage 3. O.V.
Find the optimal heat generation time corresponding to . As a result of referring to the table, the optimal heat generation time when the head applied voltage is 3 and OV is 2.6 m5ec 't'h'), and this 2.6 m
A signal is continuously output to the driver part 4 via the signal line S4 so as to apply the power supply voltage of the dry battery 6 to the head part 9 for a period of 5 ec. After the heat generation time of 2.5 m5ec has elapsed, a signal is applied to the motor section 5 via the signal line S2 to cause the driver section 4 to advance the stamping motor. In this way, the two tables shown in FIG. 4 and FIG. 1 are sequentially referred to, and the heat generation time corresponding to the voltage applied to the head for each print cycle is determined to perform optimal print head control. Reference numeral DTI in Figure 3
DT7 is a print signal, and the pulse width of each print signal indicates the heat generation time determined from the table corresponding to FIG.

As shown in Figure 3, the characters ""C", "M" in each printing digit,
C" is printed in 5 cycles each. Printing of one digit is completed by a total of 7 cycles including 1 cycle for detecting battery voltage between digits and 1 cycle between digits in addition to these 5 cycles.

Note that in FIG. 4, Sφ1-8φ4 indicates a drive pulse given to the pulse motor.

The relationship between the number of dots that generate heat at the same time and the voltage change shown in FIG. 4 takes into consideration the characteristics that occur when a dry battery such as a manganese battery or an alkaline manganese battery is used as a power source. In other words, the voltage applied to the head decreases due to the saturation of the driver used as the electromotive force decreases, the IF decreases, the internal resistance r increases, and the load changes due to changes in the number of dots that generate heat at the same time. It is determined by considering characteristics such as change.

Note that the electromotive force of dry batteries is restored when the load is cut off. Furthermore, as the electromotive force decreases, the voltage recovered when the load is cut off increases, so the voltage when a pseudo load is applied is detected after the voltage has stabilized.

In the embodiments described above, the power supply voltage is measured using the stepping motor as a load during space movement, and in particular, an optimal configuration for avoiding power consumption for measurement has been shown. but,
Of course, instead of this configuration, a desired impedance element such as a resistor can be used as a pseudo load.

10- Also, although we have explained using a pulse motor as an example of a means for moving the thermal head and recording paper relative to each other to perform printing, it goes without saying that a DC motor, ratchet feed using a plunger, etc. can also be used. be. These moving means can also be used as pseudo loads.

Since the present invention is configured and operates as described above, non-uniformity in print density due to fluctuations in power supply voltage can be corrected for each print. Furthermore, since the voltage is detected during the space period between characters, it provides advantages such as no time loss.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the voltage applied to the head and the heat generation time. The second factor is a block diagram of a thermal printer showing one embodiment of the present invention. 311ii The valley of the thermal printer shown in FIG. 2 4 is a graph showing the relationship between the number of dots that generate heat at the same time and the voltage. Here, l...host computer, 2...CPL
JfR (, 5 - Motor section, 6... Dry 1 Pond, 7
...1! h voltage detection if (.Patent applicant: Canon Kyusi Company

Claims (1)

[Claims] A recording apparatus characterized in that the recording device is configured to detect a power supply voltage when the recording element moves in space, and to control the energization time to the recording element based on the detected power supply voltage during recording.