JPH0118871B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image recording method, and in particular controls the energization time to the recording element during the next image recording according to the detected power supply voltage value. The present invention relates to an image recording method for recording images.

[Prior Art] Recording is performed by driving a recording element with a power source. For example, the print density of a thermal type printer changes depending on the amount of heat generated by a dot. Therefore, in order to obtain uniform print density, it is necessary to keep the amount of heat generated per dot of the thermal head used constant. That is, the amount of heat generated per dot in the thermal head is W (mJ), the resistance value is R (Ω),
The applied voltage is V (v), and the heat generation time is t (msec).
Then, it is necessary to keep the calorific value W (mJ)=V ² /Rt constant. For example, if the resistance value of the head per dot is 11Ω, and the optimum heat generation amount for each dot is 2.1 (mJ), the relationship shown in Figure 1 is satisfied between the voltage applied to the head and the heat generation time. There is a need. In a thermal printer that uses dry batteries as a power source, printing density can be kept constant for a relatively long period of time by adding a circuit that lowers the electromotive force and lengthens the heat generation time.

Japanese Patent Laid-Open No. 55-5883 discloses this type of prior art, in which a thermal printing machine using a heating head connected to a DC power source detects voltage fluctuations in the DC power source, and uses this detection signal to energize the heating element. A method of driving a heating element is disclosed in which the time is controlled according to voltage fluctuations of a DC power source. However, since this method does not apply a pseudo load, voltage fluctuations in the DC power supply are detected by using an operational amplifier based on the difference between the power supply voltage and the reference voltage, or by using an operational amplifier and a nonlinear element. It must be detected by the difference between the power supply voltage and the reference voltage. This has the disadvantage of complicating the circuit configuration.

[Problem to be Solved by the Invention] The present invention is proposed to solve the disadvantages of the prior art, and its purpose is to apply a pseudo load to the power supply while driving the head moving motor. The object of the present invention is to propose an image recording method that can control the energization time to the recording element with a simple circuit configuration that only detects the power supply voltage given as .

[Means for Solving the Problems] In order to achieve the above object, the image recording method of the present invention records an image by energizing the recording element from a power source, and the head provided with the recording element is moved. the motor is driven prior to image recording, and while the motor is being driven, the motor is applied to the power source as a pseudo load to detect the voltage of the power source, and the voltage of the power source is detected. The object of the present invention is to perform image recording by controlling the energization time to the recording element during the next image recording according to the power supply voltage.

[Operation] In the above configuration, while the motor for moving the head is being driven, the motor is applied to the power supply as a pseudo load, and the power supply voltage at this time is detected.
The power supply time to the recording element is controlled during the next image recording according to the detected power supply voltage value.

[Example] Hereinafter, a typical example of the present invention will be described in detail with reference to the accompanying drawings.

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. The present invention can also be applied to a single printing element printing device, but will be described in detail below based on an embodiment applied to a thermal printer.

In addition, in the embodiment described below, when printing each character (characters include printing information such as symbols and patterns), in the process of creating a space part, the motor is applied as a pseudo load to the power supply. It determines the energization time and allows each character to be printed at a constant density regardless of fluctuations in power supply voltage, and non-uniformity in print density due to fluctuations in power supply voltage can be corrected for each print. Moreover, since the voltage is detected during the space period between characters, it is possible to obtain effects such as no time loss.

As shown in FIG. 2, reference numeral 1 is a host computer (HOST) connected to the thermal printer, which provides a print command to the CPU unit 2 via a signal line S1. The CPU section 2 receives a print instruction from the host computer 1 to print data to the RAM section 3.
The excitation information of the pulse motor stored in is changed to the next excitation information, a signal is given to the driver section 4 via the signal line S2, two phases of the motor section 5 are excited, and a space corresponding to one dot is generated. (See the slope part in the pulse motor drive pulse in Figure 3). In this state, a pseudo load is applied to the power supply consisting of the dry cell battery 6, so the CPU section 2 simultaneously detects the battery voltage detection section 7 (in this embodiment, the 8bit AD
(using a converter) to detect the battery voltage of the dry battery 6. After exciting the motor, the battery voltage detection unit 7 waits for the motor to stabilize in that phase (2 to 3 msec in this embodiment), and then calculates the voltage based on the average of two or more sample values. To detect. The detected voltage value is digitized and sent to the signal line S.
3 to the CPU section 2.

In addition, the case where the detected value is 5V will be explained below as an example. CPU part 2 stores the detected value 5V in RAM
Store in section 3. It is also sent from the host computer 1 and acts as a character generator.
The heat generation time of the head is determined by referring to the dot pattern corresponding to the print code stored in the ROM section 8.
The CPU section 2 determines each cycle.

For example, when printing "C" in the first column of a print line, the print code "43" is stored in the RAM section 6 as an ASCII code, so based on this code "43", 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 1 x 7 head configuration with left-aligned printing for "C", and also refers to the dot pattern of "3E" that generates heat in the same way. Find the number of. After that, the numerical value of the number of dots that generate heat is given to the CPU section 2, and by referring to the table (voltage change depending on the number of dots that generate heat at the same time) shown in FIG. If
Get 3.0V.

Furthermore, the CPU section 2 is configured so that the voltage applied to the head is
To determine the heat generation time when the voltage is 3.0V, refer to the table in FIG. 1 that shows the heat generation time for the voltage applied to the head stored in the CPU section 2.
Find the optimal heating time corresponding to the head applied voltage of 3.0V. As a result of referring to the table, the optimum heat generation time when the voltage applied to the head is 3.0V is 2.6 msec.
A signal continues to be output to the driver section 4 via the signal line S4 so as to apply the battery voltage of . 2.6msec
After the heat generation time has elapsed, a signal is given to the motor section 5 via the signal line S2 in order to cause the driver section 4 to move the stepping 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 symbols DT1 to DT7 in FIG. 3 are print signals, 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 letter “C” in each printing digit,
"M" and "C" are printed in 5 cycles each. In addition, printing of one digit is completed by a total of seven cycles including these five cycles, a cycle for inter-digit + battery voltage detection, and one cycle for inter-digit.

In FIG. 4, Sφ1 to Sφ4 indicate drive pulses 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, it takes into account characteristics such as a decrease in the saturation voltage of the driver used due to a decrease in electromotive force, an increase in internal resistance r, and changes in the voltage applied to the head due to load fluctuations due to changes in the number of dots that generate heat at the same time. determined.

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 a stepping motor that is moving in space as a load, and in particular, an optimal configuration for avoiding power consumption for measurement has been shown.

Furthermore, although a pulse motor has been described as an example of a means for moving the thermal head and recording paper relative to each other for printing, it goes without saying that a DC motor or the like can also be used. These moving means can also be used as pseudo loads.

[Effects of the Invention] As explained above, according to the present invention, while the head moving motor is being driven, the motor is applied to the power supply as a pseudo load to measure the power supply voltage, and in the next step, the energization time corresponding to this measured value is determined. Since the recording element is energized by the recording element, it is possible to provide a recording method that obtains good image density using a simple circuit configuration.

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between the voltage applied to the head and the heat generation time, Fig. 2 is a block diagram of a thermal printer showing an embodiment of the present invention, and Fig. 3 is a diagram of the thermal printer shown in Fig. 2. A time chart showing the temporal relationship of each part. Figure 4 is a graph showing the relationship between the number of dots that generate heat at the same time and the voltage. Here, 1... host computer, 2...
CPU section, 5...Motor section, 6...Dry battery, 7...
...Battery voltage detection section.

Claims (1)

[Claims] 1. An image recording method for recording an image by energizing a recording element from a power source, comprising a motor for moving a head provided with the recording element, and prior to image recording, the motor is activated. and, while the motor is being driven, apply the motor to the power source as a pseudo load, detect the voltage of the power source, and energize the recording element during the next image recording according to the detected power source voltage. An image recording method characterized in that image recording is performed by controlling energization time.