JPS61181664A - Recorder - Google Patents

Abstract

PURPOSE:To permit recording to be made at fixed density all the time by determining the driving time of a recording head according to the temperarure- recording density characteristics of the recording head. CONSTITUTION:A pulse is generated in a signal line 11 to actuate a monostable multi-vibrator 3 to generate a long-time pulse to be determined by the time constant of a temperature sensor 7 varying with ambient temperatures. CPU1 recognizes ambient temperature near a thermal head 8 on the basis of the output time of the vibrator 3. The corrected table of output time-temperature of the vibrator 3 determined according to the temperature-resistance value characteristics of the sensor 7 is stored in ROM, and the present ambient temperature is recognized by making reference to the table. In this way, CPU1 detects ambient temperature near the head 8. By making reference to temperature on the table previously formed according to the temperature-density characteristics of the head 8, proper electrifying time for obtaining a given density can be determined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a printing apparatus, and more particularly to a printing apparatus in which the driving time of a printing head is determined according to the ambient temperature obtained by a temperature detection means.

[Prior Art] In recent years, thermal printers have been widely used in office equipment such as facsimile machines as low-noise and inexpensive recording devices. Thermal printers often use a method in which a recording head consisting of a heating element directly develops color on thermal paper, or a thermal transfer method in which ink on an ink ribbon is melted and transferred onto plain paper.

In either system, it goes without saying that the thermal characteristics of the recording head greatly affect the recording quality, and it is well known that the recording density varies depending on the ambient temperature.

Therefore, in the conventional apparatus, a configuration has been used in which a temperature sensor such as a thermistor is used as a time constant of a monostable multivibrator, and the recording head is driven for an output time of the multivibrator that changes depending on the ambient temperature.

However, since the ambient temperature to recorded density characteristics do not match the detection characteristics of a temperature sensor such as a thermistor, the concentration difference due to ambient temperature is alleviated to some extent, but correction cannot be performed correctly in a certain temperature range, and In some cases, it was not possible to obtain a constant concentration across the range.

[Objective] The present invention has been made in view of the above problems, and an object of the present invention is to provide a recording device that can always perform recording at a constant density in any temperature range.

[Structure 1 of the Invention] In order to achieve the above object, the present invention provides a recording apparatus in which the driving time of the recording head is determined according to the ambient temperature obtained by the temperature detecting means, in which the ambient temperature detected by the temperature detecting means is means for outputting as a time amount, and measuring the output of the time amount output means to recognize the ambient temperature according to the temperature detection characteristics of the temperature detecting means, and based on the recognized ambient temperature, the temperature of the recording head to the recording density. A configuration is adopted that includes a control means that determines the driving time of the recording head according to the characteristics.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIG. 1 shows an embodiment of a recording apparatus according to the present invention, and here is a block diagram of a thermal printer having a recording head consisting of eight dot heating elements.

In FIG. 1, the reference numeral 1 denotes a CPU (Central Control Processing Unit), which is composed of a microcomputer chip and the like, and controls the entire recording operation. C.P.
The UI provides a recording signal to the driver 2 via a signal line 10 in accordance with the characters to be recorded.

The driver 2 is composed of a latch element and a switching element such as a transistor on a chip, and converts a CPU logic level signal into a current and voltage level sufficient to drive the thermal head 8. The output of the driver 2 is connected to the thermal head 8 via a connector 6 provided near the thermal head 8.

The thermal head 8 is composed of 8 dots of heat generating resistors, and the side of the heat generating resistors opposite to the side to which the output signal of the driver 2 is applied is commonly grouped together and connected to the switching transistor 5 via one of the terminals of the connector 6. connected to the collector.

The transistor 5 energizes the heating resistor of the thermal head 8 to which a recording signal is applied from the thermal head power source 4 for a predetermined period of time. transistor 5
The emitter of is connected to the output terminal of the monostable multivibrator 3.

The monostable multivibrator 3 is a retriggerable monostable multivibrator and is composed of an IC chip such as TTL or 0MO3. The monostable multivibrator 3 can be set and reset by receiving pulses from the CPU via the signal line 11, and when activated by the CPU, generates a pulse with a length corresponding to a time constant formed by the temperature sensor 7 and a capacitor (not shown). . Monostable multivibrator 3
The output of is input to the transistor 5 and the signal ff
112 to the CPUI, and the CPUI measures the pulse time length.

The temperature sensor 7 is composed of a temperature detection element such as a thermistor, is provided near the thermal head 8, and changes its resistance value according to the ambient temperature around the thermal head 8. Temperature sensor 7 is connected to monostable multivibrator 3 via connector 6 .

Next, the operation of the above configuration will be explained in detail.

In this embodiment, the CPUI detects the ambient temperature, performs correction according to the detection characteristics, and determines the current application time during recording.

Figure m2 is a flowchart showing the flow of the temperature detection program of the CPUI.

In step 521 in FIG. 2, the CPU cuts off all recording signals on the signal line 10 so that the thermal head 8 is not heated, and turns the thermal head 8 off.

Next, in step S22, a time measurement counter (not shown) provided together with the CPUI is reset by software or hardware.

Next, in step S23, a pulse is generated on the signal line 11 to start the monostable multivibrator 3. As a result, the monostable multivibrator 3 generates a pulse with a time length determined by the time constant of the temperature sensor 7, which changes depending on the ambient temperature.

Next, in the loop of steps 324 and 25, step S24
The time measuring counter continues counting up until it is confirmed that the output of the monostable multivibrator 3 has stopped.

When it is confirmed in step S24 that the output of the monostable multivibrator 3 has stopped, the process moves to step 326, and the contents of the time measurement counter are checked. Since the temperature sensor 7 is connected as a time constant of the monostable multivibrator 3, the ambient temperature is stored in the counter as the output time amount of the monostable multivibrator 3. Therefore, C.P.
The UI recognizes the ambient temperature near the thermal head 8 based on the output time of the monostable multivibrator 3.

A calibration table for the output time to temperature of the monostable multivibrator 3, which is determined according to the temperature to resistance value characteristics of the temperature sensor 7, is stored in advance in the ROM provided with the CPU, and by referring to this table, the current can recognize the ambient temperature.

As described above, the CPUI detects the ambient temperature near the thermal head 8.

Next, the energization control of the thermal head 8 according to the detected ambient temperature will be explained with reference to FIG. Figure 3 shows the CPU
FIG. 2 is a flowchart showing part of a control program during a recording operation.

Step 331 in FIG. 3 shows the temperature detection routine shown in FIG.

When the temperature detection routine in step 331 is completed, the process moves to step 532, and the energization time is determined. However, as in the past, the output time of the monostable multivibrator 3 according to the resistance value of the temperature sensor 7 is the same as the energization of the thermal head 8. When used as time, there is a slight discrepancy between the temperature-density characteristics of the thermal head 8 and the temperature detection characteristics of the temperature sensor 7, resulting in density differences depending on the temperature range.

Therefore, in this embodiment, the energization time is determined according to the temperature detected in step S31. That is, in step S32, a table created in advance according to the temperature-density characteristics of the thermal head 8 is referred to from the temperature detected in step S31, and an appropriate energization time to obtain a predetermined density is determined.

Subsequently, in step S33, a recording signal corresponding to the characters and figures to be recorded is applied to the driver 2 via the signal line 10, and then, in step 334, the monostable multivibrator 3 is driven. At this time, the CPU directly sets and resets the monostable multivibrator 3 via the signal line 11 according to the energization time determined in step 532.

Thermal head 8 given the recording signal in this way
The heating resistor is energized via the transistor 5 for a time properly determined depending on the temperature.

Next, in step 535, it is determined whether recording of one line has been completed. Step 5 unless one line of recording is finished.
33 and S34 are repeated to perform recording using the same energization time.

When recording of one line is completed, it is determined in step S36 whether all the data to be recorded has been recorded by checking the contents of the recording data buffer. If the recording has not been completed, the process returns to step 331, a new energization time is determined from the temperature, and the recording operation is continued using that time.

As described above, the atmosphere temperature is accurately detected for each line of recording according to the detection characteristics of the sensor, and the software is configured to select an appropriate energization time according to the temperature-concentration characteristics of the thermal head. Therefore, it is possible to perform recording at an appropriate density over the entire possible temperature range without causing a difference in recording density due to the detection characteristics of the temperature sensor as in the conventional case.

Furthermore, according to the present embodiment, the same monostable multivibrator can be used for both temperature detection and energization control, so the device can be constructed simply and inexpensively without increasing the number of parts compared to the conventional device.

In the above configuration, the energization time is determined for each line of recording, but depending on the temperature characteristics of the place where it is used, the temperature may be detected every time a page is recorded or after a certain period of recording operation, and the temperature of the thermal head 8 is determined. The energization time may be determined.The technology of the present invention is not limited to thermal printers, but can be implemented in various recording devices of the types described in the technical field section.

[Effects] As is clear from the above description, according to the present invention, in a recording apparatus in which the driving time of the recording head is determined according to the ambient temperature obtained by the temperature detecting means, the ambient temperature detected by the temperature detecting means means for outputting as a time amount, and measuring the output of the time amount output means to recognize the ambient temperature according to the temperature detection characteristics of the temperature detecting means, and detecting the recording head temperature to recording based on the recognized ambient temperature. By adopting a configuration that includes a control means that determines the drive time of the print head according to the density characteristics, we provide an excellent, simple and inexpensive printing device that can always print at a constant density in any temperature range. can do.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a thermal printer according to the present invention, FIG. 2 is a flowchart showing a temperature detection routine by the CPU of FIG. 1, and FIG. 3 is a recording by the CPU of FIG. 1. FIG. 3 is a flowchart showing energization control operation. l...CPU 2...Driver 3...
・Monostable multivibrator 5...Transistor 7...Temperature sensor 8...
Thermal head ice Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1) In a recording apparatus in which a driving time of a recording head is determined according to an ambient temperature obtained by a temperature detecting means, means for outputting the ambient temperature detected by the temperature detecting means as a time amount; The output of the time amount output means is measured, the ambient temperature is recognized according to the temperature detection characteristics of the temperature detection means, and the driving time of the recording head is determined based on the recognized atmospheric temperature from the recording head temperature to the recording density characteristics. A recording device characterized in that it is provided with a control means for determining. 2) The time amount output means is composed of a monostable multivibrator, and the output of the monostable multivibrator controls turning on and off of the recording head. Recording device.