JPS597068A - Thermal recorder - Google Patents

Abstract

PURPOSE:To obtain a thermal recorder capable of giving a high-speed recording with high-quality pictures by using a system in which the temperature of a base plate is detected, and voltage is adjusted to one suitable for the arrival of the temperature of a heating element to a given one and then supplied to the heating element. CONSTITUTION:The temperature of a base plate 11 is detected by a detection element 13, and the temperature is regarded as the initial temperature T0 of a heating resistor 12 and sent out from A-D converter 14. The address designation of ROM constituting a voltage decision part 16 is made by the initial temperature T0 of the heating resistor 12 digitalized, and a given voltage value is stored in the designated address. When the voltage value is decided, an analog signal corresponding to a set voltage value is supplied through the D-A converter 17 to a power amplifier type power source 18. From the power source 18, a drive signal having a voltage corresponding to the input analog signal is sent out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal recording device that performs recording using heat.

[Technical Background of the Invention and Its Problems] As information processing devices become more widespread, demands on information terminal equipment are becoming stricter. For example, in a recording device,
Merely being able to record is not enough, and there is an increasing demand for the ability to record on plain paper, to have clear images, to be able to print in color, to have low running costs, to be noiseless, and to be able to do so.

A thermal transfer recording device is a recording device that meets this demand.

This thermal transfer recording device applies a thermal pattern according to a recorded image from a heating element to an ink carrier coated with ink that softens or melts when heated, and transfers the pattern to recording paper.

Such a thermal transfer recording device can record on plain paper, can print in color, and has low noise. However, one drawback is that the printing speed is slow.

The cause of this will be explained in detail. Usually, a plurality of heating elements are arranged in parallel on a thermal head and are selectively energized. During low-speed recording and when the same heating resistor was not continuously energized, the thermal head had a large heat capacity and heat radiation, and no heat was accumulated, so there was no image deterioration.

However, when recording at high speed and repeatedly energizing the same heating resistor, heat accumulates in the thermal head, causing
As shown in Figure 1, the temperature T of the substrate of the thermal head
o is rising rapidly. As long as no current is applied, the temperature 'ro of the board is the same as the temperature of the heating resistor. Therefore, if energization is repeated, the temperature of the heat generating resistor that is continuously energized will rise more than necessary, and the temperature of the heat generating resistor that is not energized will also rise. This causes deterioration in image quality such as uneven recording density and blurring of image edges.

To solve this problem, the following methods have been proposed as conventional techniques. The first method is to control the pulse voltage or pulse width applied to the heating resistor according to the temperature of the thermal head substrate. The second method is to control the current applied pulse voltage or applied pulse width from past recording patterns.

According to the first method, when the temperature of the thermal head substrate rises due to heat accumulation, the applied pulse voltage or the applied pulse width is reduced, so the temperature rise is certainly somewhat suppressed2. There was no quantitative analysis of which physical quantities should be controlled and how, and the only technology available was to reduce the supplied energy when the temperature rose, so it was hard to say that it was effective.

On the other hand, the second method is a control method in which the current amount is also considered effective. This method is used, for example, in Japanese Patent Publication No. 57-1178
As shown in Publication No. 4, attention is paid to each heating element, and when the energized state continues, the pulse width applied to that element is narrowed. This method is reported to be effective in dealing with temporally rapid thermal fluctuations of each heating element.

However, as a result of experiments conducted by the present inventor, high-speed printing, for example, when the heating element was repeatedly energized at intervals of 2 to 3 m5ec, as shown in Figure 2, the heating resistor to which the electric signal was supplied The temperature TR that is reached is once significantly lowered, and the rise in temperature T□ is somewhat suppressed.

However, the temperature T of the substrate. is increasing, and there is almost no change from the first method. Therefore, there was a similar problem of heat storage.

[Object of the Invention] An object of the present invention is to provide a thermal recording device that eliminates one or more drawbacks, has high image quality, and can perform high-speed recording well.

[Summary of the Invention] This invention provides that, regardless of the temperature of the substrate including the heating element, if a certain applied voltage is applied to the heating element, -
This was based on an experiment in which the temperature of the substrate was detected by causing a certain temperature rise.

The voltage is adjusted to a voltage suitable for the heating element to reach a predetermined temperature, and then supplied to the heating element.

[Effects of the Invention] In the present invention, the temperature of the substrate is detected, the voltage is adjusted according to a predetermined temperature difference, and the voltage is supplied to the heating element, so that excessive heat accumulation in the substrate is prevented. Therefore, recording is performed well and no power is wasted.

Furthermore, since the heating element is set to the transfer temperature of the ink applied to the ink carrier, the recorded ink has a beautiful hue.

[Embodiments of the Invention] Next, the present invention will be described in detail. Prior to this explanation, the results of experiments conducted by the present inventor will be explained.

The points that the inventor has confirmed are that, firstly, as shown in FIG. The temperature increase ΔT of the resistor is determined and is more dependent on the pulse voltage V. Second, in thermal transfer, the recording density depends on the temperature TFL reached by the heating resistor, as shown in FIG. 4, and the initial temperature of the heating resistor TFL. Cllo, Ill are shown in FIG. )
does not depend on

That is, in thermal transfer recording, the temperature TIL reached by the heating resistor
Controlling this is the key to improving image quality. The ultimate temperature TFL of this heating resistor can be controlled more easily and accurately by adjusting the applied pulse magnetic pressure V than by the applied pulse width 1n in the case of high-speed driving. For this purpose, data on the initial temperature To of the heating resistor, a constant determined by the final temperature Il inc, and the characteristics of ΔT (=T To) versus pulse '1 pressure V are required.

The following examples use this experimental result as its principle.

As shown in FIG. 6, the thermal transfer recording device in this embodiment includes a substrate (1) as a heat sink made of ceramic.
, a heating resistor H provided on this substrate αl by, for example, thin film technology, and a substrate temperature detection element a (provided on IIl and outputting an analog magnetic signal corresponding to the temperature of this substrate 01). ) and this substrate temperature detection element (
A-D converter a←L that converts the analog signal from 1"lI into a digital signal. Using the digital signal from this A-D converter side, the following voltage m!l
151 (!:, A-D converter f14 color.

A voltage determining unit FIE outputs a voltage value as a corresponding digital signal from a digital signal, and this voltage determining unit O
D-A converts the digital signal from e into an analog quantity
A converter (17), a power amplifier type power source (151) that outputs a drive signal having a voltage corresponding to the output from the D-A converter αη, and a power amplifier type power source (151) that supplies an image signal to the power amplifier type power source, It consists of an image signal supply device (11) that controls the output of the power amplifier type power source (1119), the output of the power amplifier type power source a81 corresponds to the heat generating resistor (12), and the voltage setting means is a voltage determining unit (t). Corresponding to (i), the voltage generating means corresponds to a power amplifier type power source decoy.

Now, the heating resistor 0, which is supplied with the drive signal, generates heat. A part of this heat (l!υ) is supplied to an ink carrier (not shown) coated with ink, and the remaining eυ flows to a substrate αυ on which a heating resistor (ta) is provided.

A portion of the heat that has leaked to the substrate θυ flows to the outside.

In such a heat balance, the temperature of the substrate circle is determined by the balance between the incoming heat θ9 and the outgoing heat (2 sides).

The temperature of such a substrate Qll is determined by the substrate temperature detection element 0.
The output of a is the initial temperature T of the digitized heating resistor Oz. It is.

As shown as the principle of the invention described above, the temperature rise ΔT of the heating resistor α2 versus the applied pulse voltage ■characteristic is required.

『〕≦2 Initial temperature T at the zero point of the heating resistor. There is a one-to-one relationship between ・and the temperature increase, and the initial temperature is ql. All you have to do is specify.

On the other hand, the voltage determining section Oe is a read-only memo! j
(Read -0nly -11emory: hereinafter abbreviated as R and OM). Addressing of this ROM is performed using the initial temperature T of the digitized heating resistor (ls6), and the voltage value specified in FIGS. 3 and 4 is stored at the specified address. However, In this embodiment, the pulse width of the output from the power amplifier type power supply (18) is not adjusted.

When the voltage value is determined in this manner, an analog signal corresponding to the set voltage value is supplied to a known power amplifier type power source 0 barrel via the DA converter αη.

The power amplifier type power supply frame a outputs a drive signal having a voltage (capable of driving the heating resistor α) according to this input analog signal. However, the output from this arrow amplifier type power supply a8 is controlled by the output from the image signal supply device (li).
On/off (that is, pulse width is also included) is controlled by the output signal from 1, and only the voltage is adjusted by this power amplifier type power supply (181).

The present inventor performed high-speed continuous recording to confirm the effects of this embodiment, and as shown in FIG. 7, the temperature T of the substrate αυ. An increase in the temperature was prevented, and as a matter of course, the temperature reached by the heating resistor Q2 remained constant.

The quality of the recorded images was clear and without blurring.

[Second Embodiment of the Invention If the contents of l'LOM are changed in the above embodiment,
More complex control becomes possible.

For example, it is also possible to take into consideration the time required for temperature detection, signal conversion, time delay in heat transfer, and the like. That is, from the change in temperature +1+o of the board 0υ, it is determined whether the board is rising or falling, and from the data at the measured time, the board at the time when the heating resistor (12) actually generates heat. The temperature of Qll (the initial temperature of the two substrates (111)) is estimated.

Specifically, the digital substrate temperature detection element (the signal from the first floor is
Differentiate. As shown in FIG. 8, a temperature estimating section C(1) and a voltage determining section (32 are provided as corresponding to the voltage determining section OQ in FIG. 6. Temperature estimating section C) υ , and the voltage determination unit C37J are both R and OM. The temperature estimator (3υ) performs address designation by digitally representing the temperature of the substrate OB and its differential value.

The address specified is a power amplifier type power supply (1
The estimated value of the initial temperature T of the heating resistor (121) when the heating resistor (1'ID) generates heat due to the electric signal from 81 is stored.

This temperature estimating section (3υ) uses the temperature read from the TtOM to specify the address of the cardiac pressure estimating section (2). It is exactly the same as C3a, and contains information about the α throne.

An electric signal having a voltage according to this voltage value information is D
- A converter (17) and a power amplifier type power supply (18) realize the power and supply it to the heating resistor a.

In this way, since the voltage of the electrical signal supplied to the heating resistor a is determined by predicting the initial temperature of the heating resistor (+J), the heat of the substrate aυ is more appropriately controlled.

[Third Embodiment of the Invention] Next, a third embodiment of the invention will be described with reference to the drawings. In this device, among the pulse signals applied to each heating resistor, the pulse width is determined for each heating resistor in the past. The pulse voltage is determined based on the pulse application history, and the pulse voltage is determined based on the temperature history of the substrate on which the heating resistor is provided. If you want to clearly state your purpose, you can control the pulse width applied to the heating resistor in a fine area (hereinafter referred to as micro control), and control the common voltage to all heating resistors. , the energy flowing into the entire heating resistor, and therefore the heat accumulation in the entire board, is controlled a1 (hereinafter referred to as macro control).

As shown in FIG. 9, this device includes a substrate (91) having a heat dissipation effect, a substrate temperature detection element (92) provided on this substrate (91) and detecting the temperature of the substrate (91), An A-D converter (93) that converts the analog signal from this substrate temperature detection element (92) into a digital signal (!
: A CPU (94) that controls the following using digital signals from the A-D converter (93), and under the control of this CPU (94), the temperature of the board (91) is controlled. A temperature estimating unit (95) to estimate and this temperature estimating unit (9
A voltage determining unit (97) that determines the voltage supplied to a heating resistor (96), which will be described later, based on the temperature from 5), and a D-A that converts a digital signal from this voltage determining unit (97) into an analog signal. converter (98) and this D-A converter (
a power amplifier type power source (99) that converts the analog signal from the analog signal (98) into an electrical signal having a voltage corresponding to the voltage; and an image signal supply unit (99) that supplies a pulse signal corresponding to the image f# to be recorded.
ioo) and a pulse width determination unit (101) that adjusts the pulse width of the pulse signal from the image signal supply unit (100).
), of the output from the pulse width determining section (101,), the on/off timing is held, and only the pulse voltage thereof is adjusted by the power amplifier type power source (99). Power amplifier type power supply like this (99)
A drive signal from the heating resistor (96) is supplied to the heating resistor (96). The temperature estimation unit (95) measures the arrangement state of the board temperature detection element (92) and the heat generating resistor (96) provided on the board (91), the energization state of the plurality of heat generating resistors (96), and the heat The temperature of the substrate (9) when the heating resistor (96) actually generates heat is estimated from the detected temperature of the substrate (91), taking into account the time delay of conduction, the time delay of measurement, etc.

In order to have such a function, the temperature estimator (95) is configured with a ROM. The board (9
1) a heating resistor (91) and a substrate temperature detection element (92)
) and store the actual measurement data after implementing it.

To extract data from this ROM, the temperature of the board (91) (digital signal from the A-D converter (93)) and the differential coefficient (A-
This is done by specifying the address using the differential coefficient of the digital signal from the D converter (93).

The address specified by such addressing is
The estimated temperature of the substrate (91), or more precisely, the estimated temperature, which is a type of state variable indicating the temperature state of the substrate (91), is stored.

On the other hand, the voltage determination unit (97) determines the minimum voltage required to raise the temperature of the substrate (91), that is, the initial temperature of the heating resistor (96) to a temperature (achieved temperature) TFL suitable for ink transfer. Determine.

As described above, the temperature rise of one heating resistor (96) is greatly influenced by the applied pulse voltage, and is determined one-to-one with respect to the applied pulse voltage using the applied pulse width as a parameter.

Therefore, the voltage determining section (97) is configured with a ROM which is a type of table. The ROM includes the temperature estimator (
The applied pulse voltage data for the estimated temperature determined in step 95) is stored. The addressing of R and OM is performed using the estimated temperature. The corresponding applied pulse voltage data is stored at the specified address.

In this way, the applied pulse voltage data determined by the voltage determining section (g7) is converted into a corresponding analog signal and amplified by the power amplifier type power source (99).

The power amplifier type power supply (99) in this embodiment has the following performance. The number of input terminals and the number of output terminals are the same, and the output signal is synchronized with the input signal.

However, the voltage of all output signals is
99). It is the voltage determining section (97) that determines this.

The input signal to this power amplifier type power supply (99) is inputted to the image signal supply unit (i) after passing through the pulse width determination unit (101).
This is an image signal from oo). The image signal is "0" [moon signal] corresponding to the recorded image, and each heating resistor (96)
This is a pulse signal with the same pulse width that is supplied every time.

For this pulse signal, the pulse width determining unit (101)
For example, as shown in Japanese Patent Publication No. 57-11784, when a pulse signal is continuously applied to the same heating resistor (96), the pulse width is reduced.

In this way, the pulse width of each pulse from the power amplifier type power source (99) is adjusted depending on the current supply status to the heating resistor (96), and the pulse voltage of all pulse signals is adjusted depending on the temperature of the board (91). and is supplied to the heating resistor (99).

Macro control in which the pulse 'magnetic pressure of all pulse signals is adjusted as described above eliminates unnecessary injection of energy into the entire substrate (91). In contrast, each heating resistor (9
By micro-controlling the pulse width of the pulse signal (6), it is possible to finely control the ink transfer due to the heat generated by the heating resistor (96).

In this example, it is important to note that the substrate temperature detection element (92)
This is the position of What is detected by this substrate temperature detection element (92) is the temperature of the substrate (91), but originally it is the temperature of the heating resistor (96). Therefore, the heating resistor (96)
Ideally, it should be placed in contact with the However, actually establishing one is hopeless.

Therefore, one heating resistor (96) may be provided on the same substrate (91). In this way, once one or more heat generating resistors (96) are provided, the heat generating resistors (96) are provided.
96) is energized based on various recording patterns, and the temperature distribution and temperature change of each heat generating resistor (96) and the temperature are measured by the substrate temperature detection element (92).

How to use such measurement data is when the number of substrate temperature detection elements (92) installed is small.
The initial temperature 1r of the heating resistor (!f5) is determined from the temperature measured by the substrate temperature detection element (g2), taking into consideration the past recording pattern from the image signal supply unit (100).

It is preferable to guess. The reason why the past recorded pattern is used is that if the number of substrate temperature detection elements (96) installed is small, the temperature distribution of the heat generating resistor (96) cannot be grasped only by actual measurement data.

Conversely, when controlling the voltage of the applied pulse signal using only a small amount of actual measurement data from the substrate temperature detection element (92), the voltage of the applied pulse signal is roughly changed to the extent that there is no energy loss. Then, the pulse width determining section (
101) to readjust the pulse width.

For example, if the voltage is lowered below a predetermined value (if the measurement data from the substrate temperature detection element (92) indicates a high temperature),
It is transmitted to the pulse width determining section (101).

In the pulse width determining section (101), energization to one heating resistor (96) decreases the pulse width by 1-running time K continuously, but the temperature of the heating resistor (96) to which energization is not continuous is , it is thought that there will be a large difference from the measurement data of the substrate temperature detection element (92). Therefore, it is preferable to set the pulse width of the heating resistor (96) ・\ which has not been energized for a long time to a predetermined value or more.

When a plurality of substrate temperature detection elements (92) are provided,
The temperature distribution and temperature change of the plurality of heating resistors (96) can be accurately estimated. Therefore, there is no need to refer to the supply state of the image signal.

In short, in the temperature estimating section (95), the heating resistor (96
), and the voltage determining unit (97) determines the applied pulse voltage for this predicted state so as not to inject unnecessary energy.

Although several embodiments have been described above, any modifications are included in the invention as long as they do not depart from the spirit of the invention. For example, it does not have to be a flat board. The number of heating elements may be any number.

The temperature detection means may be located at any position where the temperature of the substrate can be detected, and does not necessarily have to be on the curtain plate. The voltage setting means may be of any type as long as it determines the applied voltage value with respect to the measured temperature and the set temperature.

As described above, it is natural that the present invention includes any modifications as long as they do not depart from the spirit of the invention.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the temperature changes of the heating resistor during high-speed printing using conventional thermal control in a thermal transfer recording device, and FIGS. 3 to 5 show the experimental results on which the present invention is based. 6 is a configuration diagram showing one embodiment, FIG. 7 is a diagram showing temperature changes of the heating resistor in the embodiment shown in FIG. 6, and FIGS. 8 and 9 are diagrams showing other embodiments. FIG. (111...Substrate, α...heating resistor, (13)
...Substrate temperature detection element, aO...Voltage determination section, H.
...Power amplifier type power supply. Agent Patent attorney Kensuke Chika (and 1 other person) 1. Prisoner room 2. Time 3. V. 4.R. 5. Fig. N6

Claims (1)

[Claims] (1) A thermal recording device that performs recording using heat from a heating element, which includes a substrate on which the heating element is provided, a temperature detection means for detecting the temperature of this substrate, and a temperature of the substrate detected by the temperature detection means. Voltage setting means in which a voltage value of an electrical signal to the heating element is stored, which is set in correspondence with the temperature and the set temperature of the heating element; A thermal recording device comprising voltage generating means for generating a signal.