JPH10264431A - Thermal recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform conduction time control of a heating element based on the print record through a simple constitution by receiving a heat-up record mode signal from a heat-up record mode decision means to generate a conduction pulse being applied to the heating element in a thermal head and performing conduction control. SOLUTION: An applying command pulse generation means 3 outputs applying command signals t1-t4 having width narrower than the maximum conduction pulse width of a thermal head H for a single time recording trigger. A conduction pulse generation circuit 4 subdivides the maximum conduction pulse width depending on the applying command signal and several conduction pulses divided depending on the heat-up record mode are selected and applied to the thermal head H side. The type of heat-up record mode depends on the number of lines being printed before a dot at same position is printed finally among a data for a plurality of immediately preceding lines. When the data has been printed a line before, the condition pulse generation circuit 4 generates a conduction pulse of shortest duration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a thermal recording apparatus having a function of controlling an energizing time based on a print history of a heating resistor of a thermal head.

[0002]

2. Description of the Related Art Conventionally, a thermal recording apparatus has been known as a non-impact recording apparatus (printer). By applying heat with a thermal head, printing is performed directly on thermal paper or an ink ribbon is printed. The used indirect printing is performed. By the way, the heating of the thermal head is performed by controlling the energizing pulse.
For example, when the black pixels are continuous, the temperature of the thermal head rises, so that uneven printing may occur.

Therefore, in the conventional thermal recording apparatus, the entire temperature of the thermal head is detected, and the energization control is performed based on a change in the temperature. In other words, when the temperature of the thermal head is low, a high voltage or a pulse with a long energizing time is applied, and when the temperature of the thermal head is high,
A low voltage or short-duration pulse is applied.

[0004]

However, in the above-described conventional thermal recording apparatus, since the energizing time cannot be controlled for each heating element, density unevenness occurs in the printed data due to the past heat generation state, and the density of a photograph or the like is increased. For recording halftone images,
This effect was growing. In particular, when printing at high speed, the temperature of the heating resistor that constitutes the thermal head does not drop immediately after energizing and printing. It is accumulated in the resistor, and the influence on the printing density is increased.

The present invention has been made in view of such circumstances, and a heat-sensitive recording apparatus which can control the power-on time based on the printing history of the heating resistor of the thermal head with a simple configuration is provided. It is intended to provide.

[0006]

According to a first aspect of the present invention, there is provided a thermal recording apparatus for printing a plurality of lines of print data immediately before the current data to be printed. The thermal history mode signal is received from the means for determining the thermal history mode for the heating resistor of the thermal head on a pixel-by-pixel basis and from the means for determining the thermal history mode each time the print position of the thermal head is fixed. Print head driving means for generating an energizing pulse to be applied to the heating resistor of the thermal head and performing energization control.

Here, the thermal history mode is determined by referring to data of a plurality of lines immediately before the data to be printed. However, since the immediately preceding recording most affects the temperature of the head, the dots at the same position are not affected. The energizing pulse width generated by the print head driving means is set so as to change from a short time to a long time in order from the one line before, depending on how many lines are before the last line printed. .

A second aspect of the present invention proposes a means for determining the thermal history mode of the first aspect, wherein the determination means sequentially shifts dot data to be printed and stores the dot data for each print line. A combination of a data storage unit and a logic circuit that fetches the corresponding dot data from the dot data of each print line stored in the print data storage unit and determines the thermal history mode for the same heating resistor of the thermal head. It is composed.

Here, the print data storage means comprises a plurality of shift registers for storing the data of the current line to be printed and the data of a plurality of lines immediately before, for each line. Based on the data taken from each storage unit in units, determine the thermal history mode,
Outputs the thermal history mode signal. In claim 3, claim 1
Print head driving means, an application command pulse generating means for outputting an application command signal to be superimposed on the same print line at a timing corresponding to an energizing pulse, and receiving an application command signal and a heat history mode signal. And a power supply pulse generating circuit for generating a power supply pulse to be applied to the heating resistor of the thermal head.

The thermal history mode signal specifies whether or not to output an energizing pulse to the thermal head for each of the same number of application command signals as the number of overprints. Therefore, the type of the heat history mode signal needs to be equal to or more than the type of the application command signal.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a main part of a thermal recording apparatus, and FIG. 2 is a schematic diagram showing a configuration of a thermal head. The thermal recording apparatus A is provided with a thermal head H. As shown in FIG.
The heating resistor of 8 dots is divided into 21 groups (G1 to G21) of 8 dots (# 0 to # 7), and the energizing pulse is sequentially applied to each group, so that the data of the shift register 5 with the latch circuit can be obtained. Is used to drive the thermal head H to perform printing. That is,
The thermal head H is provided with a heating resistor of 168 dots in the vertical direction in FIG. 2, and each time the printing position is fixed, the energizing pulse is transferred by 8 dots at a time, and all groups G1 to G2
When the voltage is applied to the recording paper K after the transfer, the printing position is moved in the horizontal direction to perform printing on the recording paper K.

In the present invention, each time the current data to be printed is fetched, the thermal history mode for the heating resistor of the thermal head H is determined for each pixel by referring to the print data for a plurality of lines immediately before the current data. Each time the print position of the head H is fixed, an energization pulse to be applied to the heating resistor of the thermal head H is generated based on the determined thermal history mode, and energization control is performed.

Therefore, the thermal recording apparatus A includes a print data storage means for sequentially shifting dot data to be printed and storing dot data for each print line as means for determining the thermal history mode; A logic circuit for fetching the corresponding dot data from the dot data of each print line stored in the means and determining the thermal history mode for the same heating resistor of the thermal head H is configured.

In FIG. 1, a shift register 1 of 21 bytes (8.times.21) which shifts by 8 bits (1 byte) by a byte shift clock as print data storage means.
Is provided for each print line (D0 to Dn), and a thermal history mode determination circuit 2 is provided for each bit (print dot) (# 0 to # 7) as a logic circuit for determining the thermal history mode. I have.

Here, the data of the current line to be printed is stored in the shift register 1 (D0), and the data of the previous line is shifted one line before, two lines,. Register 1 (D1), (D2),.
(Dn). Each of the thermal history mode discriminating circuits 2 receives n-bit data, one bit at a time, from all the shift registers 1 (D0 to Dn) to determine the thermal history mode. In this thermal history mode, the last line on which dots at the same position are printed is
It is determined by the number of lines before, etc. In this case, if the data up to the nth line is stored in the shift register 1, n + 1 types (including no printing up to the current line) of the thermal history mode signal are output.

The thermal recording apparatus A shown in the drawing has a print head driving means for controlling the energization based on the thermal history mode, and applies an application command signal to be overprinted on the same print line at a timing corresponding to the energization pulse. An energizing pulse generating circuit 3 for generating an energizing pulse to be applied to the heating resistor of the thermal head H, and an AND circuit (# 0 to # 0) 7) is combined.

The application command pulse generating means 3 outputs a plurality of application command signals having a width sufficiently smaller than the maximum energizing pulse width to the thermal head H in response to one recording trigger (in the figure, t1 to t4). (4 types), the energizing pulse generation circuit 4 divides the maximum energizing pulse width into a plurality in accordance with the applied command signal. Head H
Side.

For example, in the thermal history mode, the type differs depending on how many lines before the last line on which the dot at the same position is printed out of a plurality of lines of data immediately before the data to be printed. In the pulse generation circuit 4,
If printing is performed one line before, the shortest energizing pulse is generated, and if there is no line printed on multiple lines,
An energizing pulse (maximum energizing pulse width) for the longest time is generated.

That is, if printing is performed one line before,
Of a plurality of applied command signals, only one applied command signal generates a divided energizing pulse, and unless all the immediately preceding multiple lines are printed, all of the plurality of applied command signals are What is necessary is just to generate an energizing pulse. As described above, in the thermal history mode signal, it is specified whether or not an energizing pulse is to be output to the thermal head H for each of a plurality of application command signals for overprinting. Then, the latch data of the shift register with latch circuit 5 is rewritten by the energizing pulse, and the thermal head H is driven in consideration of the thermal history.

Next, the processing of the thermal history mode determination circuit 2 (thermal history decoder) will be described with reference to FIG. Here, there are four shift registers 1 (D0 to D3),
The dot data d0 (current data) of the current line and the dot data d of one line before, two lines before, and three lines before
1, d2 and d3 are input, the thermal history mode signal m
This shows data of all patterns (16 patterns) when 0 and m1 are output.

Here, the current data d0 is "0".
In the case of (white data), the data finally input to the shift register with latch circuit 5 is the AND circuit (# 0
To # 7), the signal is set to “0”, and is therefore excluded from the mode signal output (indicated by “X”). The input four data d0 to d3 are calculated by the logical expressions in the figure and are converted into mode signals m0 and m1. Note that the logical expression here is that the data at the same position is printed, that is, the history (“only the current line”) depends on how many lines out of the plurality of lines the last line that was the black data “1”. ,
4 types of “one line before” to “three lines before”).

The reason why the four types of thermal history mode signals are output is to determine whether or not to transfer the black data to the head H at the respective timings of the four types of application command signals t1 to t4. In the figure, as the transmission data, the case of transmitting “1” and the case of not transmitting “0” are shown, and the application counts “0” to “4” are also shown accordingly. Here, as the number of times of application increases, t1 to t1
Although a case where data is sequentially transferred to t4 is shown, the present invention is not limited to this.

Here, the energizing pulse generation circuit 4
Is composed of tables such as ROM and RAM,
The address (address 0, address 1, address 3, address 7) is designated by the application command signal from the application command pulse generating means 3, indicating that the energizing pulse is changed by hardware. That is, one line of dot data is transferred and stored in each shift register 1 by the recording trigger,
As shown in FIG. 4, the application command pulse generating means 3 sets all of the first to fourth application command signals to OFF "0",
Address "0000" is designated, and then the second to fourth application command signals are sequentially turned on "1", and the first address "0001",
The address “0011” and the address “0111” are designated.

Thus, the energizing pulse generation circuit 4
Upon receiving the first to fourth application command signals, generates an energizing pulse during each of t1 to t4 according to the thermal history mode. Therefore, from the energizing pulse generation circuit 4 to the shift register with latch circuit 5, four (-) data transfers are performed for one recording trigger.

When printing of one line is completed by transferring data four times (21 times for 8 dots each time), the feedback mode of the shift registers D0 to Dn is turned off, and the next one line data is transferred. The data stored in the shift register D0 and the data in the register D0 are sequentially transferred to the register D1, and thereafter, the feedback mode is turned on, and recording (data transfer) for the next line is started. That is, t1 to t
In each period of No. 4, recording is performed on the same line, and thus feedback is performed in each of the registers D0 to Dn.

As described above, according to the present invention, since the recording data itself is changed based on the history, the driving power to the head H may be kept supplied while recording one line. It should be noted that even if data is transferred while a voltage is applied to the head H,
There is no problem because this transfer is fast. Next, another configuration of the application command signal output from the application command pulse generating means 3 is shown in FIG.

Here, the first to fourth application command signals shown in (b) are sequentially output by the recording trigger shown in (a) (t1 to t4), and the power is supplied in synchronization with the switching timing of these signals. A pulse is generated, and the latch data of the shift register with latch circuit 5 is rewritten and held (t1 'to
t4 '). What is shown here is
This is a case in which printing is not performed on all of the plurality of lines immediately before, but the current data is printed, and energizing pulses are generated for all print command signals to perform data printing.

[0028]

As can be understood from the above description, according to the thermal recording apparatus according to the first to third aspects of the present invention, every time the current data to be printed is fetched, a plurality of lines immediately before the current data are taken. With reference to the print data, the thermal history mode is determined in dot units, and based on this, an energizing pulse is generated, and energizing control of the heating resistor constituting the thermal head can be performed. As described above, since the recording data itself is changed based on the history, the driving power to the head may be kept supplied while recording one line, and the configuration is simple.

Further, according to the configuration of the present invention, the print data is automatically taken in, and the energizing pulse to be applied to the heating resistor of the thermal head is automatically generated. Since it is not used, the program can be simplified. Therefore, with a simple configuration, it is possible to prevent density unevenness from occurring in data to be recorded.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of a main part of a thermal recording apparatus of the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a thermal head.

FIG. 3 is a diagram for explaining an operation of a thermal history mode determination circuit.

FIG. 4 is a diagram illustrating an example of an application command signal output by an application command pulse generation unit.

FIG. 5 is a diagram showing a relationship between an application command signal and an energizing pulse.

[Explanation of symbols]

 A: Thermal recording device 1: Shift register 2: Thermal history mode discriminating circuit 3: Application command pulse generating means 4: Energizing pulse generating circuit 5: Shift register with latch circuit H ..Thermal head d0-dn... Dot data m0, m1... Thermal history mode signal t1...

Claims (3)

[Claims] 1. A means for determining a thermal history mode for a heating resistor of a thermal head for each pixel by referring to print data for a plurality of lines immediately before the current data to be printed, and a thermal head. Each time the printing position of is fixed, receiving a heat history mode signal from the determination means,
A thermal recording apparatus comprising: a print head driving unit that generates an energizing pulse to be applied to a heating resistor of a thermal head and controls energization. 2. A print data storage means according to claim 1, wherein said means for judging the thermal history mode shifts dot data to be printed sequentially and stores dot data for each print line. And a logic circuit which fetches the corresponding dot data from the dot data of each printing line stored in the thermal head and determines a thermal history mode for the same heating resistor of the thermal head. 3. An application command pulse generating means according to claim 1, wherein said print head driving means outputs an application command signal to be superimposed on the same print line at a timing corresponding to an energizing pulse. A thermal recording apparatus configured to receive a thermal history mode signal from the thermal history mode determining means and generate an energizing pulse to be applied to the heating resistor of the thermal head.