JPS61184048A - Heat sensing recorder - Google Patents

Abstract

PURPOSE:To attain control with high grade and simple data transmission by using sweep information of a counter to drive a switch circuit thereby flowing a current to a heat resistor for a time corresponding to a required recording density. CONSTITUTION:A clock signal CLK2 consists of 2<n> sets of pulse train having a period of t/2<n> (t is maximum print pulse width) and a counter 71 starts inputting the CLK2 and count down. When it is supposed that the content of a shift register group 101 is 2 and the information is preset to the counter 71, the counter 71 uses two pulses of the CLK2 and outputs an L signal from a terminal RCY. A FF81 brings the level of Q to L while receiving this signal and a switching element 31 is turned off. Further, a gate 111 is closed and the input to the counter 71 of the CLK2 is inhibited. The state is kept since the next STROBE signal is applied. That is, the print pulse is applied to the heater for t/2<n>X2 to the content of the register 101.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a g-thermal recording system, and more particularly to a driving system for a thermal recording apparatus that performs dot recording.

[Prior Art] The l&thermal recording method is simple and has been widely used in recent years. In this method, a heating element formed on a substrate is selectively energized to color a recording sheet, and various driving methods are known.

As an example of this, there is a so-called direct drive system introduced in Japanese Patent Laid-Open No. 59-133081, and an example of the circuit is shown in FIG. This is a linear heating element (51).

(52)...(5n) each has a switching element (31).

(32)...(3n) are connected and integrated into the thermal head, and shift registers (11), (12)...(1n) or lunch times lif! for - lines are connected. r(21).

Recording data is sent to (22)...(2n). That is, for each heating element, one set of switch circuit (31), strobe gate circuit (41), launch circuit (2i), and shift register circuit (li) 1
Drive cells (6i)' consisting of stages are prepared for n stages, and DATAI is stored in n stages of shift register (100).
Input one line of data from one NIIM child in series,
Next, the gate circuits (41), (42) are activated by the strobe signal that transfers the contents of each stage of the shift register (100) to the launch circuits (21), (22), = (2n) by the launch signal input from the LATCH terminal.
・= (4n) turns on and launch circuit (21), (
22)...O Hlor of each switch circuit (31), (32) - (3n) corresponding to the content of (2n)
The r state is determined and the heating element (51) + (52)...
(5n) is energized to generate heat and record an image. Note that since the strobe signal is commonly connected to all bits or arbitrary plurality of pits, the energization time to each heating element at the same timing cannot be changed individually for each dot.

In addition, in the figure, C0MM0N is the common terminal for power supply,
GND is the ground terminal, S'['ROBG is the strobe signal terminal, LATCH is the latch signal terminal, DATAIN is the data input terminal, CLOCK is the clock terminal, DAT
AOOT is the output terminal of the shift register (100), DO
I, DO2, - Don are respective heating elements (51),
(52)...(5+n) voltage application terminals are shown.

The density control of N gradations in this circuit configuration and the method for performing it will be described below.

The energy applied to the heating element is expressed by the following equation. Here, ■ is the recording power supply voltage, R is the heating element resistance value, Ront
/1flfJ The resistance component when the switching transistor is turned on, t, is during the printing pulse.

go=Pot=I'' Rt (R+Ron)2Rt (1 equation) In other words, when V and R are constant, the parameters of EO change are Ron and t.

Of these, for Ron, 35% is due to his own variation.
It is not suitable for advanced gradation control. The method of changing t is universal.

FIG. 7 is an example of a timing chart of a method of performing density control by changing the applied pulse width tf, and shows an example of 256 gradations. Symbols are assigned to correspond to the signals of each part. For one line of data, the control circuit (61) has only an Ibit shift register or launch for one heating element (51), so in order to perform gradation control corresponding to 256 gradations, clock pulses must be set at 256 gradations. The applied pulse width tt is thereby controlled. That is, each time a clock pulse of 1 is sent out, a latch signal is raised to change the 0N10FF state of the switching element so that an applied pulse width corresponding to the required concentration is obtained.

DOI is an example of 2/256 gradations. In this case DO
The bit corresponding to 2 is Kl, 2 and #1″% 3 to 2
56, the amount of data #0" is transferred.
The strobe signal (riKs-) is kept in the ON state for a period of 25 g. In this way, the energization time is varied in steps of 1/256 to obtain an arbitrary applied pulse width.

[Problem that the invention seeks to solve]

As mentioned above, the conventional system has only one shift register or latch corresponding to one heating element, so the data transfer speed f is as follows. Here, N is the number of pits in the serial shift register, m is the number of gradations, and t is the maximum value in the print pulse.

When m f = - (2 formula) % formula %, it becomes m-32 gradations, and if you want to further increase the number of gradations, you must increase f, decrease N, or t.
It becomes necessary to increase.

The increase in f is determined by the characteristics of the circuit C that makes up the circuit, but MO
The current limit is 6 MHz for S and 5 MHz for bi-CMO8. Furthermore, from the viewpoint of noise, it is not desirable to increase f. Also, an increase in t is seen as hindering high-speed drawing. Furthermore, a decrease in N results in a decrease in the number of pits in the shift register or launch, which increases the number of input data lines, which in turn leads to complexity in data processing.

[Means for Solving the Problems] The present invention was made in order to eliminate the drawbacks of the conventional system as described above.
61) has a Focus shift register and launch.

[Function] In this way, by making it possible to control k bits for one heating element, there is no need for high interference in data transmission, and high-grade gradation control can be achieved with extremely simple data transmission. It becomes possible.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention and the drawings will be described. 1st
In the drawings, the same reference numerals as in FIG. 6 indicate the same or corresponding parts. (61) is a drive cell for driving one heating element dot, and each heating element (51) has a terminal DOi.
connected to. Each auxiliary cell (61) has a kbit parallel shift register group (1 (J i), a shift register (
Clock gate circuit (9i) which becomes the transfer signal of 10i)
), counter (7i), set reset clip 70
(81), a switching element (31), and a COH2 gate circuit (lli) that serves as a clock signal for the counter (71). Shift register group (101
), SHOP-3R7 each indicates a cell of a shift register, DO-D7 is a data input terminal for inputting the corresponding data in parallel, and SOO-807 are output terminals corresponding to the cells of each shift register.

[Operation of the embodiment of the invention] FIG. 2 is a diagram illustrating the operation timing of the embodiment of FIG. 1. The data has 2n gradations (n = 7.256 in the example)
gradation) information at terminals Do and D in n-bit parallel.
I, . . . are input to the shift register (101) from D7. These data are sequentially transferred to the shift register of the next control cell by the CLK signal input through the gate circuit (91). When data is distributed to all control cells, each control cell (61), (62)...(6
n) gate circuit (91), (92)...(9n)
is closed, and the GLK signal supply is cut off.

Next, a negative pulse is applied to the STROBg terminal. This signal is connected to the load terminal of each kakunt element (71) (dakun counter) and the set terminal S of each 7 lip 70 tab (81). ) is received as preset data, and the data is held in each counter (71). In addition, 7 ribs and 70 tubes (
When the output Q of 81) is set to #E', the switching element (31) is turned on in response to this #H# signal, and the gate circuit (lli) is turned on. From this point on, the Dakun counter (71) starts receiving the GLK2 signal.

GLK2 consists of 2n pulse trains with synchronization of t/(2”) (t: maximum print pulse width). Counter (71)
starts counting when the GLK2 signal is input. If the contents of the shift register group (IUi) are #2# and the counter (7i) K's information is preset, the counter outputs a #L# signal from the terminal RCY with two pulses of GLK2. do.

In response to this signal, the clip 70 tube (81) Qt#
L", thereby switching the switching element (31)
becomes orr. Furthermore, the gate (10i) is closed and the GL
Input to the counter (10i) of K2 is prohibited. This state is maintained until the next 5TROBE signal is applied. In other words, the contents of shift register (101) "2#"
A printing pulse is applied to the developing heating element at t/211 Drive with the heating element.When n = 8, 256 printing times can be specified for each heating element.The difference in printing time is the difference in applied energy, and ultimately,
This results in a density difference of 256 gradations that appears on the image.

Note that the data in the shift register (101) is written into the counter (71) and held at the same time as the strobe signal is applied, so it may be rewritten. In other words,
Data for the next line can be transferred while printing one line of status information.

Next, considering the process of transferring this gradation data, the memory function body consisting of shift registers is 1
Since 2n types of data for the heating element can be viewed at once, m can be set as 1 in the 2 equations (listed below).

Xm f =- =± For example, t=1.1m5ec, f
.

= 4 MHz, N = 4400.

This means that for 4400' heating elements, even under the condition of f=4 MHz, data input is completed after - times of transfer. In other words, data for 4,400 heating elements can be processed with only one series of n-parallel data input terminals. In terms of 16 dots/sl, it is 4
This corresponds to a line head of 400/16 = 275+w.

As for the gradation problem, since it is determined by the bit ratio that the shift register has for each heating element, it is possible to deal with any number of floors by increasing the bit ratio.

Furthermore, since the gradation data can be input as n-bit parallel data, there is no need for a complicated external circuit that divides the data into the number of gradations and sends them out, unlike the conventional example.

Next, an example of the operation of CLK2 will be explained using FIGS. 3 and 4. FIG. 3 is an example of density characteristics with respect to gradation and energy applied to the recording medium (proportional to the width of the applied pulse). Curve A is an actual concentration curve, and curve Bt/i is a linear approximation line.

As shown in the figure, the concentration and applied energy are not linear but exhibit a figure-8 characteristic. For this reason, when performing multi-gradation recording with uniform density changes ΔD, the value of 5tep JT of the applied energy (that is, during the printing pulse) needs to be changed in all ranges where the density differs. In other words, it must be ΔT1, ΔT2, and jT3. This control is freely performed by CI and 2 as described below.

Next, the operation will be explained with reference to FIG. The switching element is turned on at the falling edge of the strobe signal, as described in FIG. 3. Simultaneously with the input of this signal, input of CLK2 to the counter (71) begins. This CLK2 does not have the same period, and for example, ΔTl)Δ'I shown in the concentration characteristic in FIG.
'2) Create a relationship of ΔT3.

In addition, in CLK2, the width ΔT is almost the same as that of the strobe signal.
The first CLOCKd with 0 is a signal for reset when the gradation level is 0 (no printing).

For example, in the case of gradation l, the strobe signal rises F
The switching element, which is turned on at the same time as the strobe, is controlled by the data 11# (binary data) that is preset in the counter, and is turned on at the second falling edge of CLK2 after the strobe falls. Similarly, in the case of gradation 2, CL
At the third falling edge of K2, if the tone is m, CL
At the m + 1st falling edge of K2, Oli”F
becomes. As is clear from the figure, the ON time of this output transistor is controlled by the period ΔTn of CLK2.

Here, ΔTl, ΔT2. . . . If ΔTn f is set to a value along the density curve shown in FIG. 3, ΔD is constant, that is, uniformly spaced gradation can be obtained.

Note that the above synchronized signals applied to CLK2 are VCM (Volta2eControlled
Multivibrator). As shown in FIG. 4, VCM is an analog signal whose input waveform approximates a concentration curve, and generates pulses with synchronization commensurate with this voltage value.

In the above embodiment, the shift register (21) is parallel k.
Although an example of a bit-based configuration has been shown, a serial configuration is also possible. For example, the control cell (61) corresponding to the first dot
SR7 to SRO of the shift register (101) in the cell are serially connected, and SRO is connected to 817 of the next cell. Similarly, all shift registers are connected in series. The image data is kblt for a single control cell.
(In the figure, n = 8) information is first stored in the shift register (1 (+1)) of the control cell (61).
), and sequentially exits from SR6 to SRO, and the data in SRO is transferred to cell SR7 of the shift register (1t12) of the next control cell (62). When data has been distributed to all cells, CLK
stops. This data is transmitted to the counter (7i) as parallel data of n pits, and thereafter the same operation as in the above example is performed.

In this method of serially connecting the shift registers (101), the number of CLKs needs to be increased by n times compared to the above example, but the number of data input terminals is reduced to 1/n. In other words, the number of connector bins serving as the interface is (n-
1) Creates a throwaway effect by reducing the number of books.

The serial connection of the shift register (101) is connected to cell 8.
Needless to say, even if the connection is made sequentially from RO to the cell SR7, or even if the cell SRO of the shift register of the next control cell is connected to the cell SR7, the purpose is achieved.

[Effects of the Invention] As described above, according to the present invention, the control cell provided corresponding to one heat generating element is provided with a Mepiri circuit consisting of an n-pin shift register, a launch circuit, etc., and the stored data is is configured to change the cycle of the successive clock signals and automatically decode and supply the energy that produces equally spaced d-gradations on the recording medium, so high frequencies are required for data transfer in the case of high gradations. This has the effect that the density gradation intervals can be controlled to be equal pitches without any problems, and the image 1 can be significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a drive circuit according to an embodiment of the present invention, Fig. 2 is a timing chart showing an example of gradation printing when the same circuit is used, and Fig. 3 is an applied energy in cursel printing. FIG. 4 is a diagram illustrating a timing chart of CLK2 and print signals when the circuit according to the same embodiment is used. FIG. 5 is a diagram illustrating an example of a variable 8-period signal generation circuit, FIG. 6 is a diagram illustrating an example of a conventional drive circuit, and FIG. 7 is a diagram illustrating an example of a timing chart of gradation printing in the circuit. , is. In the figure (101) /i shift) L/register (71
)ri counter circuit, (3i)(d switching element,
(81) is S/RFE'', (lli) is a gate circuit, (51) is a heating element, (61) is a control cell corresponding to one heating element show.

Claims (1)

[Scope of Claims] A heating resistor corresponding to each dot for thermal recording that conducts a current through the resistor and uses the heat generated to perform recording, and a switch circuit that turns on and off a voltage applied to the heating resistor; a memory for receiving and temporarily storing gradation density information of the dot to be recorded for each recording dot; a counter for receiving and accumulating information corresponding to the gradation density information from the memory and outputting the accumulated information by applying a clock signal; a signal generator that generates a pulse train corresponding to the application time of a recording signal necessary to give a unit recording density determined corresponding to a recording density S curve of thermal recording; A thermal recording device characterized in that the switching circuit is driven by using the output information of the counter as a clock signal of the counter to cause a current to flow through the heating resistor for a time corresponding to a required recording density.