JPS6023053A - Printing apparatus - Google Patents

Abstract

PURPOSE:To realize high gradation reproducibility, by respectively dividing a large number of recording electrodes and return electrodes provided to the head of an electric heat transfer printer into a large number of groups, and appropriately combining said groups to perform matrix driving while bringing a specific number of the return electrodes in each group to a potentially floating state. CONSTITUTION:A large number of recording electrodes are linearily arranged to the head of a printer for performing thermal transfer of ink to paper by supplying a current to a sheet having a current supply layer and an ink layer and a large number of return electrode pairs 101-109 are arranged along the recording electrodes forming pairs at both sides thereof. In this case, return electrode pairs 101-109 are divided into M-groups each of which comprises i-numbers of adjacent return electrode pairs and, for example, when a selection signal electrode 301 is selected, data voltage is applied to two return electrodes 101, 102 and (i-2) numbers of the remaining electrodes 103-104 are floated. By this mechanism, because (i-2) numbers of floating electrodes 103-104 are present between the return electrodes 102, 105, a current therebetween can be suppressed as small as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing device, and more specifically, the present invention relates to a printing device, in which a current is passed through a conductive sheet, heat-melting ink is melted by heat generated by Ziehl heat, and the ink is transferred onto transfer paper. This is related to the so-called energized heat transfer process.

Various attempts have already been made to use heat generated by electricity to melt solid ink and transfer it to recording paper.

The basic concept is shown in Figure 1. The energizing heat generating sheet 1 consists of an energizing layer 2, a support layer 3, and a heat-melting ink layer 4.
The support layer 3 may also serve as a current-carrying layer. The recording principle is as follows.

When a voltage according to the recording pattern is applied to the recording m-pole 5 by the signal voltage generating section 7, a return type tIIIi is generated via the current-carrying layer 2.
Current flows to 6. At this time, if the return electrode is made sufficiently larger than the contact area between the recording electrode 5 and the current-carrying layer 2, Joule heat due to energization is generated directly below the recording electrode 5. The generated Joule heat passes through the support 3 by thermal conduction and melts the hot melting ink 4, resulting in a melted portion 10 of the ink.
is transferred onto recording paper 8 and printed.

As described above, recording by energized heat transfer can be performed on plain paper. ■No noise ◇■ Capable of gradation recording. ■Can record in color. It has advantages such as However, despite having the above-mentioned advantages, the prospects for commercialization are extremely low compared to other printing methods such as the inkjet method and the thermal transfer method using a thermal head. This is due to the following reasons.

The electric heating transfer method that has been proposed in the past basically performs serial printing with a single recording electrode as shown in Figure 1, or has multiple recording electrodes and one return electrode. Either multiple N poles were driven in time division.

The former has an extremely slow recording speed, and the latter requires as many drivers to drive the recording electrodes as there are recording electrodes, making it very expensive, and the time-sharing duty is high, so the input for one pixel is required. The disadvantage is that the power is high. For this reason, the development of electrical heating systems has been hindered, although they have various advantages.

On the other hand, in order to eliminate such drawbacks, a time-division driving method has been considered in which a plurality of recording electrodes are selected simultaneously. Figure 2 shows this recording principle.

As shown in (a), the electrode shape is such that a recording electrode 20 is placed between a plurality of pairs of return electrodes 101 to 1.
1 to 206 are arranged. Hereinafter, this pair of opposing return path electrodes will be treated as one.

Figure 3 shows the equipotential surfaces when different potentials are applied to the return electrodes that meet each other. FIG. 3 shows that when an electric heating sheet having a conductive layer is brought into contact with the recording head and a potential of E (v) I O (V) is applied to each of the return electrodes 101 and 102, the equivalence of π in the conductive layer is also significant. It is. As shown in the figure, at this time, the return type t! Since almost no electric field enters the divided regions 11 of 1102, for example, the recording electrodes 13.
14 are simultaneously applied with a potential of 0 (V), a current of L flows from the return electrode 101 at the recording m pole 13, and printing is performed according to the principle of energization heating recording described above, but the vicinity of the recording electrode 14 is at the same potential. Therefore, no current flows and therefore no printing is performed. By arranging the return path electrodes as described above, selective printing can be realized by selecting the potentials of the return path N pole and the recording electrode.

In FIG. 2(b), selection signal electrode S, 301, 523
02 and S3303 are respective backflow prevention diodes 501
It is connected to the recording Tl1f and the poles 201 to 206 through 506, and becomes 0 (v) when selected, and 70-ting when not selected. Now, for example, the selection signal electrode S, 301 is selected (0 (V)), S2502, S, 505 are unselected (70-ting), and the return electrodes 101 and 103 are independently set to 0 (V) or E (V). ) is applied at the same time @
Regardless of the combination of applied potentials, the recording electrodes 201 and 202 can be independently applied because the electric field does not wrap around between the return electrodes as described above. on the other hand,
In the case of recording electrodes 205 and 204, 205 and 206, the return path [is located between the divided poles and is therefore influenced by the adjacent return path electrode. Therefore, to avoid this, adjacent return electrodes are driven as a pair. For example, when selecting the selection signal electrode 302', the set of return electrodes 101 and 102 and the set of return electrodes 106 and 10
Group 4, when selection signal electrode 603 is selected, return electrode 1
By driving the set of 02 and 103 and the set of 104 and 105, respectively, all the recording electrodes can be driven.

Although a plurality of electrodes could be selected simultaneously as described above, a current flows between adjacent return path electrodes in order to determine the potential by the return path electrodes.

The return electrode has a sufficiently larger area than the recording electrode, so
The current density is low, so there is no excessive heat generation, but it creates a thermal bias, which is not preferable for gradation reproduction.

The present invention eliminates such drawbacks.The purpose of the present invention is to suppress the leakage current between the return path m poles in the above-mentioned driving method, realize high gradation reproducibility, and eventually realize a low-cost, high-speed full-color printer. It is to provide.

The gist of the present invention is to keep the current sufficiently low by increasing the distance between return electrodes with different potentials. FIG. 4 shows the driving principle according to the present invention.

When the return path 111 pole pairs are divided into M groups of 4, and the selection signal electrode 301 is selected, for example, as described above,
A data voltage is applied to the return path electrodes 101 and 102, and the potential of the remaining (i −2) return path m poles 103 to 104 is floated. Similarly, in the equal M group, a data voltage is applied to 106 and 107, and the potential of the return electrodes 108 to 109 is raised. Between the return path msi through which the current flows, for example 102 and 105, there are return path electrodes 103 to 1 of 70-tings.
Since there are (i −2) 04, there is a physical distance between the return electrodes 102 and 105, and the current flowing between them can be kept extremely small.

As described above, by separating the return electrodes that are driven at the same time, the current between the return electrodes can be suppressed, and the negative effect on gradation reproduction can be eliminated.

Next, the tone recording according to the present invention will be described.

The sixth diagram schematically shows the potential distribution of the current-carrying layer due to the recording electrode 201 and the return electrode 101 when the recording head according to the present invention is brought into contact with a heat-generating sheet having a current-carrying layer and an ink layer and energized.
It is shown in figure (α). There is a very steep potential gradient near the recording electrode. Therefore, the heat distribution of the heat generating sheet due to the heat generated by energization becomes a mountain shape with a peak at the center as shown in (6). The wavy line indicates the case where the input energy is larger than the solid line. In Figure 0, the vertical axis is the temperature, and the horizontal axis is the position corresponding to the figure (α). If T8 is the melting point of the thermofusible ink, then
The area of heat distribution cut by T8 changes depending on the energy input. In other words, area modulation is applied to the printed dots depending on the applied energy.

Figure 7 shows the relationship between printing energy and optical density. Since modulation is applied to one dot, there is no need to construct a matrix, which is very advantageous in terms of cost and speed. As for color printing, full-color printing was made possible by selecting heat-melting inks of yellow, magenta, cyan, and black if necessary.Examples are shown below.

FIG. 7 shows a principle diagram of an embodiment according to the present invention.

The specifications of the printing device are: printing width 9o, recording density 5 dots/
Therefore, 450 recording electrodes were driven in a 75×6 matrix with M=6, N=75, and i=3.

Select signal electrode 301 for selection signal of 1/75 de=-T.
Added sequentially to ・Return trip between 81 and s25! Pole 101 (O
f, Oj++, Oj+2) (j=1.4°y, 1o, 1
s, 16), and each Oj+Oj+2
Apply the Vc data signal and set Oj+2 to 70-ting. s26 to S of the selection signal electrode 30i. When selecting COj+1, Oj+2゜Oj+3), apply data signals to Oj+1 and Oj+2, and select C
Make j+5 70-ting.

When selecting h2 tf2 K S sr ~s7a (aj++.

Cj+2, Cj+5), Of+2
．． Apply the Oj+s nitator signal and make Oj+1 floating. FIG. 8 shows a circuit for driving the return electrode used in the present invention. The output mode is switched by the output enable terminal 35, and when it is at L level, it becomes high impedance. When the output enable terminal 35 is at H level, the data input from the data terminal 36 is amplified to the level of VH 38 by the transistors 31, 32, and 53, and is output to the output terminal 57.

22 is an inverter, 23 to 27 are resistors, 28 to 3° are capacitors, 34 is a diode, and 69 is a brand level @ Fig. 9 shows an example of the drive circuit. The control unit 41 sends an LS signal 31 indicating the beginning of a line and a request clock 32 (45°pulg) to the image signal generation unit 40.

The sent 4-bit pixel data 5o synchronized with the request clock 32&j is R for image processing such as gamma correction.
The data is input to the address of the OM table 42, an image processing table corresponding to each color or output content is selected using a multi-bit signal 51, and transferred to the shift register 44 as 8-bit pixel data 52. The register 44 has 8 bits in parallel and has 6 stages. After the transfer is completed by the transfer clock 33, the signal 34 is sent to the preset counter 45. There are six preset counters 45 with 8-bit input, which are counted by a clock 53 to create a pulse width according to manual data. The set signal 65 and the carry obtained from the recent count are used to hit the 7 lip 70 knob 46 to create a pulse according to the data. Since pulse width modulation is performed as described above, there are 16 gradations, but 25
You can select the gradation in steps of 6 gradations.

The obtained modulated pulse is distributed to the return electrode by a signal 30 in a distribution section 47, and converted into a driving voltage in a driving section 48.
061 output to the nine return electrodes is an output enable signal.

- The force selection signals 401 to 450 are generated by a 75-stage shift register 49 using a clock 58 and a timing signal 59, and are outputted from an open-drain high voltage driver 60 to a selection signal electrode.

FIG. 10 shows a conceptual diagram of a full-color printer according to the present invention. A recording paper 80 wound around a roller 80 and an energized heat-generating sheet 1 supplied from a sheet supply section 82 via a feed roller 85 are overlapped on the roller 80 and recorded by a recording head 81. The head is pressed against the roller 80 by a presser spring 88, maintaining appropriate pressing pressure and maintaining uniform contact between the recording head 81, the energized heat generating sheet 1, and the recording paper.

The energized heat generating sheet 1 is in the form of a roll, and as shown in FIG. 11, a layer of heat-melting ink is coated on each page in the order of yellow 95, magenta 96, red 97, and black 98. Therefore, writing is performed four times to obtain one full color record. Therefore, highly accurate positioning is required when overlapping colors. In the present invention, the recording paper 8 is wound around the roll 80 and fixed, and the absolute position is determined by the rotary encoder 91.
A position signal from the rotary encoder 91 is sent to the control unit 91, which sends a feed bank to the roll 80 for constant speed rotation, a sheet feed roller 82, a sheet winding roller 83, and a recording head drive circuit 84 for positioning. A signal is sent to. By applying pressure as described above, the present invention achieves highly accurate alignment of position 1a.

With this printing device, we were able to make a 10cm x 10cm full-color copy in 20 seconds.

As described above, the present invention realizes the energizing heat recording method using time-division driving, and is a so-called analog modulation method that modulates the area depending on the input energy, so it can be used as a full-color printer with extremely high resolution and high speed. It is an epoch-making product that has realized low-cost color video printers, color copies, etc., and its applications are extremely wide.

[Brief explanation of drawings]

FIG. 1 shows a principle diagram of a conventional energized heat transfer recording system. FIG. 2(a) + (6) shows the principle of a conventional recording head. FIG. 3 shows the potential distribution of the current-carrying layer due to the return electrode. FIG. 4 shows a principle diagram of a recording head according to the present invention. FIG. 5(α) l (b) shows the potential distribution and temperature distribution of the current-carrying layer in the recording head according to the present invention. FIG. 6 shows the relationship between input energy and printing density in the present invention. FIG. 7 shows an outline of a recording head according to an embodiment of the present invention. FIGS. 8 and 9 show a return electrode drive circuit for driving,
The drive circuit is shown. FIG. 10 shows a conceptual diagram of a printing apparatus according to the present invention. FIG. 11 shows the electrical heating sheet used in the present invention. →1・i・・4・Electrifying heat generating sheet 2・・・・・・Electrifying layer 4・・・・・・Thermal melting ink 8
... Recording paper 101 - Return electrode 201 - Recording electrode 501 - Selection signal electrode 501 - Backflow prevention diode 42・・・
... ROM table 80 ... Recording roller 81 ... Recording head 88 ... Presser spring 84 ... Drive circuit 82 ... Sheet feed roller 86 ... Sheet winding killer roller 91 ... Position detector 90 ... Positioning controller and above Applicant Suwa Seikosha Co., Ltd. Agent Patent attorney Tsutomu Mogami No. 1 Ui No. 2)・',; Figure 3, Figure 41] -9 only 〇- Figure 10, Figure 11! ”1

Claims (1)

[Claims] (1) In a printing device in which ink is melted by heat generated by electricity and is transferred to a recording paper to produce a record, the recording head is divided into a plurality of pairs and includes a pair of return electrodes arranged facing each other, and the return electrode. It has a plurality of recording electrodes placed between pairs of divided recording electrodes, with i number of return path electrodes blinking each other as one group, M groups of said return path electrodes, and N devices per group. Matrix driving is performed by introducing the recording electrodes together, and furthermore, (i - 2) of the i return electrode pairs per group are brought to a certain potential within one cycle of writing time. A printing device characterized in that it is in a 70-ting state. (Poor) Selection signal to the recording m pole, the return path 1! 2. The printing apparatus according to claim 1, wherein a data signal is applied to the pole pair. (2) The printing apparatus according to claim 1, characterized in that a backflow prevention diode is wired to the recording electrode. ■ The output of the circuit that drives the return path am is at H level and L level.
The printing apparatus according to claim 1, characterized in that it takes three states: level and high impedance.