JPS60154772A - Imaging device - Google Patents

Abstract

PURPOSE:To obtain a high speed, low priced, tone reproducible imaging device by using a means to change pulse width of an impression voltage according to a gradation command signal. CONSTITUTION:A picture data 21 of n-bit per picture element sent from a picture signal generator 10 by a request signal 23 is stored through a gate 11 in a memory 12. An imaging device reads out (l) pieces of these data, converts the data into data of m-bit applicable to imaging characteristics by a gamma conversion table 13, and transfers them to a shift register 15 of mXl-bit. At this time, m=n is acceptable, but (m) is determined by tone reproducibility of the imaging device. The m-bit data of (l) pieces sent from the register 15 are latched by a signal 27 in a presettable down counter 16. The counter 16 is composed of m-bit with (l) pieces and the device generates a carrier signal 30 by a clock 28 according to each data. The device sets l-bit FF17 by a set signal 29 and signal 30, resets and obtains a pulse width signal 31 of (l) pieces for every data.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing device capable of expressing gradation. Specifically, the present invention relates to a printing device that can express gradation. The present invention relates to so-called energized heat-generating transfer, which obtains a print by transferring. In particular, the present invention relates to a printing device capable of expressing full color.

In recent years, various reports have been made regarding color hard copy devices. The main methods are an inkjet method and a thermal transfer method using a thermal head, but in both cases, full color is sometimes achieved by using pseudo-area gradation such as a so-called dither matrix. This is because stable modulation other than 0.1 is not applied. Therefore, in order to maintain a certain level of pixel resolution, a very high-density recording head or high-density recording is required. For example, if the pixel density is 5 dot/n In order to express 16 gradations, a 4 x 4 matrix is assembled, so a line head requires a resolution of 20 dots/mm, and a single head is 16 times slower.Therefore, it is very expensive. Or it will be very slow.

Also, an electrical thermal transfer printing device as presented in US Pat. No. 4,350,449 has been considered. As shown in FIG. 17, the recording paper 255 is opposed to an ink sheet made by laminating a resistive layer 251, a conductive layer 252, and an ink layer 254, and a write electrode &256 and a return electrode 255
7 is brought into contact with the resistance layer and a voltage is applied between them.

As a result, a current passes through the resistive layer 251 and the conductive layer 252, and 251 aK Joule heat is generated in a portion of the resistive layer. Part of the ink due to its Joule heat 25
5a is melted and transferred onto recording paper 255. Write electrode 256 because current flows into the conductive layer with low resistance.
Since the current flowing through the resistance layer directly below is concentrated, uniform printed dots 255a can be obtained. Although this type of printing device has the advantage of high feeding performance, it has the problem of high cost because it requires a matrix IJ rack similar to the above-mentioned thermal head in terms of gradation expression.

〔the purpose〕

The present invention has been made to eliminate such drawbacks, and its purpose is to provide a high-speed, low-cost printing device capable of expressing gradations by improving the above-mentioned electrical thermal transfer printing device. It is to provide.

〔overview〕

The printing principle of the present invention is shown in FIGS. 1 and 2. The energizing heat generating sheet 1 consists of a resistor@2, a support layer 3, and a heat-melting ink layer 4, and the support layer 6 may also serve as a resistance layer. The recording principle is as follows.

When a signal voltage generator 7 sets a pulse width according to a recording pattern and applies a voltage to the recording electrode 5, a current flows through the entire current-carrying layer 2 to the common electrode 6. At this time, if the common electrode is made sufficiently larger than the contact area between the recording electrode 5 and the resistance layer 2, Joule heat due to the current flow will mostly be generated directly under the recording electrode 5. The generated Joule heat is transferred to the support 3 by thermal conduction.
The heat-melting ink 4 is melted by passing through the recording paper 8, and the melted portion of the ink is transferred onto the recording paper 8, thereby making a print.

More strictly considered, the potential distribution in the resistance layer has a very steep potential gradient near the recording electrode, as shown in FIG. 2(a) VC. 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 (b). The dashed line and the solid line both indicate cases where the input energy is large. In the figure, the vertical axis indicates temperature, and the horizontal axis indicates the position corresponding to figure (a). If T8 is the melting point of the thermofusible ink, the area of the heat distribution cut by Ts changes depending on the input energy. In other words, the area of the potential distribution capable of melting the ink changes depending on the applied energy, so that the area of the printed dot is modulated. Table 3 shows the relationship between printing energy and recording density (OD). 1
Since modulation is applied to one dot, there is no need to assemble a magnetic IJ to perform area modulation, which is very advantageous in terms of cost and speed.

In order to achieve the above, the present invention modulates the input energy by changing the pulse width of the applied voltage.

FIG. 5 shows the basic configuration of the pulse width conversion circuit.

Image data 21 of vn bits per pixel sent from the image signal generator 10 in response to a request signal 25 is stored in the memory 12 through the tristate gate 11. Read out t pieces of stored data again, convert it to m-bit data suitable for the printing characteristics using the gamma conversion table 13,
Transfer to the mxt bit shift register 15. At this time, m"n may be used, but m is determined by the gradation reproducibility of the printing device. Furthermore, when the configuration is as shown in FIG. 6, it is possible to set n>m, and the memory 12 can be saved.

The t m'-bit data transferred by the shift register 15 is passed through the signal 27 and latched into the counter 16. The counter 16 has one m-pit configuration and generates a carry signal 30 according to each data by a clock 28. The set signal 29 and carry signal 60 set and reset the t-bit flip-flop 17 to obtain t pulse width signals 31 for each data. Meanwhile, during this time, the next t pieces of data are transferred to the shift register 15.

The above timing chart is shown in FIG. 5(b). 2
4.25 are addresses and control signals for the memory 12 and gamma conversion table 15.

〔Example〕

Embodiment (2) FIG. 4 shows a conceptual diagram of a recording head. The recording principle is described in Japanese Patent Application No. 58-45588VC, so it will be omitted here. 21 pairs of common electrodes 101-1 arranged oppositely
500 recording electrodes 201 are arranged between the recording electrodes 21 and 21.

As shown in (b), each recording electrode is connected to 50 selection signal electrodes 30, 10 each through a backflow prevention diode 501.
1 to 650. One sub-scanning period is divided into the first half and the second half, and in the first half, the selection signal electrodes 501 to 325 are connected to the 11th sub-scanning period as shown in 401 to 425 in FIG.
Selected chronologically with a duty of 50. During this time, common electrodes 101 and 102, 103 and 104,...
...A combination of 119 and 120, depending on the pixel data on the two common electrodes? A voltage 39 with a pulse width is applied. Therefore, in this case, 10 pixel dots can be formed with a duty of 1150.

Next, in the second half, as shown in FIG. 7 426-450, the selection signal electrodes 526-550 are selected, while the common electrodes are now 102 and 103, 104 and 105, etc.
. . . With the combination of 120 and 121, a voltage 39 with a pulse width corresponding to the pixel data is applied.

FIG. 8 shows the drive circuit. The pulse width conversion circuit including the image signal generation section shown in FIG. 4 (8,) is shown as one block 32.

In this embodiment, data of 96 pits per pixel and 500 words per line are stored in the memory 12. 1150
10 pieces of data are leaked on duty, and 1 pixel is detected on the gamma conversion table! The data is converted into 15-bit data, transferred to the 5-pit parallel 10-stage shift register 15, and converted into pulse width as described above. The ten signals 31 that have undergone pulse width conversion pass through the select gate 35 and are distributed into 21 signals 38, which pass through the driver 34 and are distributed to 21 common electrodes.

9th row of select gate 66 and driver 〇) 34
10. They are an inverter 51, a number gate 52, a capacitor 53, a resistor 54, a transistor 55, and a diode 56, respectively.

The signals 601 to 621 from the select gate 36 are connected to the common electrodes 101 to 121 through the driver 34, respectively.As mentioned above, for example, in the first half of one cycle, the select signal 67 is L, so the signals 601, 602, 6
03 and 604...619 and 620, signals 701 to 710, which have been converted into four-fold pulse width, are added, respectively.

In the driver 54, the level of the 5V signal 38 from the select gate 33 is converted to VB=40V using a pair of complementary transistors in the previous stage, and the current is amplified using a pair of hidden emitter follower transistors.

On the other hand, by applying the control signals 40 and 41 to the shift register (2), a selection signal 42 of the jp1150 duty is created and distributed from the driver 36 to the selection signal electrodes 301-550. An example of driver (2) is shown in Figure 11.

This is just a switching circuit, which turns on when each signal 401 to 450 is H, and current flows from the common @ pole.

In the present invention, in order to print in full color, yellow, magenta, and cyan are overwritten on each page in this order.

Input signal sources include television signals, full-color scanners, personal computers, and the like, but in this embodiment, a still image NTBC television signal is used as the input source. FIG. 12 shows an embodiment of the image signal generating section. NTEIC! The composite signal 83 of R8-6, Ga4 . R8
The signal is separated into eight color signals and input to the changeover switch 73. A full-color printer prints yellow, magenta, and cyan for each page in that order, so the switching signal 93
For each page, change the switch 73 in the order of R88, Ga4, and R86. In order to save memory, the printing speed for one line is set to 60 Hz, and the IC1 horizontal scanning signal is A/D converted for each field of the TV signal, latched as 6-bit data 90 by latch 75, and stored in memory. 81 and memory 82 alternately.

For example, when data is being written to the memory 81, data is read from the memory 82, so that the two line memories are operated alternately, eliminating time loss, and the data 21 is being sent to the pulse width conversion circuit. supply. These operations are controlled by the control unit 76 based on the horizontal synchronization signal 84 and vertical synchronization signal 85 obtained from the synchronization separation 72, and the request signal 23 from the pulse width conversion circuit.
Write gate made with■■77゜79, read gate■
(2) Controlled by 7B, 80, control signals 96.97 and memory control signals 98°99.

In addition, when made to correspond to the pulse width conversion circuit shown in FIG.
It corresponds to the image signal generating section 10 shown in the figure, and the memory ■Memory'■ corresponds to the image signal generating section 10 shown in FIG. Corresponding to the A and M memories 12, data 21 is input to the gamma conversion table 155 in FIG.

FIG. 15 shows a conceptual diagram of a full-color printer according to this embodiment. Recording paper 808 wrapped around roller 5aix,
The energized heat-generating sheets 1 supplied from the sheet supply unit 802 via the feed roller 805 are overlapped on the roller 800 and recorded by the recording head 801. Head is presser spring 8
12 to the roller 800 and maintain appropriate pressing pressure, the recording head 801 and the energized heat generating sheet 1
Maintain uniform contact between the paper and the recording paper.

The energizing heat generating sheet 1 is in the form of a roll, and as shown in FIG. 14, a layer of heat-melting ink is applied to each page in the order of yellow 816, magenta 814, cyan 815, and black 816. Therefore, writing is performed four times to obtain one full color record. Therefore, highly accurate positioning is required when overlapping colors. It should be noted that black 816 is not necessarily required because black can be obtained by mixing yellow 816, maze 814, and cyan 815 in equal amounts of gold. In the present invention, the recording paper 808 is wound around the roll 800 and fixed, and the absolute position is determined by the rotary encoder 811.

The position signal from the rotary encoder 811 is sent to the control unit 810, and the roll 80 rotates at a constant speed.
0, a signal is sent to a sheet feed roller 802 for positioning, a sheet winding roller 803, and a recording head drive circuit 804.

The position signal from the rotary encoder 91 is input to the control unit 76 in FIG. A sheet feed signal is supplied in synchronization with the signal.

In the above examples, when the applied voltage is 40V, yellow,
By superimposing the three colors of magenta and cyan, it was possible to record a 52-dimensional true full-color still TV image in 30 seconds.

In the above embodiment, the write electrode was bottle-shaped and the return electrode was a planar electrode, but the present invention is not limited to such a structure. A similar effect is obtained even if a voltage is applied to the

In FIG. 15, 240 and 241 indicate the contact ends of the bottle-shaped electrodes with the resistor 1, and the connection with the power source 268 is through a switch (
K-1) to (K+2)... (a) shows how current flows in the resistance layer,
(b) is its equivalent circuit. The opening and closing of the switch is 257 for "open 1" and 258 for "closed 1". In these open and closed states, the current flows as 254 and 255. Each electrode is connected to the switch (K-1), K, (K+1).・・・
Although the selection is controlled by .

FIG. 17 shows an example of a head structure using bottle needle electrodes.

Ni-0r261 and 0u2 on the ceramic substrate 260
62 was vapor-deposited, an electrode was formed by photoetching,
Electroless plating 10 of BL-W-P selectively on this ta
4 has been applied.

Furthermore, in the above embodiment, an ink sheet having an ink layer on one side of an insulating support layer and a resistance layer on the other side was used, but as shown in FIG. 16(a) (bO(0)) In (a), the resistance layer 902 directly supports the ink layer 901, and in (b), a heat-resistant resin layer serving as a color clouding prevention layer is interposed between the resistance layer 902 and the ink layer 9010. (C) is a single-layer sheet in which a resistance layer is integrated into an ink layer.

The resistance layer is made by binding carbon particles with a resin and coating them in a layered manner, and the resistance value is preferably between 100 Ω and 100 Ω between the alt poles of two needles separated by 1·α.

〔effect〕

As described above, according to the present invention, gradation recording can be achieved using the highly reliable method of pulse width conversion.

In particular, in an electrical thermal transfer printing device, an ink sheet having at least a resistive layer and an ink layer is used, a current is configured to flow between two electrodes in contact with the resistive layer, and the pulse width of the applied voltage is varied in stages. By using a combination of means to change according to the key command signal,
At least a sufficient number of gradation electrodes can be obtained, and rapid gradation display printing can be achieved.

Full color printer, full color copier, full color T
Its application range is extremely wide, such as V printers.

[Brief explanation of the drawing]

1, 2(a) and 2(b) show the printing principle of the present invention. FIG. 6 shows the relationship between input energy of the printing device and recording density. FIGS. 5(a) and 6(b) and FIGS. 6(a) and 6(b) show a pulse width conversion circuit according to the present invention. FIG. 4 shows a conceptual diagram of an embodiment of the recording head. 7 and 8 show timing charts and drive circuit diagrams of the present invention. FIG. 9 shows an embodiment of the select gate. FIGS. 10 and 11 show examples of drivers (1) and (2). FIG. 12 is a block diagram showing an embodiment of the image signal generating section. FIG. 13 is a conceptual diagram of a printing device according to the present invention. FIG. 14 is a perspective view of the energized heat generating sheet used in the present invention. FIG. 15 is a conceptual diagram showing another embodiment of the present invention. FIG. 16 is a perspective view of the head used in the embodiment of FIG. 15. FIG. 17 is a sectional view showing another embodiment of the ink sheet used in the present invention. FIG. 18 is a sectional view of a conventional electrical thermal transfer printing device. Memory 12 Gamma conversion table memory 13 Shift register - 15 Control signal generation part - 14 Counter with latch function 16 Flip-flop - 17 Applicant Suwa Seikosha Co., Ltd. Figure 1 Figure 2 E Figure 3 1N Kaisho GO -154772(6) (α) Cb> Figure 4 (α) One! -CF) Fig. 5z Fig. 6 Fig. 70 Fig. 11 TS C Fig. 12 Fig. U Fig. 1b

Claims (1)

[Claims] ■ In a printing device that can express gradations by modulating the printing amount for each pixel, its drive circuit consists of a control signal generator memory, a gamma conversion table memory, an mX7-bit shift register, a counter with a latch function, and a flip-flop. A printing device characterized by having a different pulse width conversion circuit.