JP2565915B2 - Current transfer recording device - Google Patents

Description

The present invention relates to an electric transfer recording apparatus, and more particularly to an electric transfer recording apparatus capable of driving a recording electrode with a low voltage.

(Prior Art) As one of hard copy devices suitable for a personal computer, a printer for a word processor, and the like, an electric transfer recording device is drawing attention. FIG. 11 shows a basic structure of an example of an electro-transfer printing apparatus, which uses a resistive ink ribbon 4 having a three-layer structure composed of a resistive base film 1, a conductive layer 2 and an ink layer 3. The conductive layer 2 may be omitted. An image is formed on the ink ribbon 4 by supplying a recording current from the constant current driver 10 to a large number of recording electrodes 7 on the recording head 6. In this case, the recording current 8 flows from the recording electrode 7 through the route of the resistive base film 1 of the ink ribbon 4, the conductive layer 2, the resistive base film 1 and the return electrode 9. By the Joule heat generated when the recording current 8 flows in the resistive base film 1, the ink in the ink layer 3 is softened, melted or sublimated and transferred onto the recording medium 5 to form an image. . In this current path, the recording current 8 passes directly under the recording electrode 7 and through the resistive base film 1 when flowing into the return electrode 9, but the return electrode 9 has a large area with the resistive base film 1. Since the current density immediately below the return electrode 9 becomes small, a large amount of Joule heat is generated only below the recording electrode 7 where the current is concentrated, and an image is formed.

Since such a thermal transfer recording apparatus does not use a thermal head like a normal thermal transfer recording apparatus, heat is not accumulated in the recording head 6, direct current can be supplied, and even if a large recording energy is injected, the recording head is It has features such as not destroying 6. Further, since heat is generated in the base film 1, the heat transfer efficiency to the ink layer 3 is high, and recording can be performed at a higher speed as compared with a thermal transfer recording device using a thermal head. Furthermore, since a large amount of recording energy can be supplied, high-speed recording using ink with a high melting point can also be realized. For example, resin-based ink that can record on rough paper or sublimation that can record density gradation images. High-speed recording is also possible using the above ink.

In such an electrification transfer recording apparatus, one recording electrode 7 is provided for the current path from the recording electrode 7 to the return electrode 9.
Figure 12 shows the equivalent circuit seen from above. In Fig. 12, Rf
Is the resistance between the recording electrode 7 and the conductive layer 2, Rc is the resistance of the conductive layer 2, and Rr is the resistance between the conductive layer 2 and the return electrode 9. The recording current 8 flows from the recording electrode 7 into the conductive layer 2, spreads over the entire width of the ink ribbon 4 in the conductive layer 2, and flows into the return electrode 9 as it is. Recording electrode 7
The resistance Rf from the conductive layer 2 to the return electrode 9 is actually 100 to 400Ω, while the resistance Rr from the conductive layer 2 to the return electrode 9 is
Is very small, about several Ω. Also, the resistance Rc of the conductive layer 2
Varies depending on the material and thickness of the conductive layer. For example, in the case of an Al film with a thickness of about 0.05 to 0.1 μm, several Ω to several tens of Ω
Is.

The actual configuration of the electric transfer recording apparatus is a serial printer configuration in which several tens of recording electrodes are lined up on one recording head along the transfer direction of the recording paper, or one recording electrode of several hundreds or more is used. It has a line printer configuration in which recording paper is arranged on the recording head in a direction perpendicular to the transfer direction.
Therefore, an equivalent circuit when only one recording electrode is driven and when N recording electrodes are simultaneously energized and driven is described in a twelfth example.
It shows in figure (a) (b). When a current I is made to flow from a constant current driver to one recording electrode, the voltage drop of the resistive ink ribbon 4, that is, the voltage drop between the recording electrode 7 and the return electrode 9 as shown in FIG. 12 (a). Vd becomes (Rf + Rc + Rr) I. On the other hand, when the recording current I is simultaneously applied to the N recording electrodes 7, the voltage drop Vd becomes RsI + (Rc + Rr) NI as shown in FIG. 12 (b).

Here, when performing high-speed recording of 100 cps or more, it is necessary to supply a current of, for example, I = 50 mA or more to each recording electrode 7. In this case, when the voltage of all marks is recorded as the maximum value of the voltage drop Vd, that is, when the current of 50 mA is simultaneously supplied to all the recording electrodes 7, the voltage drop Vdmax is calculated to be Rf = 250.
Assuming Ω, Rc = 15Ω, Rr = 1Ω, N = 40, Vdmax = 2
50Ω × 0.05 + {(15 + 1) × 40 × 0.05} ≒ 45V,
The power supply voltage is required to be higher than this voltage. This is the case where the number N of recording electrodes is 40 and the recording current I is 50 mA, and if these are increased, a higher power supply voltage is required.

Further, when currents are supplied to all the recording electrodes at the same time, the heat generation points on the ink ribbon are aligned, so that the ink ribbon is easily broken.

(Problems to be Solved by the Invention) As described above, the conventional energization transfer recording apparatus requires a high power supply voltage because the voltage drop in the resistive ink ribbon increases in accordance with the number of recording electrodes simultaneously driven. Further, there is a problem that the ink ribbon is easily broken when recording the all mark pattern.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems, and to provide an electric transfer recording apparatus capable of supplying a sufficient recording current to a recording electrode with a low power supply voltage and preventing ink ribbon breakage.

[Structure of the Invention] (Means for Solving the Problems) In the electro-transfer printing apparatus according to the present invention, when the number of mark signals included in the image signal sequence is small, a plurality of recording electrodes are provided according to the image signal sequence. If the number of mark signals included in the image signal sequence is large, the recording electrodes are divided into a plurality of blocks, and the recording electrodes are energized in different phases according to the image signal sequence. This is so that the electrodes are not energized at the same time.

(Operation) When the number of mark signals included in the image signal sequence is large, in the present invention, the recording electrodes are energized and driven in a sequentially shifted phase in block units, so that a large current does not flow in the ink ribbon at the same time. Therefore, the voltage drop in the ink ribbon is small and the power supply voltage can be low. Further, when the recording electrodes are energized in this way, the heat generation points on the ink ribbon are dispersed to some extent, so that the ink ribbon is less likely to break. Further, when the number of mark signals included in the image signal sequence is small, the recording electrodes are energized and driven at the same time as in the conventional energization transfer recording apparatus instead of each block. By doing so, it is possible to prevent the deterioration of the recording quality due to the position shift of the image point in the sub-scanning direction without lowering the sub-scanning speed or intermittently performing the sub-scanning. That is, since the ratio of the mark signal to the image signal sequence is small in the document image or the like to be recorded by the electric transfer recording apparatus, according to the present invention, most of the image is recorded in the mode in which the recording electrodes are simultaneously energized. Only when the ratio of the mark signal is large to some extent, recording is exceptionally performed in a mode in which the recording electrodes are phase-shifted block by block and energized, and on the average, high quality recording is performed by the former mode. Done.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an electric transfer recording apparatus according to an embodiment of the present invention, in which the same parts as those in FIG. 11 are designated by the same reference numerals. In the figure, a binary or multi-valued image signal sequence generated from a signal generator 11 such as an external device or a character generator is input to the heat storage control unit 12. Heat storage control unit 12
Drives each recording electrode 7 with what kind of current value and what kind of pattern of energizing pulse based on the arrangement state of the mark signals of the image signal sequence and further the temperature data of the recording head 6 detected by the thermistor or the like. It is determined whether or not the constant current driver 13 is controlled. Constant current driver
Each of the recording electrodes 7 has the same number of constant current sources as the number of recording electrodes 7, and supplies constant current pulses having independent widths and current values to the corresponding recording electrodes 7 based on the control data from the heat storage controller 12. The energization driving method of the recording electrode 7 according to the present invention is realized by the energization pulse to be described later being selected in the heat storage control unit 12 based on the arrangement state of the mark signals of the image signal sequence.

Next, the energization drive system based on the present invention will be described. In the present invention, the recording electrode 7 is divided into a plurality of blocks,
When the number of mark signals included in the image signal sequence is large, the recording electrodes 7 are energized and driven in different phases for each block. When the number of mark signals included in the image signal sequence is small, the recording electrodes 7 are driven. It is basically driven at the same time.

In FIG. 2, all the recording electrodes 7 are divided into two blocks consisting of odd-numbered electrodes and even-numbered electrodes. The odd-numbered electrodes are energized and driven only in the first half of the recording cycle T, and the even-numbered electrodes are driven in the latter half. This is an example in which only current is driven. Here, similarly to the above, the number of recording electrodes 7 is N, the resistance from the recording electrodes 7 to the conductive layer 2 of the ink ribbon 4 is Rf, and the resistance of the conductive layer 2 is
If Rc is the resistance from the conductive layer 2 to the return electrode 9 and R is the current flowing through one recording electrode 7, conventionally, for example, when recording an all-mark pattern, the N recording electrodes 7 are simultaneously energized and driven. Therefore, the voltage drop of the resistive ink ribbon 4, that is, the voltage drop Vd between the recording electrode 7 and the return electrode 9
Becomes (Rf + Rc + Rr) NI. On the other hand, when the recording electrode 7 is divided into two blocks as shown in FIG. 2 and the recording electrodes 7 are energized by N / 2, the voltage drop Vd of the ink ribbon 4 becomes Rf I
It becomes + (Rc + Rr) NI / 2, which is almost half of the conventional level. As a specific numerical example, Rf = 250Ω, Rc = 15
If Ω, Rr = 1 Ω, N = 40, and I = 50 mA, the maximum voltage drop Vdmax at the ink ribbon 4 in this embodiment is Vdmax.
= 250Ω × 0.05 + {(15 + 1) × 20 × 0.05} ≒ 29V, which is a large reduction compared to the conventional 45V. Therefore, the voltage of the power supply used for the constant current driver 13 is about 30V.

Note that, in practice, when energization is performed only for half of the recording cycle T as shown in FIG. 2, in order to obtain the same recording density as compared with the case where energization is performed over the entire period of the recording cycle T, that is, In order to make the Joule heat generated in the current-carrying region the same, the current must be slightly increased. Therefore, the power supply voltage must be increased by that amount, but since the Joule heat is proportional to the square of the current, the increase in the current and the accompanying increase in the power supply voltage can be small.

Although the recording electrode 7 is divided into two blocks in FIG. 2, it is possible to further reduce the required power supply voltage by dividing the recording electrode 7 into a larger number of blocks and shifting the phase for each block to perform energization drive. Can be made.

In addition, when the recording electrodes 7 are divided and driven in different phases for each block in this way, ink ribbon breakage can be reduced. In the electric transfer recording apparatus, an image is recorded by the heat generated in the resistive base film 1. However, if the heat is too large, the temperature rises up to near the melting point of the base film itself and is added to the ink ribbon 4. Ink ribbon breakage may occur due to the tension applied. When all the recording electrodes are driven at the same time, the heat generation points 21 on the ink ribbon are aligned on a straight line as shown in FIG. That is, the portions weakened by the heat are arranged in a straight line in the direction perpendicular to the direction in which the tension 22 is applied, and the tension 22 is concentrated and applied to this portion, so that the ink ribbon 4 is easily broken.

On the other hand, when the odd-numbered and even-numbered recording electrodes 7 are energized and driven as shown in FIG. 2, the heating points 21 are staggered on the ink ribbon 4 as shown in FIG. 3B. Line up. In this case, the tension applied to the ink ribbon 4
22 is dispersed and added in the peripheral portion of each heat generation point 21, so that the ink ribbon breakage hardly occurs.

Another example of the energization drive system based on the present invention is shown in FIGS. FIG. 4 basically shows a system in which the odd-numbered and even-numbered recording electrodes 7 are energized and driven by shifting the phases, as in FIG.
This is different from FIG. 2 in that a narrower pulse is used and these are alternately supplied to the odd-numbered electrodes and the even-numbered electrodes a plurality of times. In this case, in the period of the recording cycle T, since the currents are supplied to the odd-numbered electrodes and the even-numbered electrodes over a time width of T / 2, the same energy as in the case of FIG. 2 is applied. In a high-speed printer such as an electric transfer recording apparatus, a difference in drive timing of recording electrodes appears as a difference in recording image points. That is, in the energization drive method shown in FIG. 2, the positions of the image points recorded by the odd-numbered recording electrodes and the positions of the image points recorded by the even-numbered recording electrodes are perpendicular to the array direction of the recording electrodes. It shifts in the direction. This is sufficient when the recorded content is an all-mark pattern, but when recording a straight line along the array direction of the recording electrodes, 1
It becomes zigzag instead of a straight line. According to the method shown in FIG. 4, such a straight line along the array direction of the recording electrodes can be recorded as a substantially straight line pattern.

When the energizing pulse is finely divided as shown in FIG. 4, the effect of the heat storage effect is likely to appear when recording is continuously performed for a long time. Therefore, when a high density pattern such as an all mark is recorded, the energizing pulse shown in FIG. 2 is used, and when a straight line along the arrangement direction of the recording electrodes 7 is recorded, the pattern shown in FIG. It is desirable to use the energizing pulse shown in ().

Further, when one isolated straight line is recorded using the energizing pulse shown in FIG. 4 (a), the temperature rise is smaller than the case where the energizing pulse shown in FIG. 2 is used. In such a case, such a straight line can be surely recorded by adding energizing pulses for preheating and heat retention at timings before and after the straight line to be recorded as shown in FIG. 4 (b). it can. Since the preheating pulse and the heat retention pulse are simultaneously applied to all the recording electrodes, the voltage drop of the ink ribbon 4 increases. When this voltage drop exceeds the power supply voltage of the constant current driver 13, the constant current driver 13 cannot maintain the constant current operation, and as shown in FIG. 4 (c), the preheating pulse and the heat retaining pulse are applied to the recording electrode 7. The flowing current decreases. However, by adjusting the widths of the preheating pulse and the heat retention pulse, it is possible to compensate for the shortage of heat generation due to the shortage of current.

FIG. 5 shows an example in which energizing pulses with different phases supplied to the odd-numbered and even-numbered recording electrodes 7 are partially overlapped. In the case of using energizing pulses whose phases are completely shifted as shown in FIG. 2, the all-mark pattern cannot be recorded with sufficient density unless the current value is increased to some extent.
The energizing pulse shown in FIG. 5 has a pulse width longer than T / 2 instead of increasing the current value so that such a pattern can be satisfactorily recorded. In this case, N /
If the power supply voltage of the constant current driver 13 is set so that a desired current can be supplied when the two recording electrodes 7 are simultaneously driven, as in the case of FIG. 4C, FIG. ), The current value decreases at the portion where the energizing pulse of the odd-numbered recording electrode and the energizing pulse of the even-numbered recording electrode overlap. However, in this case as well, a large amount of recording energy is injected compared to the case where nothing is recorded, so by adjusting the time width of the overlapping portion, the all-mark pattern can be recorded with sufficient density without raising the power supply voltage. can do.

In the energization driving method of the recording electrode 7 according to the present invention described above, the energization pulse shown in FIGS. 2, 4 and 5 is selected in the heat storage control unit 12 based on the arrangement state of the mark signals of the image signal sequence. It is realized by being done. A specific method of heat storage control is a macro heat control method in which the current value applied to all recording electrodes 7 is uniformly controlled with respect to environmental temperature changes and temperature changes that affect the entire recording head 6. Although there is a micro thermal control method for controlling the energization time and phase for each recording electrode 7, the energization drive according to the present invention is performed as a part of the micro thermal control.

In the micro thermal control method, as shown in FIG. 6, for example, eight pixels around the pixel of interest of the image signal sequence are used as a reference area, and the pulse width and phase of the energizing pulse are determined from the arrangement state of the mark signals in this reference area. To do. When the width and phase of the energization pulse corresponding to one pixel of interest are determined, the reference region moves in the main scanning direction (recording electrode arrangement direction), and the width and phase of the energization pulse to the adjacent recording electrode are determined. It By sequentially repeating this operation in the array direction of the recording electrodes, the width and phase of the energizing pulse for each recording electrode are determined. As the energizing pulse pattern, several patterns having different pulse widths and phases are prepared in advance, and one of these patterns is selected by micro thermal control.

FIG. 7 shows a specific example of selecting the energizing pulse shown in FIGS. 2 and 4 based on the arrangement of the mark signals in the reference area. As shown in FIG. 7 (a), when the reference area is entirely a mark signal (indicated by black dots), the recording electrode corresponding to the pixel of interest has a recording period as shown in FIG. 7 (e). An energizing pulse having a pulse width of half T is supplied. In this case, the phase of the energizing pulse is selected depending on whether the recording electrode corresponding to the pixel of interest is an odd number or an even number in the arrangement direction of the recording electrodes 7.

When the reference area has a pattern in which mark signals are arranged in the main scanning direction as shown in FIG. 7 (b), FIG. 7 (f)
As shown in FIG. 4, the thin energizing pulse as shown in FIG. 4A is supplied to the recording electrode corresponding to the target pixel. Further, in this case, when the preheat pulse and the heat retention pulse as shown in FIG. 4 (b) are used, FIG. 7 (c)
Even if the mark signal does not exist in the target pixel as shown in (d), the preheating pulse and the heat retention pulse are supplied to the recording electrode corresponding to the target pixel as shown in FIGS. 7 (g) and (h). In other cases, in principle, the energizing pulse is supplied when the pixel of interest is the mark signal, and the energizing pulse is not supplied when the pixel of interest is the space signal.

In addition, briefly explaining the heat storage control itself,
First, it is basic that the pulse width of the energizing pulse is made longer as the number of mark signals in the reference area is smaller, and is shorter as the number of mark signals is larger. As shown in FIG.
If all the image signals before the line are mark signals,
An energizing pulse having a pulse width corresponding to the number of mark signals is supplied to the recording electrode corresponding to the target pixel so that the front ends of the recording periods T coincide with each other as shown in FIG. Further, as shown in FIG. 9A, when the pixel of interest and the image signal after one line are both mark signals, the trailing end of the recording cycle T is made to match as shown in FIG. 9B. An energizing pulse having a pulse width corresponding to the number of mark signals is supplied to the recording electrode corresponding to the pixel of interest. Furthermore, as shown in FIG. 10 (a), when the pixel of interest is a mark signal and one line before and after it is a space signal, and as shown in FIG. 10 (b), the pixel of interest and pixels one line before and one pixel after that When all the signals are mark signals, the width corresponding to the number of mark signals in the reference area is set so that the center position of the energizing pulse and the center position of the recording cycle T substantially match as shown in FIG. An energizing pulse is supplied to the recording electrode corresponding to the pixel of interest. In addition, from FIG.
In FIG. 10, the mark x may be either a mark signal or a space signal. 8 (a), 9 (a), and 10 (a), (b) show the case where the number of mark signals in the image signal sequence in the main scanning direction (vertical direction in the figure) is small. Both the odd-numbered and even-numbered recording electrodes are energized and driven in the same phase as shown in FIGS. 8 (b), 9 (b) and 10 (c). That is, when the number of mark signals in the image signal train is small, all recording electrodes 7 are energized and driven not at the same time for each block.

By selecting the energizing pulse based on the present invention described above together with such heat storage control, not only the heat storage effect is not required, but also a high power supply voltage is not required, and the energization transfer recording with less ink ribbon breakage is possible. Becomes

The present invention is not limited to the embodiment described above,
For example, in the embodiment, the recording electrode is divided into a block made up of odd-numbered electrodes and a block made up of even-numbered electrodes, but a block consisting of the first N / 2 and the subsequent N / 2 in the recording electrode array direction. May be divided into two blocks, or several consecutive lines may be divided into two blocks. Further, the number of divided blocks of the recording electrode may be further increased.

Further, in the above embodiment, the heat storage control section originally provided in the current transfer recording apparatus is used to perform the current drive according to the present invention, but it is also possible to perform the current control regardless of the heat storage control. For example, the number of mark signals in the image signal sequence in the recording electrode array direction is counted, and when the number is relatively large, for example, when the number of mark signals is less than half of the number N of recording electrodes, energization using the normal recording cycle T is performed. If the number exceeds half, the energization drive according to the present invention may be performed. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

EFFECTS OF THE INVENTION According to the present invention, a plurality of recording electrodes are divided into a plurality of blocks, and a mode in which the recording electrodes are energized and driven at different phases for each block is provided. When a large number of mark signals are included in, the current flowing in the ink ribbon can be limited by preventing multiple recording electrodes from being energized at the same time. Therefore,
The voltage drop in the ink ribbon becomes small, and the power supply voltage of the constant current driver can be lowered. In addition, the dispersion of a plurality of heat generation points on the ink ribbon reduces the risk of ink ribbon breakage. Further, according to the present invention, when the number of mark signals included in the image signal sequence is small, the sub-scanning speed is increased by driving the recording electrodes at the same time as in the conventional energization transfer recording apparatus instead of energizing them. Without lowering or intermittently performing sub-scanning,
It is possible to prevent the deterioration of the recording quality due to the displacement of the image points in the sub-scanning direction.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an electric current transfer recording apparatus according to an embodiment of the present invention, FIG. 2 is a view showing an example of an electric current pattern according to the present invention, and FIGS. FIG. 4 is a diagram showing a comparison of distribution of heat generation points on an ink ribbon in the present invention, FIGS. 4 and 5 are diagrams showing other examples of energization patterns according to the present invention, and FIG. 6 is a recording corresponding to a target pixel. The figure which shows the reference area | region for determining the energization pattern of the energization pulse of an electrode, FIG. 7 is a figure which shows the relationship between the mark signal arrangement | positioning state in a reference area, and an energization pattern, FIGS. FIG. 11 is a diagram showing the relationship between the arrangement state of the mark signals in the reference area and the energization pattern when performing the step, FIG. 11 is a diagram showing the basic configuration of a conventional energization transfer recording apparatus, and FIG. It is a figure for explaining. 4 ... Resistive ink ribbon, 5 ... Recording paper, 6 ... Recording head, 7 ... Recording electrode, 9 ... Return electrode, 11 ... Signal generator, 12 ... Heat storage control section, 13 ... Fixed Current driver.

Continuation of front page (56) Reference JP-A-61-230466 (JP, A) JP-A-61-234169 (JP, A) JP-A-62-165474 (JP, A) JP-A-62-128275 (JP , A) JP 63-9561 (JP, A) JP 63-60770 (JP, A) JP 63-290768 (JP, A)

Claims (4)

(57) [Claims] 1. A resistive ink ribbon, a plurality of recording electrodes contacting the ink ribbon, a return electrode contacting the ink ribbon at a position apart from the recording electrodes, and a plurality of recording electrodes for marking and A driving means for electrically driving in accordance with an image signal sequence consisting of space signals, and the heat generation of the current-carrying area of the ink ribbon immediately below the recording electrode transfers the ink in the area onto recording paper to form an image. In the recording apparatus, the driving unit simultaneously energizes the recording electrodes according to the image signal sequence when the number of mark signals included in the image signal sequence is small, and the number of mark signals included in the image signal sequence is increased. When the number of recordings is large, the recording electrode is divided into a plurality of blocks, and each block is energized and driven according to the image signal sequence at a different phase. Photo recorder. 2. The driving means is included in the image signal sequence from the arrangement state of mark signals in a reference area including a group of pixels around the pixel of interest in the image signal sequence in the main scanning direction and the sub scanning direction. When the number of mark signals is small, the recording electrodes are simultaneously energized and driven according to the image signal sequence, and when the number of mark signals included in the image signal sequence is large, the recording electrodes are divided into a plurality of blocks. The electric transfer recording apparatus according to claim 1, wherein the electric power is driven in accordance with the image signal sequence in a different phase for each block. 3. The driving means counts the number of mark signals included in the image signal sequence, and when the number of mark signals is small, the recording electrodes are simultaneously energized and driven according to the image signal sequence, The energization transfer according to claim 1, wherein when the number of signals is large, energization driving is performed in accordance with the image signal sequence at a different phase for each block obtained by dividing the recording electrode into a plurality of blocks. Recording device. 4. The recording electrode is divided into a first block made up of odd-numbered electrodes and a second block made up of even-numbered electrodes in the arrangement direction. The electro-static transfer recording device according to any one of items 1 to 3.