JPH05169687A - Current-carrying recording head - Google Patents

Abstract

PURPOSE:To obtain a current-carrying recording head realizing a high-speed printing and a high-quality image. CONSTITUTION:A plurality of recording electrodes 3 and return electrodes 4 are pressed down against an ink sheet 7 formed by laminating a current- carrying resistant layer 6 on an ink layer 5. In a current-carrying recording head 1 in which a voltage is selectively applied between the respective recording electrodes 3 and the return electrodes 4 to electrically heat the current-carrying resistant layer 6 for transferring the ink of the ink layer 5 to recording paper, an intermediate conductor 8 having a conductivity higher than that of the current-carrying resistant layer 6 is provided between the recording electrode 3 and the return electrode 4 to regulate an electric current flowing from the recording electrode 3 to the return electrode 4. In this manner, even if the adjacent recording electrodes 3 are simultaneously electrically driven, they are prevented from electrically interfering with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric recording head used in copying machines, printers, facsimiles and the like.

[0002]

2. Description of the Related Art In an electric recording system used in a copying machine or the like, a recording paper and an ink sheet conveyed on a platen roller are pressed against the platen roller by an electric recording head.
The ink of the ink sheet is melted or sublimated and transferred onto the recording paper by selectively energizing between the recording electrode and the common electrode of the current-carrying recording head in contact with the ink sheet.

An example of such a conventional energization recording head will be described with reference to FIG. FIG. 5 shows the structure of the main part of the electric recording head.
And a plurality of recording electrodes 3 and a return electrode 4. On the insulating layer 2, a plurality of the recording electrodes 3 are arranged in a line at predetermined intervals along the main scanning direction X of the energization recording head 1. The return electrode 4 facing the recording electrode 3 with the insulating layer 2 in between is disposed at a constant distance.

In such a structure, the leading end portion of the energization recording head 1 has an ink sheet (not shown) from above the recording paper.
Is pressed against a platen roller (not shown). Then, a voltage is selectively applied between the plurality of recording electrodes 3 and the return electrode 4 in accordance with an image signal, and a current flows in a portion of the ink sheet which is in contact with the recording electrode 3 and the return electrode 4. Heat is generated, and the ink melts or sublimes the ink on the ink sheet and transfers the ink to recording paper (not shown).

In such an energization recording head 1,
When the adjacent recording electrodes 3 are simultaneously energized and driven, the currents interfere with each other, and the current amount changes and the print density changes as compared with the case where the adjacent recording electrodes 3 are not energized simultaneously.

As a solution to such a problem, there is an electrification recording method disclosed in Japanese Patent Laid-Open No. 63-221057. In this method, the recording electrodes 3 are divided into M + 1 blocks so that every M recording electrodes 3 (M is an integer of 3 or more) are included in the same block, and each block is time-divided for energization. By doing so, the adjacent recording electrodes 3 are not simultaneously energized and driven, and the current interference between the adjacent recording electrodes 3 is eliminated.

[0007]

However, since the recording electrodes 3 are driven in a time division manner, it is necessary to slow down the printing speed, and there is a problem that the recording positions of adjacent print pixels are displaced.

Further, when black solid printing is performed, the contact state between the platen drum and the energization recording head 1 is at the end of the energization recording head 1 in the central portion in the main scanning direction X (arrangement direction of the recording electrodes 3). Since the contact pressure is lower than that of, the density of the print pixel is low and uneven density occurs.

Then, the main scanning direction X of the energization recording head 1
The temperature of the recording electrodes 3 located at both ends of the is less likely to rise than that of the recording electrodes 3 at other positions, and the density of the print pixel is reduced. That is, in the method of the above-mentioned publication, among the recording electrodes 3 of the respective blocks which are simultaneously energized and driven, the temperature of the recording electrodes 3 located at both ends in the main scanning direction X is similarly hard to rise, so that the density of the print pixel is increased. Will be reduced.

Further, when current is applied between the recording electrode 3 and the return electrode 4, a current I flows from the recording electrode 3 to the return electrode 4 side as shown in FIG. The contour of the print pixel formed by 3 becomes blurry. As a result, the image quality is deteriorated at the edges and thin lines of the printed image.

[0011]

According to a first aspect of the present invention, a plurality of recording electrodes and return electrodes are pressed against an ink sheet in which a current-carrying resistance layer is laminated on an ink layer to press the recording electrodes and return electrodes. In the energization recording head that transfers the ink of the ink layer to a recording sheet by selectively applying a voltage between the return path electrode and applying a current to the energization resistance layer of the ink sheet to generate heat, A plurality of electrically insulated intermediate conductors are arranged between the recording electrode and the return electrode.

According to a second aspect of the invention, in the first aspect of the invention, the area of the intermediate conductor is large at the central portion in the recording electrode array direction and gradually decreases from the central portion toward the end portion.

According to the invention of claim 3, claim 1 or 2
In the invention described above, the area of the intermediate conductor is increased at both ends in the arrangement direction of the recording electrodes.

According to a fourth aspect of the present invention, a plurality of recording electrodes and return electrodes are pressed against the ink sheet in which a current-carrying resistance layer is laminated on the ink layer, and the recording electrodes and the return electrodes are separated from each other. In each of the recording electrodes and the return electrode, a current-carrying recording head which transfers the ink of the ink layer to a recording paper by selectively applying a voltage to the current-carrying resistance layer of the ink sheet to generate heat And a plurality of electrically insulated intermediate conductors are provided between the recording electrodes and the recording electrodes, and the recording electrodes and the intermediate conductors are divided to form N (N is an integer of 2 or more) blocks. The areas of the intermediate conductors located at both ends in each of the blocks, which are energized in a time-divided manner in each block and simultaneously driven, are set to be large.

According to the invention of claim 5, claims 1, 2,
In the invention of 3 or 4, the length L ₁ of the intermediate conductor provided between the recording electrode and the return electrode in the sub-scanning direction is set to the distance L ₀ between the recording electrode and the return electrode. L
₁ <L _0/2 .

According to the invention of claim 6, claims 1, 2 and
In the invention described in 3, 4, or 5, the length h ₁ in the arrangement direction of the intermediate conductor provided between the recording electrode and the return electrode is
0.8 × h ₀ > h with respect to the array pitch h _{0 of the} recording electrodes
₁ > 0.5 × h ₀ .

[0017]

According to the first aspect of the invention, an intermediate conductor, through which a current easily flows from the current-carrying resistance layer of the ink sheet, is interposed between the recording electrode and the return electrode to regulate the current flowing from each recording electrode to the return electrode. This makes it possible to prevent the currents from interfering with each other even when the adjacent recording electrodes are simultaneously energized and driven.

According to the second aspect of the present invention, the platen roller is provided with a contact pressure between the platen roller and the current-carrying recording head that is low so that a current flows more easily at the central portion of the current-carrying recording head in the main scanning direction than at other positions. It is possible to prevent uneven printing density due to a difference in contact pressure between the recording head and the energization recording head.

According to the third aspect of the present invention, it is possible to prevent a decrease in print density at both end positions of the energized recording head in the main scanning direction by making it easier for a current to flow at both end positions in the main scanning direction of the energized recording head. It will be possible.

According to the fourth aspect of the invention, when the current is driven in a time-division manner, the current density is made to easily flow at both end positions of each divided block, whereby the print density is reduced at both end positions of each block and the seam of the blocks is increased. It is possible to prevent the occurrence of white stripes due to the decrease in print density at the position.

In the fifth aspect of the invention, the optimum length L ₁ of the intermediate conductor in the sub-scanning direction is limited by the distance L ₀ between the recording electrode and the return electrode, so that the characters and fine lines of the printed image can be obtained. It becomes possible to properly emphasize the edges such as.

According to the present invention, the length h ₁ of the intermediate conductors in the array direction is limited by the array pitch h ₀ of the recording electrodes, so that when adjacent recording electrodes are simultaneously energized, the adjacent pixels are It is possible to prevent the occurrence of white lines due to white spots by eliminating the gap between them.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 4. The same parts as those described with reference to FIGS. 5 and 6 are designated by the same reference numerals and the description thereof will be omitted. First, FIGS. 1 and 2 show the structure of the main part of the energization recording head 1. An ink sheet 7 in which an energization resistance layer 6 is laminated on an ink layer 5 is provided. The leading end portion of the energization recording head 1 is in contact with the energization resistance layer 6 of the ink sheet 7. Embedded conductors 8 as intermediate conductors are arranged in the insulating layer 2 between the recording electrodes 3 and the return electrodes 4 arranged in a line along the main scanning direction X at the tip of the energization recording head 1. It is set up. These embedded conductors 8 are in an electrically insulated state. A voltage E is applied between each recording electrode 3 and the return electrode 4 via a switching transistor Tr. That is,
The recording electrode 3 is connected to the collector side of the transistor Tr, the control unit 9 for controlling the switching timing of the transistor Tr is connected to the base side, and the voltage E is applied between the emitter side and the return electrode 4. ing. The control unit 9 controls each of the transistors T in accordance with an image signal.
The recording electrode 3 is controlled by controlling the switching of r.
And has a function of selectively applying the voltage E between the return path electrode 4 and the return path electrode 4.

The area of the embedded conductor 8 is large in the central portion of the main scanning direction (arrangement direction of the recording electrodes 3) X where the contact pressure between the platen roller (not shown) and the energization recording head 1 is low. The contact pressure is set to gradually decrease toward the end portion in the main scanning direction X where the contact pressure is high. Moreover, the area of the embedded conductor 8 at both end positions in the main scanning direction X where the temperature does not easily rise when energized is set larger than the area of the embedded conductor 8 at other positions.

The length L ₁ of the embedded conductor 8 provided between the recording electrode 3 and the return electrode 4 shown in FIG. 3 in the sub-scanning direction (recording paper conveying direction) Y is L ₁ <for the distance L ₀ between the recording electrode 3 and the return electrode 4
It is set to satisfy L _0/2 .

Further, the length h ₁ of the embedded conductors 8 in the arrangement direction shown in FIG. 3 is 0.8 × h ₀ > h ₁ > 0.5 × with respect to the arrangement pitch h ₀ of the recording electrodes 3. It is set to satisfy h ₀ .

The operation of this embodiment having such a configuration will be described with reference to FIGS. First, in accordance with a predetermined image signal controlled by the control unit 9, energization is selectively driven between each recording electrode 3 and the return electrode 4 of the energization recording head 1. Due to this energization, as shown in FIG. 4, a current I is generated from the recording electrode 3 to the energization resistance layer 6 of the ink sheet 7.
It flows to the embedded conductor 8, the conducting resistance layer 6 and the return electrode 4 again. As a result, the energization resistance layer 6 of the ink sheet 7 generates heat due to Joule heat, and the heat causes the ink in the ink layer 5 to be melted or sublimated and transferred to a recording paper (not shown). At this time, the current I flows through the embedded conductor 8 having a resistance value lower than that of the energization resistance layer 6 of the ink sheet 7, so that the current I flows through the energization resistance layer 6 of the ink sheet 7 as shown in FIG. , Embedded conductor 8 regulates. As a result, the path of the current I does not change between the adjacent recording electrodes 3 even if the adjacent recording electrodes 3 are simultaneously energized and driven.

As described above, by restricting the flow of the current I in the energization resistance layer 6 of the ink sheet 7 by the embedded conductor 8, even if the adjacent recording electrodes 3 are simultaneously energized and driven, each recording electrode 3 can be driven. The currents I from the return electrode 4 to the return electrode 4 do not interfere with each other, and it is possible to prevent the density change of the printed image. Moreover, like the method of the above-mentioned publication,
It is not necessary to energize in a time-sharing manner, and it is possible to obtain a high-speed, high-quality printed image.

Further, in this embodiment, by changing the area of the embedded conductor 8, each recording electrode 3 and the return electrode 4 can be easily formed.
It is possible to change the resistance value between and. That is,
When the area of the embedded conductor 8 is increased, the resistance value between the recording electrode 3 and the return electrode 4 decreases, so that the flowing current I increases and the amount of heat generation increases. On the contrary, when the area of the embedded conductor 8 is reduced, the resistance value increases, so that the flowing current I decreases and the heat generation amount decreases. Therefore, the area of the embedded conductor 8 is large at the central portion in the main scanning direction X where the contact pressure between the platen roller and the energization recording head 1 is low, and gradually increases toward the end portion in the main scanning direction X where the contact pressure is high. It is set to be small and the area of the embedded conductor 8 is changed according to the change of the contact pressure between the platen roller and the energization recording head 1 to adjust the amount of current I flowing through the energization resistance layer 6 of the ink sheet 7. As a result, the main scanning direction X of the energization recording head 1
It is possible to prevent density unevenness of the printed image at the positions corresponding to the central portion and the end portions of the. Moreover, at the end portion of the energization recording head 1 in the main scanning direction X, the area of the embedded conductor 8 is increased to facilitate the flow of the current I, thereby printing the end position of the energization recording head 1 in the main scanning direction X. It is possible to prevent the concentration from decreasing. This makes it possible to obtain a high-quality printed image without density unevenness.

As shown in FIG. 4, for each recording electrode 3, the embedded conductor 8 regulates the path of the current I, so that the print pixel formed corresponding to each recording electrode 3 is
The outline is emphasized, and when characters or thin lines are printed, their edges can be emphasized.
However, the degree of edge enhancement depends on the embedded conductor 8 shown in FIG.
The length L ₁ in the sub-scanning direction Y increases, but if the length L ₁ is too long, only the edges are emphasized, and the color is lost at the center of the print pixel, which rather reduces the image quality. I will let you. Therefore, the length L ₁ of the embedded conductor 8 in the sub-scanning direction Y is set so as to satisfy L ₁ <L _{0/2 with} respect to the distance L ₀ between the recording electrode 3 and the return electrode 4. As a result, it is possible to prevent the deterioration of the image quality due to the edge of one print pixel being overemphasized. As a result, it is possible to obtain a high-quality printed image such as characters and fine lines with moderately emphasized edges.

Further, the shorter the length h ₁ of the embedded conductor 8 in the main scanning direction X shown in FIG. 3 is, the more the current interference between the adjacent recording electrodes 3 is eliminated, but the length h ₁ is shortened. Too much,
When the adjacent recording electrodes 3 are simultaneously energized and driven, a gap is generated between the adjacent print pixels, and white stripes are generated when black solid printing is performed. Therefore, the length h ₁ of the embedded conductors 8 in the arrangement direction is set so as to satisfy 0.8 × h ₀ > h ₁ > 0.5 × h ₀ with respect to the arrangement pitch h ₀ of the recording electrodes 3. By limiting the length h ₁ of the embedded conductors 8 in the arrangement direction by the arrangement pitch h ₀ of the recording electrodes 3, it is possible to prevent the electric current I from interfering between the adjacent recording electrodes 3 and to print the printed image. It is possible to prevent white stripes between adjacent pixels.

As a modification of this embodiment, each recording electrode 3 and the embedded conductor 8 are divided into N (N is an integer of 2 or more) blocks, and each block is time-divided. It is also possible to set the area of the embedded conductors 8 located at both ends in each of the blocks that are simultaneously driven simultaneously to be large and to set a large area. In this case, by increasing the area of the embedded conductors 8 located at both ends in each block when energized in a time-division manner to facilitate the flow of the current I, the positions of both ends of each block and the joint position of the blocks can be improved. It is possible to prevent the occurrence of white stripes due to a decrease in print density. This makes it possible to obtain a high quality printed image.

[0033]

According to the first aspect of the present invention, a plurality of recording electrodes and return electrodes are pressed against an ink sheet in which a current-carrying resistance layer is laminated on an ink layer to press the recording electrodes and the return electrodes. In the energization recording head that transfers the ink of the ink layer to the recording paper by selectively applying a voltage between the electrodes and applying a current to the energization resistance layer of the ink sheet to generate heat, the recording electrodes and the return path A plurality of electrically insulated intermediate conductors are arranged between the electrodes, and the current flowing from each recording electrode to the return electrode is regulated by the intermediate conductor through which the current easily flows from the current-carrying resistance layer of the ink sheet. Therefore, even if the adjacent recording electrodes are simultaneously energized and driven, it is possible to prevent the currents from interfering with each other, and it is possible to obtain a high-quality printed image at a high speed.

According to a second aspect of the present invention, in the first aspect of the present invention, the area of the intermediate conductor is large at the central portion in the recording electrode array direction and gradually decreases from the central portion toward the end portion, The contact pressure between the platen roller and the energized recording head is low.Since the current is made to flow easily in the center of the energized recording head in the main scanning direction, it is possible to prevent uneven printing density due to the difference in contact pressure between the platen roller and the energized recording head. This makes it possible to obtain a high-quality printed image.

According to a third aspect of the present invention, in the first or second aspect of the invention, the area of the intermediate conductor is increased at both ends in the array direction of the recording electrodes, and the current is applied at both end positions in the main scanning direction of the energizing recording head. Since it is made easier to flow, it is possible to prevent a decrease in print density at both end positions of the energization recording head in the main scanning direction, and thus it is possible to obtain a high quality printed image.

According to a fourth aspect of the present invention, a plurality of recording electrodes and return electrodes are pressed against the ink sheet in which a current-carrying resistance layer is laminated on the ink layer, and the recording electrodes and the return electrodes are separated from each other. In a current-carrying recording head that selectively applies a voltage to the current-carrying resistance layer of the ink sheet to generate heat, thereby transferring the ink of the ink layer to a recording paper, the recording electrodes and the return electrodes A plurality of electrically insulated intermediate conductors are provided between the recording electrodes, and the recording electrodes and the intermediate conductors are divided into N pieces (N is an integer of 2 or more).
When each block is energized in a time-divisional manner and energized simultaneously, the areas of the intermediate conductors located at both ends in each block that are driven simultaneously are set large, , Since it is easy to flow the current at the both ends of each divided block, it is possible to prevent the occurrence of white stripes due to the decrease in the print density at both ends of each block and the decrease in the print density at the joint position of blocks. It is possible to obtain various printed images.

The invention according to claim 5 is the invention as claimed in claims 1, 2, and 3.
Or the length L ₁ of the intermediate conductor provided between the recording electrode and the return electrode in the sub-scanning direction is L with respect to the distance L ₀ between the recording electrode and the return electrode. ₁
<L _0/2 and then, the optimal length of the sub-scanning direction of intermediate conductor L ₁
Is limited by the distance L ₀ between the recording electrode and the return electrode, so that it is possible to obtain a high-quality printed image in which the edges of characters and fine lines are appropriately emphasized.

The invention according to claim 6 is the same as claims 1, 2 and
In the invention described in 3, 4, or 5, the length h ₁ in the arrangement direction of the intermediate conductor provided between the recording electrode and the return electrode is
0.8 × h ₀ > h _{1 with} respect to the array pitch h _{0 of the} recording electrodes
> 0.5 × h ₀ and the length h ₁ of the intermediate conductor in the array direction is
Since the arrangement is limited by the arrangement pitch h ₀ of the recording electrodes, it is possible to eliminate the gap between the adjacent pixels when the adjacent recording electrodes are simultaneously energized and driven, and it is possible to prevent the occurrence of white stripes due to white spots. As a result, a high quality printed image can be obtained.

[Brief description of drawings]

FIG. 1 is a partial vertical sectional front view of an electric recording head according to an embodiment of the present invention.

FIG. 2 is a partial bottom view of FIG.

FIG. 3 is a partial bottom view showing the size of the intermediate conductor.

FIG. 4 is a partial bottom view showing the flow of current in the energization resistance layer of the ink sheet.

FIG. 5 is a partial bottom view showing an example of a conventional energization recording head.

FIG. 6 is a partial bottom view showing a part of FIG. 5 in an enlarged manner.

[Explanation of symbols]

 3 recording electrode 4 return electrode 5 ink layer 6 energization resistance layer 7 ink sheet 8 intermediate conductor

Claims (6)

[Claims] 1. A plurality of recording electrodes and return electrodes are pressed against an ink sheet having a current-carrying resistance layer laminated on an ink layer, and a voltage is selectively applied between the recording electrodes and the return electrodes. In an energization recording head that applies a voltage and causes an electric current to flow through the energization resistance layer of the ink sheet to generate heat, the ink in the ink layer is transferred to a recording sheet, and an electrical connection is made between each recording electrode and the return electrode. An electrically conductive recording head having a plurality of intermediate conductors insulated from each other. 2. The current-carrying recording head according to claim 1, wherein the area of the intermediate conductor is large at the central portion in the array direction of the recording electrodes and is gradually reduced from the central portion toward the end portions. 3. The electric recording head according to claim 1, wherein the area of the intermediate conductor is increased at both ends in the arrangement direction of the recording electrodes. 4. A plurality of recording electrodes and return electrodes are pressed against an ink sheet having a current-carrying resistance layer laminated on an ink layer, and a voltage is selectively applied between each of the recording electrodes and the return electrodes. In an energization recording head that applies a voltage and causes an electric current to flow through the energization resistance layer of the ink sheet to generate heat, the ink in the ink layer is transferred to a recording sheet, and an electrical connection is made between each recording electrode and the return electrode. A plurality of insulated intermediate conductors are provided, the recording electrodes and the intermediate conductor are divided to form N (N is an integer of 2 or more) blocks, and each of these blocks is time-divided. An energizing recording head is characterized in that the areas of the intermediate conductors located at both ends in each of the blocks that are simultaneously energized and simultaneously driven are set to be large. 5. The length L ₁ of the intermediate conductor provided between the recording electrode and the return electrode in the sub-scanning direction is L ₁ <with respect to the distance L ₀ between the recording electrode and the return electrode. L _0/2 and to claim 2, 3 or 4 energized recording head, wherein the a. 6. The length h ₁ in the arrangement direction of the intermediate conductors provided between the recording electrode and the return electrode is 0.8 × h ₀ > h ₁ > with respect to the arrangement pitch h _{0 of the} recording electrodes. 6. The current-carrying recording head according to claim 1, 2, 3, 4, or 5, characterized in that it is set to 0.5 × h ₀ .