JP2886785B2 - Electrostatic recording head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording head suitable as a recording head of an electrostatic recording system. More specifically, the present invention relates to an improvement in the structure of a control electrode of an electrostatic recording head.

[0002]

2. Description of the Related Art As shown in FIG. 8, an electrostatic recording head of the same surface control type generally has two rows of recording electrodes 101a and 101b arranged at a high pitch at a constant pitch, and two rows corresponding thereto. The control electrodes 102a and 102b are fixed by an electrode support block 103 made of an electrically insulating resin or the like. For example, M (= 128) is set as one set and N (= 5
5) M × N (= 7040) first recording electrodes 101a composed of a set, and M × N (= 7040) second recording electrodes 101b arranged in parallel with this at a predetermined interval.
And control electrodes 102a and 102b arranged further outside the rows along the rows of the first and second recording electrodes 101a and 101b. It is provided so as to be exposed. In the drawing, reference numeral 104 denotes a wiring board, 1
Reference numerals 05a,..., 105m denote terminals for collectively connecting recording electrodes grouped every N lines.

Conventionally, this electrostatic recording head uses control electrodes 102a and 102b which are formed by cutting a copper alloy and processing it into, for example, a simple cubic block as shown in FIG. The control electrodes 102a and 102b are supported by two control electrode support plates 203 and 204, and
01 is accommodated in the resin casting groove 202. Then, a thermosetting resin is poured into the resin casting groove 202, and the control electrode 102a (or 102b) is solidified and held by an insulating resin. As the thermosetting resin, a one-part epoxy resin that is convenient for handling is employed.
This one-part epoxy resin is composed of a main component, a curing agent, and a curing accelerator, and starts curing by destroying the curing accelerator enclosed in the capsule by heating. Control electrode support plate 20 opposed to each other across control electrode 102a
A hole 206 through which a tip 207 of a conductive pin 205 previously connected to the control electrode 102a penetrates is fitted to one of the control electrodes 102a, and a small mounting projection 208 formed on the surface of the control electrode 102a is fitted to the other. The control electrodes 102a are provided between the control electrode support plates 203 and 204 by fitting the holes 206 and 209 with the pin tips 207 or the projections 208, respectively. After casting, the surface of the electrode support block 103 is polished, including the mounting projections 208 protruding from the electrode support block 103, formed into a predetermined shape, and exposing the surfaces of the control electrodes 102a and 102b. I have.

[0004]

However, the control electrodes 102a, 102a are formed by machining a copper alloy by cutting or the like.
In the case of obtaining b, it is not easy to form a small pin-shaped projection 208 on the surface of the block as shown in the figure, since the processing cost is too high for a complicated surface shape. Therefore, it is conceivable to support the entire block on the control electrode support plates 203 and 204 without providing the mounting projections 208. In this case, too, the entire surface of the control electrode protruding from the surface of the electrode support block 103 has a considerable amount. Since polishing must be performed, the cost is high.

A control electrode 102a made of a copper alloy,
Since the linear expansion coefficient of the electrode support block 103 is significantly different from that of the electrode support block 103 made of resin, the electrode support block 103 and the control electrodes 102a and 102b are separated by cooling after casting, and the control electrodes 102a and 102b are made of resin electrodes. There are cases where the support block 103 cannot firmly hold it.

Further, the present inventors have established control electrodes 102a, 1
02b has been considered to be insert-molded into the electrode support block 103 in a state where the control electrode 102b is soldered to a wiring board (printed board) in advance.
The solder connecting the control electrodes 102a, 102b and the circuit board may be broken due to the difference in the linear expansion coefficient between the control electrodes 102a, 102b and the electrode support block 103.

Therefore, the present inventors considered that the control electrode was formed of a sintered alloy having conductivity, thereby simultaneously forming irregularities for positioning and mounting, and omitting complicated cutting. However, because of the porous structure, the main component of the epoxy resin used as the material of the electrode support block and the curing agent penetrate into the pores by a chromatogram before curing, but the curing accelerator encapsulated in these larger capsules has the pores. The uncured resin component remains in the pores because it is too large to enter, and the uncured resin expands as the temperature rises during transportation or use, and oozes out into the head to improve image quality. It has been found that a problem of lowering occurs. In addition, even if the pressure is reduced during resin casting, the air inside the pores cannot be completely degassed, but the temperature remaining during curing of the resin expands the gas remaining in the pores, causing a bubble row (pinhole) around the control electrode. ) Has been found. There is a problem that foreign matter or the like enters the unevenness due to the bubble row at the time of recording, causing a deterioration in image quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrostatic recording head which has a low production cost of a control electrode, a high bonding force to a resin electrode support block, a circuit board, and the like, and can obtain a high quality image. I do.

[0009]

According to the present invention, there is provided an electrostatic recording head having a recording electrode and a control electrode.

(Equation 2) The control electrode is formed of a sintered alloy having conductivity set in a range of 0.7 to 0.9 with a relative density defined by Expression 2. If the relative density is less than 0.7, the exudation rate of the uncured resin component and the pinhole generation rate at the resin interface increase sharply, causing deterioration in image quality. If the relative density exceeds 0.9, the advantage that molding of the control electrode is easy is lost.

[0010]

Accordingly, the control electrode is formed into an arbitrary block shape in the process of sintering, and at the same time, irregularities for positioning and mounting are formed. Moreover, since the relative density is set in the range of 0.7 to 0.9, the number of continuous pores is small, and the irregularities and pores on the surface do not reach deep. For this reason, even if the main agent and the curing agent of the epoxy resin used as the material of the electrode support block try to penetrate into the irregularities on the surface of the control electrode or the pores opened on the surface by the chromatogram phenomenon before curing, they cannot penetrate deeply, Also, the amount is extremely small. On the other hand, the shallow irregularities and pores on the surface of the control electrode solidify the solder of the wiring board and the resin of the electrode support block that have penetrated, and the control electrode and the electrode support block and the solder are firmly connected to each other by an anchoring effect.

In addition, since the surface of the control electrode is porous, the polishing resistance is small, and the mounting projection is formed small, so that the control electrode can be easily polished. In addition, the portion of the control electrode exposed on the head surface is polished, and the unevenness and holes are crushed to provide a substantially same smooth surface as the cut block.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be described below in detail with reference to the embodiments shown in the drawings.

FIGS. 1A to 1C show an embodiment of a control electrode used in the present invention. These control electrodes 13a, 13b
Are formed in a rectangular block by a sintered alloy of a metal having good conductivity such as a copper alloy, and are provided with mounting protrusions 11 ((A) to (A) in FIG. 1) protruding from a surface exposed from the electrode support block. C)) and a concave portion 12 which functions as a positioning for applying a wiring board 18 provided on the opposite side. The protrusion 11 has a shape that fits into a positioning hole 31 provided in the control electrode support plate 22 shown in FIG. 2 and is formed to be substantially the same as or slightly thinner than the thickness of the control electrode support plate 22. I have. In the case of the present embodiment, the protrusion 11 is formed in a rectangular shape, but is not particularly limited to this. Further, instead of the protrusion 11, a concave portion 11 'as shown in FIG. Further, the overall shape of the control electrodes 13a and 13b is not particularly limited to that shown in FIG. 1, but the shape shown in FIG. 1 is easier to position and the like than a simple rectangular parallelepiped block. It is preferable to perform the above. This control electrode 13
a and 13b are obtained by solidifying and sintering the metal powder into the above-mentioned shape by a known method of manufacturing a sintered alloy. At this time, the relative density of the sintered alloy is

(Equation 3) The relative density defined by Expression 3 is set in the range of 0.7 to 0.9. For example, in the case of a sintered alloy of 85% Cu and 15% Ni, the low density side is 6.24 and the high density side is 8.0.
And 2. In the case of a 90% Cu, 10% Sn sintered alloy, the low density side was 6.03 and the high density side was 7.76. Further, Cu 89.6%, Sn 10.0%, P0.4
%, The low-density side was 6.01 and the high-density side was 7.73. Here, the pure density value of each material used is Cu: d (20) = 8.93 (g / cm ³ ), Ni: d
(20) = 8.845 (g / cm ³ ), Sn (α): d
(20) = 5.8 (g / cm ³ ), phosphorus was used as phosphorus pentoxide, and P ₂ O ₅ : d (crystal forms S1, S2,
(Average value of S3) = 2.5 (g / cm ³ ). In this case, as shown in FIGS. 5 and 6, in any case, even if the temperature rises during transportation or use, the uncured resin component hardly seeps out, and pinholes are generated at the resin interface. There was no.

An example of an electrostatic recording head using a control electrode having such a configuration and a method of manufacturing the same will be described below.

The electrostatic recording head is manufactured using a winding jig 1 as shown in FIG. 2, for example. This winding jig 1
This is a two-piece winding jig for simultaneously obtaining two electrostatic recording heads, and constitutes a split mold in which two winding jigs 1 having the same structure are used by abutting each other. This pair of winding jigs 1 and 1 is composed of a wire 15 forming one control electrode 13a and the recording electrode 101a.
And the other control electrode 13b and the wire 15 constituting the recording electrode 101b are mounted, respectively.
A space formed between the pair of winding jigs 1 and 1 when the pair of winding jigs 1 and 1 are abutted so that the reference electrodes 1a and 101b and the control electrodes 13a and 13b are arranged parallel to each other and in a fixed positional relationship. Is provided so as to define a space into which the resin constituting the electrode support block 33 is injected.

In the winding jig 1, two resin casting grooves 2 and 3 for accommodating the control electrode 13a and injecting resin are formed in parallel with each other. Jetty portions 4, 5, and 6 are formed between the resin casting grooves 3 and outside the resin casting grooves 2 and 3, respectively. In jetty 4, 5, 6,
Wire rod holding grooves 14 for holding the wires 15 constituting the recording electrodes are formed at a constant pitch. In the case of this winding jig 1, the outside of the jetty portions 5, 6 on both sides, that is, the winding jig 1
Orienting pins 7 for orienting wire 15 on both side walls
_L, 7 _R and bundled pin 8 bundling by grouping the wire of the same kind which are divided for each block _L, provided 8 _R and entangled the wire 15 Tanpin 9 _L, 9 _R, each of the right and left pins 7
_L, 7 _R, it is the _{8 L, 8 R, 9 L} , 9 position of utilizing _R in tension pass the wire as well as change the orientation. Wire rod 1
5, between the orientation pin 7 _L, 7 _R, stretched so as to traverse resin casting grooves 2,3, the resin casting groove 2
The ridge 4 between the resin casting groove 3 and the ridges 5, 6 outside the resin casting grooves 2, 3 are held by wire holding grooves 14, 14. The resin casting grooves 2 and 3 are formed in the axial direction of the winding jig 1, and plate fitting grooves 16 and 17 are provided at the bottom thereof.

Each of the resin casting grooves 2 and 3 of the pair of winding jigs 1 and 1 has control electrodes 13 a and 13 b and a plate 25.
And the nut 26 are mounted. This state will be described by enlarging FIG. 3 to show only the resin casting groove 2 portion. here,
The control electrode 13a is previously soldered to the wiring board 18.
It is housed in the resin casting groove 2 in a state where it is attached. The wiring board 18 is not particularly limited, but it is preferable to use a printed board made of glass reinforced plastic as a base material, for example, a printed board manufactured by so-called FRP in which glass fiber or the like is added to epoxy resin. As shown in FIG. 2, a wiring pattern 18a is formed on the wiring board 18 in advance so as to collectively extract the control electrodes 13a (or 13b) for each block. Each wiring pattern 1 is provided on a side edge of the wiring board 18.
8a are formed respectively, and the control electrode 13a (or 13
b) is electrically connected in advance by the solder 10. At this time, the solder 10 enters shallow irregularities and holes on the surface of the control electrode 13a having a porous structure. The control electrode 13a is supported at a fixed pitch by being soldered to the wiring board 18 in advance.
It can be easily set in a fixed positional relationship. Further, the other side edge 29 on which the terminal portion 18c is formed is connected to the terminal portion 18c.
The protrusions c are provided so as to protrude from portions where no c is formed, and to engage with the notch grooves 30 formed in the control electrode support plates 20 and 21, respectively. Therefore, the side edge 29 where the terminal portion 18 c is provided is completely exposed outside the electrode support block 33. The wiring board 18 is preferably provided with a plurality of holes 39 into which the resin constituting the electrode support block 33 enters so as to avoid the wiring pattern 18a.

Control electrode 13 soldered in advance
a and the wiring board 18 are supported by, for example, a plurality of control electrode support plates 19, 20, 21, 22, 23, 24 fitted in the plate fitting grooves 16, 17 of the winding jig 1. These control electrode support plates 19,
20, 21, 22, 23 and 24 are plate fitting grooves 1
The plate jigs 6 and 17 are fixed by plate support pins 35 inserted into the through holes 36 of the winding jig 1 in a state where they are fitted respectively. , 24 are provided with holes 37 through which the plate support pins 35 pass. Also, the control electrode support plates 20 and 21 disposed inside
Has a notch groove 30 which engages with the end portion 29 of the wiring board 18.
Are provided so as to be engaged only in the depth direction of the resin casting grooves 2 and 3. The support plate 22 is provided with holes 31 for fitting with the mounting projections 11 of the control electrode 13a at a predetermined pitch.
And grooves in the depth direction of the resin casting grooves 2 and 3. Therefore, after inserting the end portion 29 of the wiring board 18 into the notch groove 30 of the plate 21, the mounting projections 11,... Of the control electrodes 13a,.
If 11 is fitted into the holes 31, ..., 31 of the plate 22,
The control electrodes 13a,..., 13a can be automatically set at predetermined positions. Note that a release agent is applied to at least the inner control electrode support plates 21 and 22 and the bottoms of the resin casting grooves 2 and 3.

At the bottom of the resin casting grooves 2 and 3, the recording electrode and the control electrode 13 are provided on the side of the electrode support block 33.
A rigid plate 25 such as an iron plate arranged along a,..., 13a is installed. A hole 34 is provided at a predetermined position in the plate 25 and a nut 26 is fitted therein. That is, the plate 25 and the nut 26 are previously installed in the resin casting grooves 2 and 3 in a combined state,
It is embedded in the electrode support block 33 as an insert part. The plate 25 has a large number of holes 38 through which the resin passes during insert molding. It is preferable to use a tapered hole or a stepped hole having a larger hole diameter toward the outside of the hole 38. As the nut 26, a closed cap nut is used except for a portion facing the bottom of the resin casting grooves 2 and 3. The shape and structure of the nut 26 are not particularly limited, but it is preferable that the shape of the outer peripheral surface of at least the portion surrounded by the resin is non-circular in order to increase the engaging force of the nut 26. Here, the wiring board 18 is also supported by the nut 26 as long as the height of the nut 26 reaches the wiring board 18. At the same time, the nut 26 is supported not only by the plate 25 but also by the wiring board 18 so that the head is pressed down.

As described above, the control electrodes 13a and 13b and the wiring board 18 are provided in the resin casting grooves 2 and 3 of the winding jig 1, respectively.
After arranging the wire members 15, the wire 15 is fixed to the wire holding groove 14 at a constant pitch using the left and right pins 7 _L , 7 _R , 8 _L , 8 _R , 9 _L , 9 _R of the respective winding jigs 1. The wire 15 is wound around the resin casting grooves 2 and 3 while being aligned. Each pin 7 _L , 7 _R , 8 _L , 8 of this wire 15
_R, 9 _L, 9 for hanging the way to _R is not particularly limited, may be employed for example how over such as disclosed in JP-A-2-239953 or other novel over how . Then, when the alignment of the last set of wires is completed, N bundles of M sets of wires are respectively turned to the turn pins 9.
_L, 9 and fixed by the adhesive fast drying in a portion close to the _R,
Make sure that each set of M wire bundles does not fall apart,
The wire 15 pulled out from the nozzle of the winding machine is cut.

When the M × N wires have been aligned, they are brought into contact with the other pair of winding jigs 1, and both end surfaces of the pair of winding jigs 1 are illustrated. It is closed with a fixing plate (not shown) having a resin inlet not shown. And
Resin casting grooves 2 and 3 of a pair of opposed winding jigs 1 and 1
An insulating resin, for example, a one-component epoxy resin, which is alternately melted, is cast into each wire 15 and control electrodes 13a, 13b.
The electrode support block 33 for fixing is formed. At this time, the wires 15 arranged and stretched in parallel with each other are stretched.
It is needless to say that the resin is injected so as not to disturb the alignment state of and the arrangement relationship between the plate 25 and the nut 26.

Here, there are countless irregularities and holes on the surface of the control electrodes 13a,..., 13, but since the relative density of the sintered alloy is set in the range of 0.7 to 0.9, There are few continuous pores, and irregularities and pores on the surface do not connect deeply. For this reason, even if the main agent and the curing agent of the epoxy resin used as the material of the electrode support block try to penetrate into the irregularities on the surface of the control electrode or the pores opened on the surface by the chromatogram phenomenon before curing, they cannot penetrate deeply,
Also, the amount is extremely small.

After casting, the plates 12 _L and 12 _R are respectively removed from the winding jig 1, and the bundles of the wires 15 wound around the respective turn pins 9 _L and 9 _R are respectively removed. Then, the plate support pins 35 of the winding jig 1 are pulled out, and the control electrode support plates 19, 20, 21, 22 of the resin casting grooves 2, 3 are pulled out.
After releasing the restraints of 2, 23 and 24, the winding jig 1 is lowered, and the head material fixed by the electrode support block 33 from the resin casting grooves 2 and 3 is removed from the control electrode support plates 21 and 2.
Take out relatively with 2 etc. Next, the head material is similarly removed from the winding jig 1 side. This head material is separated into two head materials by cutting the wire material 15 at the portion engaged with the wire holding groove 14 of the central jetty 4 in the middle.

The head material obtained as described above is
As shown in FIG. 4, the wire 1 wound around the winding jig 1
M × N first recording electrode rows and second recording electrode rows arranged in a staggered manner by 5 and 15 are formed, and are controlled by being spaced apart on both sides along these recording electrode rows. Electrode 13
a and 13b are arranged. Here, the electrode support block 33 shrinks as cooling proceeds immediately after molding. However, the wiring boards 18, 18 having the control electrodes 13a, 13b soldered to one side edge in advance and the plates 25, 25 on both sides of the electrode support block 33 work together to contract or deform (undulate) the electrode support block 33. Suppress. In particular, the wiring board 1 embedded in the block 33
Reference numerals 8 and 18 denote recording electrodes (wires 15) and control electrodes 13
It suppresses contraction and deformation of the electrode support block near a and 13b, and maintains these positional relationships. In addition, the resin forming the electrode support block 33 and the solder 1 on the wiring board 18 are provided on the unevenness and the communication holes on the surfaces of the control electrodes 13a and 13b.
Since the zeros penetrate and harden, the connection is strong due to these anchoring effects and does not peel off from each other at the boundary surface.

After that, the head material is polished to form an arc surface having a constant curvature except for the portion indicated by the imaginary line in FIG. At this time, the mounting projections 11, 11 of the control electrodes 13a, 13b projecting from the electrode support block 33.
The surfaces of the control electrodes 13a and 13b and the surface of the electrode support block 33 are polished. As a result, the surfaces of the control electrodes 13a and 13b exposed on the head surface are crushed with irregularities and holes, are formed on the same smooth surface as the cut block, and function as a single control electrode.

The above embodiment is a preferred embodiment of the present invention, but the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention.

[0027]

As is apparent from the above description, the electrostatic recording head of the present invention has the following features.

(Equation 4) Since the control electrode is formed of a conductive sintered alloy set in the range of 0.7 to 0.9 with a relative density defined by, the number of continuous pores is small, and irregularities and pores on the surface are reduced. Even if the main component of epoxy resin used as the material of the electrode support block and the curing agent try to penetrate into the irregularities on the surface of the control electrode or the pores opened on the surface without curing by the chromatogram phenomenon before curing, they cannot penetrate deeply. And the amount is very small. Further, even if only the main agent and the curing agent enter alone, the pores communicated are extremely small, so that the resin component does not permeate the discharge surface (the sliding surface of the recording medium) of the control electrode. Therefore, good discharge is possible, and good image quality is obtained.

Further, even when the electrostatic recording head of the present invention is degassed by depressurizing the resin during casting, the degassing becomes easy because the number of communicating mechanisms is extremely small, so that the interface between the control electrode and the resin becomes difficult. No pinholes occur, and the recording medium slides smoothly and there is no concave portion to which foreign matter adheres. Accordingly, good image quality can be obtained.

In addition, since the control electrode of the electrostatic head of the present invention is formed of a sintered alloy, it can be formed at the same time as the block is formed, even if it has a complicated shape having unevenness for positioning and mounting. Therefore, the manufacturing cost can be reduced. Further, since the surface is porous, solder or resin for the support block enters, and the bonding strength is increased by the anchoring effect, thereby preventing problems such as peeling. Moreover, the polishing resistance at the time of polishing the head surface is small, the pores are crushed by polishing, and the head becomes smooth, and a good discharge is possible at the time of recording, and a good image quality is obtained.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a control electrode of an electrostatic recording head according to the present invention, wherein (A) is a plan view, (B) is a side view, and (C).
Is a front view, and (D) is a plan view showing a state where a concave portion is used instead of the mounting projection.

FIG. 2 is an exploded perspective view illustrating a state in which a control electrode, a control electrode support plate, and the like are mounted in a resin casting groove of a winding jig.

FIG. 3 is a cross-sectional view showing a state in which a control electrode and the like are mounted in a winding jig.

FIG. 4 is a longitudinal sectional view showing one embodiment of the electrostatic recording head of the present invention.

FIG. 5 is a graph showing a relationship between a relative density of a control electrode and an uncured resin component exudation rate.

FIG. 6 is a graph showing a relationship between a relative density of a control electrode and a pinhole occurrence rate at a resin interface.

FIG. 7 is a perspective view showing an electrostatic recording head.

FIG. 8 is an exploded perspective view illustrating a control electrode in a conventional electrostatic recording head and a method of manufacturing the control electrode in a winding jig.

[Explanation of symbols]

 13a, 13b Control electrode 18 Wiring board 33 Electrode support block

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Akiyoshi Ushikoshi 5329 Shimosuwa-cho, Suwa-gun, Nagano Pref. Sankyo Seiki Seisakusho Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) B41J 2 / 395

Claims (1)

(57) [Claims] 1. An electrostatic recording head having a recording electrode and a control electrode, wherein: The electrostatic recording head, wherein the control electrode is formed of a sintered alloy having conductivity having a relative density defined by the above formula 1 in a range of 0.7 to 0.9.