JPS5820031B2 - Hidoukiseidengenzouki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the development of a charge image deposited on an electrophotographic paper, ie a semiconductor mount coated with a dielectric layer, with a so-called +1 toner" liquid.

Electrostatic printing presses are one of the best known applications of electrophotographic paper.

One of the obstacles to the increased application of this electrostatographic method is that
It is necessary to apply a constant velocity to the paper at least during the period when the paper passes through the developer.

In fact, there is an optimum period of contact between developer and paper on the order of 0.5 seconds.

If this period is not observed, the contrast will be weakened.

If the paper remains in contact for longer than this period, a noticeably darker gray texture appears.

Continuously moving the paper becomes extremely cumbersome when the stamping machine is connected 6-on-1 to the computer.

Computers usually perform a variety of tasks and are not always used to send data to printing presses.

In such a case, the printing press will stop and wait for the next data transmission, but the data will not arrive as expected.

This behavior is called asynchronous.

If an electrostatic printing press is operated in this way, and the computer sends complete lines or complete groups of lines to the press, different groups of lines will have different contrasts;
And even more importantly, dark streaks appear at the end of each print.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an asynchronous electrostatic development method which, in contrast to stiffness, makes it possible to completely develop each line of the original text, regardless of irregularities in computer data delivery or pause periods. It is.

The electrostatic development method according to the invention uses a device that is reliably controlled to vary the amount of developer in contact with the paper as a function of the movement of the paper, making it practical for The paper is kept in contact with the developer for a certain period of time.

In an embodiment of the first type, a developing machine carrying out the method of the invention has a tank or enclosure, the opening of which is closed with paper, and one part of the tank extending transversely to the paper. The side walls are movable in the direction of paper movement, and
It has a device for moving this movable side wall as a function of paper movement.

In another type of embodiment, a developing machine carrying out the method of the invention has a tank or an enclosure, the paper entering the tank through the lower part of the tank and vertically traversing the tank. and further includes a device for varying the developer level as a function of paper movement.

In another type of embodiment, a developing machine carrying out the method of the invention comprises a series of nozzles aimed at the paper and a device for moving pixel elements in front of these nozzles as a function of the movement of the paper. It has

In the case of this last embodiment, the developer comprises, on the one hand, a paper supporting insulating wall which is inclined with respect to the horizontal and in which the counter electrode is embedded, and on the other hand, a first insulating wall accommodating the electrode.
It is divided by an insulating wall, a second insulating wall, and a third wall that is movable with respect to the first and second walls and forms a pixel element, and a nozzle is opened inside the third wall and is connected to a developer discharge duct. an assembly having a chamber in communication therewith, the assembly being stationary in a position in which the tongue nozzle is positioned proximate the paper with the electrode aligned with the counter electrode, or the assembly is stationary in a position where the nozzle is directed toward the paper; It can be moved relative to the insulating wall and brought to said position.

The paper supporting insulating wall may be vertical, or it may be sloped in a manner sufficient to allow developer solution to flow out, provided that the slope of the drainage duct corresponds thereto.

In operation, developer is ejected from a nozzle across the filter paper, varying as a function of paper velocity, and returned to the tank through a drainage duct.

The movable insulating wall may have a rim parallel to and in contact with the rim of the insulating wall carrying the electrode to form the chamber.

In such a situation, when the two limbs are pressed against each other, the chamber is virtually sealed so that liquid can circulate within the chamber even when no developing action is taking place. Although applicable to electrostatic printing machines, it is equally applicable to any electrostatic recording device, such as a graph tracer.

Several examples of different types of developing machines implementing the method according to the invention will now be described with reference to the accompanying drawings.

An electrophotographic paper 1 with a dielectric layer on its top surface is shown in FIG.

This paper 1 is moved from left to right on the drawing between a recording electrode 2 and a counter electrode 3 which impart a charge on the surface of the paper in the form of letters so as to form lines extending at right angles to the drawing. .

The developing machine for carrying out the method of the invention has a surrounding wall 4, the lower side of which is open and a paper 1 is applied to seal it, the paper 1 being placed at the level of the counter electrode 3. It is supported by a curved support wall 5.

The partition wall 6 is movable within the enclosure wall 4 containing the developer 7.

The lower surface of the partition forms a scraper which dries the paper at the end of the development process.

A rod 8 is fastened to the partition wall 6, for example, which rod has a recess in the form of a rack and meshes with a gear wheel 9 which is keyed to the shaft 10.

This movement of shaft 10 therefore causes partition wall 6 to move.

``The enclosure wall 4 is provided with two lateral openings, one opening 11 of which is connected by a pipe 12 to a pump 13, the inlet of which is connected by a pipe 14 to a container 15 containing developer solution. and the other opening is connected to this container 15 by a return pipe (not shown).

Therefore, the developer solution 7 can be continuously circulated within the enclosure wall 4 by the pump 13.

This developing machine can print 10 lines of original text per second,
If it is assumed that the optimum development period is 0.5 seconds, the maximum distance between the partition wall 6 and the inner surface 4a of the surrounding wall 4 needs to be a distance corresponding to five lines.

The movement of the paper 1 is normally carried out intermittently, one line at a time, between each movement there is a stop period that is either larger or smaller than the period of movement.

It is easy to change the position of the partition wall 6 every tenth of a second to set an optimum development period of 0.5 seconds for each row.

If the stop period is extended, the partition wall 6 is moved to the left, but if the partition wall 6 is moved until it comes into contact with the inner surface 4a of the surrounding wall 4, the developing action is stopped because the developer is depleted.

FIGS. 2 and 3 are drawings showing the law relating the movement of the paper 1 to the movement of the partition wall 6. FIG.

In these figures, the abscissa X of the paper and the distance y between the partition wall 6 and the inner surface 4a of the enclosure wall 4 are plotted as a function of time.

Every time the paper 1 moves forward by one line (curve 16), the bulkhead 6 moves forward by one line in the same direction, remains in that position for 0.5 seconds and moves backward by one line (curve 17).
.

In FIG. 2, the paper 1 is stopped for more than 0.5 seconds, the partition wall 6 is initially in contact with the inner surface 4a of the surrounding wall 4, and the paper 1 advances by one line, and the partition wall 6 is moved forward by one line. At the same time, it moves forward by one line and returns to the position where it contacts the inner surface 4a of the surrounding wall 4 after 0.5 seconds.

If the advance of the paper 1 is controlled according to a potentially complex and irregular law, the partition wall 6 corresponds to each elementary advance of the paper 1.
By establishing the algebraic sum of the movements of , we can plot the advance graph of the paper and bulkhead as shown by curves 16' and 17' in FIG.

Furthermore, to generalize, when the equation x=f(t) represents the movement of paper, the movement of the partition wall 6 is expressed by the following equation.

θ is the selected development period.

If the movement of the paper 1 is carried out incrementally, as in the previous example, the movement of the partition wall 6 can be determined by a shift register 18 and a summer 19 (see FIG. 4).

The shift register 18 has n settings equal to the number n of lines to be printed during the optimum development period, shown as 5 lines in the numerical example given above, and delays the signal X representing the abscissa of the paper 1 and It is inverted and supplied to the totalizer 19, and the totalizer 1
9 receives the signal X and the signal transmitted from the shift register 18, and generates a signal y representing the movement of the partition wall 6 as its output.

The summer 19 is connected to a branch circuit 20 which converts the rising wavefront of the signal y into pulses and sends them to a reversible motor 21 that controls the movement of the partition 6.

Furthermore, the signal X is fed to a second branch circuit 22, which generates pulses that are sent to an electric motor 23 which controls the advancement of the paper 1.

FIG. 5 shows an example of a practical form for advancing the paper 1 and moving the partition wall 6, in which the summation process is carried out mechanically.

The output of the shift register is connected directly to a branch circuit 20, which is connected to an electromagnet 21' having a plunger core provided with a hook 29.

The second branch circuit 22 is connected to an electromagnet 23' having a plunger core provided with a hook 25, and further has a hook 28.
The plunger core is connected to an electromagnet 24 having a plunger core.

The electromagnet 23' activates the hook 25 which cooperates with the ratchet wheel 26, the shaft 27 of which is connected to the roller shaft which drives the paper 1 once.

Each electromagnet 21 and 24 has a corresponding hook 29
and 28, these hooks are connected to the same ratchet wheel 3.
The shaft 31 of this ratchet wheel is connected to the shaft 10 of a gear 9 that moves the partition wall 6.

In an example of a developing machine of the type shown in FIG. 6, the recording electrode 2 is embedded within a wall 32 of an enclosure, the movable partition 33 of which is attached to a stationary part of the enclosure by bellows. 3
4 and is also coupled to the drive member 35.

The counter electrode 3 is embedded in a support wall 5 that supports the paper 1.

The thickness of the portion of the lower wall 32 adjacent to the paper 1 and isolating the electrode 2 from the developer is less than the width of the blank space separating the two lines of the original text, so that the printed original text will be blocked if the machine stops. However, it can be viewed as soon as it is developed.

The drive member 35 can be moved, for example, as described for the rod 8 in FIG.

As a variant of this, the drive member 35 can be omitted, the paper 1 can be moved vertically, and the partition wall 33 can be fixed as the top wall of the enclosure wall as shown.

In this case, the level of the developer solution 7 is varied by controlling the opening and closing of a valve inserted in a tube 12 supplying the developer solution within the enclosure wall.

In the example of the developing machine of the type shown in FIG. You can view the original text as soon as it is printed.

The developer level is varied, as in the previously described variant, by controlling a valve inserted in the developer supply pipe according to the aforementioned rules.

In an example of a developing machine of the type shown in FIG. 8, paper 1 is moved in front of a series of nozzles 38 from which jets of developer are projected onto the underside of the paper.

A shutter 39 can be moved in front of the nozzle to block all or part of the jet.

This shack 39 is attached to a drive member 40,
The drive member 40 is driven according to the previously defined rules, e.g.
It is designed to be controlled in the same way as rod 8 in the figure.

In the example of the developer shown in FIGS. 9 and 10, two recording electrodes, shown as electrodes 2a and 2b, are embedded in the thickness of the wall 32, and two opposing electrodes 3a and 3b are used to carry the electrons. It is embedded in the support wall 5 that supports the photographic paper 1.

In this embodiment, the paper 1 moves from bottom to top in front of three nozzles 38, and jets from each nozzle are projected onto the paper 1.

Each nozzle is oriented toward a character-line, respectively.
A septum 39 moves in front of the nozzles and acts as a shutter that can block the jet from all or some of the nozzles.

Each nozzle/I/38 is connected to a developer source by a passage 41 in wall 42.

Wall 42 is connected to wall 32 by transverse walls (not shown) to ensure a substantially sealed chamber 43 delimited by movable partition 39 and wall 5.

This chamber 43 communicates with a drainage passage 44, and the cross-sectional area of the drainage passage is selected to be sufficiently large in relation to the total flow rate of the jets of each nozzle 38, so that the chamber 43 is completely drained. It cannot be filled with liquid.

Leakage through the rear seams and side wall seams is thereby prevented.

The upper surface 32a of the wall 32 is sloped toward the drainage passageway 44 to assist in draining the developer solution into the drainage passageway.

As previously mentioned, the septum 39 can be moved as a function of paper movement according to the following law:

f(t) represents the movement of the paper, and θ is the development period chosen to be on the order of 0.1 to 0.5 seconds.

This movement of the partition wall 39 can be effected by a ratchet wheel 30 shown in FIG. 5 which operates as a stepping motor.

A pulley 45 is attached to the shaft 31 of the ratchet wheel 30, and a cable 46 is wound several times around the pulley.

The central turn of the cable 46 is secured to the pulley 45 with a peg 47, and both ends of the cable are secured to the bulkhead 39 by pegs 48 and 49, with tension springs 50 interposed.
are fixed at the upper and lower ends of the

In such a situation, when the shaft 31 rotates, the partition wall 39 will move in a straight line.

In operation, the developer jet projected from the nozzle 38 impinges on the paper 1 over a wider or narrower width, and the paper remains in contact with the developer for an effective period of time.

The colored particles contained in the developer adhere to the portions of the paper 1 charged by the electrodes 2a and 2b, so that the electrostatic latent image is developed into a visible image.

In FIG. 9, the bulkhead 39 is at the highest position, for example 1
Three lines of characters are exposed that are hit by a column or more of jets.

In FIG. 10, on the contrary, the septum 39 is in its lowest position and no part of the paper is exposed to the developer.

In this case, excess developer is returned to the storage container through the drainage channel 44.

In the area in contact with the paper 1, the end of the partition 39 forms a polished scraper 51 which ensures that the paper 1 is dry as it exits the developer.

The upper surface 39a of the partition wall 39 is sloped downwardly towards the paper so that the last character line can be read as soon as the developer has completed development.

The lower surface 39b of the partition wall 39 is parallel to the upper surface 32a of the wall 32, ensuring a substantially hermetic closure when the partition wall 39 is in its lowest position (FIG. 10).

The inner surface 39 of the partition wall 39 partially delimiting the chamber 43
c has a concave surface and forms a baffle plate, which returns the developer jet toward the passage 44 in step with the lowering of the partition wall 39.

Just before the developer is completely deactivated, the developer jet is completely discharged through passage 44 (FIG. 10).

In this state, the developer no longer reaches the paper 1, but it continues to circulate in the chamber 43 at the same flow rate, entering the chamber through the passage 41 and leaving again through the drainage passage 44.

The configuration of the device that ensures downward deflection of the developer jet in the closed position is not limited to the configuration of this example, but any other suitably oriented protrusion or A wall can perform this function.

The turbulence created in this way is very advantageous for achieving triboelectric charging of the colored particles and homogeneous dispersion of the colored particles in the liquid.

In order to prevent the edges of the chamber 43 in contact with the paper 1 from forming undesirable blemishes on the paper, the potential is optimally applied to produce a slight repulsion of the colored particles close to these edges. It is advantageous to construct the edge surface of the chamber in contact with the paper with a metal that can be reinforced.

This applies, of course, in the case of two side walls, wall 32 and partition wall 3.
This also applies to the respective surfaces 32a and 39b of 9, in which case these metal surfaces are designated by 52 and 53.

In the surface of the wall 32 coplanar with the end surface of each electrode 2a and 2b, a groove 54 is provided, located between the electrodes and the surface 32a of this wall, the end of which is open to the surrounding atmosphere. It is provided.

This groove 54 is provided to prevent the electrode from getting wet and making it impossible to record at all.

It is desirable to generate a slight negative pressure of about 5 to 15 α in the water column in the drain passage 44.

This prevents the developer from leaking from the gap between the developing machine and the paper; in this case, air flows into the gap and no liquid flows out.

Furthermore, when the development action is complete, the developer can be removed from the paper without danger (FIG. 11).

This may be necessary if it is desired to advance the paper very quickly between two printed lines, as is the case with printing presses employing mechanical impressions.

This separation also makes the last developed line more legible.

FIG. 12 shows an example of a type of feeding device that can reliably generate negative pressure within the drain passageway 44.

The developer 7 is stored in a tank 5 sealed by a filling rob plug 56.
It is housed within 5.

The inlet of the '1 submersible type 11 pump 57 is connected to the bottom of the tank 55, and the outlet thereof is connected to the passage 41.

Drain passage 44 communicates with the upper part of tank 55 .

Furthermore, an air pump 58 whose suction port is connected to the upper part of this tank 55 generates negative pressure in the tank 55, and this
Negative pressure is transmitted into the developer chamber 43.

In order to reduce to a minimum pollution of the surrounding air by developer vapor, this negative pressure needs to be as low as possible, and a magnitude of 6 crrL in water column gives good results.

In the example of the developing machine of the type shown in FIG. 42
The hinged joint with the elastic backing 61 is lightly compressed against the wall 60 and held on the end face of the wall 42 by the action of the rollers 62.
This is done in a properly sealed state.

Roller 62 may be stationary or may be rotatable about its axis.

It should be noted that this configuration makes it possible to pick up a small amount of longitudinal movement of the wall 60 forced by the linear trajectory of the edge against the paper 1 supported by the support wall 5.

A spring 63 fixed at one end to the wall 42 and engaged at the other end to the edge of the wall 60 ensures constant contact between the wall 60 and the paper 1, regardless of the position of the wall. The spring 64, which makes it possible to carry out the drying operation reliably, keeps the wall 60 in constant contact with the cam 65 fixed to the shaft 31 of the ratchet wheel in FIG. 5, which operates as a stepping motor. do.

Although this cam 65 is shown in the chamber 43 of the developing machine,
It can also be placed outside the chamber 43.

Nozzle 38 consists of one or more rows of orifices provided in passage 41 communicating with a developer source.

The wall 60 is integral with a deflecting plate 66, and the deflecting plate 6
6 is irradiated with a jet to return the developer to the drain passage 44 when the wall 60 is closed.

The walls 60 and 67 delimiting the chamber 43 are made of metal and are connected to a voltage source of a value calculated to eliminate any fabric stains and interference stains.

A conductive wall 68 is embedded within the insulating support wall 5 to provide the correct electrical potential to the back side of the paper 1 during the development operation.

This is particularly useful when the counter electrode 3 is segmented and provides widely varying potentials.

As is clear from the foregoing description, the developing machines corresponding to FIGS. 9 through 13 are of a single block forming a self-developing recording head.

The head can be separated from the paper once the development operation is complete, useful if the paper is to be viewed or moved rapidly.

This head does not allow any developer to escape to the outside, but the developer normally continues to circulate within the head.

It is clear that the invention is not limited to the embodiments using a developing machine of the type described and illustrated above, but includes all of the various variants.

Thus, in particular, although the paper is illustrated as being moved vertically in the developer example of FIGS. In some cases, the paper may be moved obliquely.

'On the other hand, other devices can be used to move the movable bulkhead 39 or wall 60, such as a rack.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example of a first type of developing machine for carrying out the method of the present invention. 2 and 3 are graphs illustrating paper movement and movement of the movable bulkhead as a function of time. FIG. 4 is a block diagram schematically showing a device for controlling movement of a movable partition wall. FIG. 5 is a schematic diagram illustrating an example of one type of such a control device. FIG. 6 is a schematic sectional view showing an example of a second type of developing machine for carrying out the method of the present invention. FIG. 7 is a schematic sectional view showing an example of a third type of developing machine for carrying out the method of the present invention. FIG. 8 is a schematic sectional view showing an example of a fourth type of developing machine for carrying out the method of the present invention. FIG. 9 is a sectional view showing an example of a fifth type of developing machine for carrying out the method of the present invention. FIG. 10 is a sectional view showing a case where the movable partition wall of the developing machine shown in FIG. 9 is closed. FIG. 11 is a sectional view showing a state in which the developer injection part of the developing machine shown in FIG. 9 is separated from the paper support wall. FIG. 12 is a schematic diagram showing a method of supplying a developer to a developing machine implementing the method of the present invention. FIG. 13 is a sectional view showing an example of a sixth type of developing machine for carrying out the method of the present invention. DESCRIPTION OF SYMBOLS 1... Electrophotographic paper, 2, 2a, 2b... Recording electrode, 3.3a, 3b... Counter electrode, 4... Enclosing wall, 5
...Supporting wall, 6...Partition wall, 7...Developer, 8...
・Bar, 9...gear, 10...shaft, 11...opening,
12...Pipe, 13...Pump, 14...Pipe, 15
...Developer container, 4a...Inner surface of enclosure wall 4, 18.
...Shift'' register, 19...Totalizer, 20...
Branch circuit, 21... Reversible motor, 22... Second branch circuit, 23... Electric motor, 21', 23', 24.
...Electromagnet, 25,28,29...Hook, 26.3
0... Pawl wheel, 27.31... Axis, 32... Wall,
33... Partition wall, 34... Bellows, 35... Drive member, 36... Surrounding wall, 37... Side wall, 38.../
Zuru, 39...Shutter, 40...1 Drive member, 4
1...Aisle, 42...Wall, 43...Room, 44...
・Drainage passage, 32a...Top surface of wall 32, 45...Pulley, 46...Cable, 47, 4B, 49...Set nail, 50...Tension spring, 51...Skleno \
39a...Top surface, 39b...Bottom surface, 52, 53.
... Metal surface, 55 ... Tank, 56 ... Filling robot plug, 57 ... Pump, 58 ... Air pump, 60 ...
...Wall, 61...Elastic backing, 62...Roller, 63...Spring, 64...Spring, 65...Cam,
66... deflection board, 67... wall.

Claims (1)

[Scope of Claims] 1. Electrostatic printing is achieved by bringing a developer into contact with a moving electrostatographic paper and limiting the length of the area of the electrostatographic paper in contact with the developer according to a function of the speed of movement of the electrostatographic paper. A method of developing an electrostatic image deposited on electrophotographic paper, which involves a fixed contact period between the electrophotographic paper and the developer solution, in which the electrostatic image is fed at varying speeds of movement, i.e. at irregular time intervals. When the movement of the electrostatic photographic paper is x = f (t), the length y of the contact area between the electrostatic photographic paper and the developer is expressed by the formula y = f (t) - f (-θ) However, in the formula, θ represents a fixed period of time during which each part of the electrostatic photographic paper is brought into contact with a developer solution.