US3910232A - Color reproduction device - Google Patents

Abstract

In a color reproduction device using multi-color developing agents, the developing agents which have been mixed in the course of the development are re-used as a black color developing agent, for which purpose the device is provide with a plurality of developing with, a mixed developing agent recoverying unit, and a conveying unit for the mixed developing agents to be transported from the recovering unit to the developing unit.

Description

United States Patent Kondo et al. Oct. 7, 1975 COLOR REPRODUCTION DEVICE 3,627,410 12/1971 Jugle .1 355/4 3,663,100 5/1972 ltoh et al. 355/4 [75] Inventors Kond"! Kawasak" Show 3,701,337 10/1972 BOlelll et al. 1. 118/637 lnoue, Fuss?! both of Japan 3,712,203 1/1973 Kishi et a1 118/637 3,734,607 5/1973 Davis et al. 355/4 [73] Asslgnee' f Kabush'k' Tokyo 3,748,125 7 1973 Hercock et al. 117/37 LE 3,797,930 3 1974 Tanaka et a1. 355/4 22 Ffl d; June 11 974 3,807,998 4/1974 Kinoshita et a1. 355/4 [21] Appl 478,317 Primary Examiner-Mervin Stein Assistant Examiner-Douglas Salser [30] Foreign Application Priority Dat Attorney, Agent, or FirmFitzpatrick, Cella, Harper June 14, 1973 Japan 48-67049 & Scmto [52 US. 01. 118/637; 117/37 LE; 1l8/DIG. 23; [57] ABSTRACT 355/4 In a color reproduction device using multi-color devel- 51 Int. Cl. G03G 15/06 oping agents, the developing agents which have been [53] Fi ld f S h 118/ 37 G 23; 355/4 mixed in the course of the development are re-used as 355/10; 96/12, 1 LY; 117/37 LE a black color developing agent, for which purpose the device is provide with a plurality of developing with, a [56] R f re Cited mixed developing agent recoverying unit, and a con- UNITED STATES PATENTS veying unit for the mixed developing agents to be transported from the recovering unit to the developing 3,253,913 5/1966 Smlth et al 96/12 unit 3,420,151 l/l969 Levine et al.... 96/].2 3,494,328 2/1970 Maloney 117/37 LE 4 Claims, 4 Drawing Figures U.S. Patent Oct. 7,1975 Sheet 1 of3 3,910,232

COLOR REPRODUCTION DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to color reproduction techniques in electrophotography using multi-color developing agents, and, more particularly, it is concerned with such color reproduction method and a device therefor, in which the developing agents are used'most effectively and sparingly.

2. Description of the Prior Art For color reproduction, there have so far been at tempted various electrophotographic methods such as Carlson process and NP process, wherein an electrostatic latent image is formed on a photosensitive body; TESI process, wherein the electrostatic latent image is once transferred onto recording paper (or an image transfer sheet), followed by development of the recording paper, on which the latent image has been transferred; or a screen process, etc. Also, as has been already known, these electrophotographic methods are further divided into a direct system, wherein the reproduced picture image is fixed on the photosensitive body as it is, and a transfer system, wherein the reproduced picture image formed on the photosensitive body is transferred onto a transfer member, after which the transferred image is fixed. In more detail, the direct system is to obtain the color picture image by repeating three to four times the processes of electric changing, exposure through color resolution filters, development, and fixation, while the transfer system is to obtain the color picture image by repeating the processes of cleaning of the photosensitive plate, electric changing, exposure through color resolution filters, development, and transferv The problem which has been encountered in the devices to carry out the above-mentioned process steps is that the color developing agents to be used for the color reproduction tend to bring about mixing at the developing section and the cleaning section of the device. And, it has quite naturally been done that such mixed developing agents are thrown away as waste, scince they are liable to deteriorate the color tone of the colorreproduced image. However, accumulation in such waste would inevitably cause undesirable effect on the maintenance of the reproduction device and the environment, in which such waste is thrown away.

SUMMARY OF THE INVENTION In view of the above-described problem inherent in the conventional device, it is a primary object of the present invention to provide an improved color reproduction method and a device therefor.

It is a secondary object of the present invention to provide an improved color reproduction method and a device therefor capable of recovering and regenerating for re-use the residual developing agents on the photosensitive body without making them waste.

It is a tertiary object of the present invention to provide an improved color reproduction device provided with control mechanisms which can be used without impairing quality of the image to be reproduced at the time of re-use of the regenerated developing agent.

It is a further object of the present invention to provide an improved color reproduction device capable of performing also masking and monochromatic reproductions, wherein a mechanism for effectively distributing an amount of the developing agent so as to operate the reproduction device most economically.

According to the present invention in one aspect thereof, there is provided a method for color reproduction using multi-color developing agents which comprises recovering the multi-color developing agents which have been used for the image development and intermingled during the developing operation, and regenerating the recovered developing agents as the Waste for reuse as a black color developing agent.

According to the present invention in another aspect thereof, there is provided a device for color reproduction of an original color image wherein an electrostatic latent image formed on an electrostatic latent image carrying member is developed with multi-color developing agents, which comprises in combination: (a) a plurality of developing means, at least one of the developing means containing therein a black color developing agent, (b) means for recovering the been intermingled during the image developing process; and (c) means for transferring the intermingled multi-color developing agent from the recovering means to one of the developing means containing therein the black color developing agent.

The color reproduction device, wherein the transfer means for the intermingled multi-color developing agents further includes means to detect a transfer quantity of the intermingled developing agent, and means to control the transfer operation.

The color reproduction device, wherein the developing agent recovering means includes means for storing the recovered developing agents, and means to detect the color phase of the intermingled multi-color developing agents in storage.

The color reproduction device, wherein the devoloping agent storing means further includes means for feeding and mixing an additional quantity of black color developing agent in accordance with a detection signal from the color phase detecting means.

The foregoing objects and the actual construction and operations of the device to perform the intended method according to the present invention will become more clearly understandable from the following detailed description of a preferred embodiment when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side elevational view showing the general construction of the color reproduction device according to the present invention;

FIG. 2 is a perspective view of the recovering means for the color developing agent provided at the cleaning section of the reproduction device;

FIG. 3 is a block diagram to explain one example for regenerating the intermingled developing agents for reuse; and

FIG. 4 is a wiring diagram showing one actual example of the means for detecting concentration of the primary color developing agents in the black color developing agent which have been intermingled as the result of the developing operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS veloping method and an NP type photosensitive plate I for the photosensitive member to obtain multi-color reproduction of an original color picture, the color origina] 2 which is placed on a transparent bed I is irradiated by a light source 3. The light irradiated from the light source 3 passes through the color resolution filter 7a which is held on a turret 7 for the color resolution filters which can be changed over in accordance with color resolution by each of mirrors 4 and 5, and a lens 6, and then is reflected by mirrors 8 and 9 upon a photosensitive drum 10 through an alternate current charger l2.

Of the abovementioned optical system, the light source 3, the mirrors 4 and shift to their respective positions 3', 4' and 5 in synchronism with rotation of the photosensitive drum 10. The photosensitive drum is cleansed by a cleaning blade 24, is electrically charged by a primary charger II, and is discharged by the ac charger l2 simultaneously with light exposure.

The thus exposed photosensitive drum I2 is again subjected to the exposure overall its surface by another light source 13, and developed by one of the developing vessels 14, I5, 16 and 17. To each of the developing vessels, a designated developing agent is supplied from each of developer tanks l4, l5, l6 and 17. The developing vessels are so constructed that they may shift to and from the designated position for the development in synchronism with movement of any of the corresponding color resolution filters 7a, 7b, 7c and 7d set in the filter turret 7. Surplus amount of the developing agent adhered onto the photosensitive drum 10 is squeezed out by an electric charger 18 for squeezing. On the other hand, a transfer paper 19 is sent out by a roll 20 and held on an image transfer drum 21 positioned contriguous to the photosensitive drum 10. The developed image on the photosensitive drum I0 is therefore transferred onto the transfer paper held on the drum 2] at the tangential point between the two drums.

In the case of obtaining color reproduction, the afore-mentioned process steps are repeated for three to four times, after which the transfer paper 19 is separated from the transfer drum 21 and carried by a conveyor belt 22 up to an image fixing device 23 where the transferred image is fixed to complete a reproduced copy. Incidentally, the transfer roll 21 is cleansed by a movable cleaning blade so that no back surface of the subsequent transfer paper may become stained with any foreign matter remaining thereon.

In order to obtain a monochromatic copy. on the other hand, light exposure is done through the filter 7d and the exposed image on the photosensitive drum is developed by the developing vessel 17. In this case, it is quite natural that the transfer paper is separated from the transfer roll upon completion of one transfer process, fixed at the fixing device, and delivered.

In the course of the development and cleaning operations as mentioned in the foregoing, however, there inevitably takes place mixing or intermingling of the developing agents at the cleaning blade 24 of the reproduction machine. Also such mixing may take place in the vicinity of the developing vessels 14, 15, 16 and 17, because, at these places, the developing agents are prone to drop. Further, the developing agents which have been squeezed from the surface of the photosensitive drum 10 by the electric charger l8 undergo the color mixing. The mixed or intermingled developing agents are recovered by various kinds of expedient. For

instance, a receptacle is provided on each of the developing vessels, the electric charger for squeezing, cleaning blade, etc. so as to receive thereinto the dropping liquid developer and to lead it to the developing vessel for black toner or the storage tanks for the corresponding developing agent through a conduit pipe. Further as will be explained hereinafter, it is of course possible to forward such collected developing agent into the desired vessel after the color phase and concentration of the color developing agent are properly adjusted.

At the cleaning blade 24, a diluent for the developing agent may be caused to flow through a liquid feeding pipe 27 to prevent the recovered developing agent from adhering thereonto and to effectively recover the developer together with the diluent. Also, at the cleaning blade 25, the toner which has been collected by the blade is caused to flow out with a colorless diluent for the developing agent and recovered so as not to stain the transfer paper held on the transfer drum. For such liquid recovery, the construction of the photosensitive body as described in detail in the specification of British Pat. No. 1,326,786(DAS 2,047,130), for example,

is considered particularly suitable.

it is also possible that the recovered liquid is once stored in a collecting vessel and then subjected to adjustment for a definite concentration with a concentrated black color developing liquid for re-use, or the recovered liquid is directly introduced into vessel for the black color developing agent, and re-used by adding thereto concentrated black color developing agent depending on necessity.

FIG. 3 explains one example of a control mechanism for adjusting concentration of the developing agent. According to this control mechanism, the recovered developing agent is once stored in a collecting tank 31 and then sent into a mixing tank 35 through a valve 33. The mixing tank 35 is provided with a terminal detector 351 of the control circuit to detect and control the color phase, and an agitator 352 to make concentration of the developing agent uniform.

FIG. 4 shows one example of the color phase detection and control mechanism, wherein the terminal detector 351 is provided with a plurality of photocells CdSl, CdS2 and CdS3 having red, blue and green filters fl, f2 and f3, respectively, and a single white light source LPl common to them. In this circuit construction of the terminal detector 351, the valve 33 or 34 in FIG. 3 are opened or closed in accordance with the detection output of this detector.

In the color phase control, when the detection output of each photocell is substantially the same, for instance, the valve 33 is opened, and, when any one of the photocells has a different output, the valve 34 is opened. Otherwise, the valve 33 is constantly opened and an upper value for the latitude of each color tone is established, and when any one of the detection elements exceeds the upper limit of the established value, the valve 34 is opened to obtain the effective result of the color phase adjustment. The example shown in FIG. 4 corresponds to this design, in which each established value can be arbitrarily set by regulating one of the input terminal potentials of each operational amplifier by each variable resistor VR,, VR or VR Thus, the developing agent in the mixing tank 35 in FIG. 3 can always be kept in black color or in a color tone which may be recognized as the substantial black.

On the other hand, opening and closing of a valve 37 provided between the mixing tank 35 and a developing unit 38 is controlled by a detection output of another terminal detector 381 provided in the develolping unit 38, whereby concentration of the developing agent can be maintained at a constant level.

Although the foregoing description has been made on the basis of the liquid developed to be used, it is of course possible that almost the same construction, function and effect are attained as in the case of using the dry type developer. in this case, the recovering blades and so forth may be made in the same construction as shown in the drawing, although particular consideration should be given in designing the recovering and conveying devices for the developing agent which is in powder form. That is to say, as shown in FIG. 2, a screw 28 of a full length of the drum breadth is provided just in front of the cleaning blade 24 to transport the powdery developing agent scraped by the blade in the lateral direction. The powder developer thus transported sideways is then collected at a trough 29, through which it is conveyed to the developing unit. In other way, the collected powder developer is led into the developing unit through a duct by means of a suction fan. ln still another way, a hopper 291 for storing a a definite quantity of the transported developing agent is provided at the end of the trough or duct 29, and a valve is caused to open and close by operating a solenoid SOL open detection of a predetermined amount of the transported powder developer by means of a lamp LP and a photocell CdS.

As a means conducive to the understanding of the present invention as has been described in the foregoing, the following experimental result is presented, by which cristical quantity of each of primary color developing agents which is permitted to be present in the black color developing agent has been experimentally verified.

Color developing agents of cyan, magenta, and yellow were prepared, and each of the developing agents was mixed with the black color developing agent in a definite quantity for each of the below-listed instances. Subsequently, by using the above-described reproduction device, a monochromatic reproduction was conducted to find out the critical mixing quantity of each primary color, at which the color tone of the reproduced picture image could not be recognized as real black. The results are as follows.

Color Developing Agent Mixed with Black Critical Mixing Quantity with Black Developing Note: Each developing agent in an equivalent amount As has been detailed hereinabove, the reproduction device according to the present invention is capable of regenerating the mixed developing agents, hence there is no apprehension of wastes occuring after the development, and any loss of the developing agent can be reduced, which highly contributes to maintenance and operations of the reproduction machine in good economy.

Moreover, in the reproduction machine for office use which serves both purposes of the multi-color reproduction and the monochromatic reproduction, the mixed developing agent can be used as it is without requiring any intricate control of the color phase, if the monochromatic reproduction does not pose a problem on the color tone of the reproduced image.

Furthermore, when the mixed developing agent is intermingled with the black color developing agent for re-use, good color tone of black can be maintained easily in utilization of the detection and control element of the known type, hence construction of the operative device can be realized very effectively.

Although the present invention has been described and illustrated by way of preferred embodiment thereof, it is to be understood that such is merely illustrative and not restrictive, and that variations and modifications may be made therein without departing from the spirit and scope of the present invention as recited in the appended claims.

We claim:

1. A device for color reproduction of an original color image wherein an electrostatic latent image formed on an electrostatic latent image carrying member is developed with multi-color developing agents, which comprise in combination:

a. a plurality of developing means, at least one of said developing means containing therein a black color developing agent;

b. means for recovering said multi-color developing agents which have been intermingled during the image developing process; and

0. means for transferring said intermingled multicolor developing agents from said recovering means to one of said developing means containing therein the black color developing agent.

2. The color reproduction device as defined in claim 1, wherein said means for transferring the intermingled multi-color developing agents includes means to detect a transfer quantity of said intermingled developing agents, and means to control the transfer operation.

3. The color reproduction device as defined in claim 1, wherein said developing agent recovering means includes means for storing said recovered developing agents, and means to detect the color phase of said intermingled multi-color developing agents in storage.

4. The color reproduction device as defined in claim 3, wherein said developing agent storing means further includes means for feeding and mixing an additional quantity of black color developing agent in accordance with a detection signal from said color phase detecting Patent No. 3 910 232 4 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION jci-nher 7, 1 97';

Inventor(s) EIICHI KONDO, AL.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby' corrected as shown below:

Title Page, in the Abstract, line 5 provide" should read Column Column Column Column Column Column Column Column Column Column Column Column Column --provided---;

1, line 33, '"changing" should read -charging-;

1, line 43, "scince" should read -since-- 1, line 66, "performing also masking" should read --performing masking--;

2, line 19, "been" should read means;

3, line 34, "contriguous" should read -contiguous-;

3, line 67, "expedient" should read -expedience;

4, line 24, "it" should read -It---;

4, line 49, "are" shouldread is-;

5, line 4, "develolping" should read develo ping--;

5, line 8, "the" (second occurrence) should read I -using-; "developed to be used" should 'read "developer";

5, line 10, "attained as in" should read --attained in'--;

5, line 11, "the dry" should read dry-; "in" should read -In-;

5, lines 22 and 23, "In other way" should read In another way--;'

I Column 5, line 36, "agents" should read --agents,-'

UNITED STATES PATENT OFFICE Page 2 CERTIFICATE OF CORRECTION Patent No. 3,910,232 4 Dated October 7, 1975 Inventor) EIICHI KONDO I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column '5, line 26, "a a" should read --a-;

Column'5, line 35, "whi oh cristical" should read -which a critical--; "primary" should read --the primary;

Column 5, line 37, "agent" should read --agent,---'

Column 6, line 11,- "reproduotiom," should read -reproduction,-. 1

Signed and Scaled this A ttes t.

RUTH C. MASON C. MAR Arresting Offi SHALL DANN ommissioner oflarenls and Trademarks

Claims (4)

1. A device for color reproduction of an original color image wherein an electrostatic latent image formed on an electrostatic latent image carrying member is developed with multi-color developing agents, which comprise in combination: a. a plurality of developing means, at least one of said developing means containing therein a black color developing agent; b. means for recovering said multi-color developing agents which have been intermingled during the image developing process; and c. means for transferring said intermingled multi-color developing agents from said recovering means to one of said developing means containing therein the black color developing agent.

2. The color reproduction device as definEd in claim 1, wherein said means for transferring the intermingled multi-color developing agents includes means to detect a transfer quantity of said intermingled developing agents, and means to control the transfer operation.

3. The color reproduction device as defined in claim 1, wherein said developing agent recovering means includes means for storing said recovered developing agents, and means to detect the color phase of said intermingled multi-color developing agents in storage.

4. The color reproduction device as defined in claim 3, wherein said developing agent storing means further includes means for feeding and mixing an additional quantity of black color developing agent in accordance with a detection signal from said color phase detecting means.

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