US3623503A

US3623503A - Developing liquid feed device for wet process electrophotographic apparatus

Info

Publication number: US3623503A
Application number: US31629A
Authority: US
Inventors: Shigeru Suzuki
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1969-04-25
Filing date: 1970-04-24
Publication date: 1971-11-30
Anticipated expiration: 1988-11-30
Also published as: DE2020132C3; GB1267269A; JPS4841901B1; FR2046404A5; DE2020132B2; DE2020132A1

Abstract

A developing liquid feed device to be used in a wet process electrophotographic apparatus for feeding a developing liquid having a toner concentration higher than that of the developing solution in the main developing chamber, comprising a developing liquid feed storage tank having a normally closed valve therein which valve is opened by appropriate means when the tank is mounted upon the main developing chamber permitting the developing liquid therein to be metered into the main developing solution. A premix chamber is floated in the main developing solution beneath the valve in the storage tank to receive the developing liquid passing therethrough. This premix chamber is provided with means for exerting a buoyant force sufficient to overcome the head of the developing liquid and thus maintains the uppermost edge of the premix chamber above the level of the developing solution. When the developing solution is at a predetermined level, the developing liquid in the premix chamber closes off the valve so that there is no metering of the developing liquid from the storage tank, but when the solution drops below the predetermined level, the concurrent dropping of the premix chamber opens the valve, permitting developing liquid to pass through the premix chamber into the main developing chamber until the solution is again raised to the predetermined level.

Description

Unite States Patent Inventor 8 Suzuki Primary Examiner-M. Cary Nelson Yokmamav Japan Assistant Examiner David R. Matthews PP 31,629 AttorneysHenry T. Burke, Robert Scobey, Robert S. [22] P"- 1970 Dunham, P. E. Henninger, Lester W. Clark, Gerald W. [45] Patented Nov. 30, 1971 Griffin, Thomas F. Moran, R. Bradlee Boal, Christopher C. 1 Asslsnee Riwh Dunham and Thomas P. Dowd Tokyo, Japan [32] Priority Apr. 25, 1969 [33] Japan ABSTRACT: A developing liquid feed device to be used in a [31] 44/32510 wet process electrophotographic apparatus for feeding a developing liquid having a toner concentration higher than that of the developing solution in the main developing chamber, comprising a developing liquid feed storage tank having a normally closed valve therein which valve is opened [54] DEVELOPING LIQUID FEED DEVICE FOR WET by appropriate means when the tank is mounted upon the PROCESS ELECTROPHOTOGRAPHIC mam develop|ng chamber permitt ng the developmg liquld APPARATUS therem to be metered into the mam developing solution. A 4Claims2brawlng Figan premix chamber s floated In the mam developing solut on beneath the valve In the storage tank to receive the developing [52] U.S. Cl 137/454, quid passing h r thmu h. This premix chamber is provided 137/575- 137/581 with means for exerting a buoyant force sufficient to over- [51] Int. CL G05d 9/00 come the head fth developing quid and thus maintains the [50] Field of Search 137/386, uppermast edge f the premix chamber above the |eve| f he 409, 4301 454, 58]; developing solution. When the developing solution is at a 251/251;95/89; 101/48, 364 determined level, the developing liquid in the premix References Cited chamber closes off the valve so that there is no metering of the developing liquid from the storage tank, but when the solution UNITED STATES PATENTS drops below the predetermined level, the concurrent dropping 2,279,166 4/ 1942 Hodil et a1. 137/386 of the premix chamber opens the valve, permitting developing 2,360,894 10/1944 Ryan 251/251 X liquid to pass through the premix chamber into the main 3,145,653 8/1964 Lake 137/454 X developing chamber until the solution is again raised to the 3,491,675 1/1970 Gold 137/414X predetermined level.

9 26 I8 I00 25 L S i 2 7 [3b =fi=? T 2O 3 '0 1-H? a 7 l6 15b 0 7 4 I I lb |4l 1 la 60 lo DEVELOPING LIQUID FEED DEVICE FOR WET PROCESS ELECTROPIIOTOGRAPI'IIC APPARATUS BACKGROUND OF THE INVENTION The present invention relates to a developing liquid feed device for a wet process electrophotographic apparatus.

The developing liquid for the wet process electrophotography consists of a carrier having a high electric resistance and the toner or finely divided resinous powder such as carbon black. Only when the toner concentration in the developing liquid is maintained at a predetermined level, a latent electrostatic image is developed into a visible image of better quality.

When a large number of copies are developed by the same developing liquid, the toner and the carrier are consumed as they are adhered to the copies or sensitized members so that the toner concentration as well as the quantity of the developing liquid are decreased. The toner concentration must be maintained at a predetennined degree by supplying the toner itself or the new developing liquid. In this case, it will be very advantageous to supply the developing liquid in the developing liquid chamber with the developing liquid feed whose concentration is previously adjusted so as to maintain the toner concentration in the developing liquid in the developing liquid chamber when the quantity of the developing liquid is decreased less than a predetermined value. The toner concentration Dp (gJt) in the developing liquid feed is given by Dp= [DV- Dn (V- Vrl)]/Vn where D (g./t) desired toner concentration in the developing liquid in the developing liquid chamber:

Dn(g./L) toner concentration of the developing liquid after a number of n copies or sensitized members have been developed;

Vn (L) quantity of the developing liquid required for the development of a number of n copies or sensitized members; and

V(L) quantity of the developing liquid which must remain in the developing liquid for a desired image quality.

Dn and Vn may be detennined empirically and statistically depending upon the sizes of the copies or sensitized members, the density of black area to white area of a pattern to be copied, etc. V may be determined depending upon a design capacity of a photocopying machine. Thus, Dp may be determined from the above relation. The concentration D has a bolerance so that the developing liquid feed having a concentration Dp (g./:.) is supplied into the developing chamber, the developing liquid in the chamber may be maintained at a predetermined level.

In order to supply the developing liquid feed into the developing liquid chamber, a feed valve which is opened when the liquid level in the developing liquid chamber falls below a predetermined level is generally used. However, when the feed valve is simply opened in this manner into the developing liquid, the developing liquid feed may be automatically supplied depending upon the liquid level in the developing liquid chamber, but the developing liquid in a storage tank is in communication with the developing liquid in the chamber so that the toner in the developing liquid feed is deposited or dispersed into the developing liquid, thereby reducing the toner concentration in the liquid. Therefore, even when the developing liquid feed is fed into the developing liquid a predetermined toner concentration in the developing liquid cannot be maintained because the toner concentration of the liquid is less than a desired level.

SUMMARY OF THE INVENTION It is therefore the broad object of the present invention to provide an improved developing liquid feed device for use in a wet process electrophotography which can completely separate the developing liquid feed from the developing liquid to which is added the feed, except the time when the feed must be supplied to the developing liquid, thereby preventing undesired drop of toner concentration of the developing liquid feed and maintaining the toner concentration of the developing liquid in the developing liquid chamber always at a desired level.

Another object of the present invention is to provide an improved developing liquid feed device which can automatically feed the developing liquid feed having a toner concentration higher than that of the developing liquid when the liquid level in the developing liquid chamber falls below a predetermined level, thereby maintaining always the toner concentration of the developing liquid in the chamber at a predetermined level.

A further object of the present invention is to provide an improved developing liquid feed device simple in construction yet highly reliable and dependable in operation at less cost.

To attain the above and other ends, the present invention provides an improved developing liquid feed device comprising a developing liquid feed tank in which is tored the developing liquid feed whose toner concentration is so adjusted that when it is added to the developing liquid, the latters toner concentration may be maintained at a desired level, said storage tank having a valve of the type which is opened and closed depending upon the level of the developing liquid means for normally opening said valve when said storage tank is mounted upon a developing liquid chamber; a premix developing liquid chamber within said developing liquid chamber in opposed relation with said valve for vertical movement in response to the liquid level within said developing liquid chamber; and means for exerting the buoyancy on said premix developing liquid chamber so as to position the uppermost peripheral edge of said premix developing liquid chamber at a level substantially equal to or higher than said liquid level in said developing liquid chamber; whereby when said premix developing liquid chamber lowers in response to the falling of said liquid level in said developing liquid chamber, said storage tank is communicated with said developing liquid chamber through said premix developing liquid chamber.

According to one embodiment of the present invention, the premix developing liquid chamber is movably fixed to the side wall of the developing liquid chamber through a laterally extending arm, but according to another embodiment of the present invention, the premix developing liquid chamber is floating in the developing liquid in the developing liquid chamber and its vertical movement is guided by a rod extending from the bottom of the developing liquid chamber and being fitted loosely into a guide fixed to the bottom of the developing liquid chamber so that the lateral deviation of the intermediate chamber is prevented when it moves vertically.

The developing liquid feed device in accordance with the present invention can supply the developing liquid feed in an accurate quantity depending upon the liquid level or quantity of the developing liquid in the developing liquid chamber so that the quantity and concentration of the developing liquid within the chamber can be always maintained at desired levels. When the desired quantity of the developing liquid is in the chamber, the developing liquid can be completely separated from the developing liquid feed in the storage tank so that the dilution of the developing liquid feed due to the deposition and dispersion of the toner can be completely prevented, even though the conventional valve which is opened or closed in response to the liquid level in the developing solution chamber is employed. The device of the present invention is simple in construction requiring no special valve.

The above and other objects, features and advantages of the present invention will become more apparent from the description of the following embodiments thereof with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional view of one embodiment of a developing liquid feed device in accordance with the present invention; and

FIG. 2 is a fragmentary sectional view of another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Fig. 1, reference numeral 1 designates a developing liquid chamber; 2, a developing liquid; and 3, a passageway of a copy paper. Middle plates 4 are firmly fixed to stepped portions la and lb of the chamber 1. The passageway 3 of the copy paper is defined by a guide plate 5 supported by the middle plates 4, another guide plate 6 spaced upwardly of the lower guide plate 5, a pair of feed rollers 7 and 8 pressed against each other and a pair of discharge rollers 9 and 10 which serve also as a pair of squeeze rollers. The copy paper is inserted into the nip between the feed rollers 7 and 8 in the direction indicated by the arrow. The upper and lower guide plates 6 and 5 are bowed or concaved downwardly so that the copy paper may be immersed into the developing liquid 2 and constructed of metal plates having a plurality of

elongated slits

5a and 6a extending in the longitudinal direction. A developing liquid mixing frame 1! in the chamber 1 is pivotably fixed to the lower end of a depending arm 13a of a rocking member 13 which is pivotably fixed to a sidewall by a pin 12. An uprightly bent edge 13b of the other arm of the rocking member 13 is normally pressed by a spring 14 against an eccentric cam 10a carried by the shaft of the roller l0. It is therefore readily seen that the rocking member 13 is caused to rock upon rotation of the roller 10 which drives the eccentric cam 100 which in turn drives the uprightly bent edge 13b, so that the mixing frame 1 1 is reciprocated from left to right and from right to left in Fig. 1. Therefore, the developing liquid 11 is suitably agitated so that the deposition of the toner can be prevented and the new developing liquid may be always applied to the copy paper being developed.

Upwardly of the upper guide plate 6 is disposed a premix developing liquid chamber 15 having a buoy 15a such as cork attached to the bottom. A free end of an arm 15b extending from the premix developing liquid chamber 15 is pivotably fixed by a pin 16 to the sidewall 1a of the chamber 11. A developing liquid feed tank 18 is disposed above the intermediate chamber 15. The tank 18 is provided with a developing liquid feed valve 17 which is opened and closed depending upon the level of the developing liquid in the chamber 15. When the tank 18 is not mounted in the photocopying machine a valve 17a is normally is firmly pressed against a valve seat 17d by a spring 17c fitted over a valve stem [7b, so that the developing liquid 18a within the tank 18 is completely sealed from the exterior. When the tank 18 is mounted as shown in Fig. l, the valve stem 17b is caused to move upwardly against the spring 170 by a stationary valve receiving member 19 having its supporting arms 19a securely fixed to the sidewall la of the chamber 1 so as to be interposed between the valve 17 and the intermediate chamber 15. Therefore, the outlet or valve 17 of the tank 18 is normally opened. As described hereinbefore, the concentration of the developing liquid feed 20 in the tank 18 is maintained at a desired value so that when it is supplied to the chamber 1, the developing liquid in the chamber may be always maintained at a predetermined value.

The feed tank 18 is supported resiliently by retaining

members

22 and 23 which in turn are securely fixed to resilient members. A felt 25 attached to the side surface of a tank-supporting frame 24 is pressed by a spring 26 against the roller 9 so that the toner and the like attached to the roller 9 may be removed therefrom.

Next the mode of operation will be described. It should be noted that the intermediate chamber 15 and the valve-receiving member 19 are constructed independently. Since the intermediate chamber 15 is applied with the buoyancy by the buoy 150, so that the peripheral side edges of the intermediate chamber 15 is positioned at a level equal to or higher than the level of the developing liquid 2 within the chamber 1, the valve 17 is normally opened. When the level of the developing liquid 2 in the chamber 1 rises or falls, the intermediate chamber 15 also rises or lowers about the pin 16 so that the supply of the developing liquid feed 2a in the tank 18 is started or stopped in response to the movement of the intermediate chamber 15. More specifically, when the developing liquid 2 is consumed so that the intermediate chamber 15 is moved downwardly in the direction indicated by the arrow b, the developing liquid feed 2a in the tank 18 is supplied first into the intermediate chamber 15 and then into the chamber 1. When the level of the developing solution 2 reaches a predetermined level, the intermediate chamber 15 rises so that the developing liquid 2 in the intermediate chamber 15 closes the opening of the valve 17, thereby stopping the supply of the developing liquid feed 20 in the tank 18 into the intermediate chamber 15. It is seen that the sidewalls of the intermediate chamber 15 serve to the developing liquid 2 from the developing liquid feed 2a. The height D from the level of the developing liquid 2 to the peripheral side edge of the intermediate chamber l5 may be suitably designed so that the timing of the supply of the developing liquid feed 2a from the tank 18 to the intermediate chamber 15 may be suitably selected.

Next the second embodiment of the present invention will be described with reference to Fig. 2. A guide rod llSb extending from the bottom of the intermediate chamber "5 having the buoy 1150 is loosely fitted into a guide member 116 which is securely fixed in turn to the chamber 1 so that the vertical movement of the intennediate chamber is controlled. As in the case of the first embodiment described hereinabove, when the intermediate chamber 115 is lowered in the direction indicated by the arrow 0 with the fall of the level of the developing liquid 2, the developing solution feed 2a in the tank 18 is supplied into the chamber 1 through the intermediate chamber I15. When the level of the developing liquid 2 rises as the feed 2a is supplied, the opening of the valve 17 is closed by the developing liquid 2. The side wall of the intermediate chamber 115 serves to separate the developing liquid 2 from the developing liquid feed 2a when the developing liquid 2 reaches a predetermined level. Further description of the second embodiment will not be required since the arrangements and functions of other components are similar to those of the first embodiment.

The present invention has been described so far with particular reference to the preferred illustrative embodiments thereof, but it will be understood that variations and modifications can be effected without departing the true spirit of the present invention as described hereinabove and as defined in the appended claims.

I claim:

1. A developing liquid feed device for wet process electrophotography comprising a developing liquid feed tank containing a developing liquid feed whose toner concentration is so previously adjusted that when it is added to a developing liquid in a developing chamber, a desired toner concentration of the developing liquid may be always maintained, said tank having a valve of the type which is normally closed means for opening said valve when said tank is mounted upon said developing liquid chamber;

a premix developing liquid chamber within said developing liquid chamber in opposed relation with said valve for vertical movement in response to the liquid-level in said developing liquid chamber; and

means for exerting on said intermediate chamber the buoyancy so as to position the uppermost peripheral edge of said premix developing liquid chamber at a level substantially equal to or higher than the liquid level in said developing liquid chamber,

whereby when said intermediate chamber is lowered in response to the falling of the liquid level in said developing liquid chamber said tank is intercommunicated with said developing liquid chamber through said intermediate chamber, thereby feeding the developing liquid feed to said developing liquid.

2. A developing liquid feed device as specified in claim I wherein said premix developing liquid chamber has an arm whose one end is securely fixed to said intermediate chamber and whose the other end is pivotably fixed to the chamber, said tank having a valve therein for metering sidewall of said developing liquid chamber, whereby said said second supply of developing liquid to said developing intermediate chamber may move along a predetermined chamber; path when the liquid level in said developing liquid c. apremix chamber floated in the first supply of developing chamber varies. 5 liquid in said developing chamber in cooperating relation 3. A developing liquid feed device as specified in claim 1 with said valve; and wherein said intermediate developing liquid chamber hasa d. means for exerting a buoyant force on said premix rod extending downwardly from the bottom of said inter- Chamber sufiicient to maintain the uppermost edge of mediate chamber and fitted into guide means securely Said p i h fn above h le el f h first supply of fixed to the bottom of said developing liquid chamber, 10 defelopingliquld in Said q p f chamber, such thereby preventing the lateral deviation of said inter- Said Valve Closed y f P Chamber when said mediate chamber wh n it i moved i ll first supply of developing llquld IS above a predetermined 4. Apparatus for wet process electrophotography, comprislevel Sald developing chamber and said Valve Opens i communicating said second supply of developing liquid to a a developing chamber containing a first Supp|y of 15 said developing chamber through said premix chamber developing liquid; when said first supply of developing liquid drops below b. a developing liquid feed tank containing a second supply Predetermmed levelof developing liquid and mounted on said developing

Claims

2. A developing liquid feed device as specified in claim 1 wherein said premix developing liquid chamber has an arm whose one end is securely fixed to said intermediate chamber and whose the other end is pivotably fixed to the sidewall of said developing liquid chamber, whereby said intermediate chamber may move along a predetermined path when the liquid level in said developing liquid chamber varies.
3. A developing liquid feed device as specified in claim 1 wherein said intermediate developing liquid chamber has a rod extending downwardly from the bottom of said intermediate chamber and fitted into guide means securely fixed to the bottom of said developing liquid chamber, thereby preventing the lateral deviation of said intermediate chamber when it is moved vertically.
4. Apparatus for wet process electrophotography, comprising a. a developing chamber containing a first supply of developing liquid; b. a developing liquid feed tank containing a second supply of developing liquid and mounted on said developing chamber, said tank having a valve therein for metering said second supply of developing liquid to said developing chamber; c. a premix chamber floated in the first supply of developing liquid in said developing chamber in cooperating relation with said valve; and d. means for exerting a buoyant force on said premix chamber sufficient to maintain the uppermost edge of said premix chamber above the level of the first supply of developing liquid in said developing chamber, such that said valve is closed by said premix chamber when said first supply of developing liquid is above a predetermined level in said developing chamber and said valve opens communicating said second supply of developing liquid to said developing chamber through said premix chamber when said first supply of developing liquid drops below said predetermined level.