Toner recovery device

A toner fill sensor for a toner recovery device with a recovery box into which residual toner is scraped from the latent image carrying member with a cleaning means, has a window comprising a transparent or translucent housing projecting upwardly through said recovery box; an optical sensor having a light emitting and receiving elements arranged across said projected housing; a flat float member vertically movable on top of the toner recovered in the recovery box; and a light shielding flag erected on said float member at the position corresponding to the projected housing so that as the level of toner recovered rises, the light shield of the float member blocks the light path of the optical sensor, providing a toner fill signal.

BACKGROUND OF THE INVENTION 
The present invention relates to electrostatographic printing apparatus and 
more particularly to a toner recovery device for recovering the residual 
toner on the latent image carrying member of such apparatus. More 
specifically, the present invention provides an indication of the quantity 
of toner recovered in the recovery device preferably with the use of 
optical sensors. 
In an electrostatographic reproducing apparatus commonly in use today, a 
photoconductive insulating member is typically charged to uniform 
potential and thereafter exposed to a light image of an original document 
to be reproduced. The exposure discharges the photoconductive insulating 
surface in exposed or background areas and creates an electrostatic latent 
image on the member which corresponds to the image areas contained within 
the usual document. Subsequently, the electrostatic latent image on the 
photoconductive insulating surface is made visible by developing the image 
with developing powder referred to in that art as toner. Most development 
system employ a developer material which comprises both charged carrier 
particles and charged toner particles which triboelectrically adhere to 
the carrier particles. During development the toner particles are 
attracted from the carrier particles by the charge pattern of the image 
areas in the photoconductive insualting area to form a powder image on the 
photoconductive area. This image may subsequently be transferred to a 
support surface such as copy paper to which it may be permanently affixed 
by heating or by the application of pressure. 
Many commerical applications of the above process employ a modular concept 
for the various processing stations. For example, the imaging member, 
developer assembly and cleaner asssembly may be combined in a single unit 
or cartridge which has a limited life at the end of which it may be 
discarded and replaced with a new unit or cartridge. Alternatively, a 
charging device may be added to the unit or the unit may contain either of 
the developer or the cleaner. 
PRIOR ART 
U.S. Pat. No. 3,985,436 (Tanaka et al.) describes a copying apparatus in 
which an imagining member, developing device and cleaner may be 
incorporated in a casing as one unit to be releasably inserted into the 
main apparatus housing. 
U.S. Pat. No. 4,470,689 (Nomura et al.) also describes such a unit which is 
provided with a movable protection cover for protecting the image bearing 
member and illustrates in FIGS. 15A-15F several different alternative of 
process elements which may be included in such a process unit. 
U.S. Pat. No. 4,551,000 (Kanemitsu) also illustrates a process kit which 
includes in addition to the imaging member, the developer and the cleaner. 
This process kit is also provided with appartus for indicating when the 
useful life of the process kit is about to expire and when it has expired. 
U.S. Pat. No. 4,501,484 (Shimura) discloses a toner cleaning and residual 
toner collecting apparatus which includes a photoelectric sensor with a 
light emitting element and a light receiving element adapted to sense the 
level of collected toner in the container and when the cleaned toner 
container is filled up with collected toner that condition is displayed on 
a panel by an output signal of the sensor. 
FIG. 8 shows a toner recovery device that has been used wherein residual 
toner is scraped from a photosensitive drum 1 into a toner receiver 3 by 
means of a cleaning blade 2. The toner is then transported to a toner 
recovery box 5 by means of a rotary conveyor member 4. when the toner 
recovery box 5 is filled with recovered toner, it must be replaced and 
therefore it is necessary to detect without failure when the recovery box 
is filled with toner. To accomplish this, the conventional toner recovery 
box 5 has been designed to have an outer box 5a and an inner box 5b. The 
toner from the toner receiver 3 is housed in the inner box 5b, which is 
supported within the outer box 5a by a spring 6. A switch 7 is provided 
between the outer and inner boxes 5a and 5b for sensing whether the inner 
box is filled with toner. Since the inner box 5b is lowered according to 
the weight of toner recovered, the switch 7 will operate at a 
predetermined position to generate a signal indicating that the inner box 
is filled with toner. 
The device suffers from the difficulty that the inner box 5b of this toner 
recovery device needs spaces above and below itself for its vertical 
movement thereby making the device larger and less desirable for use in a 
compact copier. In addition, some of the recovered toner can adhere to the 
electrical switch 7, causing poor contact of the switch, leading to a 
malfunction. An alternative to this structure and one which is similar to 
that illustrated in U.S. Pat. No. 4,501,484 described above is shown in 
FIG. 9. A transparent or translucent housing 11 is secured to the ceiling 
of the toner recovery box 5 so that its central portion is projected 
upward through an opening 10 in the top of the toner recovery box 5. An 
optical sensor 12 consisting of a light emitting element 12a and light 
receiving element 12b is placed across the projected housing 11. As toner 
fills the toner recovery box 5 and the projected housing 11, it blocks the 
light path of optical sensor 12, changing the output of the sensor, 
indicating that the toner recovery box is filled with toner. 
However, if the power of conveyor member 4 is insufficient to push the 
recovered toner up to the projected housing 11, the detection of a toner 
fill condition will be unreliable. Moreover, some of the recovered toner 
filling the recovery box can leak through seals of the box or may become 
airborne as a result of the conveyor action. If floating toner deposits on 
the projected housing either inside or outside the housing the toner 
deposition will block the light path of sensor 12. Consequently, the 
sensitivity of sensor 12 must be adjusted so as to compensate for the 
blockage by the deposited toner which is a troublesome operation. 
Furthermore, the toner recovery box 5 usually extends in the axial 
direction of photosensitive drum 1 and the distribution of toner recovered 
in the box 5 can be polarized in the axial direction having peak areas and 
low areas. If the peak of toner recovered corresponds to the projected 
housing 11 and blocks the light path of sensor 12, the entire recovery box 
5 may be mistaken to be filled with toner when it is not. To solve this 
problem a number of optical sensors 12 and projected portions of cover 11 
may be provided along the length of toner recovery box 5. However this 
requires the use and assembly of more parts resuling in higher 
manufacturing cost. 
SUMMARY OF THE INVENTION 
In a principle aspect of the invention, a toner recovering device for 
recovering residual toner from an imaginign bearing member comprises a 
toner recovery box haing a transparent or translucent window in its upper 
portion and a float member vertically movable to float on top of toner 
recovered having a flag member on top at a position corresponding to the 
window so that as the level of toner increases the float member rises 
correspondingly and the flag may be viewed in the window providing an 
indication of the amount of toner recovered in the toner recovery box. 
In a further principle aspect of the invention, the window comprises a 
housing projecting upwardly through the top of the recovery box and at 
least one optical sensor having light emitting and recieving elements 
arranged across the projected housing to provide a signal when the light 
path is blocked by a lifht shielding flag member indicating the amount of 
toner recovered in the toner recovery box including whent he recovery box 
is substantially full. 
In a further aspect of the present invention, the light shielding flag 
member has a plurality of step portions and a plurality of optical sensors 
corresponding to sa id step portions to provide a plurality of signals 
indicating a plurality of conditions of the amount of toner recovered. 
In a further aspect of the present invention, the float member is suspended 
from the top of of the recovery box by at least one flexible sheet. 
In a further aspect of the present invention, the recovery device includes 
a cleaning assembly and an image bearing member mounted in cooperative 
association with each other to provide a processing unit. 
In a further aspect of the present invention, the signals generated by the 
optical sensor provide a display of the condition of the amount of toner 
recovered. 
In a further aspect of the invention an inexpensive toner fill sensor for a 
toner recovery device for sensing a toner fill condition of the recovery 
box without failure regardless of the state of a toner distribution within 
the box is provided.

DESCRIPTION OF PREFERRED EMBODIMENTS 
According to the invention there is provided at toner fill sensor for a 
toner recovery device with a recovery box into which residual toner is 
scraped from the latent image carrying member with a cleaning means, which 
has a window comprising a transparent or translucent housing projecting 
upwardly through said recovery box; an optical sensor having a light 
emitting and receiving elements arranged across said projected housing; a 
flat float member vertically movable on top of the toner recovered in the 
recovery box; and a light shielding flag erected on said float member at 
the position corresponding to the projected housing so that as the level 
of toner recovered rises, the light shield of the float member blocks the 
light path of the optical sensor, providing a toner fill signal. 
The toner recovery device may be either separated from or united with a 
cleaning device and a latent image carrying member. The shape and 
positioning of the toner recovery box may be modified as long as a toner 
inlet is provided at the lower portion of the toner box so as to assure 
vertical movement of the float member as the amount of recovered toner 
increases. The material of the projected housing may be any transparent or 
translucent resin. The shape and positioning of the projected housing may 
be modified as needed. The material and size of the float member may be 
modified, but a light material is desirable becuase it must be pushed up 
by the rising toner surface. The size may be sufficiently large to offset 
the polarization of a toner distribution, but it is preferred that it is 
substantially equal to the shape and area of a horizontal section of the 
recovery box. The supports for the float member may be any means for 
supporting it above the toner inlet so that the float member may rise 
along with the rising level of toner. Preferably, the supports for the 
float member are flexible shields which also perform a sealing function 
together with the physical barrier presented by the float member for 
preventing airborne toner from getting on top of the float member, and 
depositing on the projected housing and block the light path of the 
optical sensor under the toner fill condition. 
According to the invention, as the level of toner recovered rises and 
finally reaches the toner fill condition, the light shield enters the 
projected housing and blocks the light path of the optical sensor, 
providing a toner fill signal. Even if the toner distribution is polarized 
lengthwise or widthwise in the box, the float member although slightly 
inclined, is lifted as a whole and blocks the light path at a point 
substantially corresponding to the toner fill condition. When the level of 
a toner fill signal is set at an absolute zero, meaning zero light is 
received by the light detector, there is little or no possibility that the 
optical sensor makes an error providing a toner fill signal because of the 
presence of some toner adhering to the projected housing. 
Referring now to FIGS. 1, 2 and 3, there is shown in cross section a toner 
recovery device constituting a unit along with a rotatable photosensitive 
drum 1, a cleaning blade 2, a toner receiving member 3, and a toner 
conveyor member 4. The toner receiving member 3 is secured to the toner 
inlet 5c of a toner recovery box 5. The photosensitive drum 1, cleanind 
blade 2, and toner conveyor member 4 are all mounted to the unit case C. 
The toner conveyor member 4 with a rectangular cross section is placed at 
the toner inlet 5c for rotation in contact with the toner receiving member 
3. A partition 8 extends downaward from the ceiling of unit case C to 
define the toner recovery box 5. A toner scraper 9 is secured to the 
partition 8 at the end for scraping off the toner adhering to the conveyor 
member 4. 
The toner sensor consists of a trasnparent or translucent housing 11 
secured to the ceiling of recovery box 5 so as to project upward through 
an opening 10, an optical sensor 12 having a light emitting element 12a 
and a light receiving member 12b arranged across the projected housing 11, 
a float member 20 vertically movable within the recovery box 5, and a 
light shield 30 erected on the float member 20. The preferred float member 
20 is made of ABS resin in the form of a rectangular plate with a size 
substantially equal to the shape and area of a horizontal section of the 
recovery box 5. This float is suspended from the ceiling of recovery box 5 
with a pair of flexible sheets 21 (21a and 21b) for vertical movement. The 
preferred support sheet 21 is made of a polyethylene terephthalate or 
polypropylene film 25 to 50 microns thick and has bent portions 22 and 23 
secured to the ceiling of recovery box 5 and the float 20, respectively, 
with double-sided adhesive tape or the like. The preferred light shield 30 
may be made of ABS resin or other black opaque material, and its height is 
set so that when toner fills evenly the recovery box, the shielding piece 
30 blocks the light path of optical sensor 12. 
In operation, as shown in FIGS. 1 and 2, the residual toner is scraped off 
the photosensitive drum 1 into the toner receiver 3 by the cleaning blade 
2. The toner is then transported to and collected in the recovery box 5 by 
means of the conveyor member 4. The level of toner recovered in the box 
rises according to the amount of use and reaches the bottom of float 20 in 
a certain time. As the toner level further rises, the float 20 also rises 
along with the rising toner level as shown with broken lines in FIGS. 1 
and 2 and stops rising when the box is filled with toner. At this point, 
the light shield 30 of float 20 enters the projeced housing 11, blocking 
the light path of optical sensor 12. The output of optical sensor 12 
changes from its high to low, indicating that the box is filled with toner 
which condition is displayed on the copier control panel by an output 
signal of the sensor 12. 
As FIGS. 4 and 5 show, when the distribution of toner recovered is 
polarized in lengthwise or widthwise in the recovery box 5, the float 20 
may be inclined according to the toner distribution, but the light shield 
30 will still be able to block the light path of optical sensor 12. When 
the toner-fill signal of optical sensor 12 is set at an absolute zero, 
there is no possibility that the optical sensor 12 makes an error, 
providing a toner fill signal because of the presence of the adhering 
toner on the projected housing. When the amount of toner filling the box 
is set to be equal to the life span of photosensitive drum 1, the toner 
fill signal may be used for a unit replacement display. In this case, the 
toner recovery device, cleaning device, and photosensitive drum do not 
have to be inspected and maintained one by one, thus making the 
maintenance of the copier simpler. 
The width of float 20 is so close to the width of recovery box 5 that 
little toner may get on the float through the gaps between the float and 
the box, assuring stable rise of the float and containment of toner. The 
flexible sheets 21 suspending the float 20 at the longitudinal ends also 
serve as a seal for preventing the recovered toner from getting on the 
float. Consequently, even if the length of float 20 is made a little 
smaller than that of recovery box 5, the recovered toner is prevented from 
getting on the float through the longitudinal ends. If such flexible 
sheets are also applied to the sides of float 20, the sealing quality of 
float 20 is enhanced in this case, even if the width of float 20 is made a 
little smaller than that of recovery box 5, the recovered toner is 
prevented from getting on the float through the sides. In the illustrated 
embodiment, the flexible sheet 21 is so thin that there is some difficulty 
in handling it in the assembling operation of the float 20. As shown with 
broken lines in FIG. 3, a cut 28 is provided in the 50-micron thick 
polyethylene terephthalate or polypropylene film 21, making the suspension 
of the float 20 easier and giving the flexible sheet 21 a sufficient 
margin to deform. 
In the alternative embodiment of FIG. 6, a pair of support pieces 25 (25a 
and 25b) of synthetic resin or the like are secured to the ceiling of 
recovery box 5 so as to extend downward, with their free ends bent inward 
to form a pair of bent portions 26 for supporting the float 20. As the 
level of recovered toner rises, only the float plate 20 rises together 
with the rising toner level along the support pieces 25. When the toner 
fills the box, the light shield 30 of float 20 blocks the light path of 
optical sensor 12, producing a toner-fill signal. 
In addition, FIG. 6 illustrates the use of a plurality of optical sensors 
12 in operative association with a plurality of step portions on the light 
shielding flag member to provide a plurality of signals indicating a 
plurality of conditions of the amount of toner recovered. While only two 
step portions and sensors are indicated it will be understood that any 
number could be used. The two portions could, for example, provide an 
indication when blocking their respective light paths of a partly full, 
one half, condition and a completely full recovery box condition. 
In FIG. 7, on opposite sides of recovery box 5 there are provided widthwise 
a pair of shoulders 27 (27a and 27b), on which the float 20 is placed. 
Since this float also rises together with the rising toner level, a toner 
fill condition may be sensed in the same way as described above. 
Thus according to the present invention one is able to sense a toner fill 
condition regardless of variations in the distribution of toner recovered 
in the box or the contamination of the optical sensor with toner. Only a 
flat float member is added to the conventional toner recovery device, 
minimizing the additional manufacturing cost. 
The disclosure of the patents referred to herein are hereby specifically 
and totally incorporated herein by reference. 
While the invention has been described with reference to specific 
embodiment, it will be apparent to those skilled in the art that many 
alternatives, modifications and variations may be made. Accordingly, it is 
intended to embrace all such alternatives and modifications that may fall 
within the spirit and scope of the appended claims.