Multiple cartridge keying apparatus

The present invention insures that the proper color toner used in a color printer is replaced once the present supply is consumed The printer has several of receptacles, one receptacles for each colored toner. Each receptacle has a unique key receptacle. The replacement toner comes in a cartridge, one cartridge for each color of the several of colored toners. A cartridge is constructed from a common body to which an endcap is attached. The endcap has a unique key that mates with only one of the unique key receptacles. Each cartridge is removably inserted in the correct receptacle.

TECHNICAL FIELD 
The present invention generally relates to cartridge replacement; and more 
specifically, to replacing toner cartridges in a multi-color 
electrophotographic printer. 
BACKGROUND OF THE INVENTION 
As known in the art of electrophotographic printers, a photographic surface 
in the electrophotographic printer is first charged to a uniform potential 
and then is "exposed" to an image to be reproduced by the scanning of a 
laser beam thereacross. The photoconductor thereby obtains and 
electrostatic latent image that constitutes a matrix of discharged pixels 
on the photoconductor's surface. In a black and white printer, the 
photoconductive surface is generally developed using a black toner that 
adheres to the discharged pixel areas to form the image. Thereafter, the 
toned photoconductive surface is then carried to a transfer station where 
the image is transferred to a media sheet. 
In a multi-colored printer, successive images are developed employing 
different color toners supplied from corresponding toner modules. Color 
printing is normally done with yellow, cyan and magenta toner that are 
applied, in registration, during successive rotations of the 
photoconductive surface. The printer also generally includes a toner 
module with black toner. 
As the toner in a cartridge, or reservoir, (herein referred to as a 
cartridge) is expended, the cartridge must be replaced. A toner cartridge 
must be replaced with a new cartridge of the same color. This, like for 
like, replacement reduces chances for contaminating the new toner with old 
toner of a different color. An additional benefit from like for like 
replacements is reduced printer complexity because the printer does not 
need to sense the location of each color. However, like for like 
replacement requires that the user insert the proper color in the proper 
location. 
One approach is to color the toner cartridge to correspond to the toner 
color. This simple solution does not take into consideration the 
significant percentage of the population that is color blind. Another 
approach requires that the printer sense that the correct type toner 
cartridge has been inserted. One skilled in the art understands that this 
sensing requires additional hardware and firmware. 
SUMMARY OF THE INVENTION 
The present invention insures that the proper color toner used in a color 
printer is replaced once the present supply is consumed The printer has 
several receptacles, one receptacle for each colored toner. Each 
receptacle has a unique key receptacle. The replacement toner comes in a 
cartridge, one cartridge for each color of the several of colored toners. 
A cartridge is constructed from a common body to which an endcap is 
attached. The endcap has a unique key that mates with only one of the 
unique key receptacles. Each cartridge is removably inserted in the 
correct receptacle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention is not limited to a specific embodiment illustrated 
herein. Turning to FIG. 1, a color electrophotography system 10 comprises 
a drum 12 that is coated, in the known manner, with a photoconductive 
surface 14. While a drum 12 is shown, those skilled in the art will 
realize that any continuous photoconductive surface 14 may be employed 
with this invention. An electrostatic charging station 16 charges 
photoconductive surface 14 as it passes therebeneath. A laser 18 
subsequently exposes selected areas of pre-charged photoconductive surface 
14 to create image areas that exhibit a different charge level. 
Electrophotographic system 10 is controlled by a microprocessor 30 which, 
in combination with image information in raster image buffers 32, feeds 
image data to laser 18 through laser control circuit 34. Microprocessor 30 
also issues signals to operate toner supply control module 36 which in 
turn generates signals to control cyan, yellow, magenta, and black toner 
supplies 38, 40, 42, and 44, respectively. A toner conditioning roller 48 
both compresses and heats toner applied to photoconductive surface 14. A 
transfer roller 50 provides both heat and pressure to a media sheet 52 
thereby enabling toner transfer to occur from photoconductive surface 14 
to media sheet 52. 
In performing a color printing action, raster image buffers 32 contain at 
least three color planes, e.g., cyan, yellow and magenta. In synchronism 
with the rotation of drum 12, a color plane is read out and controls laser 
18 to cause the particular color plane image to be produced on 
photoconductive surface 14. Toner supply control 36 then causes the 
appropriate toner module (e.g., cyan module 38), to operate and to develop 
the exposed cyan image on photoconductive surface 14. That image is then 
conditioned by roller 48 and proceeds around drum 12, past electrostatic 
charging station 16 where photoconductive surface 14 is again charged. A 
second color plane from raster image buffers 32 is then read out and 
controls laser 18 to discharge areas of photoconductive surface 14 that 
are to be developed using a second color toner. (At this point, it is to 
be noted that there is no media sheet present in contact with drum 12 and 
such contact will not occur until all color planes have been read out to 
control laser 18 to produce registered images.) The exposure/development 
actions proceed through the cyan, yellow, magenta and black toner 
stations, in sequence, until photoconductive surface 14 has been toned in 
accordance with the image information contained in all raster image 
buffers 32. 
From the above simplified description of the operation of a color 
electrophotographic printer, it should be clear that microprocessor 30 
must know the proper location of the individual colors to properly render 
a color image. The preferred embodiment of the present invention uses a 
unique keying system to insure that a toner cartridge can only be inserted 
in its designated receptacle. A side view, best illustrating the preferred 
embodiment, is shown in FIG. 2. Housing 201 depicts a portion of the color 
electrophotographic system designed to receive the toner cartridges. 
Formed into housing 201 are four receptacles, one each for four different 
colored toner cartridges. Each receptacle includes a unique key hole that 
is designed to receive a corresponding key on a specific colored toner 
cartridge. Thus, by using the unique end-caps, toner cartridge 202 cannot 
accidentally be placed into the incorrect receptacle. See FIG. 3. 
Another advantage of the housing of FIG. 2 is the ease of replacing a 
consumed cartridge. Most electrophotographic imaging systems require the 
user to open the device to gain access to the toner cartridge. By using 
the preferred embodiment of the present invention, the toner cartridges 
are designed to be aesthetically pleasing such that there is no need to 
hide the cartridges behind panels. However, the present invention may also 
be used behind cabinet doors should the designer so choose. 
FIG. 4 shows a single toner cartridge 202. Each toner cartridge is 
constructed from a common cartridge body 101 and a unique end-cap 102. The 
shape of the end-cap's key 206 indicates the color contained in the toner 
cartridge. A cartridge is designated a particular color by placing the 
appropriate end-cap on the cartridge body, Thus, manufacture costs are 
minimized by requiring manufacture of only one type of the more 
complicated body 101. One skilled in the art will understand that 
cartridge body 101 may incorporate changes due to toner differences, the 
present invention does not preclude such unique designs to the body. 
Also shown in FIG. 4 is indicator 104. Illumination of indicator 104 
provides visual feedback to the user that toner cartridge 202 is properly 
seated in the housing 201. Additionally, indicator 104 might flash 
indicating that toner cartridge 202 is low or out of toner. One skilled in 
the art can devise other uses and meanings for the indicator. The present 
invention is not meant to be limited to those functions described here. In 
the preferred embodiment, indicator 104 is a colored lens that is 
illuminated by a light source from housing 201. By arranging it so, the 
disposable toner cartridge 202 does not need electrical contacts through 
which the indicator 104 is powered. 
FIG. 5 is a perspective view showing cartridge 202 partially inserted into 
housing 201. As described earlier, the endcap 102 of cartridge 202 is 
formed to include key 206. Indentation 401 is formed in the endcap 
providing a convenient gripping area for the users fingers to extract 
toner cartridge 202 from housing 201. Also visible in FIG. 5 are 
receptacles 403 and 404. These two receptacles are shown with their 
respective toner cartridges removed showing the respective key receptacle 
areas therein. 
FIG. 6 shows a perspective view of toner cartridges 202, 203, 204, 205. 
Each toner cartridge includes a common body 101-101C which is identical 
for all of the toner cartridges and a unique endcap 102, 207, 208, and 
209. Focusing on one cartridge, the unique endcap 102 includes unique key 
206. It is this unique key 206 which prohibits accidental insertion of one 
cartridge into another receptacle. Endcap 102 includes indentation 401 
which provides easy access to the user to extract toner cartridge 202 from 
housing 201. Also shown in FIG. 6 is indicator 104. 
Although the preferred embodiment of the invention has been illustrated, 
and that form described, it is readily apparent to those skilled in the 
art that various modifications may be made therein without departing from 
the spirit of the invention or from the scope of the appended claims. 
While the preferred embodiment has been described in conjunction with an 
electrophotographic printer, the present invention is equally applicable 
to other type of printing methods. For example, a color off-axis ink-jet 
printers stores the ink in several non-movable reservoirs. As the ink in a 
reservoir is consumed, the reservoir must be replaced. Thus, by using the 
present invention, each reservoir is keyed and only a properly keyed 
reservoir may be inserted thereby insuring that the correct color ink in 
replaced.