Electrical connector, process cartridge and electrophotographic image forming apparatus

An electrical connector for an electrophotographic image forming apparatus includes memory; a socket having the memory; plural electric contacts electrically connected with a contact of the memory; a short-circuit contact short-circuited with at least one of the electric contacts.

FIELD OF THE INVENTION AND RELATED ART 
The present invention relates to an electrical connector, a process 
cartridge, and an electrophotographic image forming apparatus. 
In this specification an slectrophotographic image forming apparatus 
includes an electrophotographic copy machine, an electrophotographic 
printer (LED printer, laser beam printer, and the like) an 
electrophotographic facsimile apparatus, an electrophotographic word 
processor, and the like. Also in this specification, a process cartridge 
means such a process cartridge that is removably installable in the main 
assembly of an electrophotographic image forming apparatus, and integrally 
comprises an electrophotographic photosensitive member as well as a 
charging means, a developing means, and/or a cleaning means. It also means 
such a process cartridge that is removably installable in the main 
assembly of an image forming apparatus, and integrally comprises an 
electrophotographic photosensitive member, and at least a developing 
means. 
Further, the present invention relates to any unit removably installable in 
the main assembly of an image forming apparatus. More specifically, it 
relates to any unit such as a developing device, a toner cartridge, a 
process cartridge, or the like, which is removably installable in the main 
assembly of an image forming apparatus. 
It is common knowledge that some image forming apparat uses such as copy 
machines and laser beam printers, which employ an electrophotographic 
image formation process can be rendered maintenance-free with the use of a 
process cartridge which integrally comprises an electrophotographic 
photosensitive member, and one or a plurality of processing means, such as 
a cleaning unit or a development unit, which acts on the 
electrophotographic photosensitive member. 
In the case of such an image forming apparatus as described above, after 
the functions of the structural components in a process cartridge 
deteriorate due to usage, the process cartridge is entirely replaced with 
a fresh process cartridge. This process cartridge replacement operation is 
an extremely simple operation comprising a step of opening the main 
assembly of the image forming apparatus, a step of removing the process 
cartridge with worn components out of the main assembly of the image 
forming apparatus, and a step of installing a fresh process cartridge in 
the main assembly of the image forming apparatus. Therefore, such an image 
forming apparatus can be easily maintained by a user alone. 
Recently, the aforementioned conventional art has been further developed to 
improve the utility of the above described image forming apparatus. More 
specifically, it has been considered to add a data storing following to 
the above image forming apparatus. 
Data regarding manufacturing conditions and the like are written into an 
electronic device such as a memory provided in a process cartridge, at the 
time of manufacturing or shipment, and when the process cartridge is 
installed in the main assembly of an image forming apparatus, the data is 
looked up by the image forming apparatus in order to carry out an image 
forming operation under the optimum condition for the process cartridge. 
In order to add the above function to an image forming apparatus, it is 
necessary to mount an electronic device such as an EEPROM or the like in a 
unit such as a process cartridge which is removably installable in the 
image forming apparatus. As the means for mounting the electronic device 
in the process cartridge, it is conceivable to provide the process 
cartridge with a printed circuit on which electronic devices such as a 
memory, and a connector, have been mounted. 
Generally, the aforementioned non-volatile memory and connector are mounted 
on the printed circuit provided in a process cartridge, along with the 
electrically functional components such as a diode, a resistor, or a 
condenser, which protects the IC from electrical surge. 
SUMMARY OF THE INVENTION 
A primary object of the present invention is to provide an electrical 
connector which makes it easier to mount a memory in a unit such as a 
process cartridge which is removably mountable in an image forming 
apparatus, as well as to provide a unit which is removably mountable in an 
image forming apparatus and comprises such an electrical connector, and an 
image forming apparatus compatible with such a unit. 
Another object of the present invention is to provide an electrical 
connector which makes it possible to compactly mount a memory in a unit 
such as a process cartridge which is removably mountable in an image 
forming apparatus, as well as to provide a unit which is removably 
mountable in an image forming apparatus and comprises such an electrical 
connector, and an image forming apparatus compatible with such a unit. 
Another object of the present invention is to provide an electrical 
connector which makes it possible to reliably establish electrical 
connection between a memory and the main assembly of an 
electrophotographic image forming apparatus, as well as to provide a unit 
which is removably mountable in an image forming apparatus, and an image 
forming apparatus compatible with such a unit. 
Another object of the present invention is to provide an electrical 
connector comprising a memory, a unit comprising such an electrical 
connector, and an image forming apparatus compatible with such a unit. 
According to an aspect of the present invention, there is provided an 
electrical connector electrically connectable with a main assembly 
connector provided in the main assembly of an electrophotographic image 
forming apparatus, comprising storing means for storing information; a 
plurality of electrical contacts for separably connecting with a contact 
of the main assembly connector, when they are connected electrically with 
the main assembly connector; wherein the storing means is electrically 
connected with each of the electrical contacts with lead lines. 
According to another aspect of the present invention, an electrical 
connector comprises storing means for storing data, and a plurality of 
electrical terminals which are connected to, or disconnected from, the 
corresponding electrical terminals of the counterpart connector provided 
on the main assembly side of an image forming apparatus, wherein the 
storing means is electrically connected to each of the plurality of 
electrical terminals by a lead wire; and a unit removably installable in 
an image forming apparatus comprises such an electrical connector. 
Further, an image forming apparatus is rendered compatible with such a 
unit. 
Another object of the present invention is to provide an electrical 
connector capable of signaling whether or not a removably installable 
process cartridge or the like has been installed in the main assembly of 
an image forming apparatus, a process cartridge comprising such an 
electrical connector, and an electrophotographic image forming apparatus 
compatible with such an electrical connector. 
Another object of the present invention is to provide an electrical 
connector which is superior in terms of noise related characteristics to 
the electrical connectors based on the prior art, a process cartridge 
comprising such an electrical connector, and an sleectrophotographic image 
forming apparatus compatible with such an electrical connector. 
Another object of the present invention is to provide an electrical 
connector in which one of the electrical terminals is rendered longer than 
the rest of the terminals, being enabled to make contact with its 
counterpart before the rest do with their counterparts, when the connector 
is engaged with the counterpart, and being enabled to be disconnected last 
from the counterpart, when the connector is disengaged from its 
counterpart, so that the static electricity accumulated on an electronic 
memory device can be discharged before the rest of the electrical 
terminals make their contacts; a unit comprising such an electrical 
connector; and an image forming apparatus compatible with such an 
electrical connector. 
Another object of the present invention is to provide an electrical 
connector which increases reliability in image formation by turning off 
the electrical power to an electronic device, and preventing access to the 
electronic device, in order to protect the information stored in the 
electronic device, when a removably installable process cartridge or the 
like is removed from the apparatus main assembly;, a process cartridge 
comprising such am electrical connector; and an image forming apparatus 
compatible with such an electrical connector, 
Another object of the present invention is to provide: an electrical 
connector comprising: a memory; a socket for the memory; and a plurality 
of electrical terminals which come in contact with corresponding pins of 
the memory, wherein a pair among the plurality Of electrical terminals are 
directly connected to each other; a process cartridge comprising such an 
electrical connector; and an image forming apparatus compatible with such 
an electrical connector. 
Another object of the present invention is to provide: an electrical 
connector comprising: a memory; a socket for the memory; a plurality of 
electrical terminals in contact with corresponding contact pins of the 
memory, wherein at least one of the plurality of electrical terminals is 
longer than the rest; a process cartridge comprising such an electrical 
connector; and an image forming apparatus compatible with such an 
electrical connector. 
These and other objects, features and advantages of the present invention 
will become more apparent upon a consideration of the following 
description of the preferred embodiments of the present invention taken in 
conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Hereinafter, the desirable embodiment of an electrical connector in 
accordance with the present invention will be described in detail, along 
with a process cartridge comprising such an electrical connector and an 
image forming apparatus compatible with such an electrical connector, with 
reference to the appended drawings. 
Embodiment 1 
FIG. 1 is a section of an embodiment of a typical electrophotographic image 
forming apparatus 1, that is, a color laser beam printer (hereinafter, 
printers), in accordance with the present invention, depicting the general 
structure thereof, The printer in the drawing has a resolution of 600 dpi, 
and records color images based on multi-level data in which a picture 
element for each color component is expressed with eight bits. This color 
laser beam printer illustrated in FIG. 1 is also referred to in the 
following several embodiments of the present invention. 
In the image forming apparatus illustrated in FIG. 1, a recording paper P 
fed from a sheet feeding section 101 by a conveying means 102 or the like 
is wrapped around the peripheral surface of a transfer drum 103 by a 
gripper 103f which grips the leading edge of the recording paper P. During 
this movement of the recording paper P, the leading edge of the recording 
paper P is detected by a detector 8, and a vertical synchronization signal 
(which will be described later) is generated based on the detection signal 
from the detector 8. The latent image, which is formed for each color 
component, on a drum-type electrophotographic photosensitive member 100 
herainafter, "photosensitive drum") by an optical unit 107, is developed 
by a developing device Dy, Dc, Db, or Dm for the corresponding color 
component, and is transferred, in a superimposing manner, onto the 
recording paper P on the peripheral surface of the transfer drum 103, 
forming thereby a composite multicolor image: Thereafter, the recording 
paper P in separated from the transfer drum 103, and the multicolor image 
is fixed to the recording paper P in a fixing unit 104. Then, the 
recording paper P is discharged into a delivery 106 from a paper discharge 
section 105 as conveying means. 
The developing device Dy, Dc, Db, or Dm has a rotational axis on both 
lateral surfaces, and is rotatively supported by a developing device 
selector mechanism 108. With this arrangement, the developing devices Dy, 
Dc, Db or Dm is enabled to face always the same direction even though the 
developing device selector mechanism 108 is rotated about a rotational 
axis 110. After a selected developing device is moved to the developing 
position, the frame 109 which holds the developing device selector 
mechanism 108 is pulled by a solenoid 109a, and as a result, the frame 109 
is pivoted about a pivot 209b, moving thereby the developing device se 
lector mechanism 108 toward the photosensitive drum 100. 
Next, the color image forming operation of a Color laser beam printer with 
the above described structure will be more specifically described. 
First, the photosensitive drum 100 is uniformly charged to predetermined 
polarity by a charging device 111, and than is exposed to a laser beam L 
to form a latent image correspondent to, for example, a magenta color 
component on the photosensitive drum 100. The latent image correspondent 
to the magenta color component is developed by the developing device Dm, a 
developing device for magenta color. As a result, a first toner image, 
that is, a magenta color toner image is formed on the photosensitive drum 
100. Meanwhile, a recording paper P is fed with a predetermined timing, 
and a transfer bias voltage (+1.8 kV) which has polarity opposite (for 
example, positive polarity) to the toner is applied to the transfer drum 
103. As a result, the first toner image on the photosensitive drum 100 is 
transferred onto the recording paper P, and at the sane time, the 
recording paper P is electrostatically adhered to the peripheral surface 
of the transfer drum 103. Thereafter, the magenta color toner remaining on 
the photosensitive drum 100 is cleaned by a cleaner 112 to prepare the 
photosensitive drum 100 for the following latent image formation and the 
subsequent image development process. The toner removed from the 
photosensitive drum 100 is sent to a toner container 180 for the removed 
toner. The cleaner 112, the toner container 280 for the removed toner, the 
photosensitive drum 100, and the charging device 111 are integrated in the 
form of a process cartridge 199 (pohotosensitive drum cartridge) which is 
removably installed in the main assembly of the printer by an installing 
means 80. 
Next, a latent image corresponding to a second color component, that is, 
the cyan color component, is formed on the photosensitive drum 100 by the 
laser beam L. This second latent image is developed by the developing 
device Dca the developing device for the cyan color component. As a 
result, a second color toner image of cyan color is formed on the 
photosensitive drum 100. The cyan colored second toner image is 
transferred onto the very recording paper P on which the magenta colored 
first toner image has just been transferred; it is superposed onto the 
magenta colored first toner image in alignment. therewith. During the 
transfer operation for the second toner image, a bias voltage of 2.1 kV is 
applied to the transfer drum 103 starting immediately before the recording 
paper P arrives at the transfer section. 
Similarly and sequentially, third and fourth latent images for yellow and 
black color components, respectively, are formed on the photosensitive 
drum 100, are developed by the developing devices Dy and Db, respectively, 
into a yellow colored third toner image and a black colored fourth toner 
image, respectively, which are transferred onto the recording paper P in 
alignment with the toner images having been transferred onto the recording 
paper P. In other words, four toner images of different color are 
superposed on the recording paper P in alignment with each other. During 
the transfer operations for the third and fourth color toner images, bias 
voltages of +2.5 kV and +3.0 kV, respectively, are applied to the transfer 
drum 103 immediately before the recording paper P arrives at the transfer 
point. 
The reason for increasing the transfer bias voltage after each toner image 
transfer is to prevent deterioration in transfer efficiency. The main 
cause of the transfer efficiency deterioration is accumulation of 
electrical charge on the recording paper. More specifically as the 
recording paper is separated from the photosensitive drum 100 after each 
image transfer, aerial discharge occurs between the recording paper and 
the photosensitive drum 100, charging the surface of the recording paper 
to the polarity opposite to the polarity of the transfer bias voltage 
(transfer drum which supports recording paper also is slightly charged). 
This charge having the polarity opposite to that of the transfer bias 
voltage is accumulated on the recording paper each time a toner image is 
transferred onto the recording paper. Therefore, the transfer electric 
field is weakened if the transfer bias is kept constant. 
When the leading edge of the recording paper arrives at the starting point 
for the transfer inclusive of the adjacencies immediately before and after 
the starting point for the transfer) during the transfer operation for the 
fourth color, an effective AC voltage of 5.5 kV (frequency: 500 Hz), and a 
DC voltage of +3.0 kV, which is the same in polarity and potential as the 
transfer bias applied during the transfer of the fourth toner image 
transfer, are applied to the charger 111 in a superimposing manner. The 
reason for activating the charger III when the leading edge of the 
recording paper arrives at the transfer starting point is to prevent image 
anomaly related to toner image transfer. More specifically, in the case of 
a full-color image, even a slight transfer anomaly which may be 
inconspicuous in the case of a monochromatic image is liable to manifest 
conspicuously as substantial color difference. Therefore, it is necessary 
to apply a predetermined bias voltage to the charger 111 to cause 
electrical discharge. 
Next, as the leading edge of the recording paper P, on which the four color 
toner images have been transferred in a superposing manner, approaches the 
separation point, the tip of a separation claw 113 comes in contact with 
the peripheral surface of the transfer drum 103, and separates the 
recording paper P from the transfer drum 103. The tip of the separation 
claw 123 remains in contact with the surface of the transfer drum 103 
while separating the recording paper P from the transfer drum 103. After 
the separation of the recording paper P, the tip of the separation claw 
113 moves away from the transfer drum 103 and returns to its home 
position. The charger 111 is kept activated from when the leading-edge of 
the recording paper arrives at the transfer starting point for the last 
color (fourth color) until when the trailing edge of the recording paper 
becomes separated from the transfer drum 103, to remove the charge (having 
the polarity opposite to the toner) accumulated on the recording paper, so 
that the recording paper separation by the separation claw 113 becomes 
easier, and also, so that the aerial discharge which occurs during the 
recording paper separation is reduced. The transfer bias voltage applied 
to the transfer drum 103 is turned off (reduced to the ground potential) 
when the trailing edge of the recording paper arrives at the transfer 
ending point (exit side of the nip formed at the contact between the 
photosensitive drum 100 and the transfer drum 103). At the same time, the 
bias voltage being applied to the charger III is turned off. Thereafter, 
the separated recording paper P is conveyed to a filing device 40, in 
which the toner image (images) on the recording paper P is fixed to the 
recording paper, and the recording paper is discharged into a delivery 
tray 106. 
Next, the image forming operation based on laser beam scanning will be 
described. 
In FIG. 1, a reference numeral 107 designates an optical unit which 
comprises a detector 9, a semiconductor laser 120, a polygon mirror 121, a 
scanner motor 122, a lens 123, and a mirror 125. In synchronism with the 
timing with which the leading edge of the recording paper 1 fed into the 
image forming apparatus is conveyed to the transfer drum 103, a batch of 
image signals VDO equivalent to a single page of recording paper is 
outputted to the semiconductor laser 120. Then, a light beam L modulated 
with the image signal VDO is projected from the semiconductor laser 120 
toward the polygon mirror 121 being rotated by the scanner motor 122. 
Then, the light beam L is deflected by the polygon mirror 121, and is 
guided to the photosensitive drum 100 through the lens 123 and the mirror 
125. Further, the light beam L is also detected by the detector 9 disposed 
on the main scanning axis, to output a BD (beam detection) signal, that 
is, a horizontal synchronization signal. The light beam L is oscillated in 
response to this horizontal synchronization signal, scanning, or exposing, 
the peripheral surface of the photosensitive drum 100. As a result, an 
electrostatic latent image is formed on the photosensitive drum 100. 
The color laser beam printer in this embodiment outputs images at a 
resolution of 600 dpi through the image forming process described above. 
As for the input data for this printer, the following image data are 
conceivable,; color image data (for example, data for RGB color 
components) generated by a host computer (hereinafter, "host"), image data 
which are stored in any given recording medium after being generated by 
image data generating apparatus (still image recorder or the like) other 
than the host computer; and the like. Therefore, this printer is provided 
with a printer controller which receives the image information from the 
host and generates image data, and a signal processing section which 
processes the image data. 
In the following several embodiments, the input data for the printer are 
described as color image data. 
FIG. 2 is a block diagram of the operation of the printer I in accordance 
with the present invention. In FIG. 2, the printer 1 comprises the printer 
controller 2-and a printer engine 3. The printer controller 2 receives 
image information 5 expressed in a predetermined descriptive language, 
from a host 1000, and develops the image information 5 into a YMCBk image 
signal 6 in which each color is expressed by eight bits (D0-D7). 
Sometimes, the host 100 sends, as the image information 5, bit data such 
as RGB data read in through an image reader or the like. In such cases, 
the printer controller 2 processes the bit data without interpreting them 
In addition to the image signal 6, various other image signals are 
exchanged in the form of serial communication between the printer 
controller 2 and the printer engine 3. They are page synchronization 
signals PSYNC (scanning in the secondary direction), line synchronization 
signals LSYNC (scanning in the primary direction), and data transfer clock 
signals VCLK. The printer controller 2 outputs the image signal 6, that 
is, an eight bit signal, for each color component, in synchronism with the 
data transfer clock signal VCLX. Designated by reference numbers 208 and 
209 are a display panel and a cable. 
FIG. 3 is a block diagram of the operation of the printer engine 3 in 
accordance with the present invention In FIG. 3, the referential clock 
from a reference clock generator 10 included in the optical unit 107 is 
divided by a frequency divider 11. The scanner motor 122 is controlled by 
a motor control circuit 12 (contained in an unillustrated phase control 
circuit of a known type) so that it rotates at a constant speed, 
maintaining a predetermined phase difference between the divided reference 
clock and the feedback signal from the scanner motor 122. The rotation of 
the scanner motor 112 is transmitted to the polygon mirror 121, rotating 
the polygon mirror 121 at a constant speed. 
On the other hand, as the transfer drum 103 is rotated by a motor 
(unillustrated) at a constant speed, the leading edge of the recording 
paper P on the transfer drum 103 is detected by the detector 8. As a 
result, a vertical synchronization signal VSYNC is sent to the signal 
processing section 4. Based on this vertical synchronization signal, the 
positioning of the leading edge of each color toner image is controlled in 
response to the vertical synchronization signal VSYNC. After the vertical 
synchronization signal VSYNC is outputted, the image signal VDO is 
sequentially sent to the semiconductor laser 120 in synchronization with 
the BD signal, as the horizontal synchronization signal HSYWC, generated 
by the detector 9. 
A built-in CPU 14 of the signal processing section 4 exchanges control 
signals with the printer controller 2 in the form of serial communicator 
through a communication line 15, so that the operations of the printer 
controller 2 and the printer engines 3 remain synchronized. Further CPU 14 
communicates with the memories 203-206 of the developing devices, the 
memory 207 of the photosensitive drum 100, and backup memory 230, through 
serial communication line 202. The memories 203-206 are EEPROMs, and are 
attached to the corresponding developing devices. The memory 207 is also 
an EEPROM, and is attached to a process cartridge, that is a 
photosensitive drum cartridge. 
The timing for the aforementioned vertical synchronization signal VSYCd, 
horizontal synchronization signal Y, and image signal VO is as shown in 
FIG. 4 
FIG. 5 is a circuit diagram pertaining to the signal exchange between the 
signal processing section 4 and the memory 206 for the black color 
developing device, and between the signal processing section 4 and the 
memory 207 for the photosensitive drum. 
Referring to FIG. 8, one half of the connector 196 (first connector) on the 
photosensitive drum side (CRG side) constitutes the main socket, and the 
other half constitutes the socket for an IC. The memory for the 
photosensitive drum, that is, the EEPROM 207, is indirectly attached to 
the photosensitive drum cartridge 199; it is inserted in the IC socket of 
the connector 196 attached to the photosensitive drum cartridge 199. Thus, 
as the connector 196 is fitted with the connector 195 (second connector) 
attached to the main assembly of the printers signals are enabled to be 
sent to the CPU 14 of the signal processing section 4. In this 
specification, "socket" means a member which supports the memory 207. 
The voltage Voc supplied to the EEPROm 207 is turned on or off by-the CPU 
14. When the VCCOW at the CPU port is LOS, the power source is ON, and 
when it is HIGH, the power source is OFF. The CPU 14 turns on the power 
supply during a read or write operation of the EEPROM. During a read 
operation, the CPU 14 reads a data signal 184 in synchronism with a clock 
signal 182, and during a write operation, it outputs a data signal 183, 
which is written into the EEPROM in synchronism with the clock signal 182. 
A signal 186 is a signal pertaining to the presence or absence of the 
photosensitive drum. When the level of the signal 186 is LOW, the CPU 
determines that a photosensitive drum cartridge is absent, and when the 
level of the signal 186 is HIGH, it determines that a photosensitive drum 
is present. More specifically regarding the level of the signal 186, as a 
photosensitive drum cartridge is inserted into the main assembly of the 
printer, the connectors 195 and 196 become engaged. Then, the voltage Vcc 
of the EEPROM is returned to raise the level of the signal 186 to HIGH. 
The connector 198 on the CRG side is attached to the development cartridge 
for black color, with the EEPROM 206 for the developing device for black 
color being inserted in the socked thereof. Its signal exchange with the 
CPU is the same as the signal exchange of the photosensitive drum 
cartridge with the CPU. 
The EEPROMs 207 and 206 both are Dip type ICs integrated circuits), and are 
directly connected to the connectors 196 and 198 on the CRG side, 
respectively. FIG. 6 shows an example of pin arrangement for a Dip type 
EEPOM-IC. Designated by R1 to R5 and Q1 are resistors and a transistor. 
Designated by CSOPC and NC are a ship selection signal and a non-contact 
pin. Designated by SCK, OPCSET, CSBK, BKSET and SK are an SCK port, an SCK 
port, an OPCSET port, a CSBK port, a BKSET port and an SK port. 
FIG. 7 shows how the photosensitive drum cartridge 199, the EEPROM 207, and 
the connector 196 on the cartridge side, are put together. The 
photosensitive drum cartridge 199 comprises the photosensitive drum 100, 
the toner container 180 for the removed toner, the EEPROM 207, the 
connector 196 on the cartridge side,, and screws 360 for attaching the 
connector 196 to the cartridge 199. 
FIG. 8 shows the configurations of the connector 196 (or 198) on the 
cartridge side, the connector 195 (or 197) on the main assembly side, and 
the EEPROM 207 (or 206). As is evident from the drawing, the connector 196 
on the cartridge side is fixed to the connector mount portion 354 with the 
use of the screws 360. The connector 195 on the main assembly side is 
fixed to the mount portion 358 of the main assembly with the use of the 
screws 356. 
FIG. 9 is a longitudinal section of the connector 196 (or 198) on the 
cartridge side, and the connector 195 (or 197) on the main assembly side, 
which are illustrated in FIG. 8. 
In this embodiment, the connector main structure 196 (198) on the process 
cartridge side contains a contact 352 which is placed in contact with the 
IC 207 This connector main structure 196 (198) on the process cartridge 
side is fixed to the process cartridge. As for the connector main 
structure 195 (197) on the image forming apparatus main assembly side, 
which is the counterpart of the connector main structure 196 (198) on the 
process cartridge side, is fixed to the connector mount 358, that is, a 
part of the image forming apparatus main assembly, with the use of the 
small screw 356. However, since the connector main structure 196 (198) 
attached to the process cartridge B side is firmly fixed to the process 
cartridge B, it is necessary to make it sure that imperfect alignment 
between the process cartridge and the image forming apparatus main 
assembly does not generate stress in the connector main structures 196 
(198) and 195 (197). Therefore, the connector main structure 195 (197) on 
the image forming apparatus main assembly side must be floatingly attached 
to the connector mount 358 of the image forming apparatus main assembly 
FIG. 9, a sectional view, depicts a connector designed in consideration of 
such a requirement. More specifically, the diameter of the hole 357a of 
the connector main structure 195 (197) on the image forming apparatus main 
assembly side is rendered slightly larger than that of the small screw 356 
to create a gap large enough to compensate for the aforementioned 
misalignment. Therefore even though the small screw 356 is firmly screwed 
into the female screw threads 358a of the connector attachment portion 358 
of the image forming apparatus main assembly, the connector main structure 
195 (197) on the image forming apparatus main assembly side is floatingly 
attached to the connector mount 358 of the image forming apparatus main 
assembly A. 
The connector main structure 196 (198) on the process cartridge side is 
formed of synthetic resin. It is hollow, and has a substantially square 
cross-section Its base side half (top side in the drawings) is larger than 
its engagement portion side (bottom side in the drawings). The internal 
space of the connector main structure on the process cartridge side is 
occupied by the IC mount 353c. The IC mount 353c is integrally formed with 
the connector mains structure 196 (198), or is first formed independently 
from the connector main structure 196 (198), and then attached to the 
external wall portion 353a and engagement portion wall 353b of the 
connector main structure 196 (198). The longitudinal section of the IC 
mount 353c is in the form of a character T as shown in FIG. 9. The surface 
of the IC mount 353c and the base side external wall 353a, and the surface 
of the IC mount 353c and the engagement portion side external wall 353b, 
form a continuous terminal mounting space 353d which opens outward at the 
top and bottom. The contact 352 exclusive of a portion 352a, the bottom 
end portion, is disposed in the IC mounting space, substantially in 
contact with the IC mount 353c. More specifically, in order to assure that 
the contact 352 is reliably placed in contact with the contact 355 on the 
image forming apparatus main assembly side, the bottom end of the contact 
352 is bent outward to form the contact portion 352a. As for the IC 207, 
the main structure 352a of a chip is disposed directly above the IC mount 
353c, with the provision of a predetermined gap. The lead wires pine 351b 
of the IC 207 are inserted from above into the electrode mounting space 
353d, and made to directly press on the contact 352. The IC 207 is 
electrically connected to each of the contacts 352, by one of the lead 
wires 351b. 
The connector main structure 195 (197) on the image forming apparatus main 
assembly side integrally comprises a mount portion 357b provided with the 
aforementioned hole 357a for the small screw, and an engagement portion 
357c in the form of a rectangular parallelepiped. Wiring 359 is connected 
to a contact 355 fined to the connector main structure 195 (197) on the 
image forming apparatus main assembly side. The contact 355 is in contact 
with the internal surface of the engagement portion 357c. A reference 
symbol 357c2 designates a cavity provided in the engagement portion 357c. 
As the-process cartridge is inserted into the image forming apparatus main 
assembly the internal periphery 353b of the connector main structure 196 
(198) on the process cartridge side fits against the external periphery 
357c of the connector main structure 195 (197) on the image forming 
apparatus main assembly side, and the contact portion 352a of the contact 
352 on the process cartridge side is pressed against the contact 355 on 
the image forming apparatus main assembly side, being elastically bent 
inward, and establishes electrical connection. 
FIG. 10 is a section of the connector 196 on the cartridge side, having 
been horizontally rotated 90 deg. from the position illustrated in FIG. 9; 
it is a sectional drawing at a plane passed through the fifth to eighth 
pins of the EEPROM IC. As shown in the drawing, no contact 352 is in 
connection with the seventh pin of the IC. The contact 352 connected to 
the eighth pin (electrical power source Vcc) of the IC branches into two 
(portion 361) portions which extend to the engagement portion 352b. 
The contact corresponding to the fifth pin, the GHD pin, of the IC is 
rendered longer than the other contacts so that the contact corresponding 
to the fifth pin is first connected when the connector 196 is engaged with 
the connector 195, and is disconnected last when the connectors are 
disengaged. With this arrangement, even when the EEPROM-IC is statically 
charged, the static electricity is discharged through the GHD pin before 
the other contacts are connected to their counterparts, and therefore, the 
input/output port of an EEPROM is prevented from being damaged when the 
connectors are engaged. 
In this embodiment, the present invention was described with reference to 
the photosensitive drum cartridge 199 as a process cartridge However, an 
EEPROM may be attached in the same manner as described above to the 
development toner cartridges containing magenta toner, cyan toner, yellow 
toner, or black toner. Further, the aforementioned connector and memory 
may be attached in the same manner to a process cartridge integrally which 
comprises a developing device containing developer, and a container for 
the toner removed from a photosensitive drum. 
Also, the memory IC referred to in this embodiment was an EEPROD, but the 
present invention is compatible with nonvolatile memories of other types. 
Further, the voltage Vcc supplied to the EEPROM was returned to the main 
assembly side. However, the GND signal and the EEPROM control signal may 
be returned to the main assembly-side in the same manner. FIG. 11 depicts 
a structure by which a chip selection signal CS, that is, an EEPROM 
control signal, is returned to the main assembly side to detect whether or 
not a photosensitive drum cartridge is present. Designated by 405 is a 
signal indicative of presence or absence of the process cartridge. 
Reference numeral 401 designates a CPU and 402, 403 and 404 are the signal 
processor, the main apparatus connector and the cartridge side connector 
as shown in FIG. 11. 
Embodiment 2 
FIG. 12 depicts the second embodiment of the present invention. It is a 
circuit diagram which shows the wiring placed between the CPU on the 
apparatus main assembly side and the EEPROM of a photosensitive drum to 
detect the presence (absence) of a photosensitive drum cartridge. 
In this embodiment, the control signal of the EEPROM is not returned. 
Instead, two independent signal lines 410, 411 are added to the connector 
409 on the cartridge side. When the connector 409 on the cartridge side is 
not in connection with the connector 408 on the main assembly side, a 
cartridge detection signal 410 is pulled up to a HIGH level by a resistor 
R6, and when the two connectors 409 and 408 are in connection, the 
cartridge detection signal 41-0 remains at a LOW level. Designated by 406 
and 407 are the CPU and the signal processor, as shown in FIG. 12. Element 
412 in FIG. 12 is a short circuit contact. 
FIG. 14 is an external perspective view of the connector 413 on the 
cartridge side in this embodiment. As shown in the drawing, a metallic 
plate 414 is extended from the fifth pin (GHD pin) of the IC socket, being 
indirectly connected to the first pin through a diode D3, to the second 
pin through a diode D2, to the third pin through a diode D1, and to the 
eighth pin through a condenser C1. The diodes D1-D3 and the condenser C1 
are fixed to the metallic plate 414 by soldering. With this arrangement in 
place, an EEPROM is inserted from above into the IC socket. 
According to this embodiment, connector reliability can be improved while 
maintaining low cost. 
Embodiment 3 
FIG. 13 depicts the third embodiment of the present invention. It shows the 
electrical connection between the signal processing section 4 of the main 
assembly of a prints, and the EEPROM of a cartridge. In this embodiment, 
the present invention is described with reference to only the EEPROM of a 
photosensitive drum cartridge. However, the same description applies to 
development toner cartridges for different colors. 
The signal processing section 4, the connector 195 on the main assembly 
side, the EPEPROM 207, and the signal lines 181-187 in this embodiment are 
the same as those in the first embodiment. Built in this embodiment, a 
condenser C1 and diodes D1-D3 are mounted in the connector 413 on the 
cartridge side as shown in FIG. 13. The condenser C1 smoothes out the 
noise sent to the Vcc line from the EEPROM 207 during the programming of 
the EEPROM 207. It also absorbs the external static electricity which 
enters the Vcc line, so that the external static electricity does not 
affect the EEPROm. The diodes D1-D3 allows the internal static 
electricity, which enters the CS line, the SK line, and the DI line to be 
discharged through the GND line so that the EEPROM is not affected by the 
external static electricity. 
Embodiment 4 
FIG. 15 is a block diagram which depicts the electrical connection in the 
fourth embodiment of the present invention. FIG. 16 is a flow chart for 
the control executed by the CPU 14. In FIG. 15, the members having the 
same functions as those in the first embodiment are given the se 
referential numeral as the one used in the first embodiment. 
In FIG. 15, a photosensitive drum door sensor 416 is a switch that detects 
the opening or closing of the door which occurs when a photosensitive drum 
cartridge is exchanged or removed. When a signal 418 outputted by this 
sensor 416 indicates that the door is open, the CPU 14 determines that the 
photosensitive drum cartridge is to be exchanged with a fresh one, or 
removed, and then updates the contents of the photosensitive drum memory 
207. It is approximately one second or more from when the photosensitive 
drum door sensor 416 detects the opening of the door to when the 
photosensitive drum is removed by the user, that is, when the I/O of the 
photosensitive drum memory becomes disconnected from the main assembly of 
the printer. A developing device door sensor 415 is a switch which detects 
the opening or closing of the door when one or more of the developing 
devices or different color are exchanged or removed. When a signal 417 
outputted by this sensor 417 indicates that the door is open, the CPU 14 
determines that one or more of the developing devices are to be exchanged 
or removed, and updates the contents of the developing device memories 
203, 204, 205 and/or 206. There will be approximately one second or more 
from when the developing device door sensor 145 detects the opening of the 
door to when one or more of the developing devices are removed by the 
user. 
FIG. 16 is a flow chart for the control, in particular, the control for the 
photosensitive drum memory, executed by the CPU 14 as a photosensitive 
drum cassette is installed. 
As the electrical power source of the main assembly of a printer is turned 
on (419), it is determined whether or not the photosensitive drum 
cartridge door is closed (420). When it is confirmed that the 
photosensitive drum cartridge door is closed, a voltage Vcc is supplied to 
the photosensitive drum memory 207 (421) to confirm (422) that a 
photosensitive drum cartridge is present (422). As for the method for 
confirming the presence of the photosensitive drum cartridge, confirmation 
is made eased on the logic level of the voltage Vcc of the return signal 
from the connector on the cartridge side. When it is confirmed that there 
is no cartridge, the absence of the cartridge is reported to the user 
through a display panel or a host computer (427). When it is confirmed 
that there is a cartridge, necessary information is read from the EEPROM, 
that is, the memory of the photosensitive drum (423). At this point, the 
printer enters a state of being on standby, or being ready for a printing 
operation. When the photosensitive drum cartridge door is not open (425) 
after a printing operation, the state of the main switch of the printer 
main assembly is checked (426) then the main switch is ON, the printer 
goes back to the state of being on standby (424) for the nest printing 
operation. 
On the other hand, when the photosensitive drum cartridge door is open 
(425), the contents of the photosensitive drum memory 207 are updated 
(429), and the voltage Vcc is turned OFF (428). 
When the main switch of the printer main assembly is OFF (426), the 
contents of the photosensitive drum-memory 207 are updated (430); the 
voltage Vcc is turned OFF (431); and the electrical power source for the 
entire printer is turned OFF (432). 
It should be noted here that the information to be updated in the 
photosensitive drum memory 207 means, for example, the data pertaining to 
the remaining service life of the photosensitive drum, the number of the 
sheets printed, and the like. 
Embodiment 5 
In each of the first to fourth embodiments, cases in which the present 
invention was applied to the color laser beam printer in which a plurality 
of toner images formed on the photosensitive drum 100 are transferred onto 
the recording paper P carried on the peripheral surface of the transfer 
drum 103 were described. However, in this embodiment, the present 
invention is applied to a color laser beam printer, illustrated in FIG. 
17, in which a plurality of toner images formed on a photosensitive drum 
71 are temporarily transferred onto an intermediary transfer unit, and 
then, all the toner images on the intermediary transfer unit are 
transferred all at once onto a recording paper P. 
Referring to FIG. 17, a photosensitive drum 71 is rotatively driven in the 
direction of an arrow mark by an unillustrated driving means, being 
uniformly charged to a predetermined potential by a roller type charger 
72. Then, a laser light is projected onto the photosensitive drum 71 from 
an exposing apparatus 73 in which signals reflecting the image pattern 
composed of yellow color component are being inputted. As a result, a 
latent image is formed on the photosensitive drum 71. 
Meanwhile, a supporting member 75 which supports developing apparatuses 
74a, 74b, 74c, and 74d is rotated to position the developing apparatus 
74a, in which yellow toner is contained, to directly oppose the 
photosensitive drum 71. As the photosensitive drum 71 is farther rotated 
in the arrow direction, the latent image is developed into a toner image, 
that is, a visible image. Then, the toner image is transferred onto an 
intermediary transfer belt 66, which constitutes the intermediary transfer 
member. 
The intermediary transfer belt 66 is stretched around support rollers 61, 
62 and 63, and is moved in the direction of an arrow mark by the rotation 
of the support roller 62 connected to an unillustrated driving power 
sources At the location where the intermediary transfer belt 66 comes in 
contact with the photosensitive drum 72, a primary transfer roller 64, to 
which a predetermined bias is applied from an unillustrated high voltage 
power source to transfer the toner image on the photosensitive drum 72 
onto the intermediary transfer belt 66e is disposed on the inward side of 
the intermediary transfer belt 66. 
The above described process carried out for the yellow color component is 
also carried out for magenta, cyan, and black color components, for 
example, in this order, by the developing apparatuses 74b, 74c, and 74d. 
As a result, four color toner images are placed on the intermediary 
transfer belt 66. 
Meanwhile, a recording paper P is conveyed from a sheet feeding apparatus 
76 by a conveying means 77 in synchronism with the movement of the 
intermediary transfer belt 66, and these four color toner images are 
transferred all at once onto the recording paper P by a secondary transfer 
roller 65. Next, the toner images are fused to the recording paper P by a 
forming apparatus 78 which uses heat and pressure. As a result, a color 
print is obtained. 
The toner which remains on the photosensitive drum 71 after transfer is 
cleaned by a cleaning apparatus 79 comprising a blade. 
In this embodiment, a charge roller 72, the photosensitive drum 71, and the 
cleaning apparatus 79 are integrated in the form of a process cartridge 90 
which is removably installed in the main assembly of an image forming 
apparatus by a cartridge guiding means 80. Further, the process cartridge 
90 is provided with a connector 84. The connector 84 is provided with the 
same IC memory IC, and first and second types of contacts, as those 
described in each of the preceding embodiments. 
Further, each of the four color developing apparatuses 74a-74d is also 
rendered removably installable in the image forming apparatus main 
assembly as is the process cartridge 90. With the provision of the above 
described structural arrangement, the services, such as exchanging of the 
aforementioned cartridges or apparatus maintenance, which, conventionally, 
are carried out by a trained service personnel can be simply done by the 
user. 
The present invention may be applied to the full-color image forming 
apparatus described above, in the same manner as described in the first to 
fourth embodiments to obtain the same operational results as those 
described in the first to fourth embodiments. 
As is evident from the above description of the embodiments, according to 
the present invention, a process cartridge inclusive of a photosensitive 
drum cartridge or the like units are structured so that an electronic 
device, which constitutes a memory and a control circuit, is directly held 
by the connector on the cartridge or unit side; therefore, cost and size 
can be reduced. Further, the electrical power supplied to a memory is 
returned to the main assembly of an image forming apparatus through the 
connector on the process cartridge or the like unit, and this return 
signal is monitored to detect the presence or absence of a cartridge; 
therefore, a sensor SW, which is necessary according to the prior art to 
detect the presence or absence of a cartridge, can be eliminated to reduce 
cost. 
In other words, according to the present invention, it is possible to 
provide the following: 
(1) a small and inexpensive electrical connector comprising an IC such as 
an EEPROM which makes it possible to determine whether or not a removably 
installable process cartridge or the like is in the main assembly of an 
image forming apparatus; a process cartridge comprising such an electrical 
connector; and an image forming apparatus compatible with such an 
electrical connector; 
(2) an electrical connector better in terms of noise related 
characteristics than connectors based on the prior arts; a process 
cartridge comprising such an electrical connector;-and an image forming 
apparatus compatible with such an electrical connector; 
(3) an electrical connector which increases reliability in image formation 
by turning off the electrical power to an electronic device, and 
preventing access to the electronic device, in order to protect the 
information stored in the electronic device, when a removably installable 
process cartridge or the like is removed from the apparatus main assembly; 
a process cartridge comprising such an electrical connector, and an image 
forming apparatus compatible with such an electrical connector; and 
(4) an electrical connector in which one of the electrical terminals is 
rendered longer than the rest, being enabled contact with its counterpart 
before the rest do with their counterparts, so that the static electricity 
accumulated on an electronic memory device can be discharged before the 
rest of the electrical terminals make their contact; a unit comprising 
such an electrical connector; and an image forming apparatus compatible 
with such an electrical connector. 
While the invention has been described with reference to the structures 
disclosed herein, it is not confined to the details set forth and this 
application is intended to cover such modifications or changes as may come 
within the purposes of the improvements or the scope of the following 
claims.