JP2009210602A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing data corruption caused when opening a door during communication with a memory tag without rise in cost caused by increase in the number of parts. <P>SOLUTION: The image forming apparatus includes: an opening for making a process cartridge get in/out of the image forming apparatus; a door provided at the opening; a door switch whose one end is connected to a power source and which turns on/off a circuit from the power source interlocked with opening/closing the door; a communication means provided in the image forming apparatus and communicating with the process cartridge in an attached state; and a control means fetching voltage at the other end of the door switch, comparing it with a plurality of thresholds and performing required control based on a result of comparison. The control means starts processing for finishing communication with the process cartridge by the communication means (S1003) when the voltage at the other end of the door switch lowers to be equal to or under the first threshold, and performs shut-down processing (S1007) when the voltage thereat lowers to be equal to or under a second threshold lower than the first threshold. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as a laser beam printer, and more particularly to an end process of communication with the process cartridge.

2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus using an electrophotographic image forming process is equipped with a mechanism for managing process cartridges and extracting optimum performance using a memory (hereinafter referred to as a memory tag) attached to the cartridge. Exists.
In addition, the communication between the memory tag and the printer uses a non-contact communication method and a contact-type communication method. However, the contact-type communication contact is less expensive, so the contact-type communication contact is used. The method is often adopted.
This contact type communication system is generally connected to the communication control circuit of the main body, and this contact point contacts the contact surface of the memory means to communicate with the memory tag attached to the process cartridge. .

However, in the contact system, data loss occurs if the connector and the memory tag are separated during communication. Therefore, after detecting the opening / closing of the door by the door switch, the configuration is such that the contact portion is separated after the end processing of the data communication is performed so that data loss does not occur (Patent Document 1).
JP 2004-69943 A

  However, in the method of moving the connector contact portion in conjunction with opening / closing of the door, the time from when the door switch detects door opening / closing until the memory tag and the connector contact are separated is determined by the door opening / closing speed. Therefore, the time required for the termination process is determined by the user.

For this reason, it is necessary to estimate the time for performing the termination process very short, which increases the cost of the electric circuit in order to perform the termination process at high speed.
In addition, in order to detect door detection as soon as possible, if the door switch mechanism is configured with priority given to detection of door opening / closing, there is a possibility of false detection that the door is open even though the door is not open. There was a problem of increasing.
Further, as in Patent Document 1, when the door is opened by a mechanical mechanism and the door switch detects the door opening, the time from when the memory means and the connector are separated from each other is kept longer than a certain time. A complicated mechanical configuration is required, which increases the cost.

  The present invention has been made under such circumstances, and provides an image forming apparatus capable of preventing data destruction that occurs when a door is opened during communication with a process cartridge without an increase in cost due to an increase in parts. It is an object to do.

  In order to solve the above problems, in the present invention, the image forming apparatus is configured as described in the following (1) and (2).

(1) In an image forming apparatus in which a process cartridge having a photosensitive drum is detachable,
An opening for taking the process cartridge into and out of the image forming apparatus;
A door provided in the opening;
A door switch, one end of which is connected to a power source, and turns off / on power to the circuit from the power source in conjunction with the opening / closing of the door;
A communication unit provided in the image forming apparatus and configured to communicate with the mounted process cartridge;
Control means for taking in the voltage at the other end of the door switch and performing a required control based on a comparison result compared with a plurality of threshold values;
With
When the voltage at the other end of the door switch drops below a first threshold value, the control means starts an end process of communication with the process cartridge by the communication means, and is lower than the first threshold value. An image forming apparatus that performs a shutdown process for stopping various apparatuses when the threshold value falls below a second threshold.

(2) In an image forming apparatus in which a process cartridge having a photosensitive drum is detachable,
An opening for taking the process cartridge into and out of the image forming apparatus;
A door provided in the opening;
A door switch, one end of which is connected to a power source, and turns off / on power to the circuit from the power source in conjunction with the opening / closing of the door;
A communication unit provided in the image forming apparatus and configured to communicate with the mounted process cartridge;
Control means for taking in the voltage at the other end of the door switch and performing a required control based on a comparison result compared with a plurality of threshold values;
With
When the voltage at the other end of the door switch drops below a first threshold value, the control means starts an end process of communication with the process cartridge by the communication means, and is lower than the first threshold value. An image forming apparatus that performs a shutdown process to stop various devices when the second predetermined time has elapsed since the time when the voltage falls below the second threshold and falls below the first threshold.

  According to the present invention, when the door is opened during communication with the process cartridge without an increase in cost due to an increase in the number of parts due to the need for an electrical circuit and a complicated mechanical configuration for performing the termination process at high speed. Data corruption that occurs can be prevented.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  An “image forming apparatus” that is Embodiment 1 will be described.

(1) Overview of Configuration and Operation of Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an image forming apparatus according to this embodiment. The image forming apparatus of this embodiment is an example of an electrophotographic type and a process cartridge detachable laser printer.
In FIG. 1, reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (photosensitive drum) as a latent image carrier. The photosensitive drum 1 in this embodiment is a negatively charged organic photosensitive member, and is rotationally driven in a clockwise direction indicated by an arrow at a predetermined peripheral speed by a driving motor (not shown).
The photosensitive drum 1 is uniformly charged to a predetermined negative potential by a charging device during its rotation. In this embodiment, the charging device is a contact charging device using a charging roller 2 as a charging member. The charging roller 2 rotates following the photosensitive drum 1. A bias voltage is applied to the charging roller 2 from a charging bias power source (not shown). As the charging bias voltage, a method is used in which a DC voltage corresponding to a desired on-drum potential is superimposed on an AC voltage having a peak-to-peak voltage that is twice or more the discharge start voltage. This charging method aims to eliminate local potential unevenness on the photosensitive drum by applying an AC voltage superimposed on the DC voltage, and to uniformly charge the photosensitive drum to a potential equal to the DC applied voltage.

  Next, image exposure by the exposure device 21 is performed. The exposure device 21 forms an electrostatic latent image on the uniformly charged photosensitive drum 1, and a semiconductor laser scanner is used in this embodiment. The exposure device 21 outputs a laser beam L modulated in accordance with an image signal sent from a host device (not shown) in the image forming apparatus, and exposes the reflecting mirror 21a and a process cartridge C described later. The uniformly charged surface of the photosensitive drum 1 is subjected to scanning exposure (image exposure) through the window a. On the surface of the photosensitive drum, an electrostatic latent image corresponding to image information is sequentially formed as the absolute value of the potential of the exposed portion becomes lower than the absolute value of the charging potential.

Next, the electrostatic latent image is developed by the developing device 5 to be visualized as a toner image. In this embodiment, a jumping development method is used. In this method, a developing bias voltage in which alternating current and direct current are superimposed is applied to a developing roller 7 (hereinafter referred to as a developing sleeve) from a developing bias power source (not shown). As a result, the toner charged negatively by frictional charging at the contact point between the developer layer thickness regulating member 6 and the developing sleeve 7 is applied to the electrostatic latent image on the surface of the photosensitive drum to reversely develop the electrostatic latent image.
The toner image on the photosensitive drum surface is transferred by a transfer device to a recording medium (transfer material) such as paper fed from a paper supply unit (not shown). In this embodiment, a contact transfer device using a transfer roller 22 is used. The transfer roller 22 is pressed against the photosensitive drum 1 in the central direction of the photosensitive drum by an urging means such as a pressing spring (not shown). When the transfer material is conveyed and the transfer process is started, a positive transfer bias voltage is applied to the transfer roller 22 from a transfer bias power source (not shown), and the toner on the photosensitive drum 1 is charged to a negative polarity. Is transferred onto the transfer material.
The transfer material that has received the transfer of the toner image is separated from the surface of the photosensitive drum, introduced into the fixing device 23, subjected to a fixing process of the toner image, and discharged onto the discharge tray 25 through the sheet path 24. The fixing device 23 fixes the toner image transferred onto the transfer material to a permanent image using means such as heat or pressure.

The photosensitive drum surface after separation of the transfer material is cleaned by scraping off the transfer residual toner by the cleaning device 4 and is repeatedly used for image formation. The cleaning device 4 of this embodiment uses a cleaning blade 3. The cleaning blade 3 collects transfer residual toner that has not been completely transferred from the photosensitive drum 1 to the transfer material during the transfer process, and contacts the photosensitive drum 1 with a constant pressure to collect the transfer residual toner. Clean the surface. After completion of the cleaning process, the photosensitive drum surface again enters the charging process.
The image forming apparatus forms an image by repeating the steps of charging, exposing, developing, transferring, fixing, and cleaning using the above-described means.

  A process cartridge C is detachable and replaceable with respect to the image forming apparatus main body 20. The process cartridge C of this embodiment includes a photosensitive drum 1 as a latent image carrier, a charging roller 2 as a charging member that contacts the photosensitive drum 1 and charges the surface thereof, a developing device 5, and a cleaning device. Four process members of the apparatus 4 are included. Further, the process cartridge C is provided with a memory tag 10 as a storage unit. Information is read from and written to the memory tag 10 via a communication unit (not shown) on the image forming apparatus main body side.

The process cartridge C is attached to and detached from an opening (not shown) of the image forming apparatus main body 20 formed by opening and closing a main body door (cartridge door) 20 a of the image forming apparatus main body 20. The mounting is performed by opening the main body door 20a, inserting and mounting the process cartridge C in the image forming apparatus main body 20 in a predetermined manner, and closing the main body door 20a (corresponding to the mounting state in the claims). The process cartridge C is mechanically and electrically connected to the image forming apparatus main body 20 side by being mounted at a predetermined position with respect to the image forming apparatus main body 20. Therefore, it is necessary to read / write information from / to the memory tag 10 only when the main body door 20a is closed. If the main body door 20a is opened and electrical connection is released while reading / writing information with the memory tag 10, information on the memory tag 10 is destroyed.
Removal of the process cartridge C from the image forming apparatus main body 20 is performed by opening the main body door 20a and pulling out the process cartridge C in the image forming apparatus main body 20.

  FIG. 2 shows the process cartridge C in a removed state. When the process cartridge C is removed, the drum cover 8 is moved to the closed position to conceal and protect the exposed lower surface of the photosensitive drum 1. The exposure window portion a is also held closed by the shutter plate 9. When the process cartridge C is mounted in the image forming apparatus main body 20, the drum cover 8 and the shutter plate 9 are respectively moved to the open position and held.

  Here, the process cartridge is a cartridge in which a charging unit, a developing unit or a cleaning unit and an electrophotographic photosensitive member are integrally formed, and this cartridge can be attached to and detached from the image forming apparatus main body. Further, at least one of the charging unit, the developing unit, and the cleaning unit and the electrophotographic photosensitive member are integrally formed into a cartridge that can be attached to and detached from the main body of the image forming apparatus. Further, it means that at least the developing means and the electrophotographic photosensitive member are integrated into a cartridge so that it can be attached to and detached from the apparatus body.

(2) Printer Operation Sequence An outline of the printer operation sequence in this embodiment will be described with reference to FIG.
First, when the power supply in the image forming apparatus is turned on (step 1, hereinafter referred to as S1), the pre-multi-rotation process (S3) starts. In this step, while the main motor rotates the photosensitive drum 1, detection of the presence or absence of the process cartridge C, cleaning of the transfer roller, and the like are performed.
When the front multi-rotation is completed, the image forming apparatus enters a standby (standby) state (S4). When image information is sent from the output means such as a host computer (not shown) to the image forming apparatus (Yes in S5), the main motor drives the image forming apparatus main body and enters a pre-rotation process (S6). In the pre-rotation process, printing preparation operations of various process devices are performed. Mainly, preliminary charging on the photosensitive drum 1, start-up of the exposure device 21, determination of the transfer print bias, temperature adjustment of the fixing device 23, and the like. Done.
When the pre-rotation process is completed, the printing process is started (S7). In the printing process, transfer material feeding, image exposure on the photosensitive drum 1, development, and the like are performed at a predetermined timing. When the printing process is completed, if there is a next print instruction, the process enters the sheet interval process until the next transfer material arrives and waits for the next printing operation (S8).

If there is no next print instruction after the printing operation is completed, the image forming apparatus enters a post-rotation process (S10). In the post-rotation process, processes such as charge removal on the surface of the photosensitive drum 1 and discharging of toner adhering to the transfer roller 22 to the photosensitive drum 1 (cleaning of the transfer roller 22) are performed.
When the post-rotation process is completed, the image forming apparatus main body 20 enters the standby (standby) state (S4) again and waits for the next print signal.

(3) Communication with Memory Tag In FIG. 4, the control unit 71 in the engine controller 41 communicates with the memory tag 10 which is a storage unit on the process cartridge C side via the memory tag contact 10c, and reads and writes information. Do. The engine controller 41 uses the information in the memory tag 10 to perform various controls such as predicting the remaining amount of toner and applying a bias according to the usage state to the drum.

The memory tag 10 can store information related to the process cartridge C, and has an area for storing, for example, information related to the number of printed pages and the amount of drum used. Therefore, the control unit 71 periodically communicates with the memory tag 10 to write and read information.
On the other hand, since the memory tag contact 10c is in the process cartridge C, for example, when the user opens the main body door 20a, the contact is separated. If the contact is released while the control unit 71 is reading from or writing to the memory tag 10, the information on the memory tag is destroyed.
In order to prevent the destruction of this information, the control unit 71 monitors the opening / closing information 43 of the main body door 20a, and immediately detects the end of communication when it detects that the door has been opened during reading / writing with the memory tag 10. And immediately stop reading and writing.

  As a mechanism to detect the opening and closing of the door, the main body door and the switch are interlocked so that the switch is turned on when the main body door is closed, and the switch is turned off when it is open. A reading configuration is commonly used.

Here, for convenience of explanation, a conventional mechanism for detecting opening / closing of a door and tag communication end processing will be described with reference to FIGS.
That is, conventionally, as shown in FIG. 5, it is detected that the door has been opened by changing the voltage entering the port of the control unit 51 between when the door is closed and when the door is open.
Hereinafter, a mechanism for detecting opening and closing of the door will be described with reference to FIG.
The door switch 52 connected to the 24V power supply 50 is interlocked with the main body door, and is in an ON state when the door is closed. At this time, by setting the ratio of the resistor 1 and the resistor 2 to 24: 3, the voltage of the door open detection port Dopen of the control unit 51 can be set to about 3V. Here, 55 is a capacitor for preventing malfunction due to external noise and the like, and 56 is a protective diode for preventing a voltage higher than the CPU power supply voltage Vcc from being applied to the Dopen port.
The door switch 52 is connected to a high voltage power source 57 and a drum motor 58 using a 24V power source. Capacitors for voltage stabilization are mounted on the substrates of the high voltage power source 57 and the drum motor 58, respectively.
On the other hand, since the door switch 52 is open when the door is open, the voltage of the door open detection port Dopen of the control unit 51 is approximately 0V.
The control unit 51 determines whether the door is open or the door is closed by comparing the threshold value with the value of the door open detection port Dopen.

As shown in the figure, many capacitors are connected after the door switch 52 and are charged when the door is closed. For this reason, as shown in FIG. 6, when the door is opened by the user, the voltage of the door open detection port Dopen is lowered with a slow inclination. When this voltage reaches the “Low” detection level of the port Dopen of the control unit 51 or less, the control unit 51 detects “Low”, that is, “door open”. This voltage level is usually about 0.6 to 0.9V.
When this “door open” is detected, various drive motors, fixing devices, high voltage output, etc. are stopped. Further, when communication with the memory tag is being performed, the control unit 51 immediately starts a termination process with the memory tag communication. If the tag contact is electrically separated before the communication end processing is completed, information on the memory tag is destroyed. In order to prevent this, it is necessary to provide a complicated mechanical mechanism as described in Patent Document 1 so that the time from when the door is opened to when the tag contact is released always exceeds a certain value. (See FIG. 6).

Subsequently, a mechanism for detecting opening / closing of a door and a tag communication end process in the present embodiment will be described with reference to FIGS.
FIG. 7 is a diagram showing a schematic configuration of a main part of the present embodiment. In FIG. 7, the voltage obtained by dividing the voltage of the other end of the door switch 72 (hereinafter, this position is referred to as the other end of the door switch) with one resistor connected to the power source is input to the input of the AD converter 79. . When the AD converter 79 operates with the power supply voltage Vad, the ratio of the resistor 73 and the resistor 74 is set to 24: Vad. As shown in FIG. 8, the control unit 71 performs the following processing shown in the flowchart of FIG. 10 based on the information on the voltage at the other end of the door switch obtained by the AD converter 79. This process is performed by a CPU (not shown) in the control unit 71.
That is, when the door switch 72 turns off / on power to the circuit from the power source in conjunction with opening / closing of the door, the control unit 71 digitally converts the voltage at the other end of the door switch with the AD converter 79. It is converted into a value and compared with a plurality of threshold values stored in the memory M, and a required process is performed according to the comparison result.
When the control unit 71 detects that the voltage is equal to or lower than the memory tag communication end processing start voltage V1 after the door is opened by the user (Yes in S1002), the control unit 71 starts the tag communication end processing (S1003). At this time, various drive motors, fixing devices, high-voltage power supplies, etc. are not stopped.
The control unit 71 detects the door open when the tag communication end process is completed (Yes in S1004) and the voltage at the other end of the door switch 72 becomes equal to or lower than the door open detection voltage V2 (Yes in S1005) ( S1006). Then, shutdown processing is performed to stop various drive motors, fixing devices, high-voltage power supplies, etc. (S1007) (V1 corresponds to the first threshold value in the claims, V2 corresponds to the second threshold value, and the control unit 71 controls the first It is detected that the threshold value is less than or equal to the second threshold value.)

As shown in FIG. 9, when external noise enters the voltage at the other end of the door switch 72, if the noise level is V1 or less and exceeds V2 (No in S1005), a predetermined time Td (claim) (Equivalent to the first predetermined time) elapses (S1008).
Thereafter, if the voltage does not become V2 or less even after a predetermined time Td (Yes in S1008), it is determined that the noise is detected, and a process of restarting tag communication is performed (S1009).

  This prevents the destruction of data that occurs when the door is opened during memory tag communication without increasing the cost due to the increase in the number of parts due to the need for a complicated mechanical configuration and an electrical circuit for high-speed termination processing. can do.

  An “image forming apparatus” that is Embodiment 2 will be described. Since the hardware configuration of the present embodiment is the same as that of the first embodiment, the description of the first embodiment is cited and the description thereof is omitted here.

  The principal part of a present Example is demonstrated with FIG. 11 and FIG.

As shown in the flowchart of FIG. 11, when it is detected that the voltage is equal to or lower than the memory tag communication end processing start voltage V1 as in the case of external noise (Yes in S1102), the tag communication end processing is started ( S1103).
The control unit 71 determines whether or not the door open detection voltage V2 is equal to or lower. If the door open detection voltage V2 is lower than V2 (Yes in S1104), the elapsed time from V1 or lower becomes Tn (claim). (Corresponding to the second predetermined time) or more (S1105). When the elapsed time is equal to or longer than Tn, it is detected that the door is open (S1106). If the tag communication end process has been completed (Yes in S1107), a shutdown process such as stopping the drive motor and high voltage output is performed (S1108).
In S1105, if the elapsed time is less than Tn (No in S1105), it is checked whether V2 or less continues until Tn time elapses (S1104). If the voltage returns to a voltage exceeding the voltage V2 before the time Tn has elapsed (No in S1104), it is checked whether the tag communication end process is completed (S1109), the tag communication end process is completed, and the voltage is If V1 or higher (Yes in S1110), tag communication restart processing is performed (S1111).

  The processing of this embodiment will be described with reference to FIG. As shown in the figure, it is assumed that the voltage at the other end of the door switch 72 decreases as shown by the broken line as the door is opened, and it takes Tn time to reach the voltage V1 to V2. Then, as shown by the solid line, when the voltage at the other end of the door switch 72 decreases from V1 to V2 or lower and then returns to a voltage exceeding the voltage V2 within Tn time, the voltage is not decreased due to door opening. Thus, the tag communication is resumed after the memory tag communication end process is completed and the voltage at the other end of the door switch returns to a voltage exceeding the memory tag communication end process start voltage V1.

  This prevents data destruction that occurs when the door is opened during memory tag communication without increasing the cost due to the increase in the number of parts required for an electrical circuit and complicated mechanical configuration for the termination process. can do. Furthermore, it is possible to minimize the influence of malfunction caused by external noise.

Sectional drawing which shows schematic structure of the image forming apparatus of Example 1 and Example 2 Sectional drawing which shows the structure of the process cartridge removed from the image forming apparatus Flowchart showing operation sequence of image forming apparatus The block diagram which shows schematic structure of the principal part of Example 1 and Example 2. Conventional circuit diagram corresponding to the circuit diagram of FIG. The figure explaining operation | movement of the circuit of FIG. Circuit diagram of essential parts of Example 1 The figure explaining operation | movement of the circuit of FIG. The figure explaining operation | movement of the circuit of FIG. Flowchart showing processing in the first embodiment. Flowchart showing processing in the second embodiment. The figure explaining operation | movement of Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 10 Memory tag 20 Image forming apparatus main body 20a Main body door 42 Control part 72 Door switch C Process cartridge

Claims (4)

In an image forming apparatus in which a process cartridge having a photosensitive drum is detachable,
An opening for taking the process cartridge into and out of the image forming apparatus;
A door provided in the opening;
A door switch, one end of which is connected to a power source, and turns off / on power to the circuit from the power source in conjunction with the opening / closing of the door;
A communication unit provided in the image forming apparatus and configured to communicate with the mounted process cartridge;
Control means for taking in the voltage at the other end of the door switch and performing a required control based on a comparison result compared with a plurality of threshold values;
With
When the voltage at the other end of the door switch drops below a first threshold value, the control means starts an end process of communication with the process cartridge by the communication means, and is lower than the first threshold value. An image forming apparatus that performs a shutdown process to stop various devices when the value falls below a second threshold. The image forming apparatus according to claim 1,
When the voltage at the other end of the door switch does not drop below the second threshold even after the first predetermined time has elapsed since the voltage at the other end of the door switch drops below the first threshold, the communication means And restarting the communication with the process cartridge. In an image forming apparatus in which a process cartridge having a photosensitive drum is detachable,
An opening for taking the process cartridge into and out of the image forming apparatus;
A door provided in the opening;
A door switch, one end of which is connected to a power source, and turns off / on power to the circuit from the power source in conjunction with the opening / closing of the door;
A communication unit provided in the image forming apparatus and configured to communicate with the mounted process cartridge;
Control means for taking in the voltage at the other end of the door switch and performing a required control based on a comparison result compared with a plurality of threshold values;
With
When the voltage at the other end of the door switch drops below a first threshold value, the control means starts an end process of communication with the process cartridge by the communication means, and is lower than the first threshold value. An image characterized by performing a shutdown process for stopping various devices when the second predetermined time has elapsed since the time when the voltage falls below the second threshold and falls below the first threshold. Forming equipment. The image forming apparatus according to claim 3.
The control means starts a process for ending communication with the process cartridge, and then the voltage at the other end of the door switch drops below the second threshold, and then drops below the first threshold. When the voltage returns to a voltage exceeding the second threshold before the second predetermined time elapses, the process waits for the voltage at the other end to return to a voltage exceeding the first threshold. An image forming apparatus restarting communication with a cartridge.

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