JPH08244316A - Image forming apparatus - Google Patents

Abstract

PURPOSE: To monitor the condition of connection/non-connection of a peripheral instrument and to miniaturize an interface connector by providing a means for inputting a signal to initialize the peripheral instrument to the peripheral instrument from an image forming apparatus main body. CONSTITUTION: Data transferred to a peripheral instrument 2 from an image forming apparatus main body 1 are transmitted through a serial circuit part 13 and the first driver element 15 and are furthermore received by the peripheral instrument 2 through an interface connector 3. In addition, a signal for initializing the peripheral instrument is transmitted through a parallel signal input- output part 14 and the second driver element 16. Data received in the peripheral instrument 2 and an initializing signal are respectively pulled up by means of a resistance R1 and are input into a CPU 21 in the peripheral instrument 2 or a serial circuit part 23 to initialize the peripheral instrument and an operation for achieving an automatic both face unit function is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to interface control of an image forming apparatus to which peripheral devices such as an automatic duplex unit can be attached and detached.

[0002]

2. Description of the Related Art Peripheral devices for image forming apparatuses such as laser beam printers and copiers, especially automatic double-sided units, are similar in shape to ordinary paper feed cassettes. Many people set and use the automatic duplex unit as if it were set. As described above, a peripheral device mounted in the image forming apparatus in a form similar to that of a normal paper feeding cassette is electrically connected to the main body of the image forming device only by mounting (plugging) the peripheral device into the main body of the image forming apparatus. Is connected to the interface connector, power is supplied from the main body side, and peripheral devices are controlled by a data signal supplied from the main body side. Further, since peripheral devices are attached and detached while the main unit is powered on, hot plugging and unplugging must be taken into consideration. Conventionally, peripheral devices that are hot-plugged and unplugged have a signal line in the interface connector that detects connection / disconnection of the device, and the main unit monitors the signal from the connected / disconnected signal line. By doing so, the presence / absence of peripheral devices was determined.

However, the conventional image forming apparatus and the interface connector of the peripheral device attached to and detached from the image forming apparatus need to be provided with a signal line for simply monitoring the connection / disconnection state, and the interface connector becomes large in size and high in cost. However, there is a problem in that

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention utilizes signals of other signal lines of an interface connector without providing a signal line for monitoring the connection / disconnection state of an image forming apparatus and peripheral devices attached / detached thereto. It is an object of the present invention to provide an image forming apparatus capable of reducing the size and cost of an interface connector by monitoring the connection / disconnection state of peripheral devices.

[0005]

To achieve the above object, a first means of an image forming apparatus according to the present invention is an image forming apparatus in which peripheral equipment such as an automatic duplex unit is attachable / detachable to the image forming apparatus main body. An interface connector using an asynchronous serial line for connecting to a peripheral device, a resistor for pulling down a data signal transmitted from the peripheral device through the interface connector in the image forming apparatus body, and an interface for the peripheral device. Data sent from the peripheral device when the interface connector is connected to the image forming device main body and the peripheral device, and a resistor for pulling up a data signal transmitted from the image forming device main body through the connector. The signal level becomes high, and the interface Data is the image forming apparatus main body and peripherals and low-level data signal level sent from the peripheral device in the image forming apparatus main body when in the disconnected state,
The peripheral device is provided with a unit for setting each resistance value to a high level and outputting a signal for initializing the peripheral device from the image forming apparatus main body to the peripheral device. To do.

The second means of the image forming apparatus according to the present invention is, in addition to the first means, applied a data signal from a peripheral device to an input port on the image forming apparatus main body side to bring the interface connector into a connected state. A high-level signal is input to the input port at a certain time, and a low-level signal is input to the input port when the interface connector is not connected.

The third means of the image forming apparatus according to the present invention is, in addition to the first means, a CP in the main body of the image forming apparatus.
When the U monitors the state of the serial line in the image forming apparatus main body and determines that the data signal input to the serial line is not in the break state, it determines that the interface connector is in the connected state and the peripherals are connected via the serial line. When the CPU cooperates with the peripheral device while communicating with the CPU of the device, and when it detects that the serial line in the main body of the image forming apparatus is in the break state, it determines that the interface connector is not connected, When the image forming apparatus main body is operated in the mode in which the peripheral device is not connected and the serial line changes from the break state to the non-break state, it is determined that the interface connector has transitioned from the non-connection state to the connection state, Outputs a signal for initialization to the peripheral device, and CP in the peripheral device
After U is initialized, the communication between the image forming apparatus main body and the peripheral device is restored via the serial line, and the image forming apparatus main body is operated in cooperation with the peripheral device.

A fourth means of the image forming apparatus according to the present invention is, in addition to the second means, a CP in the main body of the image forming apparatus.
U monitors the state of the input port in the main body of the image forming apparatus,
When the low level is not input to the input port for a preset time or longer, it is determined that the interface connector is in the connected state, and the CP of the peripheral device is connected via the serial line.
The interface connector is determined to be in the disconnected state when it cooperates with peripheral devices while communicating with U, and when a low level signal for a preset time or longer is input to the input port in the main body of the image forming apparatus. Then, the image forming apparatus main body is operated in the mode in which the peripheral device is not connected, and after the low level signal for a preset time or more is input to the input port, the signal level of the input port becomes the high level. In this case, it is determined that the interface connector has transitioned from the unconnected state to the connected state, and a signal for initializing the peripheral device is output, and the CPU in the peripheral device is output.
After initialization, the communication between the image forming apparatus main body and the peripheral device is restored via the serial line, and the image forming apparatus main body is operated in cooperation with the peripheral device.

[0009]

With the above first and third means, when the peripheral device is connected to the main body of the image forming apparatus, a high level data signal is received by the serial line portion of the main body of the image forming apparatus, and the peripheral device and the image forming apparatus are formed. When the device main body is not connected, a low-level data signal is received by the serial line unit, so that the CPU of the image forming apparatus main unit monitors the serial line, and when a high level is detected in the serial line unit, the peripheral unit detects the high level. It is determined that the device is attached, and a signal for initializing the peripheral device is output from the image forming apparatus main body to the peripheral device, and
The image forming apparatus main body operates in the peripheral device mounting mode, while it is determined that the peripheral device is removed when the low level is detected in the serial line section, and the image forming apparatus operates in the peripheral device non-mounting mode. Accordingly, by monitoring the connection / disconnection state of the peripheral device without providing a signal line for monitoring the connection / disconnection state of the peripheral device attached / detached to / from the image forming apparatus main body, the interface connector can be downsized and reduced Cost can be reduced.

By the second and fourth means, when the peripheral device is connected to the main body of the image forming apparatus, a high-level data signal is received by the parallel signal input / output unit of the main body of the image forming apparatus, and the peripheral device and the peripheral device are connected to each other. When the parallel signal input / output unit receives a low-level data signal when the image forming apparatus main body is not connected, the CPU of the image forming apparatus main body monitors the parallel signal input / output unit, and the parallel signal input / output unit When the high level is detected, it is determined that the peripheral device is attached, and the signal for initializing the peripheral device is output from the image forming apparatus main body to the peripheral device, and the image forming apparatus main body operates in the peripheral device attaching mode, On the other hand, when a low level is detected in the parallel signal input / output unit, it is determined that the peripheral device is removed, and the image forming apparatus operates in the peripheral device non-attachment mode. In addition, the interface connector can be miniaturized and the cost can be reduced by monitoring the connection / disconnection state of the peripheral device without providing the signal line for monitoring the connection / disconnection state of the peripheral device attached / detached to / from the image forming apparatus main body. Can be realized.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to the present invention and peripheral devices connected to the image forming apparatus. In the figure,
Reference numeral 1 is a main body of the image forming apparatus, 2 is a peripheral device, and 3 is an interface connector. The image forming apparatus main body 1 controls the main body, and when a peripheral device is connected, exchanges information with the peripheral device through a serial line.
Memory 1 that stores a program for 1 to operate
2, a serial line unit (UART) 13 for communicating with the peripheral device 2, and a parallel signal input / output unit (PI /
O) 14 and the first driver element 15 of open collector output for driving the serial transmission signal (TXD) from the main body to the peripheral device, and the open collector output for driving the initialization signal (RESET) from the main body to the peripheral device. Output second driver element 16 and resistor R3 for pulling down the signal from the peripheral device 2.
With. The serial line unit 13 has a so-called break detection function of determining a break state and generating a status when a LOW level of 2 bytes or more is continuously input to the reception signal input terminal.

On the other hand, the peripheral device 2 includes a CPU 21 for controlling the peripheral device, a memory 22 storing a program for the CPU 21 to operate, a serial line section 23 for communicating with the main body, and the peripheral device. To drive the serial reception signal (RXD) transmitted from the
A third driver element 24 having an open collector output,
The serial reception signal (TXD) and the initialization signal (RES
ET) and a resistor R1 for pulling up the serial reception signal (RXD).
With. The resistor R1 is not particularly limited as long as it has a value capable of pulling up the outputs of the first and second driver elements 15 and 16, and for example, about 4.7 kΩ is suitable.

The data transferred from the image forming apparatus main body 1 to the peripheral device 2 is sent out via the serial line section 13 and the first driver element 15, and further received by the peripheral device 2 via the interface connector 3. A signal for initializing the peripheral device is sent out via the parallel signal input / output unit 14 and the second driver element 16.

In the peripheral device 2, the received data and the initialization signal are pulled up by the resistor R1 respectively, and the CPU 21 or the serial line unit 2 in the peripheral device 2 is pulled up.
Input to 3 to initialize peripheral devices and drive them,
For example, an operation is performed to achieve the automatic duplex unit function. In addition, the response signal from the peripheral device 2 is the CPU 2
1 to serial line unit 23 and third driver element 24
And is further transmitted to the image forming apparatus main body 1 via the interface connector 3. At this time, the transmission data is pulled up by the resistor R2 of the peripheral device 2, further pulled down by the resistor R3 of the main body 1, and then received by the serial line unit 13 of the main body 1.

In the image forming apparatus main body 1 and the peripheral device 2 thus configured, when the interface connector 3 is cut off, that is, when the peripheral device 2 is removed,
The reception signal to be received by the main body 1 (transmission signal (RXD) from the peripheral device) becomes LOW level, and
When the interface connector 3 is connected, that is, when the peripheral device 2 is attached, the reception signal (RXD) received by the main body 1 becomes HIGH level, so that the attachment / detachment state of the peripheral device 2 can be grasped. It will be possible.

Here, in order that the signal level becomes LOW level and HIGH level in the serial line section 13 of the main body 1 by attaching and detaching the peripheral equipment 2, the value of the resistance R2 of the peripheral equipment 2 is the value of the resistance R1 of the main body 1. It is preferably less than 1/10 compared with. Therefore, it is appropriate that the value of the resistor R2 is about 1 kΩ and the value of the resistor R3 is about 47 kΩ.

When the respective resistance values are set in this way, the reception signal (RXD) input of the serial line section 13 is pulled down to the ground level by the resistor R3 when the interface connector 3 is not connected, and the resistor R2 and the resistor R2 when the interface connector 3 is connected. 5 (V) / (47 + 1) by resistance R3
Since it is pulled up to × 48 = 4.89 (V), it is easy to connect / connect using the break function of the serial line unit 13.
It becomes possible to recognize the non-connection.

Next, the operation of the image forming apparatus and peripheral equipment shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a flowchart showing the control procedure. First, the serial line unit 13 monitors the break detection state at a constant cycle (step 1). When the break is detected, the CPU 11 of the main body judges that the peripheral device has been removed (step 1). 2), the image forming apparatus main body operates in a mode without peripheral devices. When the break is not detected in step 1, the CPU 11 of the image forming apparatus main body checks whether or not the state of the last monitoring was the break state (step 3). That is, it is determined whether or not the peripheral device has been attached or previously attached by determining whether or not the state has changed.

When the CPU 11 of the main body determines that the peripheral device was in the break state last time, the peripheral device determines that the peripheral device is newly connected while the main body of the apparatus is operating, or is reconnected after the peripheral device is disconnected. C of the peripheral device through the signal input / output port 14 and the second driver element 16
The PU 21 and the serial line unit 23 are reset (step 4). CPU of the main body after initialization of peripheral devices
11 and the CPU 21 of the peripheral device restore the line via the mutual serial line units 13 and 23 (step 5),
The CPU 11 of the main body operates the main body device in cooperation with the peripheral device while communicating with the peripheral device in the mode with the peripheral device (step 6).

If it is determined in step 3 that the previous break was not made, that is, if the peripheral device was already connected at the time of the previous monitoring, the CPU 11 of the main body is in the peripheral device presence mode. While communicating with the peripheral device, continue to operate the main unit in cooperation with the peripheral device. As described above, the signal of the other signal line of the interface connector (in the case of the present embodiment, the reception signal is received in the interface connector is not provided for exclusive use of the signal line for monitoring the connection / disconnection state of the image forming apparatus and the peripheral device attached / detached thereto. Connection of peripheral devices using data signals)
Since the non-connection state is monitored, it is possible to downsize the interface connector and provide a low-cost image forming apparatus.

FIG. 3 is a diagram showing a second embodiment of the present invention. The difference from the first embodiment is that the signal transmitted from the peripheral device 2 is converted into a serial line section 13 and a parallel signal input / output section. 14 is the point applied. With this configuration, when the interface connector is not connected, the serial line unit 13 and the parallel signal input / output unit 14 are connected.
Ground level signal is input to the serial line section 13 and parallel signal input / output section 14 when the interface connector is connected, and a predetermined signal (4.89 V if the same resistance value as in the above embodiment is set) is input. Therefore, even when the serial line unit 13 having no break function is used, the connection of the peripheral device can be surely recognized.

FIG. 4 is a flow chart showing the control procedure of the second embodiment. First, the CPU 11 of the main body device monitors the input state of the parallel signal input / output unit 14 at a constant cycle (step 11), and the parallel signal is detected. When the input of the input / output unit 14 detects LOW, and whether or not the LOW level state is maintained longer than a preset time (determination time) is monitored (step 12). When the input level of the parallel signal input / output unit 14 maintains LOW for the determination time or longer, the CPU 11 of the main body device determines that the peripheral device is disconnected from the main body device, and operates the main body device in the mode without the peripheral device. (Step 13).

On the other hand, when the LOW level signal is not detected in the step 11 or when the LOW level signal is not detected for the predetermined time or more in the step 12, the CPU 11 of the main body device performs the previous monitoring. (Whether the LOW state was longer than the determination time last time) is checked (step 14).

Here, if it is determined that the LOW state is longer than the determination time last time, the CPU 11 of the main body is reconnected after the peripheral device is newly connected while the main body device is operating or once disconnected. It is determined that the CPU 21 and the serial line unit 23 of the peripheral device are reset via the parallel signal input / output port 14 and the second driver element 16 (step 15). After the peripheral device is initialized, the CPU 11 of the main body and the CPU 21 of the peripheral device restore the line via the serial line portions 13 and 23 of each other (step 16), and the CPU 11 of the main body is in the mode with the peripheral device. The main device is operated in cooperation with the peripheral device while communicating with (step 17).

In the step 3, the last time LO
When it is determined that the W state is shorter than the determination time, that is,
When it is determined that the peripheral device has already been connected at the time of the previous monitoring, the CPU 11 of the main body continuously communicates with the peripheral device in the mode with the peripheral device and continuously operates the main body device in cooperation with the peripheral device. .

[0026]

As described above, the present invention does not have a signal line dedicated to monitor the connection / disconnection state of the image forming apparatus main body and the peripheral equipment attached / detached to / from the image forming apparatus main body, and other signals that the interface connector has. Since the connection / non-connection state of the peripheral device is monitored by using the received data signal of the line, the interface connector can be downsized and the image forming apparatus can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to the present invention and peripheral devices connected to the image forming apparatus.

FIG. 2 is a flowchart showing a control procedure.

FIG. 3 is a diagram showing a schematic configuration of an image forming apparatus according to a second embodiment of the present invention and peripheral devices connected to the image forming apparatus.

FIG. 4 is a flowchart showing a control procedure.

[Explanation of symbols]

1 ... Image forming apparatus main body, 2 ... Peripheral device, 3 ... Interface connector, 11, 21 ... CPU, 12, 22 ... Memory, 13, 23 ... Serial line unit (UART) ), 14 ... Parallel signal input / output unit (P I / O), 15 ... First driver element, 16 ... Second driver element, 24 ... Third driver element, R1, R2 ...・ Pull-up resistance, R3 ・ ・ ・ Pull-down resistance,

Claims (4)

[Claims] 1. An image forming apparatus in which a peripheral device such as an automatic duplex unit is detachable, and an interface connector using an asynchronous serial line connecting the image forming device main body and the peripheral device, and the image forming device main body. A resistor for pulling down a data signal transmitted from a peripheral device via the interface connector, and a resistor for pulling up a data signal transmitted from the image forming apparatus main body via the interface connector in the peripheral device, When the interface connector is connected to the image forming apparatus main body and the peripheral device, the level of the data signal transmitted from the peripheral device becomes high, and the interface connector is not connected to the image forming apparatus main body and the peripheral device. Sent from the peripheral device when The signal values for setting the respective resistance values such that the data signal level to be set is low level on the image forming apparatus main body side and the peripheral device side is high level, and a signal for initializing the peripheral equipment is supplied to the image forming apparatus. An image forming apparatus comprising means for outputting from a main body to peripheral equipment. 2. The image forming apparatus according to claim 1,
A data signal from a peripheral device is applied to an input port on the image forming apparatus main body side, and a high level signal is input to the input port when the interface connector is in a connected state,
An image forming apparatus characterized in that a low level signal is inputted to the input port when the interface connector is in a non-connection state. 3. The image forming apparatus according to claim 1, wherein the CPU in the main body of the image forming apparatus monitors the state of the serial line in the main body of the image forming apparatus and determines that the data signal input to the serial line is not in the break state. In this case, the interface connector is determined to be in the connected state, the CPU of the peripheral device is contacted via the serial line, and the linked operation with the peripheral device is performed, and the serial line in the main body of the image forming apparatus is in the break state. If it is detected, it is determined that the interface connector is not connected, the image forming apparatus main body is operated in the mode where the peripheral device is not connected, and the serial line changes from the break state to the non-break state. In this case, it is determined that the interface connector has transitioned from the unconnected state to the connected state, and After outputting a signal for initialization and initializing the CPU in the peripheral device, the communication between the image forming apparatus main body and the peripheral device is restored via the serial line, and the image forming apparatus main body cooperates with the peripheral device. An image forming apparatus characterized in that the image forming apparatus is operated. 4. The image forming apparatus according to claim 2, wherein the CPU in the image forming apparatus main body monitors a state of an input port in the image forming apparatus main body, and a low level is maintained for a predetermined time or more in the input port. If no input is made, it is determined that the interface connector is in a connected state, and the CPU operates the peripheral device through a serial line to perform a cooperative operation with the peripheral device and preliminarily connect to the input port in the main body of the image forming apparatus. If a low level signal is input for more than the set time, it is determined that the interface connector is not connected, and the image forming apparatus main unit is operated in the mode in which peripheral devices are not connected, and The interface connector is not connected when the signal level of the input port becomes high level after the low level signal is input to the input port. After determining that the state has changed to the connection state, outputting a signal for initialization to the peripheral device, initializing the CPU in the peripheral device, and then between the image forming apparatus main body and the peripheral device via the serial line. The image forming apparatus is characterized in that the communication of the image forming apparatus is restored, and the image forming apparatus main body is operated in cooperation with peripheral devices.