JP3426710B2 - Printing equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing device such as a laser printer.

[0002]

2. Description of the Related Art In a conventional laser printer, a thermistor, which is a temperature sensor for controlling the surface temperature of the fixing device, is usually connected to a main body substrate through a connector.

[0003]

However, in such a laser printer, the connection of the above-mentioned connector may be forgotten when the laser printer is assembled. In such a case, since the surface temperature of the heat roller cannot be detected by the temperature sensor, the surface temperature of the heat roller is always determined to be low. As a result, the heating of the heat roller may be mistakenly continued and the fixing device may be thermally destroyed. For this, conventionally, a method has been used in which it is determined whether or not a connector is forgotten to be connected by detecting whether or not there is a resistance change in a temperature sensor (thermistor) within a predetermined time after starting to energize a heater. In addition, JP-A-62-42177
As disclosed in Japanese Patent Publication No. JP-A-2003-187, a connector for connecting to a temperature sensor has three terminals, and by detecting the potential of one terminal, it is possible to judge that the connector is forgotten to be connected and to shut off the heater from the power supply. Can also be considered. However, in the case of the former, it cannot be judged until the heater rises to a predetermined temperature,
It takes time to detect. Further, in the latter case, it is necessary to additionally provide a terminal for detection and a signal line in the connector, which causes a problem that the cost becomes high. Therefore, in order to deal with such a situation, the present invention can accurately recognize the forgetting to connect the connector used for connecting the temperature sensor in a printing device such as a laser printer immediately after the power is turned on, and the special It is intended to make it possible to configure inexpensively without adding a special signal line.

[0004]

In order to solve the above problems, the invention according to claim 1 is an image forming apparatus for forming print data as an image on a paper while receiving a laser beam by a photosensitive drum, A fixing device for fixing the image on the paper conveyed from the image forming device by a heat roller heated by a heater; a conveying device for conveying the paper through the image forming device and the fixing device; Using the paper detection means for detecting the presence or absence of the paper in the apparatus, the temperature detection means for detecting the surface temperature of the heat roller, and the detection outputs of the paper detection means and / or the temperature detection means. A control device for controlling heating by the heater and paper transportation of the transportation device is provided, and the control device and the paper detection means and the temperature detection means are combined into a single connector. Connect the motor, and the control device is configured to have a determining means for determining a state of the paper detecting means and the signal line connected via the connector immediately after the power is turned on.

In order to solve the above-mentioned problems, the invention according to claim 2 is the invention according to claim 1, in which the judging means causes the signal line to detect the presence of the paper by the paper detecting means immediately after the power is turned on. When it is determined that it is in the same state as the detected state, it is configured to have an informing unit that informs as an abnormal state.

[0006]

As described above, according to the first aspect of the invention, the sheet detecting means for detecting the presence / absence of the sheet in the fixing device and the temperature detecting means for detecting the temperature of the fixing device are controlled by the single connector. Whether or not it is in an abnormal state is detected by determining the state of the signal line that is connected and is connected to the sheet detecting means via the connector immediately after power is turned on. Therefore,
Immediately after turning on the power, you can immediately judge if you forget to connect the connector, etc.
It is possible to prevent the situation in which the heater is energized without the temperature detecting means operating. Further, by judging the state of the signal line to the sheet detecting means, the judgment can be made without adding a special signal line.

Further, as described above, in the invention described in claim 2, when the signal line is in a state equivalent to the presence of the paper detected by the paper detection means immediately after the power is turned on, the notification means is abnormal. Notify as the status. That is, forgetting to connect the connector can be detected and notified as a state equivalent to the presence of paper immediately after the power is turned on.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, and FIGS. 2 and 3 show a schematic overall configuration of a laser printer according to the present invention. As shown in FIG. 2, this laser printer is provided with a sheet feeding device 20 in the lower portion inside the machine body 10. The sheet feeding device 20 is provided with a sheet feeding roller 21, and a guide 23 located on the downstream side in the conveying direction. The paper 22 is guided along the sheet and is sent toward the registration roller pair 40. The registration roller pair 40 starts to rotate after a lapse of a predetermined time after the tip of the paper 22 from the paper feeding device 20 is applied to the roller pair. For this reason, the paper 22 is rotated by the pair of registration rollers 40 and the pair of registration rollers 4 is rotated.
The guide 4 is located on the downstream side in the transport direction while being sandwiched between 0s.
1, the sheet is guided by the pre-transfer roller 50, and is sent out toward the image forming apparatus 60.

The image forming apparatus 60 includes a photosensitive drum 60a.
A scanner unit 60b that performs exposure to form an electrostatic latent image on the photosensitive drum 60a; a developing unit 60c that adheres toner to the electrostatic latent image formed by exposure to form a toner image. , The toner image on paper 22
It is composed of a transfer charger 60d that transfers the sheet 22 to a sheet and a charge eliminator 60e that removes the sheet 22 from the photosensitive drum 60a after the transfer. The scanner unit 60b has a scanner motor 61 (see FIG. 3).
The polygon mirror (not shown) is rotated in accordance with the rotation, and the laser beam from the light source (not shown) is made to scan in one direction along with this rotation, and is incident on the photoconductor drum 60a under the reflecting action of the mirror 62. The sheet 22 conveyed to the image forming apparatus 60 configured as described above is in a state where the toner image formed on the photosensitive drum 60a is transferred,
It is guided toward the fixing device 70 by being guided by the guide 61 located on the downstream side of the photosensitive drum 60a in the conveying direction.

The fixing device 70 includes a paper sensor 30 (see FIGS.
3), the heat roller 70a, and the heat roller 7
0a, a pressure roller 70b and a conveying roller pair 70
c and a temperature sensor 70d (see FIG. 1). In the fixing device 70, the paper detecting unit, that is, the paper sensor 30, is provided with the heat roller 70 a and the pressure contact roller 7.
The presence or absence of the sheet 22 is detected at the downstream position of 0b. The paper sensor 30 is composed of a photo coupler.
As shown in FIG. 1 and FIG. 4, 0 is the light emitting diode 3 in each of the bifurcated portions 31a and 31b of the U-shaped sensor body 31.
2 and a phototransistor 33, respectively. Then, when the light emitting diode 32 is emitting light toward the phototransistor 33, the paper 22
Is not inside the fixing device 70, the light shielding member lever 34 is located between the forked portions 31a and 31b, and the light emitting diode 32 is
Light from the phototransistor 33 is blocked from entering. After that, when the sheet 22 is in the fixing device 70, the sheet pushes the detection end 34b of the lever, whereby the light blocking lever 34 rotates and moves from between the forked portions 31a and 31b to emit light. Light is allowed to enter the phototransistor 33 from the diode 32. As a result, the fixing device 7 for the sheet 22
Presence or absence within 0 is detected. In such a case, the paper sensor 3
0 is disposed on the substrate B in the fixing device 70. Further, the light-shielding lever 34 is adapted to rotate with reference to a rotating shaft 34a which is pivotally supported at a proper position.

In the fixing device 70, therefore, the paper 22 from the guide 61 is pressed against the heat roller 70a by the pressing roller 7a.
After the toner image is heat-fixed while being pressed by 0b, it is sent out toward the discharge guide 80 by the pair of transport rollers 70c. The paper discharge guide 80 guides the paper 22 from the conveying roller pair 70c to the paper discharge roller pair 81. In such cases,
The heat roller 70a has a heater 71 provided therein.
(See FIGS. 3 and 4). The paper discharge roller pair 81 sends the guided paper 22 onto a paper discharge tray 82 provided at the top of the machine body 10. The temperature detecting means, that is, the temperature sensor 70d (see FIG. 1) is composed of a thermistor having a negative resistance temperature characteristic.
It is arranged close to the heat roller 70a and detects the temperature of its surface.

Next, the electric circuit configuration of the laser printer will be described with reference to FIGS. 1, 3 and 4. Control device 90
Is a microcomputer including a CPU, a ROM, a RAM and a bus line (hereinafter, referred to as a microcomputer 9
0), and this microcomputer 90 uses the signal line 90e for the A / D converter 90a.
And the temperature sensor 70d via the connector 90b, and the signal line 90f to the paper sensor 30 via the connector 90b. A-D converter 9
0a receives the temperature detection output from the temperature sensor 70d via the connector 90b, converts it into a digital value, and outputs it to the microcomputer 90 as a digital temperature detection output. Further, the paper sensor 30 outputs the detection output to the microcomputer 90 via the connector 90b. A signal line 90e connected to one end of the temperature sensor 70d is connected to a low voltage power supply unit 1 described later via a pull-up resistor 91.
00 to the power supply line 100a. The other end of the temperature sensor 70d is grounded.

One end of the light emitting diode 32 of the paper sensor 30 and the collector of the phototransistor 33 are connected to the signal line 100a from the low voltage power supply unit 100 via resistors 95 and 96, respectively. The other end of the light emitting diode 32 and the emitter of the phototransistor 33 are grounded. The signal line 90f connected to the collector of the phototransistor 33 is grounded via the pull-down resistor 92. The connector 90b is composed of a pair of connector members 93 and 94 which are detachably connected to each other, and one connector member 94 is fixed on the board B. With both connector members 93, 94 connected, the temperature sensor 70d is connected to the signal line 90e, the power supply line 100a and the ground terminal as described above, and the paper sensor 30 is also connected.
Is connected to the power supply line 100a, the signal line 90f and the ground terminal as described above. The temperature sensor 70d is once connected to the board B by a connector 90c fixed on the board B and then connected to the connector 90b (see FIG. 4). The microcomputer 90 is an AD converter 90.
It is arranged on the machine board in the machine body 10 together with a and the like.

Further, the microcomputer 90 is connected to the low voltage power supply unit 100, the scanner motor 61, the high voltage power supply unit 110, the motor driver 120, the electromagnetic clutch 130, the AC driver circuit 140, the video controller circuit board 150 and the alarm 180. ing. Then, the microcomputer 90 receives the low voltage from the low voltage power supply unit 100 and executes the computer program according to the flowchart shown in FIG. 5, and during this execution, the paper sensor 30 and the AD converter. 90a and the output from the video controller circuit board 150, the scanner motor 61, the high-voltage power supply unit 1
10, motor driver 120, electromagnetic clutch 130, A
C driver circuit 140, video controller circuit board 1
The arithmetic processing required to control 50 and the alarm device 180 is performed. However, the above computer program is stored in advance in the ROM of the microcomputer 90.

When the outlet 100a is connected to an AC power source (for example, 100V), the low voltage power supply unit 100 receives an AC voltage from the outlet 100a and outputs a low voltage. The high-voltage power supply unit 110 is controlled by the microcomputer 90, and the developing unit 60
c, a high voltage is output to the transfer charger 60d and the static eliminator 60e. The motor driver 120 includes the low voltage power supply unit 10
The main motor 160 is driven under the control of the low voltage from 0 and the microcomputer 90. The main motor 160 is provided with a paper feed roller 21 and a paper transport device, that is, a pair of registration rollers 4 via various speed reduction mechanisms (not shown).
0, the photoconductor drum 60a, the paper discharge roller pair 81, the heat roller 70a, and other rollers related to paper conveyance.
The electromagnetic clutch 130 is selectively engaged under the control of the microcomputer 90 and transmits the output torque from the main motor 160 to the registration roller pair 40. In such a case, the electromagnetic clutch 130 causes the registration roller pair 4
0 is coaxially connected. AC driver circuit 140
Drives the heater 71 under the control of the low voltage from the low voltage power supply unit 100 and the microcomputer 90. The video controller circuit board 150 creates print data from the character data and control data from the external device 170, outputs the print data to the microcomputer 90 together with a print start command, and outputs the control output from the microcomputer 90 to the external device 170. To do. The alarm 180 is
The notification operation is performed based on the notification data from the microcomputer 90.

In the present embodiment configured as described above,
When the low-voltage power supply unit 100 generates a low voltage based on the AC voltage from the outlet 100a with the power switch 100b closed, the microcomputer 90
Becomes an operating state according to the low voltage, starts execution of the computer program according to the flowchart shown in FIG.
The determination unit 90g within 0 determines the potential of the signal line 90f that should be connected to the paper sensor 30. Here, if the connector members 93 and 94 are not connected, the signal line 90f
Is cut off and has a low level potential. Therefore,
The microcomputer 90 immediately determines “YES” in step 200, and outputs a warning indicating that the connector 90b is not connected as notification data to the notification device 180 in step 210. Then, the notification device 180 performs a notification operation based on the notification data. At the same time, in step 210a, the microcomputer 90 performs a drive stop process for the main motor 160, the image forming device 60, the fixing device 70, and the like. As a result, the conveyance operation of the paper 22 is stopped and the heating of the heater 71 of the image forming and fixing device is stopped. That is, most operations related to image formation are stopped. After that, if the power is turned off, step 22
The determination at 0 is “NO”.

The printing process can be executed as will be described later by opening the machine body 10 to eliminate the abnormality, for example, by connecting the connector members 93 and 94. When the power is turned on and the paper jam remains in the fixing device 70 even if the connector members 93 and 94 are connected, the paper sensor 30 causes the light of the light emitting diode 32 to enter the phototransistor 33 by the movement of the light shielding lever 34. ing. For this reason, the potential of the collector of the phototransistor 33 becomes low level, and the determination section 90g determines the low level of the signal line 90f. Therefore, the notification operation is performed in the same manner as described above, and the printing operation is stopped. Also in this case, if the machine body 10 is opened to remove the paper jam, the normal operation can be restored.

On the other hand, in step 200, if the connector members 93 and 94 are connected and there is no sheet in the fixing device 70, the sheet sensor 30 causes the light blocking lever 34 to operate.
Since the light from the light emitting diode 32 to the phototransistor 33 is blocked by this, the potential of the collector is at a high level. Therefore, the determination unit 90g determines that the signal line 90f
Is detected, the determination in step 200 becomes “NO”. Then, the determination in step 230 is performed. At this stage, when the print start command is output from the video controller circuit board 150 to the microcomputer 90, the microcomputer 90
In step 230, it is determined to be "YES", and in the print processing routine 240, the control required for the print processing is performed. This causes the scanner motor 61 to rotate steadily and the heater 71 of the fixing device 70 to heat the heat roller 70 a, so that the pair of registration rollers 40 from the paper feeding device 20.
The printing process is performed on the sheet 22 conveyed through the sheet. More specifically, the AC driver circuit 140 heats the heater 71, the main motor 160 is driven by the motor driver 120, and the paper feed roller 21, the photosensitive drum 60a, the paper discharge roller pair 81, and the heat roller 70a are driven. The registration roller pair 40 is driven by driving the main motor 160 and engaging the electromagnetic clutch 130. Then, in such a state, the sheet 22 is conveyed from the sheet feeding device 20 through the registration roller pair 40 in response to the driving of the sheet feeding roller 21, and is developed based on the print data from the video controller circuit board 150. Printing processing is performed by the unit 60c and the fixing device 70.

During this operation, since the temperature sensor 70d is connected to the microcomputer 90 through the connector 90b common to the paper sensor 30, the microcomputer 90 normally controls the temperature of the heater 71 of the fixing device 70. Be seen. Further, the paper sensor 30 outputs a signal to the microcomputer 90 through the signal line 90f by moving or blocking the light-shielding lever 34 as the paper passes, as described above, and the microcomputer 9 based on the signal.
When 0 is set, the printing process is continued or the occurrence of a paper jam is determined and the alarm device 180 is operated. Then step 2
When the determination in 50 is “YES”, the execution of the computer program ends. The alarm 180 is
A liquid crystal display, a light emitting diode, a sound generator, or the like can be used.

As described above, in this embodiment, the connector 90b which is the connecting means between the temperature sensor 70d and the AD converter 90a is also used as the connecting means between the paper sensor 30 and the microcomputer 90. By doing so, immediately after the microcomputer 90 starts executing the computer program, that is, immediately after the microcomputer 90 is powered on, it is determined whether or not the connector 90b is not connected based on the state of the signal line connected to the connector 90b. This makes it possible to determine whether or not the connector 90b is in the unconnected state without depending on the temperature sensor 70d. For this reason, when the connector 90b is not connected, it is possible to immediately notify the same connection with good timing, so that the connector 90b can be connected immediately. Therefore, it is possible to prevent a situation in which the heating of the heat roller 70a is erroneously continued and the fixing device is thermally destroyed while the connector 90b remains unconnected.

[0021]

According to the configuration and the operation of the invention described in claim 1 as described above, the state of the signal line connected to the sheet detecting means via the connector is determined immediately after the power is turned on. The forgetting to connect the connector can be reliably detected with good timing immediately after the power is turned on. Therefore, the fixing device is not destroyed by heat. In addition, it is possible to configure inexpensively because it is not necessary to add a special terminal or signal line for detection.

According to the configuration and the operation of the invention described in claim 2 as described above, it is determined that the signal line is in the same state as when the presence of the sheet is detected by the sheet detecting means immediately after the power is turned on. When this occurs, the abnormal state is notified, and in addition to the effect of the invention described in claim 1, the abnormal state, for example, forgetting to connect the connector can be reliably recognized by the notification.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a connection configuration between a control device of FIG. 3 and a temperature sensor and a paper sensor.

FIG. 2 is a schematic sectional view of a laser printer according to the present invention.

FIG. 3 is an electric circuit configuration diagram of the laser printer.

FIG. 4 is a perspective view showing a configuration of a sheet sensor in relation to peripheral elements.

5 is a flowchart showing the operation of the microcomputer of FIG.

[Explanation of symbols]

22 ... Paper, 30 ... Paper sensor, 40 ... Registration roller pair, 60 ... Image forming device, 70 ...
Fixing device, 70c ... Conveying roller pair, 70d ... Temperature sensor, 71 ... Heater, 90 ... Control device (microcomputer), 90b ... Connector.

Continuation of the front page (56) Reference JP-A-1-16811 (JP, A) JP-A-3-102383 (JP, A) JP-A-6-230619 (JP, A) JP-A-5-41256 (JP , A) JP 61-189581 (JP, A) JP 1-179062 (JP, A) JP 5-137380 (JP, A) JP 5-132161 (JP, A) JP 61-229112 (JP, A) JP 60-261953 (JP, A) JP 5-210333 (JP, A) JP 59-51367 (JP, A) JP 55-53344 (JP, A) JP-A-6-250563 (JP, A) JP-A-57-72569 (JP, A) Actually open 3-103514 (JP, U) Actually open 61-57874 (JP, U) Actually open 57 -178247 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 21/00 370-512 G03G 15/20 109

Claims (2)

(57) [Claims] 1. An image forming apparatus for forming print data on a sheet as an image while receiving a laser beam on a photosensitive drum, and a sheet on the sheet conveyed from the image forming apparatus by a heat roller heated by a heater. A fixing device for fixing the image on the sheet, a conveying device for conveying the sheet through the image forming device and the fixing device, a sheet detecting unit for detecting the presence or absence of the sheet in the fixing device, and the heat roller A temperature detecting means for detecting the surface temperature of the sheet, and a control device for controlling the heating by the heater and the sheet conveying of the conveying device by utilizing the respective detection outputs of the sheet detecting means and / or the temperature detecting means. Then, the control device and the paper detection means and the temperature detection means are connected by a single connector, and the control device is connected via the connector. A printing apparatus having a judgment means for judging the state of a signal line connected to the recording paper detection means immediately after the power is turned on. 2. When the judgment means judges that the signal line is in the same state as when the presence of the paper is detected by the paper detection means immediately after the power is turned on, a notification means is provided to notify as an abnormal condition. The printing apparatus according to claim 1, wherein the printing apparatus is configured to do so.