JP2000101789A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which never misdetects as the burnout of a lamp for document reading a case wherein the lamp for document reading is not supplied with the electric power from a stabilized power source. SOLUTION: It is judged (step S13) whether a burnout detection signal detecting a lamp current is at an H level. Then when the burnout detection signals reaches the H level (Y at a step S13), it is judged (step S16) whether or not an AC input detection signal detecting the supply of an alternating current to the stabilized power source supplying the electric power to the lamp is at an H level; when the AC input detection signal is at an L level (N at a step S16), it is judged (step S17) that the lamp has burnt out.

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 including a scanner for reading a document and a printer for forming an image of the read document by an electrophotographic method.

[0002]

2. Description of the Related Art In such an image forming apparatus, a scanner is provided with a lamp for reading an original. As means for detecting disconnection of the lamp, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-open No. 101243 discloses a technique in which a stabilized power supply that supplies power to a lamp is provided with a disconnection detection circuit that detects the presence or absence of a lamp current.

[0003]

However, Japanese Patent Application Laid-Open No. Hei 8
In the technique disclosed in Japanese Patent Application Laid-Open No. 101243, there is a problem that the disconnection detection circuit does not detect the lamp current even when power is not supplied to the stabilized power supply, so that the disconnection of the lamp is erroneously detected.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus which does not erroneously detect a case where power is not supplied from a stabilizing power supply to a document reading lamp as a disconnection of the lamp.

Another object of the present invention is to provide an image forming apparatus capable of detecting an abnormality in power supply to a stabilized power supply.

It is another object of the present invention to prevent an erroneous determination about disconnection of a lamp.

Another object of the present invention is to prevent an erroneous determination that there is an abnormality in power supply to a stabilized power supply.

Another object of the present invention is to enable a user to immediately know that an abnormality has occurred in an image forming apparatus.

[0009]

According to a first aspect of the present invention, there is provided a scanner for reading an original, and a printer for forming an image of the read original by an electrophotographic system. In an image forming apparatus having a lamp that irradiates light and a stabilized power supply that supplies power to the lamp, an extinguishing detection circuit that detects the extinguishing of the lamp and a supply of alternating current to the stabilized power supply are provided. An AC detection circuit for detecting, and when the detection of the turning off of the lamp by the turn-off detection circuit is performed when the AC supply is detected by the AC detection circuit, it is determined that the lamp is disconnected. An image forming apparatus, comprising:

Therefore, even if it is detected that the lamp has been turned off, if power is not supplied to the stabilized power supply, it is not determined that the lamp is disconnected, so that erroneous detection of lamp disconnection can be prevented.

According to a second aspect of the present invention, in the first aspect of the present invention, when there is no detection of the supply of AC by the AC detection circuit, it is determined that the power supply to the stabilized power supply is abnormal. Is provided.

Therefore, it is possible to know the abnormality of the power supply to the stabilized power supply.

According to a third aspect of the present invention, in the first or second aspect, a trigger signal output section for outputting a trigger signal for starting lighting of the lamp to the stabilized power supply is provided, and the first determination is made. The means detects that the lamp has been turned off by the light-off detection circuit when the supply of AC is detected by the AC detection circuit after a predetermined time has elapsed from the start of the output of the trigger signal. In this case, the lamp is determined to be disconnected.

Therefore, it is possible to prevent an erroneous determination that the lamp is disconnected from the start of the output of the trigger signal until the lamp is actually turned on.

According to a fourth aspect of the present invention, in the third aspect of the present invention, for a certain period of time, a rising or falling of a lamp extinguishing detection signal output by a non-extinguishing detection circuit determined by a rising characteristic of a lamp current of the lamp. It is characterized by being longer than the fall time.

Therefore, it is possible to prevent the erroneous determination that the lamp is broken from the start of the output of the trigger signal until the lamp is actually turned on.

According to a fifth aspect of the present invention, in the second aspect, a power relay for generating an AC power supply to be supplied from the DC power supply to the stabilized power supply, and outputting a signal for starting the driving of the power relay. A relay drive start signal output unit that performs a predetermined time after the relay drive signal output unit starts outputting a signal to start driving of the power relay. It is characterized by determining whether or not supply has been detected.

Therefore, the erroneous determination that there is an abnormality in the power supply to the stabilized power supply from the start of the output of the signal for starting the drive of the power relay to the actual output of the AC is prevented. Can be prevented.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, the predetermined time is longer than a rise or fall time of an AC detection output of the AC detection circuit determined by a time constant of the AC detection circuit. Features.

Therefore, the erroneous determination that there is an abnormality in the power supply to the stabilized power supply after the output of the signal for starting the driving of the power relay is started and before the AC is actually output is prevented. Can be prevented.

According to a seventh aspect of the present invention, in the first aspect of the present invention, when the first determining means determines that the lamp is disconnected, and when the second determining means determines that the power supply Is provided with a notifying means for notifying the occurrence of an abnormality when it is determined that there is an abnormality.

Therefore, the user can immediately know that an abnormality has occurred in the image forming apparatus.

[0023]

FIG. 1 is a block diagram of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus 1 includes a scanner 2 for reading a document, and a printer 3 for forming an image of the read document by an electrophotographic method.

The scanner 2 includes an original reading lamp 4.
And a stabilized power supply 5 for supplying power to the lamp.

The printer 3 includes a DC power supply 6 for supplying power to each section of the image forming apparatus 1, a control section 7 comprising a microcomputer or the like for controlling each section of the image forming apparatus 1, and an operation for operating the image forming apparatus 1. It has a panel and an operation unit 8 on which a liquid crystal display for displaying various information is formed.

The stabilized power supply 5 converts the AC power supplied from the DC power supply 6 into a stable DC power supply and supplies it to the lamp 4. The DC power supply 6 supplies an AC power supply for lighting the lamp 4 and a DC power supply for a control power supply to the stabilized power supply 5, and supplies a DC power supply to the control unit 7. The control unit 7 has a relay ON / O
The FF signal is output to the DC power supply 6, and the DC power supply 6 turns on the built-in power relay when receiving the relay ON signal.
The off drive is started, the DC power supply 6 generates an AC power supply to be supplied to the stabilized power supply 5 from the DC power supply, and stops when a relay OFF signal is received. Thus, the relay drive start signal output unit of the present invention is implemented. Also, the control unit 7
The stabilized power supply 5 outputs a trigger signal for starting the lighting of the lamp 4 to the stabilized power supply 5. This implements the trigger signal output unit of the present invention. Further, the control unit 7
A display signal for displaying an image on the liquid crystal display panel of the operation unit 8 is output.

FIG. 2 is a circuit diagram of the stabilized power supply 5. As shown in FIG. 2, the stabilized power supply 5 is connected to a power supply line of an AC power supply 11 supplied from a DC power supply 6 by an AC detection circuit 1.
2, rectifier circuit 13, smoothing capacitor 14, control circuit 1
5, the disconnection detecting circuit 16 and the lamp 4 are sequentially connected.

The AC power supply 11 is full-wave rectified by a full-wave rectifier circuit 13 and smoothed by a smoothing capacitor 14. When the trigger signal goes low, the DC power supply
Lamp 4 as a stable DC power source controlled by a chopper
Supplied to

The AC detection circuit 12 detects the presence or absence of an input of the AC 11 to the stabilized power supply 5, and outputs an AC input detection signal (H level signal) to the control unit 7 when there is an input.
Specifically, this circuit is a circuit that outputs an AC input detection signal when the voltage value of the charging circuit connected to the rectified AC power supply 11 is equal to or more than a predetermined value, and an ON signal of a power relay that turns on the AC power supply 11 Delay output with a certain time constant.

The disconnection detecting circuit 16 detects the presence or absence of a lamp current of the lamp 4 and outputs a disconnection detection signal (H level signal) to the control unit 7 when the lamp current is not detected. This implements the light-off detection circuit of the invention. Since the circuit of FIG. 2 has a circuit configuration in which the lamp current is slowly raised to prevent inrush current, the disconnection detection signal is output with a certain time constant delayed from the trigger signal for turning on the lamp 4.

FIG. 3 is a timing chart of a disconnection detection signal and the like in a normal case when an original image is read by the scanner 2 with the above circuit configuration. As shown in FIG. 3, when the trigger signal changes from the H level to the L level, the lamp current starts to flow, and the disconnection detection signal changes from the H level to the L level after a predetermined time (for example, after 200 msec). Then, when the trigger signal becomes H level again, the lamp current stops, and after a certain time (for example, after 10 msec), the disconnection detection signal changes to H level.

FIG. 4 is a timing chart of a disconnection detection signal and the like when the lamp 4 is disconnected. When the lamp 4 is disconnected, the lamp current stops, and the disconnection detection signal changes from L level to H level. Therefore, if the disconnection detection signal becomes H level at the timing when the lamp 4 is turned on, it can be determined that the lamp 4 is disconnected.

FIG. 5 is a timing chart of an AC input detection signal and the like when a relay ON signal is output. FIG.
As shown in (1), when the relay ON signal changes from H level to L level, the ON / OFF driving of the power relay starts.
Then, after a certain time (for example, after 50 msec)
Then, the AC voltage of the AC power supply 11 rises, and the AC input detection signal changes from H level to L level.

FIG. 6 is a flowchart of the AC input check process performed by the control unit 7. This process is performed when the supply of AC power from the DC power supply 6 to the stabilized power supply 5 is started. As shown in FIG. 6, the control unit 7 sets the relay ON signal for turning on the power relay of the DC power supply 6 to the L level, turns on the power relay (step S5).
1) After elapse of 50 msec or more (Y in step S2), it is determined whether or not the AC input detection signal is at the H level (step S3). When the AC input detection signal is at the L level (N in step S3), the input of the AC power to the stabilized power source 5 is assumed to be normal, and the process ends (step S4). When the AC input detection signal is at the H level (Y in step S3), it is determined that the input of the AC power to the stabilized power supply 5 is not performed normally (step S5), and the liquid crystal panel of the operation unit 8 displays A display signal for displaying the serviceman call is output, and the process is terminated (step S
6). Step S5 implements the second determining means of the present invention, and step S6 implements the notifying means of the present invention.

As described above, when the AC input detection signal is at the H level, it is determined that the input of the AC power to the stabilized power supply 5 is not performed normally (step S).
5) An abnormality in power supply to the stabilized power supply 5 can be known. Further, after waiting for a lapse of time from when the relay ON signal for turning on the power relay of the DC power supply 6 is turned to L level to when the AC voltage of the AC power supply 11 is output (step S2, see FIG. 5), the AC Since the input detection signal is determined (step S3), it is erroneously determined that there is an abnormality in the supply of the AC power supply 11 from when the relay ON signal is set to the L level until the AC voltage of the AC power supply 11 is actually output. Can be prevented from being performed. Further, when it is determined that the input of the AC power supply is not performed normally (step S5), a serviceman call is displayed on the liquid crystal panel of the operation unit 8, so that the user may be notified of the occurrence of the abnormality of the image forming apparatus 1. You can know immediately.

FIG. 7 is a timing chart of the AC voltage, the AC input detection signal, and the disconnection detection signal. When the AC voltage of the AC power supply 11 is off, both the AC input detection signal and the disconnection detection signal are H level signals, and when the AC voltage of the AC power supply 11 is on, both the AC input detection signal and the disconnection detection signal This is an L level signal. Since the lamp current does not flow when the AC voltage of the AC power supply 11 is off, the disconnection detection signal also goes high regardless of the trigger signal.

FIG. 8 is a flowchart for explaining the driving process of the lamp 4 performed when the original is read by the scanner 2. Note that the processing in FIG. 6 has already been completed prior to the processing in FIG. As shown in FIG. 8, the control unit 7 changes the trigger signal from an H level signal to an L level signal in order to start lighting of the lamp 4 (step S1).
1) After 200 msec has elapsed (Y in step S12), it is determined whether or not the disconnection detection signal is at the H level (step S13). This determination is made until the reading of the original by the scanner 2 is completed (step S1).
4) After the end (Y in step S14), the lamp 4 is turned off (step S15), and the process ends.

If the disconnection detection signal is at the H level before the reading of the document by the scanner 2 is completed (Y in step S13), it is further determined whether or not the AC input detection signal is at the H level. (Step S16) When the AC input detection signal is at the L level (N in Step S16)
It is determined that the lamp 4 is disconnected (step S1).
7) A display signal for displaying a serviceman call is displayed on the liquid crystal panel of the operation unit 8, and the process is terminated (step S18). Step S17 implements the first determining means of the present invention. When the AC input detection signal is at the H level (Y in step S16), it is determined that there is an abnormality in the input of the AC power to the stabilized power supply 5 (step S19), and a serviceman is displayed on the liquid crystal panel of the operation unit 8. A display signal for displaying a call is output, and the process ends (step S20). Step S19 implements the second determining means of the present invention.

As described above, when the disconnection detection signal is at the H level and the AC input detection signal is at the L level, it is determined that the lamp 4 is disconnected (step S17), and the supply of AC power to the stabilized power supply 5 is abnormal. Is prevented from being erroneously detected as a disconnection of the lamp 4. In addition, after waiting for the time from when the trigger signal goes low to when the lamp current rises (step S12, see FIG. 3), the disconnection detection signal is determined (step S13), so that the trigger signal goes low. Before the lamp current actually starts up,
It is possible to prevent erroneous determination that the lamp is disconnected. Further, when it is determined that the lamp 4 is disconnected or that the input of the AC power is not normally performed (steps S17 and S19), a serviceman call is displayed on the liquid crystal panel of the operation unit 8 (step S17). S18, 20), the user can immediately know that an abnormality has occurred in the image forming apparatus 1.

[0040]

According to the first aspect of the present invention, even if it is detected that the lamp is turned off, it is not determined that the lamp is disconnected when power is not supplied to the stabilized power supply. False detection can be prevented.

According to a second aspect of the present invention, in the first aspect of the present invention, it is possible to know an abnormality in power supply to the stabilized power supply.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the lamp is disconnected from when the trigger signal is output until the lamp is actually turned on. It is possible to prevent an erroneous determination from being made.

According to a fourth aspect of the present invention, in the third aspect of the present invention, it is erroneously determined that the lamp is disconnected from when the trigger signal is output until the lamp is actually turned on. It is possible to prevent a judgment from being made.

According to a fifth aspect of the present invention, in the second aspect of the present invention, the output of the signal for starting the power relay is started to the output of the stabilized power supply until the AC is actually output. It is possible to prevent erroneous determination that there is an abnormality in power supply.

According to a sixth aspect of the present invention, in the invention of the fifth aspect, the output of the signal to start driving the power relay is started and then the output to the stabilized power supply is started until the AC is actually output. It is possible to prevent erroneous determination that there is an abnormality in power supply.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the user can immediately know that an abnormality has occurred in the image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a stabilized power supply of the image forming apparatus.

FIG. 3 is a timing chart of a disconnection detection signal and the like in a normal case when a document image is read by a scanner of the image forming apparatus.

FIG. 4 is a timing chart of a disconnection detection signal and the like when a lamp of the image forming apparatus is disconnected.

FIG. 5 is a timing chart of an AC input detection signal and the like when the image forming apparatus outputs a relay ON signal.

FIG. 6 is a flowchart of an AC input check process performed by a control unit of the image forming apparatus.

FIG. 7 is a timing chart of an AC voltage, an AC input detection signal, and a disconnection detection signal.

FIG. 8 is a flowchart illustrating a lamp driving process performed when an original is read by a scanner of the image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Scanner 3 Printer 4 Lamp 5 Stabilized power supply 7 Trigger signal output part, relay drive start signal output part 12 AC detection circuit 16 Lights out detection circuit

Claims (7)

[Claims] 1. A scanner for reading a document, and a printer for forming an image of the read document by an electrophotographic method, wherein the scanner irradiates light to the document and supplies power to the lamp. An image forming apparatus having a stabilized power supply, wherein an extinguishing detection circuit for detecting the extinguishing of the lamp, an alternating current detection circuit for detecting the supply of an alternating current to the stabilized power supply, and a lamp by the extinguishing detection circuit And a first determination unit that determines that the lamp is disconnected when the AC detection circuit detects the supply of AC by the AC detection circuit. Image forming apparatus. 2. The apparatus according to claim 1, further comprising a second determination unit configured to determine that there is an abnormality in the power supply to the stabilized power supply when no AC supply is detected by the AC detection circuit. The image forming apparatus as described in the above. 3. A stabilizing power supply comprising: a trigger signal output unit configured to output a trigger signal for starting lighting of a lamp to the stabilizing power supply; And determining that the lamp is disconnected if a predetermined period of time has elapsed after the start of the output of the trigger signal. Or the image forming apparatus according to 2. 4. The lamp according to claim 3, wherein the predetermined time is equal to or longer than a rising or falling time of a detection signal for lamp extinguishing output from the extinguishing detection circuit determined by a rising characteristic of a lamp current of the lamp. Image forming device. 5. A second determining means, comprising: a power relay for generating an AC power supply to be supplied from the DC power supply to the stabilized power supply; and a relay drive start signal output unit for outputting a signal for starting to drive the power relay. And determining whether or not the AC detection circuit detects the supply of AC after a lapse of a predetermined time since the relay drive signal output unit starts outputting a signal to start driving the power relay. An image forming apparatus according to claim 1. 6. The image forming apparatus according to claim 5, wherein the predetermined time is equal to or longer than a rise or fall time of an AC detection output of the AC detection circuit determined by a time constant of the AC detection circuit. 7. A notifying means for notifying the occurrence of an abnormality when the first judging means judges that the lamp is disconnected and when the second judging means judges that there is an abnormality in the power supply. The image forming apparatus according to claim 1, wherein: