JP3130566B2 - Laser recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser printer having a safety switch for opening and closing a maintenance power supply and opening and closing a drive power supply when the member is opened and closed.
The present invention relates to a laser recording device such as a digital copying machine and a laser fax.

[0002]

2. Description of the Related Art A laser recording apparatus uses a light-emitting source such as an LD (semiconductor laser), irradiates a photosensitive member with laser light scanned by a polygon mirror, and obtains an image by an electrophotographic process. Since the laser beam has a high energy density, there is a danger that a human body will be adversely affected when exposed to radiation. Units using a high-voltage power supply such as a charger, a developing unit, a transfer separation unit, and a cleaning unit are arranged around the photoreceptor. Also,
A fixing unit for fixing toner on paper is heated to a high temperature by a heater. Such a laser recording apparatus is usually configured so that an opening / closing member, for example, a cover or a door can be opened so that a user or a service person can open the inside of the apparatus and perform a jam processing and maintenance easily.

[0003] In the device configured as described above, when the opening / closing member is opened, prevention of finger entanglement in the drive unit, prevention of electric shock due to contact with the high voltage unit, prevention of burns due to contact with the high temperature unit, prevention of exposure to laser light, and the like. Safety is emphasized, and it is regulated by public test organizations in Japan and overseas. As a specific safety mechanism for this purpose, a drive unit, a high-voltage unit, a high-temperature unit, and a door interlock switch that cuts off the power supply to the laser are provided when the opening / closing member is opened. There are things that do not occur. The door interlock switch as a safety switch requires the use of a normally open contact so that the contact is opened when a failure occurs. The laser interlock switch is more strictly defined, and safety measures such as providing a plurality of switches in series are required. Also, it is not recommended to use a power supply through a safety switch as a signal line for electrical connection because troubles in a signal system may impair the function of the safety switch.

As described above, when the opening / closing member for maintenance is opened, the first safety switch and the power supply to the laser are cut off for the purpose of cutting off the power supply to the drive section, the high voltage section, and the high temperature section. A second and third safety switch is required for the purpose. Further, an opening / closing detecting means for notifying the opening / closing state of the opening / closing member to a control unit for controlling the operation of the unit is required. The applicant of the present invention is a method of using a three-terminal type having a common contact, a normally open contact, and a normally closed contact as one of the three safety switches as the open / close detection means, and using the normally closed contact as the open / close detection means. Invented by According to this method, three switches may be opened and closed in conjunction with opening and closing of the opening and closing member.

The operation of the safety switch will be described with reference to a structural diagram of a door switch (SW) unit shown in FIG. When the opening / closing member 1 is closed, the pressing link 3 is pressed by the pressing member 2 provided on the opening / closing member 1 to rotate. The SW pressing shaft 4 fixed to the tip of the pressing link 3 presses the actuators 7a to 7c of the three safety switches a to c which are coaxially fixed on a bracket 5 fixed to the main body. With such an operation, the three safety switches a to c are closed, but the order of opening and closing is not fixed due to variation in parts.

FIG. 8 shows a connection example in which an open / close detection signal is extracted from three safety switches a to c. The connection method shown in FIG. 8A is a method in which the first safety switch a is of a three-terminal type and the normally closed contact A is used as open / close detection means. In the connection method shown in FIG. 8B, of the two safety switches b and c connected in series to the LD drive power supply 8, the preceding second safety switch b is of a three-terminal type and has a normally closed contact. This is a method in which B is used as opening / closing detection means.

[0007]

As described above, since the order of opening and closing of the three safety switches a to c is not fixed, each of the safety switches a to c when the opening and closing member 1 is not completely closed. The open / close state of c may be different. In the connection method shown in FIG. 8A, when the first safety switch a is closed when the opening / closing member 1 is not completely closed,
The control unit determines that the opening / closing member 1 is closed, and tries to make the LD emit light. At this time, if the second or third safety switches b and c are open, no power is supplied to the LD and no light is emitted. On the other hand, since there is no feedback from the light amount detector, the control unit tries to supply the current to the LD to the maximum. At this time, if both the second and third safety switches b and c are closed, a large current flows through the LD, and the amount of emitted light exceeds the rating, which may cause deterioration or destruction of the LD. FIG.
The same applies to the connection method (b). If the second safety switch b operates before the third safety switch c, a similar problem may occur.

An object of the present invention is to provide a laser recording apparatus having a safety mechanism that does not cause the LD to be degraded or destroyed in view of the above-mentioned conventional problems.

[0009]

An object of the present invention is to provide a laser light source, a power supply for driving the laser light source, and a laser light source.
Opening and closing member that can be opened and closed during maintenance,
The open / close member provided between a laser light source and the power supply;
Is opened when opened, and closed when the opening / closing member is closed.
Safety switch and that the safety switch is closed.
Detect and permit emission of laser light from the laser light source
This is achieved by a first means provided with control means . Further, in the first means, the safety switch and the control
Via coupling means electrically isolated from the means
This is also achieved by the connected second means. Further, a laser light source and a first power source for driving the laser light source are provided.
And a second power source different from the power source driving the laser light source.
Power supply and emission of laser light from the laser light source
Control means for permitting the
An opening and closing member that can be opened and closed at the time of
Provided between the first power supply and the opening / closing member is opened;
Open when the opening and closing member is closed
A safety switch, between the control means and the second power source;
The opening / closing member is opened when the opening / closing member is opened,
A second safety switch that closes when the closing member is closed.
When the opening and closing member is closed, first, the first
The safety switch closes, followed by the second safety switch
Closing, the control means closing the second safety switch;
Is detected, laser light is emitted from the laser light source.
This is also achieved by a third means for permitting

[0010]

According to the first means, the safety switch is closed.
And permits the emission of laser light from the laser light source.
By that, L at the time of opening and closing the closing member at the time of maintenance
D is not degraded or destroyed. According to the second means, the safety switch and the control means are electrically insulated.
By being connected via the coupling means ,
The safety can be more reliably improved without the trouble of the signal system impairing the function as a safety switch. According to the third means, when the opening / closing member is closed, first the first safety
Switch closes, then the second safety switch closes,
The control means detects that the second safety switch is closed and
By this <br/> and the laser beam from the laser light source is allowed to be emitted, it is unnecessary to lead to deterioration or destruction of the LD at the time of opening and closing the closing member during maintenance.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a sectional view schematically showing the structure of a laser recording apparatus according to one embodiment of the present invention. Inside the apparatus, a photoconductor 11, a writing unit 12, a developing unit 13, a paper feeding unit 14, a transfer separation unit 15, a charging unit 16, a cleaning unit 17, a fixing unit 18, a paper discharging unit 19, and a door S are provided.
Although not shown, a control unit, a power supply unit (PSU), a drive motor, and the like are provided. FIGS. 3A and 3B are perspective views showing the appearance when the front door, which is an opening / closing member, is closed and opened. When the front door 21 is opened, the door SW unit 20 closed by the pressing member 22 provided on the front door 21
Is opened, and a safety switch to be described later is operated.

FIG. 1 is a block diagram showing a connection example of a drive unit of these units and a safety switch which operates when the door is opened. As shown, the AC power supply 25 is connected to a power supply unit (PS).
U) At 26, it is converted to a DC power supply of + 24V, + 5V or the like. The safety switches a, b, and c are two-terminal normally open contacts, and are of a type that conducts when the switch is closed and shuts off when the switch is opened. + 24V is connected to the contact of the safety switch a, and the other contact is connected to the fixing heater driving unit 27, the motor driving unit 28, and the high voltage power supply 29. The front door 2
When 1 is closed and the safety switch a is closed, +24 V is supplied to the fixing heater drive unit 27, the motor drive unit 28, and the high voltage power supply 29. Further, when the front door 21 is opened and the safety switch a is opened, the power supplied to the respective parts 27, 28 and 29 is cut off.

The fixing heater driving unit 27 drives the fixing heater 30, and the motor driving unit 28 drives a driving motor 31.
The drive motor 31 is connected to the photosensitive member 11, the developing unit 13,
The paper feed unit 14, the cleaning unit 17, the fixing unit 18, the paper discharge unit 19 and the like are driven. A high-voltage power supply 29 supplies a developing bias, a charging charger, a transfer separating charger, and a pre-cleaning charger to the developing unit 13, the charging unit 16, the transfer separating unit 15, and the cleaning unit 17, respectively.

The control unit 32 and the LD driving unit 33 include +
A control power supply of 5 V or the like is directly supplied without passing through a safety switch. Further, + 5V is connected to the anode of the LD 34 via a transistor 35 at a subsequent stage through the safety switches b and c in series as a drive power supply for the LD 34. The transistor 35 is turned on when the safety switches b and c are closed and the output port signal (LDON) of the control unit 32 is low, and supplies drive power to the LD 34. The LD 34 has a built-in PD (photodiode) 36 for monitoring the light emission intensity, and has a connection method called an anode common. In addition, safety switches b and c
The subsequent stage is connected to the input of the photocoupler 37 via the current limiting resistor R, and the output of the photocoupler 37 is connected to the input port of the control unit 32 as a DOOR / OPEN signal. When the front door 21 is opened and the safety switch b or c is opened, the drive power supplied to the LD 34 is cut off, and at the same time, the DOOR OPEN signal becomes high, and the control unit 3
Reference numeral 2 indicates that the front door 21 is open.

Next, the LD driving section 33 shown in FIG. 1 will be described. The current source 40 drives a current flowing through the LD 34, and includes a transistor 41, a differential amplifier 42, and a resistor R. The current value changes according to a LEVEL voltage that is an analog output of the control unit 32. The switching circuit 43 converts the current driven by the current source 40 into an LD 34 according to a VIDEO signal which is an image signal output from the control unit 32.
It is to switch whether or not to flow. When the VIDEO signal is high, a current flows through the LD. The current-voltage conversion circuit 44 is a PD 3 that changes according to the light emission intensity of the LD 34.
6 is converted into a voltage and supplied to the analog input port of the control unit 32 as an APC voltage signal.

Next, the operation of closing the front door 21 and turning on the LD 34 will be described. When the front door 21 is open, the safety switches a, b and c are all open. At this time, the control unit 32 recognizes that the front door 21 is open by the DOOR_OPEN signal being high,
The ON signal is high. Also, the VIDEO signal is set to low and the LEVEL voltage is set to 0. Front door 21
Is closed and the safety switches b and c are closed, the control unit 32 recognizes that the front door 21 is closed by the DOOR OPEN signal, and makes the LDON signal low. The transistor 35 is turned on by this signal, and supplies drive power to the LD 34.

Next, the control unit 32 performs an APC (automatic light quantity control) operation of the LD 34. First, the control unit 32 sets the VIDEO signal to high. Next, the LEVEL voltage is gradually increased until the APC voltage reaches a predetermined value. By this operation, L
The current flowing through D34 is controlled, and the laser light quantity reaches a predetermined value. Then, by the VIDEO signal which is an image signal,
The LD 34 is turned on and off to form an image.

When the front door 21 is opened, the safety switches a, b,
c is all open, the drive power supply of LD34 is cut off, and LD3
4 stops light emission. The control unit 32 is a DOOR / OPE
When the N signal goes high, it recognizes that the front door 21 has been opened, and turns the LDON signal high. With the above configuration, the front door 21 is closed and the DOOR
-When the OPEN signal goes low, the LD drive power is reliably supplied, so that there is no possibility that the LD 34 will be deteriorated or destroyed.

FIG. 4 shows the structure of the SW unit that operates when the door is opened. The basic operation is the same as that shown in FIG. 7, and the corresponding members are denoted by the same reference numerals. By making the SW pressing shaft 4 which is the detecting means a stepped shaft,
The safety switches b and c facing the thick portion 4a are closed before the safety switch a. When the operation strokes of the safety switches a, b, and c are small and the steps cannot be increased, as shown in FIG. 5, the SW pressing shafts 4 of the actuators 7b and 7c of the safety switches b and c to be closed first.
The opening / closing order may be given by attaching an elastic member 40 such as a foamed polyurethane to a portion opposed to the above. At this time, the operation force of the switch <the deformation force of the elastic member <
An elastic member 50 is selected so as to have a breaking limit force of the switch contact. Alternatively, if the increase in the number of steps does not matter, the fixing positions of the safety switches may be made independent, and the opening and closing order of the safety switches may be set. In addition, 51 of FIG. 5 is a SW presser.

FIG. 6 is a block diagram showing another connection example of the safety switch which operates when the door is opened and the drive unit of the unit using the door SW unit of FIG. 4 or FIG.
The same reference numerals are given to members corresponding to the members described in.
As shown in the figure, the AC power supply is + 24V, +
It is converted to a DC power supply such as 5V. The safety switch a has three terminals and has a common contact, a normally open contact, and a normally closed contact. +24 V is connected to the common contact of the safety switch a, the fixing heater drive unit 27, the motor drive unit 28, and the high voltage power supply 29 are connected to the normally open contact, and the normally closed contact is the input port of the control unit 32 via the voltage dividing resistor. DOOR ・ OP
Connected as EN signal. When the front door 21 is closed and the safety switch a is closed, + 24V is supplied to the fixing heater driving unit 27, the motor driving unit 28, and the high voltage power supply 29. When the front door 21 is opened and the safety switch a is opened, the power supplied to the respective units 27, 28 and 29 is cut off, and at the same time, the input port (DOOR / OPE) of the control unit 32 is opened.
N) goes high so that the user can recognize that the front door 21 has been opened.

Next, the operation of closing the front door 21 and lighting the LD 34 will be described. When the front door 21 is open, the safety switches a, b and c are all open. At this time, the control unit 32 recognizes that the front door 21 is open because the DOOR · OPEN signal is high,
The DON signal is high. The VIDEO signal is low, and the LEVEL voltage is set to 0. When the front door 21 is closed, the safety switches b and c are closed first, and power is supplied to the collector of the transistor 35. However, since the control unit 32 recognizes that the front door 21 is still open, the LDON signal is output. Remains high, the transistor 35 does not turn on, and no drive power is supplied to the LD 34. When the front door 21 is completely closed, the safety switch a,
b and c are all closed. The control unit 32 is DOOR / OPEN
The signal recognizes that the front door 21 is closed, and
Set the ON signal to low. With this signal, transistor 3
5 turns on and supplies drive power to the LD 34.

With this configuration, when the safety switch a is closed and the DOOR OPEN signal goes low, the safety switches b and c are closed and the LD drive power is reliably supplied. The possibility of deterioration and destruction is eliminated.

[0023]

As described above, claims 1 to 3 are described.
According to the invention described above, when the front door (opening / closing member) and the safety switch are closed, the LD drive power can be reliably supplied, so that the deterioration and destruction of the LD can be prevented, and laser recording with high safety can be achieved. Equipment can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an embodiment of a laser recording apparatus according to the present invention.

FIG. 2 is a sectional view showing a schematic structure of a laser recording device.

FIG. 3 is an external perspective view of the laser recording apparatus showing an open / closed state of a front door.

FIG. 4 is a perspective view showing a door SW unit.

FIG. 5 is an external perspective view showing an example of a safety switch.

FIG. 6 is a configuration diagram showing another connection example between the safety switch and each unit.

FIG. 7 is a perspective view showing a conventional door SW unit.

FIG. 8 is an explanatory diagram showing a connection example of a conventional safety switch.

[Explanation of symbols]

 a, b, c Safety switch 4 SW pressing shaft (detection means) 7a, 7b, 7c Actuator 21 Front door (opening / closing member) 32 Control unit 33 LD drive unit 34 LD (laser light source) 35 Transistor 37 Photocoupler 40 Current source 43 Switching Circuit 50 Elastic member 51 SW presser

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/44 B41J 29/13 B41J 29/38 G03G 15/04

Claims (3)

(57) [Claims] 1. A laser light source; a power supply for driving the laser light source ;
A member , provided between the laser light source and the power supply;
Open when the member is opened and when the opening and closing member is closed
A safety switch that closes at the
A laser recording apparatus, comprising: control means for permitting emission of laser light from a source . 2. The safety switch and the control means are electrically connected to each other.
Connected via a gas-insulated coupling means
The laser recording apparatus according to claim 1, wherein the are. 3. A laser power source, a first power source for driving the laser light source, and a second power source different from a power source for driving the laser light source
When, to allow the laser beam is emitted from the laser light source
Control means and an open / close mechanism that is provided on the device housing and can be opened and closed during maintenance.
A member , provided between the laser light source and the first power supply;
The opening and closing member opens when the opening and closing member is opened, and the opening and closing member is closed.
A first safety switch that is closed when the power switch is turned on, and is provided between the control means and the second power supply;
When the opening and closing member is opened, the opening and closing member is closed,
And a second safety switch that is closed when the first safety switch is closed.
The switch closes, followed by closing the second safety switch,
The control means determines that the second safety switch is closed.
Is detected and the laser light is emitted from the laser light source.
And a laser recording device.