WO2013071853A1

WO2013071853A1 - Laser printer and modification method therefor

Info

Publication number: WO2013071853A1
Application number: PCT/CN2012/084534
Authority: WO
Inventors: 苏健强; 汪继忠
Original assignee: 珠海天威飞马打印耗材有限公司
Priority date: 2011-11-16
Filing date: 2012-11-13
Publication date: 2013-05-23
Also published as: CN102508417A; CN102508417B

Abstract

A laser printer having a housing (10). The housing (10) encloses to form a cavity (13). Arranged on the interior surface of the cavity (13) is an electrical contact point used for outputting a developing bias voltage. Arranged in the housing (10) is a printed circuit board (14). Arranged on the printed circuit board (14) is a power supply circuit. A power supply module (51) is used for outputting the developing bias voltage to the electrical contact. The power supply circuit is also provided with a rectifier module (52). The rectifier module (52) receives an electrical signal outputted by the power supply module (51); while an output end of the rectifier module (52) is electrically connected to the electrical contact.

Description

Laser printer and its modification method

Technical field

The present invention relates to the field of electronic imaging devices, and more particularly to a laser printer and a method of retrofitting an existing laser printer into such a laser printer. The present invention is based on a Chinese patent application filed on Nov. 16, 2011, the application number of which is incorporated herein by reference.

Background technique

Laser printers are a common printer that provides great convenience for modern office use. Referring to Figures 1 and 2, the prior art laser printer has a housing 10 including an upper cover 11 and an end cover 12. The housing 10 encloses a cavity 13 having electrical contacts on the inner surface thereof. (not visible in Figure 2). A circuit board 14 of a laser printer is mounted on the inner side of the end cover 12, and a control circuit of the laser printer, a power supply circuit, and the like are provided on the circuit board 14. Moreover, a process cartridge is detachably mounted in the cavity 13, and the structure of the process cartridge is as shown in FIG.

The existing process cartridge 20 has a housing 21 with a handle 22 for easy grasp by the user. Referring to Fig. 4, the casing 21 of the process cartridge 20 is composed of a drum frame 23, a toner cavity frame 24, and two

end covers

25, 26, wherein the handle 22 is located on the drum frame 23. The toner chamber frame 24 has a toner chamber for accommodating the toner, and a powder feed roller 31, a developing roller 32, and a powder discharging knife 41 are disposed outside the toner chamber.

The drum frame 23 has a waste toner chamber for accommodating waste toner, and a photosensitive drum 42, a charging roller 43, and a cleaning blade 44 are disposed outside the waste toner chamber. When the process cartridge is assembled, the drum frame 23 and the toner cavity frame 24 are fixedly connected by the

end caps

25, 26 on both sides, and the drum frame 23, the toner cavity frame 24, and the

end caps

25, 26 enclose a cavity for powder feeding. Parts such as the roller 31, the developing roller 32, the powder discharging blade 41, the photosensitive drum 42, the charging roller 43, and the cleaning blade 44 are located in the cavity.

The developing roller 32 has a mandrel 33 made of metal. The mandrel 33 is covered with an elastic layer 34, such as a sponge, rubber, etc., and one end of the mandrel 33 is connected with a conductive piece 35, and the outer end of the conductive piece 35 extends to the end cover. 26 outside. The conductive sheet 35 is in contact with electrical contacts within the cavity of the laser printer to provide electrical connection of the conductive sheet 35 to the electrical contacts. Also, the conductive sheet 35 receives the voltage supplied from the laser printer, and this voltage is referred to as a developing bias. When the process cartridge 20 is in operation, the outer surface of the developing roller 32 and the carbon powder electrostatically act to adsorb the carbon powder on the outer surface of the developing roller 32.

The toner on the outer surface of the developing roller 32 is transferred to the outer surface of the photosensitive drum 42 by an electric field force. When the laser printer is operated, the toner accommodated in the toner chamber is supplied to the outer surface of the developing roller 32 through the powder feeding roller 31, and the powder feeding roller 31 continuously rotates during operation.

The powder feed roller 31 is adjacent to the outer surface of the developing roller 32, so that the toner adsorbed on the outer surface is transferred to the outer surface of the developing roller 32 during the rotation of the powder feeding roller 31, and the developing roller 32 is continuously rotated as it operates. During the rotation of the developing roller 32, the excess carbon powder on the outer surface thereof is scraped off by the powder discharging blade 41, so that the thickness of the carbon powder layer on the outer surface of the developing roller 32 is uniform.

Further, the charging roller 43 charges the photosensitive drum 42 to uniformly charge the outer surface of the photosensitive drum 42. When the laser printer is in operation, the laser irradiates the surface of the photosensitive drum 42 with laser light with image information. This process is an exposure process, and a latent image is formed in a region where the surface of the photosensitive drum 42 is irradiated, that is, the charge in the exposed region disappears and is electrically neutral.

Since the unexposed area on the photosensitive drum 42 is negatively charged, and the exposed area is electrically neutral, and the toner on the outer surface of the developing roller 32 is also negatively charged, the toner on the outer surface of the developing roller 32 will be in accordance with the principle that the electric charge is in the electric field. The outer surface of the developing roller 32 is moved to the exposed area on the photosensitive drum 42 by the electric field force. Also, since the electric field force of the non-exposed area is higher than the developing bias, the toner of the outer surface of the developing roller 32 does not move to the non-exposed area of the outer surface of the photosensitive drum 42, and this process is a developing process.

Finally, the paper as the printing medium passes under the photosensitive drum 42, the toner is transferred onto the paper, and the toner is heated and fixed on the paper, and the printing operation is completed.

After the photosensitive drum 42 completes the transfer process, the cleaning blade 44 scrapes off the toner remaining on the outer surface of the photosensitive drum 42, and the waste toner is collected into the waste toner chamber to avoid affecting the next printing duty cycle of the photosensitive drum.

The conventional laser printers are classified according to their development modes, and can be classified into contact development and non-contact development, wherein non-contact development is also referred to as skip development, and the surface of the development roller 32 is not in contact with the surface of the photosensitive drum 42. But there is a certain distance. The developing bias supplied to the developing roller 32 by the laser printer applying this developing method is an alternating current having a direct current component.

Referring to FIG. 5, the non-contact developing laser printer power supply circuit has a power module, including an AC source AC, and is provided with a capacitor C1, a diode D1, and resistors R1, R2, and R3, wherein one end of the AC source AC is connected to the power source through the resistor R3. The output 48 of the module, the output 48 of the power module, is also the output of the power supply circuit for outputting a developing bias to the electrical contacts within the cavity 13.

The anode of diode D1 is coupled to output 48 via resistor R3 and the cathode is coupled to ground via resistor R2. It can be seen that the AC signal output by the AC source AC can be directly output through the output terminal 48. When the AC signal at the B point is positive half cycle, the current cannot be output through the diode D1. When the AC signal at the A point is negative half cycle, the current will pass through the diode D1. Output to output 48. Therefore, the developing bias output from the output terminal 48 includes an alternating current component and a direct current component.

In the non-contact developing operation mode, since the developing bias received by the developing roller 32 has an alternating current component, the direction of the electric field force formed constantly changes, and the toner is between the developing roller 32 and the surface of the photosensitive drum 42 under the action of the magnetic field force. The jump, that is, the toner, jumps to the surface of the photosensitive drum 42 under the action of the magnetic field force. Therefore, this development method tends to consume a large amount of toner and a high printing cost.

In the contact developing operation mode, the surface of the developing roller 32 is adjacent to the surface of the photosensitive drum 42, and the developing bias output from the laser printer to the conductive sheet 35 contains only a direct current component, and the direct current component is a voltage lower than 0 volt. Thus, the toner does not jump between the developing roller 32 and the photosensitive drum 42, so that the toner is directly transferred to the surface of the photosensitive drum 42 by the electric field force, and the amount of toner consumed by this developing method is small, and the printing cost is small. Lower.

technical problem

However, since the existing laser printer can only provide a development method to the user, if the laser printer is non-contact development, the user can only use the non-contact development process cartridge, resulting in high printing costs. Therefore, the Chinese utility model patent with the publication number CN201402372Y discloses an invention called "processing cartridge", in which a rectifier is arranged between the developing roller and the conductive sheet, and the developing bias with the AC component is rectified. A voltage containing only a direct current component is formed and used for the development roller. In this way, the contact-developed process cartridge can be mounted on a non-contact laser printer, saving printing costs.

However, installing a rectifier on each process cartridge increases the production cost of the process cartridge, which results in higher printing costs. Moreover, if the user modifies the process box by himself and converts the ordinary process box into the process box, the modification operation is performed every time the process box is replaced, which consumes a large amount of manpower and material resources, which is not conducive to the user's use.

Technical solution

SUMMARY OF THE INVENTION A primary object of the present invention is to provide a laser printer that can effectively reduce printing costs and is convenient for users.

Another object of the present invention is to provide a method of retrofitting an existing non-contact laser printer into a contact laser printer.

In order to achieve the above main object, a laser printer provided by the present invention comprises a casing, the casing enclosing a cavity, and an inner surface of the cavity is provided with an electrical contact for outputting a developing bias, and a circuit board, a circuit board are mounted in the casing There is a power supply circuit, the power supply circuit is provided with a power module, and the power module is used for outputting a developing bias to the electrical contact, wherein the power supply circuit is further provided with a rectifier module, and the rectifier module receives the electrical signal output by the power module, and the rectifier module The output is electrically connected to the electrical contact.

A preferred solution is that the power supply circuit is further provided with a double throw switch, the fixed end of the double throw switch is electrically connected to the output end of the power module, and the normally closed contact of the double throw switch and one of the normally open contacts are electrically connected to the rectifier module. At the input end, the normally closed contact of the double throw switch is electrically connected to the other of the normally open contacts to the electrical contact.

A further solution is that the rectifier module is further provided with a voltage stabilizing device, and the voltage stabilizing device is connected between the rectifying device and the ground.

In order to achieve the above object, in the laser printer modification method, the laser printer comprises a casing, the casing encloses a cavity, and the inner surface of the cavity is provided with an electrical contact for outputting a developing bias, and the casing A circuit board is mounted in the body, and a power supply circuit is disposed on the circuit board. The power supply circuit is provided with a power module, and the output end of the power supply circuit is electrically connected to the electrical contact. The method includes disconnecting the power between the output end of the power supply circuit and the electrical contact. The connection module is provided with a rectifier module for receiving an electrical signal output by the power module on the power supply circuit, and electrically connecting the output end of the rectifier module with the electrical contact.

A preferred solution is that after the electrical connection between the output end of the power supply circuit and the electrical contact is disconnected, a double throw switch is also disposed on the power supply circuit, and the fixed end of the double throw switch is electrically connected to the output end of the power module, and the double throw switch One of the normally closed contact and the normally open contact is electrically coupled to the input of the rectifier module, the normally closed contact of the double throw switch being electrically coupled to the other of the normally open contacts to the electrical contact.

Beneficial effect

Since the power supply circuit of the laser printer of the present invention is provided with a rectifying module, the electric signal containing the alternating current component can be converted into an electric signal containing only the direct current component, and output as a developing bias to the electrical contact, so that even in the process cartridge Without a rectifier, it can be installed in a laser printer and used normally, and it can work in contact development mode, which can effectively reduce printing costs. In addition, since the process cartridge does not need to be provided with a rectifier, the process cartridge conventionally used for contact development on the market can also be mounted on the laser printer of the present invention, and the user does not need to modify the process cartridge, and is convenient to use.

Moreover, the double-throw switch provided by the power supply circuit can select whether the electrical signal output by the power module needs to be output after passing through the rectifier module. If the user chooses to use the contact development mode, the double-throw switch can be pressed, and the double-throw switch selects the power module. The electric signal is output after passing through the rectifier module. If the user chooses to use non-contact development, the user allows the double-throw switch to select the electrical signal output by the power module to directly output to the electrical contact, which allows the user to flexibly and conveniently select the development mode of the laser printer. .

In addition, a voltage stabilizing device is arranged on the rectifier module to ensure that the DC signal voltage outputted by the rectifier module is stable, and the voltage fluctuation of the DC signal is avoided, thereby ensuring that the voltage applied to the developing roller is constant, and the magnetic field force is also stabilized, thereby ensuring carbon. The powder can be transferred to the drum.

The existing laser printer is modified by the method of the present invention, and a rectifying module is added to the power supply circuit, so that the developing bias outputted by the power supply circuit can be converted from the alternating current containing the direct current component to the direct current containing only the direct current component, thereby satisfying the contact type. Development work is required. Users can install contact-developed process cartridges on retrofitted laser printers, reducing printing costs and making them easy to use.

At the same time, a double-throw switch is arranged between the power module and the rectifier module, and whether the electrical signal output by the power module needs to be output through the rectifier module, so that the developing bias outputted by the power supply circuit may include a DC component and an AC component, It can contain only the DC component, and uses non-contact development and contact development, respectively, which is beneficial to the user.

DRAWINGS

1 is a schematic structural view of a conventional laser printer.

Fig. 2 is an exploded perspective view showing a conventional laser printer.

Fig. 3 is a structural view of a conventional process cartridge.

Fig. 4 is an exploded perspective view showing a conventional process cartridge.

Figure 5 is an electrical schematic diagram of a conventional laser printer power supply circuit.

Figure 6 is an electrical schematic diagram of a power supply circuit in a first embodiment of the laser printer of the present invention.

Figure 7 is a voltage waveform diagram of the output terminal of the power module in the first embodiment of the laser printer of the present invention.

Figure 8 is a graph showing the voltage waveform at the anode of the diode in the first embodiment of the laser printer of the present invention.

Figure 9 is a diagram showing voltage waveforms at the output end of the rectifier module in the first embodiment of the laser printer of the present invention.

Figure 10 is an electrical schematic diagram of a power supply circuit in a second embodiment of the laser printer of the present invention.

Figure 11 is a structural view showing a third embodiment of the laser printer of the present invention.

Figure 12 is an electrical schematic diagram of a power supply circuit in a third embodiment of the laser printer of the present invention.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiments of the invention

Laser printer first embodiment:

The embodiment has a casing, and the casing encloses a cavity. The process chamber is detachably mounted with a process cartridge, and the process cartridge is provided with a developing roller, and the developing roller includes a mandrel and an elastic layer wrapped around the mandrel, and One end of the mandrel is connected to the conductive sheet, and a part of the conductive sheet extends outside the casing of the process cartridge.

An electrical contact is disposed on the inner surface of the cavity of the laser printer. After the process cartridge is mounted to the cavity, the conductive sheet contacts the electrical contact, and the electrical contact outputs a developing bias to the developing roller through the conductive sheet. Further, a circuit board is mounted in the laser printer casing, and a control circuit of the laser printer, a power supply circuit, and the like are provided on the circuit board. The difference between this embodiment and the existing laser printer is that the power supply circuit is provided with a rectifying module.

Referring to FIG. 6, the power supply circuit of the embodiment has a power module 51 and a rectification module 52. The power module 51 has an AC source AC, and is provided with a capacitor C11, a diode D11, and resistors R11, R12, and R13, and an electrical signal output from the output end. Contains a DC component and an AC component, and the DC component is below 0 volts, which is a negative voltage. The voltage waveform at the output of the power module 51 is as shown in FIG. 7, which is a rectangular wave, and the highest voltage is higher than 0 volts.

The rectifier module 52 has a diode D12, a capacitor C12, resistors R14 and R15, and a Zener diode ZD1. The diode D12 functions as a rectifying device of the present embodiment, and rectifies an electrical signal output from the power module 51. The cathode of the diode D12 is connected to the output of the power module 51, and the anode is connected to one end of the resistor R15. Since the cathode of the diode D12 is connected to the output end of the power module 51, the direct current output from the power module 51 can pass through the diode D12, and the positive half of the alternating current component cannot pass through the diode D12, but the negative half cycle can pass through the diode D12, so the anode of the diode D12 The signal is DC below 0 volts.

The voltage waveform at the anode of diode D12 is shown in Fig. 8. The portion of the power module 51 output higher than 0 volts is filtered out, and only the portion below 0 volt is retained in the voltage waveform.

The rectifier module 52 is further provided with a capacitor C12 connected between the diode D12 and the ground. The capacitor C12 acts as a filter component for filtering the electrical signal to ensure that the voltage waveform of the DC signal output by the rectifier module 52 is stable.

In addition, the rectifier module 52 is further provided with a Zener diode ZD1, which is a voltage stabilizing device of the present embodiment, which is connected in series with the resistor R14 and then connected between the diode D12 and the ground. Zener diode ZD1 ensures that the voltage at the anode of diode D12 is stable.

The rectifier module 52 is further provided with a sliding resistor R15. The two ends of the sliding resistor R15 are respectively connected to the anode and the ground of the diode D12, and the center tap of the sliding resistor R15 is connected to the output end 53 of the rectifier module 52, so that by changing the center tap The position can adjust the voltage value outputted by the output terminal 53. Of course, in this embodiment, the output terminal 53 is also the output end of the power supply circuit. Therefore, the center tap is also electrically connected to the electrical contact, thereby outputting a developing bias voltage to the electrical contact.

After the electric signal outputted by the power module 51 is rectified by the rectifying module 52, an electric signal containing only a DC component is output from the output terminal 53 and output as a developing bias voltage, and the developing bias voltage is a negative voltage, which satisfies the work of contact developing. The rectifier module 52 is further provided with a filter component and a voltage stabilizing device to ensure that the developing bias waveform outputted from the output terminal 53 is stable and the output voltage is stable, which is beneficial to the operation of the process cartridge. The voltage waveform diagram of the output end of the rectifier module 52 is as shown in FIG. 9. Under the action of the filter component and the voltage stabilizing device, the rectifier module 52 outputs a DC power with a stable voltage value.

Thus, the user can mount the contact type process cartridge to the laser printer of the embodiment to perform the printing work, thereby saving printing costs.

Laser printer modification method first embodiment:

To retrofit an existing non-contact developed laser printer into the laser printer of the above embodiment, it is first necessary to disassemble the end cover of the laser printer housing, disassemble the circuit board, and then disconnect the power supply circuit from the electrical contacts. Connected and added a rectifier module on the power supply circuit, the rectifier module is disposed between the power module and the output end of the power supply circuit, and the specific circuit structure of the power supply circuit and the rectifier module is introduced in the first embodiment of the laser printer, and details are not described herein.

After the rectifier module is added, the output end of the rectifier module is electrically connected to the electrical contact, and finally the circuit board and the end cover are installed, and then can be used. After the above modification of the laser printer, the user can install the contact-developed process cartridge into the modified laser printer, saving printing costs. Moreover, the user only needs to modify the laser printer at one time, and it is not necessary to modify each processing box, which greatly facilitates the use of the user.

Laser printer second embodiment:

The embodiment has a casing, and the casing encloses a cavity. The process chamber is detachably mounted with a process cartridge, and the process cartridge is provided with a developing roller, and the developing roller includes a mandrel and an elastic layer wrapped around the mandrel, and One end of the mandrel is connected to the conductive sheet, and a part of the conductive sheet extends outside the casing of the process cartridge. The inner surface of the cavity of the laser printer is provided with electrical contacts. After the process cartridge is mounted to the cavity, the conductive sheet is electrically connected to the electrical contact, and the electrical contact outputs a developing bias to the developing roller through the conductive sheet.

A circuit board is mounted in the casing of the laser printer, and a control circuit of the laser printer, a power supply circuit, and the like are disposed on the circuit board. The electrical schematic diagram of the power supply circuit is as shown in FIG. 10, and includes a power module 56 and a rectifier module 57, and the power module 56. The AC source AC, the capacitor C21, the diode D21, and the resistors R21, R22, and R23 include an AC component and an AC component.

The input end of the rectifier module 57 is electrically connected to the output of the power module 56 to receive an electrical signal output by the power module 56. The rectifier module 57 has a bridge rectifier circuit, which is composed of four diodes D22, D23, D24 and D25. The bridge rectifier circuit constitutes the rectifier device of the embodiment, one output terminal is grounded and the other output terminal is B. point.

As can be seen from Fig. 10, one end of the bridge rectifier circuit outputting a positive voltage is grounded, and one end of the output negative voltage is connected to point B. Further, a capacitor C22 as a filter device is connected between the point B and the ground, and a Zener diode ZD2 as a voltage stabilizing device is connected in series with the resistor R24 and connected between the point B and the ground. Both ends of the sliding resistor R25 are connected to point B and ground, respectively, and the center tap is electrically connected to the output terminal 58, thereby outputting a developing bias to the electrical contact. Thus, the output 58 of the rectifier module 57 outputs a negative voltage of less than 0 volts to the electrical contacts to meet the operational needs of contact development.

Thus, the user can mount the contact-developed process cartridge to the printing operation in this embodiment, saving printing costs.

Laser printer modification method second embodiment:

To retrofit an existing non-contact developed laser printer into the laser printer of the above embodiment, it is first necessary to disassemble the end cover of the laser printer housing, disassemble the circuit board, and then disconnect the electrical connection between the power supply circuit and the electrical contacts. And a rectifier module is added on the power supply circuit, and the rectifier module is disposed between the power module and the output end of the power supply circuit. The specific circuit structure of the power supply circuit and the rectifier module is introduced in the second embodiment of the laser printer, and details are not described herein. Finally, electrically connect the output end of the rectifier module to the electrical contacts, and then install the circuit board and the end cover.

Laser printer third embodiment:

Referring to Fig. 11, the present embodiment has a housing 61 including an upper cover 62 and an end cover 63, and the upper cover 62 is provided with a pressing portion of the switch 64. The housing 61 encloses a cavity in which a process cartridge is detachably mounted, and the process cartridge is provided with a developing roller. The developing roller includes a mandrel and an elastic layer wrapped around the mandrel, and one end of the mandrel and the conductive sheet Connected, a portion of the conductive sheet extends beyond the housing of the process cartridge. The inner surface of the cavity of the laser printer is provided with electrical contacts. After the process cartridge is mounted to the cavity, the conductive sheet is electrically connected to the electrical contact, and the electrical contact outputs a developing bias to the developing roller through the conductive sheet.

A circuit board is mounted in the casing 61, and a control circuit of the laser printer, a power supply circuit, and the like are disposed on the circuit board, and an electrical schematic diagram of the power supply circuit is shown in FIG. The power supply circuit is provided with a power module 66 and a rectifier module 67. A switch 64 is connected between the output end of the power module 66 and the input end of the rectifier module 67. The switch 64 is a double throw switch, and the fixed end is electrically connected to the output end of the power module 66. Connected, the normally open contact is connected to the input of the rectifier module 67, and the normally closed contact is directly connected to the output 68 of the power supply circuit.

The power module 66 is an AC source AC, a capacitor C31, a diode D31, and resistors R31, R32, and R33. The electrical signals output by the power module 66 include a DC component and an AC component. The rectifier module 67 has a diode D32 as a rectifying device, and the cathode of the diode D32 is connected to the normally open contact of the switch 64. The rectifier module 67 is further provided with a capacitor C32 as a filter device and a Zener diode ZD3 as a voltage stabilizing device. The Zener diode ZD3 and the resistor R34 are connected in series and connected between the anode of the diode D31 and the ground.

A sliding resistor R35 is also connected between the anode of the diode D32 and the ground, and a center tap of the sliding resistor R35 is connected to the output terminal 68 to output a developing bias to the electrical contacts in the cavity.

Since the rectification module 67 can rectify the electrical signal output by the power module 66 and form an electrical signal output containing only the DC component, and the electrical signal is a negative voltage lower than 0 volts, it satisfies the work of contact development. The user can install the contact-developed process cartridge into the embodiment to perform the printing work, thereby saving printing costs.

Moreover, since the double throw switch is provided in the embodiment, the user can select the development mode of the laser printer according to the development mode of the process cartridge, and if the process cartridge is a contact development process cartridge, the switch 64 can be selected to the normally open contact. Position, the output only contains the electrical component of the DC component. If the process cartridge is a non-contact developing process cartridge, the switch 64 is selected to the position of the normally closed contact, and the electrical signal outputted by the output 68 includes the DC component and the AC component. It can meet the work needs of non-contact development.

Laser printer modification method third embodiment:

To retrofit an existing non-contact developed laser printer into the laser printer of the above embodiment, it is first necessary to disassemble the end cover of the laser printer housing, disassemble the circuit board, and then disconnect the electrical connection between the power supply circuit and the electrical contacts. And a rectifier module is added on the power supply circuit, and the rectifier module is disposed between the power module and the output end of the power supply circuit, and the specific circuit structure of the power supply circuit and the rectifier module is introduced in the third embodiment of the laser printer, and details are not described herein.

Moreover, after the rectifier module is added, it is also necessary to add a switch, which is a double throw switch, and the connection manner of the double throw switch is as described in the third embodiment of the laser printer. Finally, the output of the rectifier module is electrically connected to the electrical contacts. Of course, the output of the power module is also directly connected to the electrical contacts. In this way, the user can select the development mode of the laser printer, which is more convenient for the user to use. Of course, the pressing portion of the switch needs to be disposed on the surface of the housing of the laser printer to facilitate the user's pressing operation.

Of course, the above embodiment is only a preferred embodiment of the present invention, and there may be more changes in practical applications. For example, in the third embodiment, the normally open contact of the double throw switch is electrically connected to the output end, and normally closed. The contact is connected to the input end of the rectifier module; or the rectifier module does not have a filter component, a voltage regulator device and a sliding resistor, and the diode directly outputs an electrical signal to the electrical contact, and such a change can also achieve the object of the present invention.

Finally, it should be emphasized that the present invention is not limited to the above embodiments, and variations such as specific circuit configuration of the rectifier circuit, changes of the filter components, voltage regulator devices, and the like are also included in the scope of protection of the claims of the present invention.

Industrial applicability

The power supply circuit of the laser printer provided by the invention is provided with a rectifying module, which can convert an electric signal containing an alternating current component into an electric signal containing only a direct current component, and output it as a developing bias to the electrical contact, so that even in the processing box Without a rectifier, it can be installed in a laser printer and used normally, and it can work in contact development mode, which can effectively reduce printing costs.

In addition, since the process cartridge does not need to be provided with a rectifier, the process cartridge conventionally used for contact development on the market can also be mounted on the laser printer of the present invention, and the user does not need to modify the process cartridge, and is convenient to use.

Claims

Laser printer, including

a housing enclosing the cavity, the inner surface of the cavity being provided with an electrical contact for outputting a developing bias;

a circuit board mounted in the housing, the circuit board is provided with a power supply circuit, the power supply circuit is provided with a power module, and the power module is configured to output a developing bias to the electrical contact;

It is characterized by:

The power supply circuit is further provided with a rectifier module, the rectifier module receives an electrical signal output by the power module, and an output end of the rectifier module is electrically connected to the electrical contact.
A laser printer according to claim 1, wherein:

The power supply circuit is further provided with a double throw switch, the fixed end of the double throw switch is electrically connected to the output end of the power module, and the normally closed contact of the double throw switch is electrically connected to one of the normally open contacts to An input of the rectifier module, the other of the normally closed contact and the normally open contact of the double throw switch is electrically connected to the electrical contact.
A laser printer according to claim 1 or 2, wherein:

The rectifier module has a rectifying device that outputs a DC voltage signal below 0 volts to the electrical contact.
A laser printer according to claim 3, wherein:

The rectifying device is a diode, the cathode of which is connected to the output of the power module, and the anode of the diode is connected to the electrical contact.
A laser printer according to claim 3, wherein:

The rectifier module is further provided with a filter member connected between the rectifying device and the ground.
A laser printer according to claim 3, wherein:

The rectifier module is further provided with a voltage stabilizing device connected between the rectifying device and the ground.
A laser printer according to claim 3, wherein:

The rectifier module is further provided with a sliding resistor, two ends of the sliding resistor are respectively connected to the rectifying device and the ground, and a middle tap of the sliding resistor is electrically connected to the electrical contact.
A laser printer modification method, the laser printer having a casing, the casing enclosing a cavity, an inner surface of the cavity being provided with an electrical contact for outputting a developing bias, and a circuit board mounted in the casing Providing a power supply circuit on the circuit board, the power supply circuit is provided with a power module, and an output end of the power supply circuit is electrically connected to the electrical contact, wherein the method includes

Disconnecting an electrical connection between the output end of the power supply circuit and the electrical contact, and providing a rectifying module for receiving an electrical signal output by the power module on the power supply circuit, electrically connecting the output end of the rectifier module with The electrical contact.
The laser printer modification method according to claim 8, wherein:

The method also includes:

After the electrical connection between the output end of the power supply circuit and the electrical contact is disconnected, a double throw switch is disposed on the power supply circuit, and the fixed end of the double throw switch is electrically connected to the output end of the power module. One of the normally closed contact and the normally open contact of the double throw switch is electrically connected to an input end of the rectifier module, and the normally closed contact of the double throw switch is electrically connected to the other of the normally open contacts To the electrical contacts.
The laser printer modification method according to claim 8 or 9, wherein:

The rectifier module has a rectifying device that outputs a DC voltage signal below 0 volts to the electrical contact.
The laser printer modification method according to claim 10, wherein:

The rectifying device is a diode, the cathode of which is connected to the output of the power module, and the anode of the diode is connected to the electrical contact.
The laser printer modification method according to claim 10, wherein:

The rectifier module is further provided with a filter member connected between the rectifying device and the ground.
The laser printer modification method according to claim 10, wherein:

The rectifier module is further provided with a voltage stabilizing device connected between the rectifying device and the ground.
The laser printer modification method according to claim 10, wherein:

The rectifier module is further provided with a sliding resistor, two ends of the sliding resistor are respectively connected to the rectifying device and the ground, and a middle tap of the sliding resistor is electrically connected to the electrical contact.