Developing method and apparatus

Abstract

The embodiment of the application relates to a developing method and device, and the device comprises: a plurality of developing units, which are internally provided with powder feeding rollers and have high-voltage input ends; an alternating-current voltage generating circuit for outputting alternating-current composite voltage; a direct-current bias voltage generating circuit for outputting direct-current bias voltage; a single-pole single-throw switch group, each switch being connected in series between the alternating-current voltage generating circuit and the high-voltage input end of the corresponding developing unit, and being used for selectively transmitting the alternating-current composite voltage; the direct-current bias voltage generating circuit is directly connected with each high-voltage input end, and continuously provides the direct-current bias voltage without being controlled by the switch group; and a discharge circuit is used for providing a charge discharge path for the node of the powder feeding roller in a positive pressure state. Through alternating-current and direct-current separation control and discharge path sharing, the problems of high relay cost, easy arc damage and discharge resistance redundancy in the traditional scheme are effectively solved, the circuit cost is significantly reduced, and the reliability is improved.

Description

Technical Field

[0001] This application relates to the field of printer technology, and more particularly to developing methods and apparatus. Background Technology

[0002] Color laser printers typically use multiple developing units (such as toner cartridges corresponding to CMYK colors) to form color images. When using a skip-developing method, a composite AC voltage with a DC component is applied to the currently developing cartridge, while only a DC bias voltage is applied to the remaining cartridges not involved in development to stabilize the toner and prevent contamination. To meet this requirement, the power system needs to generate both an AC composite voltage and a DC bias voltage, and distribute them to each cartridge via a switching circuit to achieve functionality within a compact device space and control costs.

[0003] In related technologies, a single-pole double-throw relay is typically used to switch the two high-voltage circuits to the corresponding toner cartridges: the relay connects the target toner cartridge to an AC composite voltage, while simultaneously connecting the non-developing toner cartridge to a DC bias voltage. However, because the switched voltage amplitude is high, often exceeding the withstand voltage specifications of ordinary relay contacts, arcing can easily occur between the relay contacts in actual use, leading to relay damage. The high-voltage signal can also interfere with the primary circuit through the relay, causing hardware malfunctions or image defects. Using relays with higher withstand voltage specifications would significantly increase component costs. Therefore, how to reduce the cost of the high-voltage bias circuit while ensuring reliability has become an urgent problem to be solved. Summary of the Invention

[0004] This application provides a developing method and apparatus.

[0005] According to a first aspect of the embodiments of this application, a developing apparatus is provided, comprising: The system comprises multiple developing units, each with a high-voltage input terminal and a powder feeding roller; an AC voltage generation circuit for outputting an AC composite voltage superimposed with a DC component; a DC bias voltage generation circuit for outputting a DC bias voltage; a single-pole single-throw (SPS) switch group, including multiple SPS switches, each connected in series between the output terminal of the AC voltage generation circuit and the high-voltage input terminal of a corresponding developing unit, for selectively transmitting the AC composite voltage to the target developing unit; and a discharge circuit, including multiple unidirectional conductive devices and a common discharge resistor, with the input terminals of each unidirectional conductive device connected to the powder feeding roller node within a corresponding developing unit, and the output terminals of each unidirectional conductive device converging at a common node. The common discharge resistor is connected between the common node and ground, for providing a charge discharge path for the powder feeding roller node under positive pressure. The DC bias voltage generation circuit is electrically connected to the high-voltage input terminal of each developing unit, for continuously providing DC bias voltage to each developing unit without relying on the on / off state of the SPS switch group.

[0006] Optionally, the AC voltage generation circuit includes: A transformer has a secondary winding. One end of the secondary winding is used to connect to a DC voltage source to receive the DC component, while the other end of the secondary winding is used to output an AC composite voltage with the DC component superimposed.

[0007] Optionally, the device further includes: A current-limiting resistor is connected in series between the output of the AC voltage generation circuit and the common input node of the single-pole single-throw switch group to limit the current input to the developing unit.

[0008] Optionally, the DC bias voltage generation circuit includes: A Zener diode, with its cathode connected to a DC voltage source and its anode serving as the output node for the stepped-down DC bias voltage; multiple isolation resistors, connected in series between the DC bias voltage output node and the high-voltage input terminal of each developing unit, are used to prevent AC composite voltage from flowing back into the DC bias voltage generation circuit when the single-pole single-throw switch is turned on, and to isolate mutual interference between developing units.

[0009] Optionally, each developing unit may include a developing roller, a powder feeding roller, and a powder exiting blade.

[0010] Optionally, a bias distribution circuit is connected between the high-voltage input terminal and the developing roller, the powder feeding roller, and the powder exiting blade to provide a defined potential relationship for the developing roller, the powder feeding roller, and the powder exiting blade according to the voltage polarity of the high-voltage input terminal.

[0011] Optionally, the Zener diode group includes: The first Zener diode has its anode connected to the high-voltage input terminal and its cathode connected to the developing roller; the second Zener diode has its cathode connected to the high-voltage input terminal and its anode connected to the powder feeding roller; the third Zener diode has its cathode connected to the powder feeding roller and its anode connected to the powder exiting blade. When the high-voltage input terminal is positive, the first Zener diode conducts in the forward direction, while the second and third Zener diodes break down in the reverse direction, causing the potentials of the developing roller, powder feeding roller, and powder exiting blade to decrease sequentially. When the high-voltage input terminal is negative, the first Zener diode breaks down in the reverse direction, while the second and third Zener diodes conduct in the forward direction, making the powder feeding roller and powder exiting blade have the same potential, with the developing roller having a higher potential than the powder feeding roller.

[0012] Optionally, the single-pole single-throw switch group includes multiple single-pole single-throw relays, each relay corresponding to a developing unit.

[0013] Optionally, the unidirectional conductive device is a diode.

[0014] Optionally, the voltage amplitude of the DC bias voltage is higher than the voltage amplitude of the DC component contained in the AC composite voltage.

[0015] According to a second aspect of the embodiments of this application, a developing method is provided, applied to a developing apparatus having multiple developing units, each developing unit being provided with a powder feeding roller, the method comprising: A DC bias voltage is continuously applied to all developing units to meet the basic bias requirements of each developing unit. A single-pole single-throw switch group selectively introduces an AC composite voltage with a DC component into the target developing unit. In the target developing unit, the AC composite voltage is superimposed on the DC bias voltage to form the AC and DC superimposed bias voltage required for developing. When the powder feeding roller node of any developing unit is under positive pressure, the positive charge of the powder feeding roller node is discharged to ground through a unidirectional conductive device connected to the corresponding developing unit and a common discharge resistor. The single-pole single-throw switch group only controls the on / off state of the AC composite voltage and does not control the on / off state of the DC bias voltage.

[0016] According to a third aspect of the embodiments of this application, a computing device is provided. The computing device includes a memory and a processor, the memory storing a computer program, and the processor executing the program to implement the method as described above.

[0017] According to a fourth aspect of the embodiments of this application, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the methods described in the embodiments of this application.

[0018] According to a fifth aspect of the embodiments of this application, a computer program product is provided, including a computer program that, when executed by a processor, implements the methods described above in the embodiments of this application.

[0019] The developing method and apparatus provided in this application include multiple developing units, an AC voltage generation circuit, a DC bias voltage generation circuit, a single-pole single-throw switch group, and a discharge circuit consisting of multiple unidirectional conductive devices and a common discharge resistor. By completely separating the DC bias branch from the AC selection branch, the DC bias voltage is continuously applied to all developing units without the control of the switch group. Only the single-pole single-throw switch group selectively introduces the AC composite voltage into the target developing unit to form an AC-DC superimposed bias voltage, which significantly reduces the voltage stress that the switching devices need to withstand, making it possible to use low-cost, high-reliability conventional relays. At the same time, the powder feeding roller nodes of each developing unit are connected through unidirectional conductive devices and grounded through the same common discharge resistor. The unidirectional conductivity enables multiple developing units to safely reuse the discharge path in a time-division multiplexing manner, significantly reducing the amount of high-voltage resistors used. This application effectively solves the problems of high relay cost, easy arcing damage, and large number of discharge resistors in traditional solutions while ensuring developing performance, achieving cost optimization and reliability improvement of the developing apparatus. Attached Figure Description

[0020] More details, features, and advantages of embodiments of the present application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which: Figure 1 Circuit diagram of a developing apparatus provided for an exemplary embodiment of this application Figure 2 A detailed circuit diagram of a developing apparatus provided for an exemplary embodiment of this application; Figure 3 A flowchart of a development method provided for an exemplary embodiment of this application. Detailed Implementation

[0021] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While some embodiments of this application are shown in the drawings, it should be understood that embodiments of this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the embodiments of this application. It should be understood that the accompanying drawings and embodiments of this application are for illustrative purposes only and are not intended to limit the scope of protection of this application.

[0022] It should be understood that the various steps described in the method implementation of this application may be performed in different orders and / or in parallel. Furthermore, the method implementation may include additional steps and / or omit the steps shown. The scope of this application is not limited in this respect.

[0023] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc., mentioned in the embodiments of this application are only used to distinguish different devices, modules, or units, and are not used to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0024] It should be noted that the terms "one" and "more" mentioned in the embodiments of this application are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0025] The names of the messages or information exchanged between multiple devices in the embodiments of this application are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0026] As an optional but non-limiting implementation, in response to a user's active request, sending a prompt message to the user can be done via a pop-up window, where the prompt message can be presented in text format. Furthermore, the pop-up window can also include a selection control allowing the user to choose "agree" or "disagree" to provide personal information to the electronic device. It is understood that the above notification and user authorization process is merely illustrative and does not constitute a limitation on the implementation of this application's embodiments. Other methods that comply with relevant laws and regulations can also be applied to the implementation of this application's embodiments.

[0027] This application provides a developing apparatus for use in image forming equipment (e.g., a color laser printer). The developing apparatus includes a physical developing component for performing a developing operation, and circuitry for providing a bias voltage to the developing component.

[0028] Figure 1 A circuit diagram of a developing apparatus provided in an embodiment of this application. (In conjunction with...) Figure 1 As shown, the developing apparatus provided in this embodiment includes: an AC voltage generating circuit 10, a DC bias voltage generating circuit 20, a single-pole single-throw switch group 30, a discharge circuit 40, and multiple developing units.

[0029] AC voltage generation circuit 10 is used to output an AC composite voltage with a DC component superimposed on it.

[0030] In some embodiments, the AC voltage generation circuit 10 includes an AC bias voltage generation circuit 101, the output of which serves as a superposition node. This superposition node is used to simultaneously receive the AC voltage from the AC bias voltage generation circuit 101 and the DC voltage from an external source, thereby outputting an AC composite voltage signal at the superposition node.

[0031] In some embodiments, the AC voltage generation circuit 10 includes an AC bias voltage generation circuit 101 and a transformer T1, wherein the transformer T1 includes a primary winding and a secondary winding. The primary winding is coupled to the AC bias voltage generation circuit 101 to receive an AC bias voltage; the secondary winding of the transformer has a first terminal and a second terminal, wherein the first terminal of the secondary winding is used to receive a DC voltage from an external source, and the second terminal of the secondary winding serves as an output node to output an AC composite voltage signal biased with the DC voltage as a reference.

[0032] The DC bias voltage generation circuit 20 is used to output a DC bias voltage. The voltage amplitude of the DC bias voltage is higher than the voltage amplitude of the DC component contained in the AC composite voltage.

[0033] The single-pole single-throw (SPS) switch group 30 includes multiple SPS switches (e.g., first SPS switch SW1, second SPS switch SW2, third SPS switch SW3, and fourth SPS switch SW4), each of which can be implemented by a single-pole single-throw (SPS) relay. Each SPS switch is connected in series between the AC voltage generation circuit 10 and the high-voltage input terminal of a corresponding developing unit, for selectively transmitting the AC composite voltage to the target developing unit.

[0034] Multiple developing units, including a first developing unit Y, a second developing unit M, a third developing unit C, and a fourth developing unit K, correspond to four color toner cartridges: yellow (Y), magenta (M), cyan (C), and black (K), respectively, and are used to carry developer and form developed images. Each developing unit has a high-voltage input terminal, and each developing unit is equipped with a toner feeding roller.

[0035] In this embodiment, the developing apparatus may further include a current-limiting resistor R1. The current-limiting resistor R1 may be located at the front end of the AC main circuit, and is used to: limit the transient surge current in the circuit when any single-pole single-throw switch is closed or the load of the developing unit undergoes a transient change, prevent the AC voltage generation circuit 10 from overload, and protect the downstream single-pole single-throw switches (such as relay contacts) from being stuck or damaged by large current surges.

[0036] In this embodiment, the developing apparatus may further include multiple isolation resistors, including a first isolation resistor R2, a second isolation resistor R3, a third isolation resistor R4, and a fourth isolation resistor R5. These multiple isolation resistors are connected in series between the output node of the DC bias voltage (i.e., the DC bias voltage generation circuit 20) and the high-voltage input terminal of each developing unit, respectively, to prevent AC composite voltage from flowing back into the DC bias voltage generation circuit when the single-pole single-throw switch is turned on, and to isolate mutual interference between the developing units.

[0037] The discharge circuit 40 includes multiple unidirectional conductive devices and a common discharge resistor. The input terminal of each unidirectional conductive device is connected to a powder feeding roller node in a corresponding developing unit. The output terminals of each unidirectional conductive device converge at a common node. The common discharge resistor is connected between the common node and ground to provide a charge discharge path for the powder feeding roller node under positive pressure. The DC bias voltage generation circuit is electrically connected to the high voltage input terminal of each developing unit to continuously provide DC bias voltage to each developing unit without relying on the on / off state of the single-pole single-throw switch group.

[0038] Specifically, combined Figure 1 As shown, the aforementioned plurality of unidirectional conductive devices include a first unidirectional conductive device D1, a second unidirectional conductive device D2, a third unidirectional conductive device D3, and a fourth unidirectional conductive device D4, each of which can specifically be a diode. The anode of each unidirectional conductive device is connected to a corresponding powder feeding roller node within a developing unit, and the cathodes converge at a common node. In this embodiment, the unidirectional conductive device can specifically be a diode. It is understood that in other embodiments, the unidirectional conductive device can also be a circuit composed of diodes (such as a rectifier bridge) or a unidirectional thyristor; the embodiments are not limited to these.

[0039] A common bleed resistor R6 is connected between the common node and ground to provide a positive charge discharge path for each developing unit. R6 is grounded through the common ground terminal DGND.

[0040] In this embodiment, the developing apparatus may further include a bias distribution circuit connected between the high voltage input terminal and the developing roller, the powder feeding roller, and the powder exiting blade, for providing a defined potential relationship to the developing roller, the powder feeding roller, and the powder exiting blade according to the voltage polarity of the high voltage input terminal.

[0041] The electrical connections between the above components are as follows: (1) AC high voltage power supply path.

[0042] The output of the AC voltage generation circuit 10 is connected in series with a current-limiting resistor R1 and then connected to the common input node of the single-pole single-throw switch group 30. The inputs of each single-pole single-throw switch SW1, SW2, SW3, and SW4 in the single-pole single-throw switch group 30 are all connected to this common input node, and the outputs of each single-pole single-throw switch are respectively connected to the high-voltage input terminal HVY of the first developing unit Y, the high-voltage input terminal HVM of the second developing unit M, the high-voltage input terminal HVC of the third developing unit C, and the high-voltage input terminal HVK of the fourth developing unit K.

[0043] (2) DC high voltage power supply path.

[0044] The output of the DC bias voltage generation circuit 20 is directly connected to the high voltage input terminals HVY, HVM, HVC, and HVK of each developing unit through an independent DC branch path.

[0045] It should be noted that the power supply path of the DC bias voltage generation circuit 20 does not pass through the current-limiting resistor R1, nor through the single-pole single-throw switch group. In other words, the application of the DC bias voltage is not controlled by the on / off state of the single-pole single-throw switch group 30, nor is it affected by the voltage drop of the current-limiting resistor R1. It can continuously and stably act on all developing units to meet the basic bias requirements of each developing unit in the non-developing state.

[0046] In this embodiment, isolation resistors R2, R3, R4, and R5 are connected in series between the output node of the DC bias voltage generation circuit 20 and the high-voltage input terminals HVY, HVM, HVC, and HVK of each developing unit.

[0047] The isolation resistor serves the following functions: limiting the current in the DC bias voltage branch; preventing the AC high voltage from flowing back through the DC bias branch to the output node of the DC bias voltage generation circuit 20 when the corresponding single-pole single-throw switch is turned on and the AC composite voltage is applied to the high-voltage input terminal, thereby protecting the DC bias voltage generation circuit and ensuring that the AC component only acts on the target developing unit; and isolating mutual interference between developing units. In this embodiment, the function of the isolation resistor, "isolating mutual interference between developing units," specifically refers to signal-level decoupling and crosstalk isolation, aiming to reduce the mutual influence between upstream and downstream circuits and parallel loads, rather than complete electrical insulation.

[0048] Each developing unit may also be equipped with a Zener diode group (not shown in the figure, but will be described in detail in subsequent embodiments) to form the required bias voltage gradient between the developing roller, the powder feeding roller and the powder exiting blade, so as to meet the requirements of the transfer and adsorption of charged particles during the electrostatic developing process.

[0049] In this embodiment, a discharge branch is led out from the powder feeding roller node of each developing unit.

[0050] Specifically, the powder feeding roller node of the first developing unit Y is connected to the anode of the first unidirectional conductive device D1, the powder feeding roller node of the second developing unit M is connected to the anode of the second unidirectional conductive device D2, the powder feeding roller node of the third developing unit C is connected to the anode of the third unidirectional conductive device D3, and the powder feeding roller node of the fourth developing unit K is connected to the anode of the fourth unidirectional conductive device D4.

[0051] The cathodes of all unidirectional conductive devices D1, D2, D3, and D4 are connected to a common node. This common node is connected to one end of a common bleeder resistor R6, and the other end of R6 is connected to the common ground terminal DGND. Here, "connection" refers to the cathodes of each device being connected to the same potential point through a means that enables electrical conduction, including but not limited to: soldering the cathodes to the same point, connecting them to different locations on the same printed circuit board trace / copper foil, connecting them via wires, or connecting them via conductive connectors (such as busbars or terminals).

[0052] In this embodiment, when a developing unit is selected for developing operations, its powder feeding roller presents a positive potential during the positive half-cycle of the AC high voltage. The corresponding unidirectional conductive device of that developing unit is forward-biased, and the positive charge is discharged to ground via the unidirectional conductive device and the shared bleeder resistor R6, effectively limiting the positive voltage peak and eliminating residual static electricity. For the other developing units that are not undergoing developing operations, since their powder feeding rollers are not under positive voltage, the corresponding unidirectional conductive devices are in a reverse-biased cutoff state, achieving electrical isolation. Thus, the four developing units achieve time-division multiplexing of the same shared bleeder resistor R6 through the unidirectional conductivity of the unidirectional conductive devices, eliminating the need for an independent bleeder resistor for each developing unit and significantly reducing circuit costs.

[0053] In the embodiments provided in this application, combined with Figure 1 As shown, the DC bias voltage generation circuit 20 continuously applies DC bias voltage to all developing units to meet the basic bias requirements in the non-developing state. When a developing unit (e.g., the first developing unit Y) needs to perform a developing operation, the corresponding single-pole single-throw switch SW1 is closed. The AC composite voltage output by the AC voltage generation circuit 10, superimposed with a DC component, is transmitted to the high-voltage input terminal of the first developing unit Y via the current-limiting resistor R1 and SW1. This AC composite voltage, together with the originally continuously existing DC bias voltage, acts on the first developing unit Y to form the AC and DC superimposed bias voltage required for developing. At the same time, the positive charge generated by the powder feeding roller of the first developing unit Y during the AC positive voltage half-cycle is discharged to ground via D1 and the common discharge resistor R6.

[0054] After the developing operation is completed, disconnect SW1. The AC composite voltage is no longer applied to the first developing unit Y, while the DC bias voltage continues to be maintained. Subsequently, if necessary, another single-pole single-throw switch (such as SW2) can be closed to switch the AC composite voltage to the next target developing unit.

[0055] Since the power supply path of the DC bias voltage generation circuit 20 does not pass through the single-pole single-throw switch group 30, and the single-pole single-throw switch is only used to control the on and off of the AC composite voltage, the voltage stress that each single-pole single-throw switch contact needs to withstand is greatly reduced. Low-cost, high-reliability relays can be selected, which fundamentally solves the problem that relay contacts in traditional solutions are prone to arcing damage due to the AC / DC high voltage difference.

[0056] Figure 2 A detailed circuit diagram of the developing apparatus provided in an embodiment of this application. (In conjunction with...) Figure 2 The developing unit includes a transformer T1, a current-limiting resistor R1, single-pole single-throw relays RL1-RL4, a Zener diode ZD3, isolation resistors R2-R5, Zener diode groups and diode groups D1-D4 within each developing unit, and a common bleeder resistor R6. The specific circuit connections and operating principles are explained in detail below.

[0057] The primary winding of transformer T1 is used to receive externally input AC signals. One end of the secondary winding of transformer T1 is used to connect to a DC voltage source to receive the DC component, and the other end of the secondary winding is used to output a composite AC voltage with the DC component superimposed.

[0058] Specifically, the secondary winding of transformer T1 has a first terminal and a second terminal. The first terminal (i.e., the lower end of the secondary winding) is directly connected to a DC voltage source VDC to receive the DC component. The second terminal (i.e., the upper end of the secondary winding) serves as the output terminal, outputting an AC composite voltage signal superimposed with the DC component VDC. Thus, the AC bias voltage generation circuit 101 (not shown in the figure) of the externally input AC signal, transformer T1, and DC voltage source VDC together constitute the AC voltage generation circuit of the entire circuit. Figure 1 The AC voltage generation circuit 10 in the middle.

[0059] In this embodiment, the voltage amplitude of the DC bias voltage provided by VDC is set to be higher than the voltage amplitude of the DC component contained in the AC composite voltage. Specifically, in conjunction with Figure 2After being clamped by the Zener diode ZD3, the DC voltage source VDC generates a DC bias voltage at node B. The voltage amplitude of this bias voltage is VDC minus the Zener voltage of ZD3 (e.g., 200V), meaning the absolute value of this DC bias voltage is 200V higher than VDC. The DC component in the AC composite voltage output by the AC voltage generation circuit is the voltage amplitude of the DC voltage source VDC connected to the first terminal of the secondary winding of transformer T1. Therefore, the DC bias voltage applied to each developing unit is higher in absolute value than the DC component in the AC composite voltage.

[0060] By setting the aforementioned voltage difference relationship, in the non-developing state, each developing unit only receives a high-amplitude DC bias voltage, which can form a sufficiently strong and stable electric field between the developing roller and the toner feeding roller, ensuring that the toner in the non-developing toner cartridge remains in a stable adsorption state. In the developing state, an AC composite voltage is introduced into the target developing unit. Its lower DC component, after being superimposed with the higher DC bias voltage, forms an AC / DC composite electric field with an appropriate potential gradient in the developing area. This ensures both effective toner jumping and transfer during the developing process and avoids charge overload or image defects caused by excessively high voltage. This voltage difference setting allows the developing device to balance developing efficiency and non-developing stability when switching between developing and non-developing states, eliminating the need for multiple independent voltage sources for different operating modes. This simplifies the circuit structure and reduces system costs while ensuring image quality.

[0061] The first terminal of the current-limiting resistor R1 is connected to the second terminal of the secondary winding of transformer T1, and the second terminal of R1 is connected to the common node A. The current-limiting resistor R1 is used to limit the current of the AC composite voltage output from transformer T1, protecting the relay contacts in the downstream stage from large current surges.

[0062] The single-pole single-throw relay group includes four single-pole single-throw relays RL1, RL2, RL3, and RL4, corresponding to the first developing unit Y, the second developing unit M, the third developing unit C, and the fourth developing unit K, respectively. The normally open contact (input terminal) of each relay is connected to a common node A. The common contact (output terminal) of relay RL1 is connected to the high-voltage input terminal HVY of the first developing unit Y; the common contact of relay RL2 is connected to the high-voltage input terminal HVM of the second developing unit M; the common contact of relay RL3 is connected to the high-voltage input terminal HVC of the third developing unit C; and the common contact of relay RL4 is connected to the high-voltage input terminal HVK of the fourth developing unit K. The control terminal (coil terminal) of each relay receives external control signals to achieve time-division multiplexing of the target developing unit.

[0063] Each relay is used only to control the switching on and off of the AC composite voltage. When a relay is energized, the AC composite voltage is introduced into the high-voltage input terminal of the corresponding developing unit through R1 and the relay; when the relay is de-energized, the AC path is cut off, and the developing unit no longer receives the AC component.

[0064] In this embodiment, the DC voltage source VDC also has another independent DC bias branch. This branch is connected in series with a Zener diode ZD3, whose cathode is connected to the DC voltage source VDC and whose anode is connected to node B. Utilizing the voltage regulation characteristics of ZD3, the voltage at node B is clamped to VDC minus the regulated voltage of ZD3 (e.g., 200V), thereby generating a DC bias voltage that is 200V higher than VDC in absolute value.

[0065] Node B is connected to the high-voltage input terminal of each corresponding developing unit through four isolation resistors R2, R3, R4, and R5. Specifically, resistor R2 is connected between node B and HVY, resistor R3 is connected between node B and HVM, resistor R4 is connected between node B and HVC, and resistor R5 is connected between node B and HVK.

[0066] It should be noted that this DC bias path does not pass through relay groups RL1 to RL4, nor through current-limiting resistor R1. Therefore, regardless of the relay's state, the DC bias voltage is always directly applied to all developing units to meet the basic bias requirements in the non-developing state. Isolation resistors R2 to R5, while providing isolation, also limit the DC branch current: when the corresponding relay is energized and the AC composite voltage is applied to the high-voltage input terminal, the isolation resistors effectively prevent AC high voltage from flowing back to node B, protecting the DC bias branch.

[0067] In this embodiment, the bias allocation circuit includes: The first Zener diode has its anode connected to the high-voltage input terminal and its cathode connected to the developing roller.

[0068] The second Zener diode has its cathode connected to the high-voltage input terminal and its anode connected to the powder feeding roller.

[0069] The third Zener diode has its cathode connected to the powder feeding roller and its anode connected to the powder exiting blade.

[0070] When the high voltage input terminal is positive, the first Zener diode conducts in the forward direction, while the second and third Zener diodes break down in the reverse direction, causing the potentials of the developing roller, the powder feeding roller, and the powder exiting blade to decrease sequentially. When the high voltage input terminal is negative, the first Zener diode breaks down in the reverse direction, while the second and third Zener diodes conduct in the forward direction, making the powder feeding roller and the powder exiting blade have the same potential, and the potential of the developing roller is higher than that of the powder feeding roller.

[0071] Specifically, each developing unit is equipped with a Zener diode array to create a fixed bias voltage difference between the developing roller, the powder feeding roller, and the powder exiting blade, thereby meeting the requirements for the transfer and adsorption of charged particles during electrostatic developing. Taking the first developing unit Y as an example, the specific structure and connection relationship of its internal Zener diode array are as follows: The Zener diode group includes a first Zener diode ZD1, a second Zener diode ZD2, and a third Zener diode ZD4. The high-voltage input terminal HVY is connected to the common output terminal inside the developing unit. The anode of Zener diode ZD1 is connected to the high-voltage input terminal HVY, and the cathode is connected to the developing roller DR_Y. The cathode of ZD2 is connected to HVY, and the anode is connected to the toner feed roller SR_Y. The cathode of ZD4 is connected to the toner feed roller SR_Y (i.e., the anode of ZD2), and the anode of ZD4 is connected to the toner exit blade DB_Y.

[0072] When the high-voltage input terminal HVY is positive, ZD1 conducts in the forward direction, while ZD2 and ZD4 break down in the reverse direction. This results in the potential of the developing roller DR_Y being approximately equal to HVY, the potential of the toner feed roller SR_Y being HVY minus the regulated voltage of ZD2, and the potential of the toner exit blade DB_Y being the toner feed roller potential minus the regulated voltage of ZD4. Consequently, the potentials of the developing roller, toner feed roller, and toner exit blade decrease sequentially. When the high-voltage input terminal HVY is negative, ZD1 breaks down in the reverse direction, while ZD2 and ZD4 conduct in the forward direction. This results in the potential of the developing roller DR_Y being HVY plus the regulated voltage of ZD1, and the potentials of the toner feed roller SR_Y and toner exit blade DB_Y being approximately equal to HVY. At this point, the toner feed roller and toner exit blade are at the same potential, and the potential of the developing roller is higher than that of the toner feed roller.

[0073] The second developing unit M, the third developing unit C, and the fourth developing unit K each correspond to a Zener diode group with the same structure as described above (represented in the figure as ZD5~ZD7, ZD8~ZD10, ZD11~ZD13, and the connection relationship is similar), which will not be elaborated here.

[0074] In this embodiment, an independent venting branch is led out at the powder feeding roller node of each developing unit. Specifically: The powder feed roller node SR_Y of the first developing unit Y is connected to the anode of diode D1; the powder feed roller node SR_M of the second developing unit M is connected to the anode of diode D2; the powder feed roller node SR_C of the third developing unit C is connected to the anode of diode D3; and the powder feed roller node SR_K of the fourth developing unit K is connected to the anode of diode D4. The cathodes of the four diodes D1 to D4 converge at a common node C, which is connected to a common ground DGND via a common bleeder resistor R6.

[0075] The operation of this bleeder circuit is as follows: When a developing unit (e.g., the first developing unit Y) is selected for developing, its toner feed roller presents a positive potential during the positive half-cycle of the AC high voltage. The corresponding diode D1 is forward-biased, and the positive charge is discharged to ground through D1 and the shared bleeder resistor R6, effectively limiting the positive voltage peak and eliminating residual static electricity. For the other developing units that are not undergoing developing, since their toner feed rollers are not under positive voltage, the corresponding diodes are in the reverse cutoff state, thus achieving electrical isolation between the developing units. Therefore, the four developing units achieve time-division multiplexing of the same shared bleeder resistor R6 through the unidirectional conductivity of the diodes, eliminating the need for an independent bleeder resistor for each developing unit, significantly reducing circuit cost and space requirements.

[0076] Under normal conditions, all relays RL1 to RL4 are in the off state, and each developing unit only receives the DC bias voltage from the DC bias branch, which meets the requirement of toner stability in non-developing state.

[0077] When a toner cartridge (e.g., the first developing unit Y) needs to perform a developing operation, a control signal is sent to the coil of relay RL1, causing its contacts to close. At this time, the AC composite voltage output from the second terminal of the secondary winding of transformer T1 is introduced into the high-voltage input terminal HVY of the first developing unit Y through current-limiting resistor R1 and RL1. This AC composite voltage is superimposed on the DC bias voltage continuously provided by the DC bias branch at HVY, forming the AC / DC superimposed bias voltage required for developing. The remaining relays RL2 to RL4 remain open, and the corresponding developing units M, C, and K only maintain the application of DC bias voltage.

[0078] After the first developing unit Y has finished developing, RL1 is disconnected, and the AC path is cut off; then another relay (such as RL2) can be closed as needed to switch the AC composite voltage to the next target developing unit.

[0079] Since each relay is only used to control the switching on and off of the AC composite voltage, while the DC bias voltage is continuously supplied through an independent path, the relay contacts only need to withstand the voltage stress from the AC component, rather than the high voltage difference between AC and DC in traditional solutions. Therefore, the relay selection requirements are significantly reduced, allowing the use of low-cost, high-reliability conventional single-pole single-throw relays, fundamentally solving the problem of relay contacts being easily damaged by arcing due to high voltage differences in traditional solutions. Simultaneously, the four developing units share a single set of bleeder resistor R6, further reducing circuit costs and saving layout space.

[0080] Based on the above embodiments, this application also provides a developing method, applied to a developing apparatus having multiple developing units, each developing unit being equipped with a powder feeding roller, such as... Figure 3 As shown, the method may include the following steps: In step S310, a DC bias voltage is continuously applied to all developing units to meet the basic bias requirements of each developing unit.

[0081] In this embodiment, the DC bias voltage can be provided by a DC bias voltage generation circuit, and applied directly and continuously to the high-voltage input terminals of all developing units through a DC bias branch independent of the AC power supply path. This DC bias voltage remains connected regardless of the operating state of the developing unit and is not disconnected by any switching device. The voltage amplitude of the DC bias voltage is higher than the voltage amplitude of the DC component contained in the subsequent AC composite voltage, for example, 200V higher, to ensure stable toner adsorption in the non-developing state.

[0082] In step S320, a composite AC voltage with a DC component is selectively introduced into the target developing unit through a single-pole single-throw switch group.

[0083] In this embodiment, the single-pole single-throw (SPS) switch group may include multiple SPS switches, each corresponding to a developing unit. When a developing unit needs to perform a developing operation, the corresponding SPS switch is closed, so that the AC composite voltage output by the AC voltage generation circuit is transmitted to the high-voltage input terminal of the target developing unit; for other developing units that do not need to be developed, their corresponding SPS switches remain open, and the AC path is cut off.

[0084] The single-pole single-throw switch group only controls the switching of the AC composite voltage and does not participate in the switching or control of the DC bias voltage. The DC bias voltage is always applied to all developing units throughout the entire process and is not affected by the state of the switch group.

[0085] In step S330, in the target developing unit, an AC composite voltage is superimposed on a DC bias voltage to form the AC-DC superimposed bias voltage required for developing.

[0086] Specifically, since the DC bias voltage is continuously applied to the high-voltage input terminal of the target developing unit, when the single-pole single-throw switch is closed and the AC composite voltage is introduced into the same high-voltage input terminal, the two are superimposed at this node to form a composite bias signal containing AC and DC components, which is applied to the load components such as the developing roller, powder feeding roller and powder discharge knife in the developing unit to meet the requirements of the transfer and adsorption of charged particles during the electrostatic developing process.

[0087] In step S340, when the powder feeding roller node of any developing unit is under positive pressure, the positive charge of the powder feeding roller node is discharged to ground via a unidirectional conductive device connected to the developing unit and a common discharge resistor.

[0088] Among them, the single-pole single-throw switch group only controls the on / off of the AC composite voltage, and does not control the on / off of the DC bias voltage.

[0089] In this embodiment, each developing unit has a unidirectional conductive device (such as a diode) connected to its powder feeding roller node. When a developing unit is selected for developing, its powder feeding roller node presents a positive potential during the positive half-cycle of the AC composite voltage. The corresponding unidirectional conductive device is forward-biased, and the positive charge is discharged to ground through the unidirectional conductive device and the shared bleed resistor. For the remaining developing units that are not undergoing developing, since the powder feeding roller node does not present a positive voltage, the corresponding unidirectional conductive device is in a reverse cutoff state, achieving electrical isolation between the developing units. Thus, multiple developing units can share the same shared bleed resistor in a time-division manner through the unidirectional conductivity of the unidirectional conductive device, without the need to configure a separate bleed resistor for each developing unit.

[0090] The developing method provided in this application completely separates the DC bias branch from the AC selection branch, ensuring a continuous and stable DC bias applied to all developing units. The selection of the AC component is controlled solely by a single-pole single-throw switch group, significantly reducing the voltage stress on the switching devices. This avoids the problem of arcing damage to the switch contacts caused by the AC / DC high voltage difference in traditional solutions. While improving system reliability, it also makes it possible to use low-cost, small-sized conventional relays. Furthermore, by setting unidirectional conductive devices at the toner feeding roller nodes of each developing unit and grounding the outputs of all unidirectional conductive devices through a single shared bleed resistor, safe time-division multiplexing of the same bleed path for multiple developing units is achieved. This effectively eliminates the impact of residual charge on image quality, significantly reduces the amount of high-voltage resistors used, further lowers circuit costs, and saves layout space.

[0091] In this embodiment, the magnitude of the DC bias voltage is set to be higher than the magnitude of the DC component in the AC composite voltage. Specifically, in conjunction with Figure 2 After being clamped by the Zener diode ZD3, the DC voltage source VDC generates a DC bias voltage at node B. The voltage amplitude of this bias voltage is VDC minus the Zener value of ZD3 (e.g., 200V), meaning the absolute value of the DC bias voltage is 200V higher than VDC. The DC component in the AC composite voltage output by the AC voltage generation circuit is the voltage amplitude of the DC voltage source VDC connected to the first terminal of the secondary winding of transformer T1. Therefore, the DC bias voltage applied to each developing unit is higher in absolute value than the DC component in the AC composite voltage.

[0092] By setting the aforementioned voltage difference relationship, in the non-developing state, each developing unit only receives a high-amplitude DC bias voltage, which can form a sufficiently strong and stable electric field between the developing roller and the toner feeding roller, ensuring that the toner in the non-developing toner cartridge remains in a stable adsorption state. In the developing state, an AC composite voltage is introduced into the target developing unit. Its lower DC component, after being superimposed with the higher DC bias voltage, forms an AC / DC composite electric field with an appropriate potential gradient in the developing area. This ensures both effective toner jumping and transfer during the developing process and avoids charge overload or image defects caused by excessively high voltage. This voltage difference setting allows the developing device to balance developing efficiency and non-developing stability when switching between developing and non-developing states, eliminating the need for multiple independent voltage sources for different operating modes. This simplifies the circuit structure and reduces system costs while ensuring image quality.

[0093] In another embodiment provided in this application, a computer-readable storage medium is also provided, which stores a computer program that, when executed by a processor, implements the methods described above in the embodiments of this application.

[0094] In another embodiment provided in this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute the methods described above in the embodiments of this application.

[0095] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk (SSD)).

[0096] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0097] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the embodiments of apparatus, computing devices, and computer-readable storage media are basically similar to the method embodiments, so the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0098] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A developing apparatus, characterized in that, include: Multiple developing units, each developing unit having a high-voltage input terminal, and each developing unit having a powder feeding roller; An AC voltage generation circuit is used to output a composite AC voltage with a superimposed DC component. A DC bias voltage generation circuit is used to output a DC bias voltage. A single-pole single-throw switch group includes multiple single-pole single-throw switches, each of which is connected in series between the output terminal of the AC voltage generation circuit and the high voltage input terminal of a corresponding developing unit, for selectively transmitting the AC composite voltage to the target developing unit; The discharge circuit includes multiple unidirectional conductive devices and a common discharge resistor. The input terminal of each unidirectional conductive device is connected to a corresponding powder feeding roller node in the developing unit. The output terminals of each unidirectional conductive device are converged at a common node. The common discharge resistor is connected between the common node and ground to provide a charge discharge path for the powder feeding roller node under positive pressure. The DC bias voltage generation circuit is electrically connected to the high-voltage input terminal of each developing unit, and is used to continuously provide the DC bias voltage to each developing unit without relying on the on / off state of the single-pole single-throw switch group.

2. The developing apparatus according to claim 1, characterized in that, The AC voltage generation circuit includes: A transformer, wherein one end of the secondary winding of the transformer is used to connect to a DC voltage source to receive the DC component, and the other end of the secondary winding is used to output the AC composite voltage.

3. The developing apparatus according to claim 1, characterized in that, The device further includes: A current-limiting resistor is connected in series between the output terminal of the AC voltage generation circuit and the common input node of the single-pole single-throw switch group to limit the current input to the developing unit.

4. The developing apparatus according to claim 1, characterized in that, The DC bias voltage generation circuit includes: A Zener diode, wherein the cathode of the Zener diode is connected to a DC voltage source, and the anode serves as the output node for the stepped-down DC bias voltage; Multiple isolation resistors are connected in series between the DC bias voltage output node and the high voltage input terminal of each developing unit. They are used to prevent the AC composite voltage from flowing back to the DC bias voltage generation circuit when the single-pole single-throw switch is turned on, and to isolate the mutual interference between the developing units.

5. The developing apparatus according to claim 1, characterized in that, Each of the developing units is also provided with a developing roller and a powder discharge blade.

6. The developing apparatus according to claim 5, characterized in that, Each of the developing units further includes: A bias distribution circuit is connected between the high voltage input terminal and the developing roller, the powder feeding roller, and the powder exiting blade, and is used to provide a defined potential relationship for the developing roller, the powder feeding roller, and the powder exiting blade according to the voltage polarity of the high voltage input terminal.

7. The developing apparatus according to claim 6, characterized in that, The bias allocation circuit includes: The first Zener diode has its anode connected to the high-voltage input terminal and its cathode connected to the developing roller. The second Zener diode has its cathode connected to the high-voltage input terminal and its anode connected to the powder feeding roller. The third Zener diode has its cathode connected to the powder feeding roller and its anode connected to the powder discharging knife. Specifically, when the high-voltage input terminal is positive, the first Zener diode conducts in the forward direction, while the second and third Zener diodes break down in the reverse direction, causing the potentials of the developing roller, the powder feeding roller, and the powder exiting blade to decrease sequentially. When the high-voltage input terminal is negative, the first Zener diode breaks down in the reverse direction, while the second and third Zener diodes conduct in the forward direction, making the powder feeding roller and the powder exiting blade have the same potential, and the potential of the developing roller is higher than that of the powder feeding roller.

8. The developing apparatus according to any one of claims 1 to 7, characterized in that, The single-pole single-throw switch group includes multiple single-pole single-throw relays, and each relay corresponds to one developing unit.

9. The developing apparatus according to any one of claims 1 to 7, characterized in that, The unidirectional conductive device is a diode.

10. The developing apparatus according to any one of claims 1 to 7, characterized in that, The magnitude of the DC bias voltage is greater than the magnitude of the DC component contained in the AC composite voltage.

11. A developing method, applied to a developing apparatus having multiple developing units, each of the developing units being provided with a powder feeding roller, characterized in that, include: A DC bias voltage is continuously applied to all developing units to meet the basic bias requirements of each developing unit. By using a single-pole single-throw switch group, an AC composite voltage with a superimposed DC component is selectively introduced into the target developing unit. In the target developing unit, the AC composite voltage is superimposed on the DC bias voltage to form the AC-DC superimposed bias voltage required for developing. When the powder feeding roller node of any developing unit is under positive pressure, the positive charge of the powder feeding roller node is discharged to ground via the unidirectional conductive device connected to the developing unit and the common discharge resistor. The single-pole single-throw switch group only controls the on / off state of the AC composite voltage, and does not control the on / off state of the DC bias voltage.

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