A high voltage control circuit and an image forming apparatus

Abstract

The application relates to the technical field of image forming, in particular to a high-voltage control circuit and an image forming device. The high-voltage control circuit comprises: a voltage boosting circuit comprising a transformer, a first end of a secondary winding of the transformer outputs a target high voltage, and a second end of the secondary winding is connected to ground through a first capacitor; an alternating-current high-voltage driving circuit used for driving the transformer to output alternating-current high voltage according to a developing alternating-current control signal; a rectification and filtering circuit used for rectifying and filtering the alternating-current high voltage into direct-current high voltage; a first voltage dividing circuit used for forming a current branch between an output node and a ground end; and a direct-current bias control circuit used for adjusting current in the current branch of the first voltage dividing circuit according to a developing direct-current control signal. The technical scheme of the embodiment of the application can utilize a single transformer to provide alternating-current and direct-current superimposed high voltage for jump developing, thereby reducing hardware cost.

Description

Technical Field

[0001] This application relates to the field of image forming technology, and in particular to a high-voltage control circuit and an image forming apparatus. Background Technology

[0002] Image forming apparatuses typically use high-voltage developing pressure to deliver a two-component developer from the developing cassette to the surface of the photosensitive drum, forming a visible image of an electrostatic latent image on the drum. To improve imaging efficiency, many apparatuses employ a skip-developing method, using superimposed AC and DC high voltage to control the developer to skip to the surface of the photosensitive drum, thereby shortening the single-page imaging time and improving overall printing speed and multitasking capabilities.

[0003] Existing skip-type developer high-voltage control circuits typically consist of two independent modules: a developer AC high-voltage module and a developer DC high-voltage module. The developer AC control signal (DEV-AC-PWM) is used to adjust the AC voltage amplitude, the developer DC control signal (DEV-DC-PWM) is used to adjust the DC bias voltage, and the clock signal (DEV-CLK) is used to control the frequency and duty cycle of the AC voltage. The AC high-voltage module drives a first transformer to generate the developer AC high voltage through an operational amplifier drive circuit, an oscillator drive circuit, and a push-pull circuit. The developer DC high-voltage module controls a second transformer to generate the developer DC bias voltage through a developer DC bias control circuit. The developer AC high voltage and the developer DC bias voltage are then superimposed and output. Its drawback is that each of the developer AC high-voltage module and the developer DC high-voltage module requires its own transformer, increasing hardware costs. Utility Model Content

[0004] This application is made in view of the above-mentioned problems. This application provides a high-voltage control circuit and an image forming apparatus.

[0005] In a first aspect, embodiments of this application provide a high-voltage control circuit, including:

[0006] The step-up circuit includes a transformer having a primary winding and a secondary winding. The first end of the secondary winding outputs a target high voltage, and the second end of the secondary winding is grounded after passing through a first capacitor.

[0007] An AC high-voltage drive circuit, electrically connected to the primary winding, is used to drive the transformer to output AC high voltage according to the developing AC control signal;

[0008] A rectifier and filter circuit, electrically connected to the secondary winding, is used to rectify and filter the AC high voltage into DC high voltage;

[0009] The first voltage divider circuit is electrically connected between the output node of the rectifier filter circuit and the ground terminal, and is used to form a current branch between the output node and the ground terminal so that the first capacitor forms a DC bias voltage.

[0010] A DC bias control circuit is electrically connected between the rectifier filter circuit and the second terminal of the secondary winding. It is used to adjust the current in the current branch of the first voltage divider circuit according to the DC control signal to control the DC bias voltage formed by the first capacitor.

[0011] Furthermore, according to a high-voltage control circuit of the first aspect of the present application, the boost circuit includes a second capacitor, one end of which is electrically connected to the output terminal of the AC high-voltage drive circuit, and the other end of which is electrically connected to the primary winding of the transformer.

[0012] Furthermore, according to a high-voltage control circuit based on a first aspect of the present application, the target high voltage output at the first end of the secondary winding includes:

[0013] The first end of the secondary winding outputs the target high voltage through a current-limiting impedance and a coupling capacitor.

[0014] Furthermore, according to a high-voltage control circuit of the first aspect of this application, the AC high-voltage drive circuit includes:

[0015] The first operational amplifier driving circuit is used to output a first driving signal according to the developing AC control signal;

[0016] An oscillation driving circuit, wherein the output terminal of the oscillation driving circuit is electrically connected to the output terminal of the first operational amplifier driving circuit, is used to convert the first driving signal into a second driving signal corresponding to the frequency and duty cycle of the clock signal according to the clock signal.

[0017] A push-pull circuit, wherein the input terminal of the push-pull circuit is electrically connected to the output terminal of the first operational amplifier driving circuit and the output terminal of the oscillation driving circuit, and the output terminal of the push-pull circuit is electrically connected to the primary winding of the transformer, for alternating charging and discharging of the transformer according to the second driving signal.

[0018] Furthermore, according to a high-voltage control circuit based on a first aspect of the present application, the rectifier-filter circuit includes:

[0019] A unidirectional rectifier, wherein the input terminal of the unidirectional rectifier is electrically connected to the first terminal of the secondary winding;

[0020] A filter capacitor, the first end of which is electrically connected to the output terminal of the unidirectional rectifier, and the second end of which is electrically connected to the second terminal of the secondary winding.

[0021] Furthermore, according to a high-voltage control circuit of the first aspect of the present application, the first voltage divider circuit includes a first resistor and a second resistor connected in series, the first resistor being electrically connected between the rectifier filter circuit and the second resistor; the second resistor being electrically connected between the first resistor and the ground terminal.

[0022] Furthermore, according to a high-voltage control circuit based on a first aspect of the present application, the DC bias control circuit includes:

[0023] Second operational amplifier driver circuit;

[0024] The second voltage divider circuit has one end electrically connected to the non-grounded end of the first capacitor and the other end connected to the output terminal of the second operational amplifier drive circuit.

[0025] A feedback circuit, wherein the first terminal of the feedback circuit is electrically connected to the non-grounded terminal of the first capacitor, and the second terminal of the feedback circuit is electrically connected to the input terminal of the second operational amplifier drive circuit, for feeding back the electromotive force of the DC bias voltage formed by the first capacitor to the second operational amplifier drive circuit;

[0026] The second operational amplifier drive circuit is used to control the resistance of the second voltage divider circuit according to the developing DC control signal and electromotive force, so as to adjust the current in the current branch of the first voltage divider circuit and control the DC bias voltage formed by the first capacitor.

[0027] Furthermore, according to a high-voltage control circuit of the first aspect of the present application, the second voltage divider circuit includes at least one transistor and at least two resistive elements;

[0028] The control terminal of each transistor is electrically connected to the output terminal of the second operational amplifier driver circuit, and is used to adjust its conduction state according to the control signal output by the second operational amplifier driver circuit, thereby adjusting the equivalent impedance of the second voltage divider circuit.

[0029] Furthermore, according to a high-voltage control circuit of the first aspect of this application, the second voltage divider circuit includes at least one transistor and at least two resistive elements, including:

[0030] First transistor and second transistor;

[0031] First resistor, second resistor, and third resistor;

[0032] The output terminal of the second operational amplifier driving circuit, the first resistor, the second resistor, the third resistor, and the non-grounded terminal of the first capacitor are connected in sequence.

[0033] The emitter of the first transistor is electrically connected to a high-level node, the base of the first transistor is connected between the first resistor and the second resistor, and the collector of the first transistor is electrically connected to the emitter of the second transistor.

[0034] The base of the second transistor is connected between the second resistor and the third resistor, and the collector of the first transistor is electrically connected to the non-grounded terminal of the first capacitor.

[0035] Secondly, embodiments of this application provide an image forming apparatus, including a high-voltage control circuit according to any of the above descriptions.

[0036] As will be described in detail below, a high-voltage control circuit and image forming apparatus according to an embodiment of this application achieves common-source output and independent control of the AC high voltage and DC bias voltage for development by setting a rectifier filter circuit and a voltage divider control circuit on the secondary side of the transformer and adjusting the DC bias voltage using a DC bias control circuit. This high-voltage control circuit and image forming apparatus according to an embodiment of this application can provide and control the AC and DC superimposed high voltage for skip development using a single transformer, thereby effectively solving the problem in the prior art that requires two transformers to output AC and DC high voltages separately, reducing hardware costs and optimizing circuit board space utilization.

[0037] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further illustration of the claimed technology. Attached Figure Description

[0038] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0039] Figure 1 This is a schematic diagram of a high-voltage control circuit according to an embodiment of this application.

[0040] Figure 2 This is another schematic diagram of a high-voltage control circuit according to an embodiment of this application.

[0041] Figure 3 This is a schematic diagram illustrating a connection between the boost circuit and the high-voltage output terminal in a high-voltage control circuit according to an embodiment of this application.

[0042] Figure 4This is a schematic diagram of an AC high-voltage drive circuit in a high-voltage control circuit according to an embodiment of this application.

[0043] Figure 5 This is a schematic diagram of a first operational amplifier drive circuit in a high-voltage control circuit according to an embodiment of this application.

[0044] Figure 6 This is a schematic diagram of an oscillation drive circuit in a high-voltage control circuit according to an embodiment of this application.

[0045] Figure 7 This is a schematic diagram of a push-pull circuit in a high-voltage control circuit according to an embodiment of this application.

[0046] Figure 8 This is a schematic diagram of a rectifier and filter circuit in a high-voltage control circuit according to an embodiment of this application.

[0047] Figure 9 This is a schematic diagram of a first voltage divider circuit in a high-voltage control circuit according to an embodiment of this application.

[0048] Figure 10 This is a schematic diagram of a DC bias control circuit in a high-voltage control circuit according to an embodiment of this application.

[0049] Figure 11 This is a schematic diagram of a second operational amplifier drive circuit in a high-voltage control circuit according to an embodiment of this application.

[0050] Figure 12 This is a schematic diagram of a second voltage divider circuit in a high-voltage control circuit according to an embodiment of this application. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this application more apparent, exemplary embodiments according to this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein.

[0052] See Figure 1 This application provides a high-voltage control circuit, including:

[0053] The boost circuit 1 includes a transformer T1, which has a primary winding and a secondary winding. The first end of the secondary winding outputs the target high voltage DEV, and the second end of the secondary winding is grounded through the first capacitor C5.

[0054] AC high voltage drive circuit 2 is electrically connected to the primary winding and is used to drive transformer T1 to output AC high voltage according to the developing AC control signal.

[0055] The rectifier and filter circuit 3 is electrically connected to the secondary winding and is used to rectify and filter the AC high voltage into DC high voltage.

[0056] The first voltage divider circuit 4 is electrically connected between the output node of the rectifier filter circuit 3 and the ground terminal, and is used to form a current branch between the output node and the ground terminal so that the first capacitor C5 forms a DC bias voltage.

[0057] The DC bias control circuit 5 is electrically connected between the rectifier filter circuit 3 and the second terminal of the secondary winding. It is used to adjust the current in the current branch of the first voltage divider circuit 4 according to the developing DC control signal, so as to control the DC bias voltage formed by the first capacitor C5.

[0058] In this embodiment, by setting a rectifier filter circuit and a voltage divider control circuit on the secondary side of the transformer, and using a DC bias control circuit to adjust the DC bias voltage, the common source output and independent control of the developing AC high voltage and the developing DC bias voltage are achieved. This embodiment of the high voltage control circuit and image forming apparatus provides a superimposed AC / DC high voltage for skip-development without the need for a second transformer, effectively solving the problem in the prior art where two transformers are needed to output AC and DC high voltages separately. This reduces system hardware costs, simplifies the circuit structure, and optimizes circuit board space utilization.

[0059] In this embodiment, the AC high voltage output from the secondary winding of transformer T1 is rectified and filtered by rectifier and filter circuit 3, generating a high voltage across the filter capacitor in rectifier and filter circuit 3. This high voltage is then divided by the fixed electronic components of the first voltage divider circuit to generate a negative high voltage. This negative high voltage serves as a DC bias voltage and can be adjusted by DC bias control circuit 5. The AC high voltage output from the secondary winding of transformer T1 can be adjusted by AC high voltage drive circuit 2. The DC bias voltage and AC high voltage can serve as the AC / DC superimposed high voltage for jump-type development. This achieves the common source output and independent control of the aforementioned development AC high voltage and development DC bias voltage.

[0060] In this embodiment, the AC high-voltage drive circuit 2 is electrically connected to the primary winding of transformer T1. It should be understood that the dashed lines in the figure indicate that other components may be included; that is, the AC high-voltage drive circuit 2 may have other components between its electrical connection to the primary winding of transformer T1. For example, see [example description]. Figure 2 and Figure 3 , Figure 2 The illustration shows another schematic diagram of a high-voltage control circuit according to an embodiment of this application, such as... Figure 2As shown, the boost circuit 1 includes a second capacitor C3. One end of the second capacitor C3 is electrically connected to the output terminal 201 of the AC high-voltage drive circuit, and the other end of the second capacitor C3 is electrically connected to the primary winding of the transformer T1. In one example, the second capacitor C3 is an electrolytic capacitor. When the second capacitor C3 and the transformer T1 form a boost circuit, when the AC high-voltage drive circuit alternately charges and discharges the second capacitor C3 and the primary side of the transformer T1, an alternating voltage will be generated on the primary side of the transformer T1 due to the device characteristics of the electrolytic capacitor. Due to the electromagnetic induction and turns ratio of the transformer, an AC high voltage will be generated on the secondary side of the transformer. It should be understood that other types of capacitors can be used in the embodiments of this application, as long as they can generate an alternating voltage on the primary side of the transformer T1.

[0061] In this embodiment, the first end of the secondary winding outputs the target high voltage DEV. It should be understood that the dashed lines in the figure indicate that other components may be included; that is, when the first end of the secondary winding outputs the target high voltage DEV, there may be other components between the first end of the secondary winding and the target high voltage DEV. For example, see... Figure 2 and Figure 3 The first end of the secondary winding is connected to the high-voltage output terminal via a current-limiting impedance R10 and a coupling capacitor C6, outputting the target high-voltage DEV. This structure not only limits the output current for protection but also blocks the DC component through the coupling capacitor, effectively transmitting only the AC high-voltage signal to the output terminal, thus achieving safe and reliable high-voltage output for development. Specifically, the first end of the current-limiting impedance R10 is electrically connected to the first end of the secondary winding, and the second end is electrically connected to the high-voltage output terminal, outputting the target high-voltage DEV; one end of the coupling capacitor C6 is grounded, and the other end is electrically connected to the second end of the current-limiting impedance R10.

[0062] In one embodiment, see Figure 2 and Figure 4 AC high-voltage drive circuit 2, including:

[0063] The first operational amplifier driving circuit 21 is used to output a first driving signal according to the developing AC control signal;

[0064] The output of the oscillation driving circuit 22 is electrically connected to the output of the first operational amplifier driving circuit 21. It is used to convert the first driving signal into a second driving signal corresponding to the frequency and duty cycle of the clock signal according to the clock signal.

[0065] The push-pull circuit 23 has its input terminal electrically connected to the output terminal of the first operational amplifier drive circuit 21 and the output terminal of the oscillation drive circuit 22. The output terminal of the push-pull circuit 23 is electrically connected to the primary winding of the transformer T1, and is used to alternately charge and discharge the transformer T1 according to the second drive signal.

[0066] In this embodiment, the first operational amplifier driving circuit 21 outputs a first driving signal based on the developing AC control signal; the oscillation driving circuit 22 converts the first driving signal into a second driving signal corresponding to the frequency and duty cycle of the clock signal based on the clock signal; the push-pull circuit 23 alternately charges and discharges the transformer T1 according to the second driving signal, causing the transformer to output AC power. This scheme achieves independent adjustable control of the frequency, duty cycle, and amplitude of the developing AC high voltage output through the joint modulation of the developing AC control signal and the clock signal, thereby meeting the high requirements of skip-type developing for AC voltage accuracy and response speed.

[0067] In one example, see Figure 2 and Figure 5 The first operational amplifier driver circuit 21 includes resistors R1, R2, R3, and R4, operational amplifier U1A, and capacitor C1. The first terminal of capacitor C1 is grounded, and the second terminal is electrically connected to the inverting input terminal of operational amplifier U1A. The first terminal of resistor R1 is connected to a 5V high voltage, and the second terminal is connected to the non-inverting input terminal of operational amplifier U1A. The first terminal of resistor R2 is grounded, and the second terminal is connected to the second terminal of resistor R1. The first terminal of resistor R4 is connected to the non-inverting input terminal of operational amplifier U1A, and the second terminal of resistor R4 is connected to the output terminal of operational amplifier U1A. The first terminal of resistor R3 is used to input the developing AC control signal DEV-AC-PWM, and the second terminal is electrically connected to the inverting input terminal of operational amplifier U1A. In this example, the first operational amplifier driver circuit 21 is controlled by the developing AC control signal DEV-AC-PWM. The operational amplifier U1A in the first operational amplifier driver circuit 21 constitutes an inverting amplifier circuit, which outputs a certain voltage at the output terminal of operational amplifier U1A to drive the push-pull circuit 23.

[0068] In one example, see Figure 2 and Figure 6The oscillation drive circuit 22 includes a resistor R6, a capacitor C2, and an NPN transistor Q5. The first terminal of resistor R6 is used to input the clock signal DEV-CLK, and the second terminal is connected to the base of transistor Q5 and the first terminal of capacitor C2. The second terminal of capacitor C2 is grounded. The emitter of transistor Q5 is grounded, and the collector serves as the output terminal, providing a drive signal to subsequent circuits. In this example, the oscillation drive circuit 22 is controlled by the clock signal DEV-CLK. Transistor Q5 converts the input first drive signal into a second drive signal with the same frequency and duty cycle as DEV-CLK to drive the push-pull circuit. Specifically, NPN transistor Q5 is turned on or off at different frequencies and duty cycles, thereby converting the drive signal output from the operational amplifier drive circuit into a drive PWM signal with a certain frequency and duty cycle as the second drive signal. The frequency and duty cycle of this second drive signal are consistent with the clock signal DEV-CLK. This second drive signal is used to drive the push-pull circuit 23. Adjusting the duty cycle of DEV-AC-PWM can adjust the AC peak-to-peak value Vpp of the high-voltage output terminal of DEV, which displays the high voltage output.

[0069] In one example, see Figure 2 and Figure 7 The push-pull circuit 23 includes resistors R7, R8, and R9, an NPN transistor Q1, and a PNP transistor Q2. The first terminal of resistor R7 receives the drive signal from the oscillation drive circuit, and the second terminal is connected to the first terminals of resistors R8 and R9. The second terminal of resistor R8 is connected to the base of transistor Q1, whose collector is connected to a 24V power supply, and whose emitter serves as the output terminal. The second terminal of resistor R9 is connected to the base of transistor Q2, whose collector is grounded, and whose emitter shares an output terminal with the emitter of Q1. They are controlled by the second drive signal output from the previous stage, causing transistors Q1 and Q2 to conduct alternately. When Q1 is on and Q2 is off, the downstream capacitor C3 and the primary side of transformer T1 are charged. When Q1 is off and Q2 is on, the downstream capacitor C3 and the primary side of transformer T1 are discharged.

[0070] In one embodiment, see Figure 2 and Figure 8 The rectifier and filter circuit 3 includes:

[0071] Unidirectional rectifier D1, the input terminal of the unidirectional rectifier is electrically connected to the first terminal of the secondary winding;

[0072] The filter capacitor C4 has its first terminal electrically connected to the output terminal of the unidirectional rectifier, and its second terminal electrically connected to the second terminal of the secondary winding.

[0073] In this embodiment, the unidirectional rectifier D1 can be a diode. The rectifier-filter circuit rectifies and filters the AC high voltage output from the secondary winding of transformer T1, generating a positive voltage across capacitor C4 with the upper positive and lower negative terminals. This rectifier-filter circuit can stably convert the AC high voltage output from the transformer secondary winding into a DC high voltage, providing a voltage basis for the DC bias control module.

[0074] In one embodiment, see Figure 2 and Figure 9 The first voltage divider circuit 4 includes a first resistor R11 and a second resistor R12 connected in series. The first resistor R11 is electrically connected between the output node of the rectifier filter circuit 3 and the second resistor R12, and the second resistor R12 is electrically connected between the first resistor R11 and the ground terminal. The first voltage divider circuit 4 can be composed of the first resistor R11 and the second resistor R12. From the current loop of current I1, it can be seen that there is a positive potential V2 across the first resistor R11 and the second resistor R12, which can be used together with the second voltage divider circuit in other embodiments to adjust the magnitude of the DC bias voltage on the first capacitor C5, that is, to determine the magnitude of the DC voltage. Transformer T1 is an electromagnetic induction transformer, and since the secondary of transformer T1 outputs an AC high voltage. Diode D1 and capacitor C4 together form a rectifier filter circuit, generating a positive voltage potential V1 across C4 with the upper positive and lower negative terminals. According to the voltage relationship, the electromotive force V2 across the first resistor R11 and the second resistor R12, the electromotive force V3 of the first capacitor C5 to ground, and the electromotive force V1 of C4 have the following relationship: V1 + V3 = V2. The first voltage divider circuit establishes a DC bias voltage for the first capacitor C5 by providing a current path from the rectifier filter output node to ground. Through the control of the branch current and the feedback mechanism, the developing DC high voltage V3 is precisely adjustable, laying the foundation for achieving AC and DC superimposed high voltage output.

[0075] In one embodiment, see Figure 2 and Figure 10 DC bias control circuit 5 includes:

[0076] Second operational amplifier driver circuit 51;

[0077] The second voltage divider circuit 52 has one end electrically connected to the non-grounded end of the first capacitor C5, and the other end connected to the output end of the second operational amplifier drive circuit 51.

[0078] Feedback circuit 53, the first end of feedback circuit 53 is electrically connected to the non-grounded end of the first capacitor C5, and the second end of feedback circuit 53 is electrically connected to the input end of the second operational amplifier drive circuit 51, used to feed back the electromotive force of the DC bias voltage formed by the first capacitor C5 to the second operational amplifier drive circuit 51.

[0079] The second operational amplifier drive circuit 51 is used to control the resistance of the second voltage divider circuit 52 according to the developing DC control signal and electromotive force, so as to adjust the current in the current branch of the first voltage divider circuit 4 and control the DC bias voltage formed by the first capacitor C5.

[0080] In this embodiment, the closed-loop precise control of the DC bias voltage is achieved through the coordinated operation of operational amplifier driving, feedback sampling and variable impedance elements. This not only improves output stability but also simplifies the bias voltage control path, further supporting the high requirements for dynamic response to negative bias voltage in jump development.

[0081] In one example, see Figure 2 and Figure 11 The second operational amplifier driver circuit 51 includes resistors R13, R14, R15, and R16, capacitors C6 and C7, and operational amplifier U1B. The first terminal of capacitor C7 is grounded, and the second terminal is electrically connected to the inverting input terminal of operational amplifier U1B. The first terminal of resistor R13 is connected to a 5V power supply, and the second terminal is connected to the non-inverting input terminal of operational amplifier U1B. The first terminal of resistor R14 is grounded, and the second terminal is connected to the second terminal of resistor R13. The first terminal of resistor R16 is connected to the output terminal of operational amplifier U1B, and the second terminal is electrically connected to the inverting input terminal of operational amplifier U1B; capacitor C6 is connected to resistor R16 to form a negative feedback loop. The first terminal of resistor R15 is used to input the developing DC control signal DEV-DC-PWM, and the second terminal is connected to the non-grounded terminal of capacitor C7. In this example, under the control of the developing DC control signal DEV-DC-PWM, the second operational amplifier drive circuit 51 uses operational amplifier U1B as a negative feedback adjustment circuit to adjust the node potential connected to its inverting input terminal. This allows for precise control of the developing DC bias voltage through feedback regulation of the output voltage. The circuit adjusts the operational amplifier output based on the feedback from the feedback resistor R20. The output voltage of operational amplifier U1B is used to adjust the voltage divider circuit.

[0082] See Figure 2 The feedback circuit 53 may include a resistor R20. One end of the resistor R20 can be electrically connected to the input terminal of the operational amplifier UIB, and the other end can be electrically connected to the output terminal of the voltage divider circuit. It is used to feed back the magnitude of the electromotive force V3 to the input terminal of the operational amplifier U1B in the operational amplifier driver circuit, forming a negative feedback loop, thereby dynamically controlling the magnitude of the developing DC voltage.

[0083] In one embodiment, the second voltage divider circuit includes at least one transistor and at least two resistive elements;

[0084] The control terminal of each transistor is electrically connected to the output of the second operational amplifier driver circuit. This allows the transistor's conduction state to be adjusted according to the control signal output by the second operational amplifier driver circuit, thereby adjusting the equivalent impedance of the second voltage divider circuit. By connecting the transistor's control terminal to the output of the second operational amplifier driver circuit, the transistor's conduction state becomes controllable, thus adjusting its equivalent impedance. This achieves continuous, precise, and closed-loop control of the developing DC bias voltage formed by the first capacitor, meeting the comprehensive requirements of a high-performance jump-type developing system for adjustable negative bias voltage, responsiveness, and stability.

[0085] In one example, see Figure 2 and Figure 12The second voltage divider circuit includes a first transistor Q3 and a second transistor Q4, a first resistor R17, a second resistor R18, and a third resistor R19. The output terminal of the second operational amplifier driver circuit 51, the first resistor R17, the second resistor R18, the third resistor R19, and the non-grounded terminal of the first capacitor C5 are connected in sequence. The emitter of the first transistor Q3 is connected to a high-level node, the base of the first transistor Q3 is connected between the first resistor R11 and the second resistor R12, and the collector of the first transistor Q3 is connected to the emitter of the second transistor. The base of the second transistor Q4 is connected between the second resistor R18 and the third resistor R19, and the collector of the first transistor Q3 is connected to the non-grounded terminal of the first capacitor C5. In this example, the second voltage divider circuit 502 includes a first transistor Q3, a second transistor Q4, a first resistor R17, a second resistor R18, and a third resistor R19. The output voltage of operational amplifier U1B is used to adjust the conduction state of the transistors in the voltage divider circuit. When the output of operational amplifier U1B is pulled low, the first transistor Q3 and the second transistor Q4 are fully turned on, and the electromotive force V3 across the first capacitor C5 is 5V. At this time, it can be regarded as the DC bias voltage of the display being 0V. When the output of operational amplifier U1B is pulled high, the first transistor Q3 and the second transistor Q4 are in the amplification state or the cutoff state, and together with the first resistor R17, the second resistor R18, and the third resistor R19, they present a high impedance. When the electromotive force V1 across capacitor C4 is constant, the greater the impedance presented by the first transistor Q3 and the second transistor Q4 in the amplification state or the cutoff state, the smaller the current I1, and the smaller the potential V2 across the first resistor R11 and the second resistor R12. Therefore, V3 = V2 - V1, and the negative potential V3 increases. Since C4 and D1 together form a rectifier-filter circuit, a positive voltage potential V1 is generated across C4, with the upper voltage positive and the lower voltage negative. Current flows out from the junction of transistor Q4, the third resistor R19, and resistor R20, passing through capacitor C4, the first resistor R11, and the second resistor R12 before returning to GND. Therefore, a positive voltage potential V2 is generated across the first resistor R11 and the second resistor R12. Since V1 + V3 = V2, both V1 and V2 are positive potentials, and V1 acts as a voltage source, its potential magnitude V1 > V2. Therefore, V3 is a negative potential. This negative potential V3 is the DC negative high voltage that this circuit aims to control. The current I1 is the current flowing through the voltage divider circuit, the filter circuit, and the voltage divider resistors.

[0086] This application also provides an image forming apparatus, including a high-voltage control circuit according to any embodiment of this application. The high-voltage control circuit is used to provide AC and adjustable DC bias voltages required for skip development.

[0087] In the technical solution of this application embodiment, a transformer is used in conjunction with a control signal to realize a jump-type developing high voltage, which is an AC / DC superimposed high voltage with both AC and DC components. The developing DC high voltage has a controllable and adjustable value; the developing AC high voltage has a controllable and adjustable peak-to-peak value; and the developing AC frequency and duty cycle are controllable and adjustable. When the developing AC high voltage control circuit outputs, it is rectified and filtered by the secondary output of the AC component circuit, combined with a second voltage divider circuit composed of transistors and resistors, and a developing AC voltage divider resistor connected to the developing AC filter circuit composed of diodes and capacitors, to generate the developing DC voltage. The second voltage divider circuit is controlled by the operational amplifier drive circuit and the PWM signal, causing the transistors in the second voltage divider circuit to be in different amplification states, thereby adjusting the magnitude of the developing DC component voltage. The two ends of the feedback resistor are connected to the output terminal of the second voltage divider circuit and the input terminal of the second operational amplifier drive circuit, respectively, to promptly feed back the developing DC voltage to the second operational amplifier drive circuit. The second operational amplifier drive circuit can control the developing DC voltage in a timely manner based on the feedback voltage.

[0088] The technical solution of this application embodiment can save a transformer, optimize the hardware solution, reduce system cost, and reduce the area occupied by the high voltage control circuit of the jump development.

[0089] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0090] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0091] Additionally, as used herein, the “or” used in a list of items beginning with “at least one” indicates a separate list, such that a list of, for example, “at least one of A, B, or C” means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word “exemplary” does not imply that the described example is preferred or better than other examples.

[0092] It should also be noted that in the system and method of this application, the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions of this application.

[0093] Various changes, substitutions, and modifications can be made to the technology herein without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims is not limited to the specific aspects of the processes, machines, manufactures, events, means, methods, and actions described above. Currently existing or later-developed processes, machines, manufactures, events, means, methods, or actions that perform substantially the same function or achieve substantially the same result as the corresponding aspects herein can be utilized. Therefore, the appended claims include such processes, machines, manufactures, events, means, methods, or actions within their scope.

[0094] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0095] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A high-voltage control circuit, characterized in that, include: The step-up circuit includes a transformer having a primary winding and a secondary winding. The first end of the secondary winding outputs a target high voltage, and the second end of the secondary winding is grounded after passing through a first capacitor. An AC high-voltage drive circuit, electrically connected to the primary winding, is used to drive the transformer to output AC high voltage according to the developing AC control signal; A rectifier and filter circuit, electrically connected to the secondary winding, is used to rectify and filter the AC high voltage into DC high voltage; The first voltage divider circuit is electrically connected between the output node of the rectifier and filter circuit and the ground terminal, and is used to form a current branch between the output node and the ground terminal so that the first capacitor forms a DC bias voltage. A DC bias control circuit is electrically connected between the rectifier filter circuit and the second terminal of the secondary winding. It is used to adjust the current in the current branch of the first voltage divider circuit according to the DC control signal, so as to control the DC bias voltage formed by the first capacitor.

2. The high-voltage control circuit according to claim 1, characterized in that, The boost circuit includes a second capacitor, one end of which is electrically connected to the output terminal of the AC high-voltage drive circuit, and the other end of which is electrically connected to the primary winding of the transformer.

3. The high-voltage control circuit according to claim 1, characterized in that, The target high voltage output at the first end of the secondary winding includes: The first end of the secondary winding outputs the target high voltage through a current-limiting impedance and a coupling capacitor.

4. A high-voltage control circuit according to claim 1, characterized in that, The AC high-voltage drive circuit includes: The first operational amplifier driving circuit is used to output a first driving signal according to the developing AC control signal; An oscillation driving circuit, wherein the output terminal of the oscillation driving circuit is electrically connected to the output terminal of the first operational amplifier driving circuit, is used to convert the first driving signal into a second driving signal corresponding to the frequency and duty cycle of the clock signal according to the clock signal. A push-pull circuit, wherein the input terminal of the push-pull circuit is electrically connected to the output terminal of the first operational amplifier driving circuit and the output terminal of the oscillation driving circuit, and the output terminal of the push-pull circuit is electrically connected to the primary winding of the transformer, for alternating charging and discharging of the transformer according to the second driving signal.

5. The high-voltage control circuit according to claim 1, characterized in that, The rectifier filter circuit includes: A unidirectional rectifier, wherein the input terminal of the unidirectional rectifier is electrically connected to the first terminal of the secondary winding; A filter capacitor, the first end of which is electrically connected to the output terminal of the unidirectional rectifier, and the second end of which is electrically connected to the second terminal of the secondary winding.

6. The high-voltage control circuit according to claim 1, characterized in that, The first voltage divider circuit includes a first resistor and a second resistor connected in series. The first resistor is electrically connected between the rectifier filter circuit and the second resistor. The second resistor is electrically connected between the first resistor and the ground terminal.

7. The high-voltage control circuit according to any one of claims 1 to 6, characterized in that, The DC bias control circuit includes: Second operational amplifier driver circuit; The second voltage divider circuit has one end electrically connected to the non-grounded end of the first capacitor and the other end connected to the output terminal of the second operational amplifier drive circuit. A feedback circuit, wherein the first terminal of the feedback circuit is electrically connected to the non-grounded terminal of the first capacitor, and the second terminal of the feedback circuit is electrically connected to the input terminal of the second operational amplifier drive circuit, for feeding back the electromotive force of the DC bias voltage formed by the first capacitor to the second operational amplifier drive circuit. The second operational amplifier driving circuit is used to control the resistance of the second voltage divider circuit according to the developing DC control signal and electromotive force, so as to adjust the current in the current branch of the first voltage divider circuit and control the DC bias voltage formed by the first capacitor.

8. The high-voltage control circuit according to claim 7, characterized in that, The second voltage divider circuit includes at least one transistor and at least two resistive elements; The control terminal of each transistor is electrically connected to the output terminal of the second operational amplifier driver circuit, and is used to adjust its conduction state according to the control signal output by the second operational amplifier driver circuit, thereby adjusting the equivalent impedance of the second voltage divider circuit.

9. The high-voltage control circuit according to claim 8, characterized in that, The second voltage divider circuit includes at least one transistor and at least two resistive elements, including: First transistor and second transistor; First resistor, second resistor, and third resistor; The output terminal of the second operational amplifier driving circuit, the first resistor, the second resistor, the third resistor, and the non-grounded terminal of the first capacitor are connected in sequence. The emitter of the first transistor is electrically connected to a high-level node, the base of the first transistor is connected between the first resistor and the second resistor, and the collector of the first transistor is electrically connected to the emitter of the second transistor. The base of the second transistor is connected between the second resistor and the third resistor, and the collector of the first transistor is electrically connected to the non-grounded terminal of the first capacitor.

10. An image forming apparatus, characterized in that, Includes the high-voltage control circuit according to any one of claims 1 to 9.

Images