JP3782570B2 - Image recording device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an image recording apparatus such as a page printer using electrophotography, and more particularly, to a charging voltage generation circuit that generates a charging voltage for uniformly charging an image carrier or on an image carrier. The present invention relates to an image recording apparatus provided with a high voltage generation circuit such as a development voltage generation circuit for generating a development voltage for developing a latent image.
[0002]
[Prior art]
FIG. 5 shows an example of a conventional image recording apparatus using electrophotography. The image recording apparatus of this example includes a drum-shaped electrophotographic photosensitive member 1 that is an image bearing member, and an electrophotographic process means is disposed around the photosensitive drum 1. That is, the electrophotographic process means includes a charging device for putting a necessary uniform charge on the photosensitive drum 1, for example, a charging voltage generating circuit 20 for supplying a high voltage to the charging roller 2, and the uniformly charged photosensitive drum 1. An exposure device 3 such as a laser generator that irradiates a laser beam on the image data according to image data to form an electrostatic latent image, and further develops the electrostatic latent image formed on the photosensitive drum 1. A developing device 4 is included. The developing device 4 includes a developing container 41 that contains a developer, and a developing sleeve 42 is disposed at a position facing the photosensitive drum 1 at an opening of the developing container 41. The developing sleeve 42 carries the developer in the developing container 41 and conveys it to the developing area facing the photosensitive drum 1. At this time, the developer on the developing sleeve 42 is regulated to a predetermined thickness by the developer thickness regulating member 43 and then conveyed to the developing area. A predetermined developing voltage is applied to the developing sleeve 42 from the developing voltage generation circuit 50, and the electrostatic latent image on the photosensitive drum 1 is developed into a visible image, that is, a toner image. This toner image is transferred to the recording material P at a transfer position where a transfer device 6 such as a corona charger is disposed. The photosensitive drum 1 is subjected to the next image forming process after the remaining toner is wiped off by a cleaning device (not shown).
[0003]
FIG. 6 shows an example of the development voltage generation circuit 50. The output DVACC from the engine controller 100 is a square wave with a normal frequency of about 1.5 KHz to 2.5 KHz, and is determined by the process speed of the engine (image forming apparatus body). As an example, the engine controller output DVACC is a square wave with a frequency of 1.8 KHz and Vpp 5 V, and a square wave with a variable duty. The engine controller controls the image recording apparatus and changes the duty of the square wave from the engine controller 100 in accordance with the density changing means for changing the density of the image, that is, the signal TCHG from the host computer 200 in this example. It is possible to change the concentration.
[0004]
The development voltage generation circuit 50 includes a power amplifier 51, amplifies a signal (output) DVACC from the engine controller 100, and inputs the amplified signal to the step-up transformer 52. The power amplifier 51 is supplied with power 24V from a multi-output power source (not shown). At this time, DVACC is amplified to about Vpp 20 V by the power amplifier 51. The multi-output power supply also supplies a power supply 5V necessary for the engine controller 100 and the like.
[0005]
The voltage input to the step-up transformer 52 is changed by the transformer 52 to a voltage corresponding to the winding. Conventionally, this voltage is 1.5 kVpp. This voltage is rectified by a rectifier circuit including a rectifier element (diode) 53 and a capacitor 54, and a development voltage DVOUT of 1.5 kVpp centered on the voltage rectified by the capacitor 54 is output. The operational amplifier 56, the transistor 57, and the capacitor 58 are for controlling the center voltage of the development voltage DVOUT. Specifically, the voltage of the capacitor 54 is set according to the value DVDCC from the D / A output of the engine controller 100. Control by changing.
[0006]
[Problems to be solved by the invention]
However, according to the conventional developing voltage generation circuit 50, there are problems such as a large number of circuit parts, an increase in cost, an increase in mounting area, and a decrease in reliability due to an increase in the number of parts. there were. Such a problem is not only the development voltage generation circuit 50 but also the high voltage generation circuit such as the charging voltage generation circuit 20.
[0007]
Accordingly, an object of the present invention is to reduce the number of components of a high voltage generation circuit such as a development voltage generation circuit and a charging voltage generation circuit, thereby reducing the cost, reducing the mounting area, and improving the reliability by reducing the number of components. It is an object to provide an image recording apparatus capable of performing the above.
[0008]
[Means for Solving the Problems]
The above object is achieved by the image recording apparatus according to the present invention. In summary, the present invention relates to an image carrier, a charging device for uniformly charging the image carrier, a charging voltage generation circuit for generating a charging voltage necessary for the charging, and the image carrier. The image forming apparatus is irradiated with image information to form an electrostatic latent image on the image carrier, a developing device for developing the electrostatic latent image formed on the image carrier, and necessary for the development. In an image recording apparatus having a development voltage generating circuit for generating a different development voltage and an engine controller for controlling the image recording apparatus,
The development voltage generation circuit includes a step-up transformer for stepping up a pulse voltage, a rectifying element and a capacitor for rectifying the stepped-up pulse voltage, and connected to both ends of the capacitor, respectively, and charges accumulated in the capacitor. A plurality of resistors for discharging, and creating a DC bias of the developing voltage generating circuit generated from the developing voltage generating circuit by resistance voltage division,
The density adjustment by the development voltage generation circuit is performed by changing the duty of the output from the engine controller based on a signal from a density change means provided in the apparatus body and inputting the duty to the development voltage generation circuit. It is a recording device.
[0009]
According to another aspect of the present invention, an image carrier, a charging device for uniformly charging the image carrier, a charging voltage generation circuit for generating a charging voltage necessary for the charging, and the image carrier An exposure device for irradiating a body with image information to form an electrostatic latent image on the image carrier, a developing device for developing the electrostatic latent image formed on the image carrier, and the development In an image recording apparatus having a development voltage generation circuit for generating a necessary development voltage and an engine controller for controlling the image recording apparatus,
The development voltage generation circuit includes a step-up transformer for stepping up a pulse voltage, a rectifying element and a capacitor for rectifying the stepped-up pulse voltage, and connected to both ends of the capacitor, respectively, and charges accumulated in the capacitor. anda resistor and a Zener diode for discharging, make a DC bias of the developing voltage generation circuit which is generated from the developing voltage generation circuit in the zener diode,
The density adjustment by the development voltage generation circuit is performed by changing the duty of the output from the engine controller based on a signal from a density change means provided in the apparatus body and inputting the duty to the development voltage generation circuit. A recording device is provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the image recording apparatus according to the present invention will be described in more detail with reference to the drawings.
[0012]
Example 1
FIG. 1 shows an embodiment of a developing voltage generation circuit 50 constituting the characteristic part of the present invention used in the image recording apparatus of the present invention. The image recording apparatus can be, for example, the electrophotographic image recording apparatus described with reference to FIG. 5, and the description in this embodiment is omitted.
[0013]
In the development voltage generation circuit 50 of the present embodiment, the same reference numerals are given to portions having the same functions as those of the conventional development voltage generation circuit 50 described with reference to FIG.
[0014]
The development voltage generation circuit 50 according to the present invention is greatly different from the conventional apparatus in that the circuit in which the conventional development voltage generation circuit 50 is composed of an operational amplifier 56 and a transistor 57 is composed of two resistors 61 and 63. The point is to configure.
[0015]
That is, in this embodiment, one end of each of the resistor 61 and the resistor 63 is connected to both ends of the capacitor 54, and the other end is connected (grounded) to GND. The pulse voltage boosted by the step-up transformer 52 is charged to the capacitor 54 at a value proportional to the duty of DVACC from the engine controller 100 by the diode 53 and the capacitor 54. At this time, the voltage across the resistors 61 and 63 is a voltage obtained by dividing the voltage across the capacitor by resistance. That is, when the development voltage (DVOUT) is Vpp, the voltage at both ends of the capacitor 54 is Vc, and the voltages at both ends of the capacitor 54 are Vr1 and Vr2, respectively, the following equations are established.
Vc ≒ Vpp × Duty
Vc = Vr1 + Vr2
When the resistance values of the resistor 61 and the resistor 63 are R1 and R2,
Vr1≈Vc × {R1 / (R1 + R2)}
Vr2≈Vc × {R2 / (R1 + R2)}
It becomes. The waveform of the development voltage (DVOUT) at this time is shown in FIG.
[0016]
In the above description, one of the resistors 61 and 63 is described as being grounded, but may be a stable potential, for example, 24V or 3.3V.
[0017]
Further, a developing voltage is generated by changing the duty by, for example, performing pulse width modulation of the output (DVACC) from the engine controller 100 based on a density changing means provided in the apparatus main body, for example, a signal (TCHG) from the host computer 200 By inputting to the circuit 50, the density adjustment by the developing voltage generation circuit 50 can be performed.
[0018]
Example 2
FIG. 3 shows another embodiment of the developing voltage generation circuit 50 that constitutes a characteristic part of the present invention. In the development voltage generation circuit 50 of this embodiment, the same reference numerals are given to the portions having the same functions as those of the development voltage generation circuit 50 described in the first embodiment, and the description thereof is omitted.
[0019]
In the development voltage generation circuit 50 of the present embodiment, a Zener diode 64 is used instead of the resistor 63 in the development voltage generation circuit 50 of the first embodiment.
[0020]
In other words, in this embodiment, one end of the resistor 61 and the Zener diode 64 is connected to both ends of the capacitor 54, and the other end is connected (grounded) to GND. The pulse voltage boosted by the step-up transformer 52 is charged to the capacitor 54 at a value proportional to the duty of DVACC from the engine controller 100 by the diode 53 and the capacitor 54. At this time, the voltage of the resistor 61 is a value obtained by subtracting the voltage of the Zener diode 64 from the voltage across the capacitor 54. That is, when the development voltage (DVOUT) is Vpp, the voltage across the capacitor 54 is Vc, and the voltages at both ends of the capacitor 54 are Vr1 and Vzd, respectively, the following equations hold.
Vc ≒ Vpp × Duty
Vc = Vr1 + Vzd
When the resistance value of the resistor 61 is R1,
Vr1≈Vc + Vzd
It becomes. The waveform of the development voltage (DVOUT) at this time is shown in FIG.
[0021]
In the above description, one of the resistor 61 and the Zener diode 64 is described as being grounded, but it may be a stable potential, for example, 24V or 3.3V.
[0022]
Similarly to the first embodiment, density changing means provided in the apparatus main body, for example, by performing pulse width modulation of the output (DVACC) from the engine controller 100 based on a signal (TCHG) from the host computer 200, for example. By changing the duty and inputting it to the development voltage generation circuit 50, the density adjustment by the development voltage generation circuit 50 can be performed.
[0023]
Example 3
In the first embodiment and the second embodiment, the case where the high voltage generation circuit which is the feature of the present invention is applied to the development voltage generation circuit 50 has been described. However, this high voltage generation circuit is also applied to the charging voltage generation circuit 20 in the same manner. It is possible and can have the same effect.
[0024]
【The invention's effect】
As described above , according to the image recording apparatus of the present invention, the development voltage generation circuit that generates the development voltage necessary for developing the electrostatic latent image formed on the image carrier boosts the pulse voltage. A step-up transformer, a rectifying element and a capacitor for rectifying the boosted pulse voltage, and a plurality of resistors connected to both ends of the capacitor for discharging the charge stored in the capacitor. and either make a DC bias of the developing voltage generation circuit which is generated from the developing voltage generation circuit using resistance division of, or commutation for rectifying the step-up transformer for boosting the pulse voltage, the boosted pulse voltage An element and a capacitor, and a resistor and a Zener diode connected to both ends of the capacitor for discharging the electric charge stored in the capacitor. Create a DC bias of the developing voltage generation circuit which is generated from the developing voltage generation circuit at over diode, the concentration adjustment by the developing voltage generation circuit, the output from the engine controller based on a signal from the density change means provided on the apparatus main body duty Therefore, the number of parts of the development voltage generation circuit is reduced, the cost is reduced, the mounting area is reduced, and the reliability is improved by reducing the number of parts. In addition, the density can be adjusted by the development voltage generation circuit.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an embodiment of a development voltage generating circuit constructed according to the present invention.
2 shows an output development voltage waveform generated by the development voltage generation circuit of FIG. 1;
FIG. 3 is a circuit diagram of another embodiment of a developing voltage generating circuit constructed according to the present invention.
4 shows an output development voltage waveform generated by the development voltage generation circuit of FIG. 3;
FIG. 5 is a schematic configuration diagram of an embodiment of an image recording apparatus according to the present invention.
FIG. 6 is a circuit diagram of a conventional developing voltage generation circuit.
[Explanation of symbols]
1 Image carrier (photosensitive drum)
2 Charging device 4 Developing device 20 Charging voltage generating circuit 50 Developing voltage generating circuit 51 Power operational amplifier 52 Step-up transformer 53 Rectifier (diode)
54 Capacitor 61, 63 Resistor 64 Zener diode

Claims (2)

An image carrier, a charging device for uniformly charging the image carrier, a charging voltage generating circuit for generating a charging voltage necessary for the charging, and irradiating the image carrier with image information to An exposure device for forming an electrostatic latent image on the image carrier, a developing device for developing the electrostatic latent image formed on the image carrier, and a development voltage necessary for the development In an image recording apparatus having a development voltage generating circuit and an engine controller for controlling the image recording apparatus,
The development voltage generation circuit includes a step-up transformer for stepping up a pulse voltage, a rectifier element and a capacitor for rectifying the stepped-up pulse voltage, and connected to both ends of the capacitor, respectively, and charges stored in the capacitor. A plurality of resistors for discharging, and creating a DC bias of the developing voltage generating circuit generated from the developing voltage generating circuit by resistance voltage division,
The density adjustment by the development voltage generation circuit is performed by changing the duty of the output from the engine controller based on a signal from a density change means provided in the apparatus body and inputting the duty to the development voltage generation circuit. Recording device. An image carrier, a charging device for uniformly charging the image carrier, a charging voltage generating circuit for generating a charging voltage necessary for the charging, and irradiating the image carrier with image information to An exposure device for forming an electrostatic latent image on the image carrier, a developing device for developing the electrostatic latent image formed on the image carrier, and a development voltage necessary for the development In an image recording apparatus having a development voltage generating circuit and an engine controller for controlling the image recording apparatus,
The development voltage generation circuit includes a step-up transformer for stepping up a pulse voltage, a rectifier element and a capacitor for rectifying the stepped-up pulse voltage, and connected to both ends of the capacitor, respectively, and charges stored in the capacitor. anda resistor and a Zener diode for discharging, make a DC bias of the developing voltage generation circuit which is generated from the developing voltage generation circuit in the zener diode,
The density adjustment by the development voltage generation circuit is performed by changing the duty of the output from the engine controller based on a signal from a density change means provided in the apparatus body and inputting the duty to the development voltage generation circuit. Recording device.

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