JPH0666863B2 - Electrostatic latent image forming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image forming apparatus for image recording used in printers, facsimiles and the like.

2. Description of the Related Art An image recording apparatus using an electrophotographic system forms an electrostatic latent image on a latent image carrier and visualizes the electrostatic latent image with a developer. Many devices are in widespread use. Also, as disclosed in U.S. Patent 4,155,093,
There is known an image recording apparatus of a system in which a dielectric is used as a latent image carrier drum and an electrostatic latent image is formed on the latent image carrier drum by discharging ions by electric discharge.

In this system, the ions generated by the ion emission recording head are controlled by an image signal from an image signal source, and an electrostatic latent image corresponding to the image signal is formed on the latent image carrier drum.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the conventional electrostatic latent image forming apparatus, the output of the recording head is easily affected by the environment such as the ambient temperature and humidity,
In particular, when the humidity is high, the mobility of the ions generated by the discharge, the discharge efficiency, etc. are reduced, and the latent image formation on the latent image carrier tends to become unstable.

For this reason, there is a problem that image defects such as density reduction and image density unevenness occur in the recorded image obtained by revealing the latent image for electric power supply.

The present invention has been made to solve such a problem, and provides an electrostatic latent image forming apparatus capable of forming a stable electrostatic latent image without being affected by the surrounding environment. With the goal.

Means for Solving the Problems In order to achieve the above-mentioned object, an electrostatic latent image forming apparatus of the present invention is provided with a latent image carrier, a latent image carrier and a latent image carrier which are arranged to face the latent image carrier. An ion emission recording head for emitting ions in a pixel unit to form an electrostatic latent image on a latent image carrier; driving means for selectively driving the ion emission recording head in a pixel unit; and the ion emission The recording head includes a recording unit that emits ions according to an image signal and a detection output unit that emits ions for detecting an ion emission state based on a detection output drive signal, and outputs the output of the detection unit. The recording head output detecting means for detecting, and the recording head output adjusting means for outputting to the driving means a control signal for adjusting the amount of ions in the recording portion according to the output of the recording head output detecting means. Composed.

As an embodiment of the present invention, the detection output unit drive signal is set such that the ratio of pixels that emit ions in the detection output unit is an average output that is the ratio of pixels that emit ions in the recording unit. Is desirable.

Here, the average output used in the present invention refers to the on / off output corresponding to the average on / off ratio (black and white ratio) of the output of the recording head that is on / off controlled. This average output is detected by the head output detection means, and the output of the recording head is feedback-controlled based on this detection signal.

The reason why the output of the detection output unit is set to the average output is
When the output of the detection output unit is always on, the deterioration of the detection unit over time becomes more significant than the recording unit that is on / off controlled according to the image output, and the output itself of the detection output unit changes and proper feedback is provided. This is because there are cases where control becomes impossible.

As this feedback control, for example, an average value of the on / off ratios of the output of the recording unit during printing of the previous page is calculated, and this average on / off ratio is used as the on / off output of the detection output unit during printing of the next page. As another feedback control, an average ON / OFF ratio of the output of the recording unit corresponding to the print amount of one original is set in advance, and the ON / OFF output according to the average ON / OFF ratio is always applied to the detection output unit. And the like can be adopted. In the present invention, since the average output is used, deterioration of the detection unit is small, and stable feedback control can be performed for a long period of time.

Operation According to the present invention, the ion ejection recording head includes a recording unit that emits ions according to the image signal and a detection output unit that emits ions for detecting the ion emission state based on the detection output drive signal. Since the output of the detection output unit is detected by the recording head output detection unit, and according to this, a control signal for adjusting the amount of ion emission by the recording unit of the ion emission recording head is output to the drive unit, An electrostatic latent image having a stable potential is formed on the latent image carrier.

Further, since the ion emission recording head is divided into a recording section and a detection output section, and a drive signal which is a pixel average output of the ion output of the recording section is input to the detection output section, it does not depend on the recording pattern. The ion output can be detected, the life of the detection output unit can be made substantially equal to the average life of the recording unit, and deterioration of only the detection output unit can be prevented.

Embodiment An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an electrostatic latent image forming apparatus to which the present invention is applied, FIG. 4 shows a schematic side view thereof, and FIG. 5 performs output control of its recording head. Shows a circuit configuration diagram for.

The recording head 1 for forming an electrostatic latent image is controlled by the output of the recording head drive circuit 6 according to the output image signal of the image signal source 7, and the latent image is generated based on the output image signal of the recording head drive circuit 6. An electrostatic latent image having a predetermined charge pattern is formed on the carrier 2. At that time, the electrode 4 of the recording head output detecting means 3 detects the output of the partial area 1a of the recording head 1.

The recording head output detecting means 3 is provided with a strip-shaped electrode 4 in a portion of the latent image carrier 2 facing the predetermined area 1a, and a current flowing in the electrode 4 is taken out through a slip ring 5. ing.

Specifically, the latent image carrier 2 uses a cylindrical conductor drum having a dielectric layer on its surface, and the electrode 4 is provided in a band shape in a region of the drum where recording is not normally performed, and is drawn out from the electrode 4. The wire is drawn out by the slip ring 5. The discharge from the predetermined area 1a of the recording head 1 to the electrode 4 is performed constantly or at a constant cycle.

The current extracted by the slip ring 5 is converted into a voltage by the current-voltage converter 8, this voltage value is amplified by the amplifier 9, and this amplified signal is input to the difference amplifier 11 as the recording head output adjusting means 10. , Where it is compared to the reference setpoint. Then, the difference amplifier 11 amplifies the voltage of the difference between the output of the amplifier 9 and the reference set value, and outputs this amplified signal to the recording head drive circuit 6. Recording head output adjusting means
Reference numeral 10 sends a control signal to the recording head drive circuit 6 so that the potential of the electrostatic latent image formed on the latent image carrier 2 becomes a desired potential, and the recording head drive circuit 6 outputs the output signal of the image signal source 7. In response to this, a predetermined image signal is output to the recording head 1.
Specifically, the recording head drive circuit 6 can be controlled by increasing or decreasing the number of discharge pulses or increasing or decreasing the discharge voltage by, for example, VF conversion.

The relationship between the current value detected by the electrode 4 and the relative humidity is as shown in FIG. 2, and the relationship between the latent image potential and the relative humidity is as shown in FIG.

When the potential of the latent image formed on the latent image carrier 2 is set to V0, the charge transfer amount flowing from the recording head 1 to the electrode 4 is set to
When I0 is set, the discharge efficiency is increased at low humidity, the charge transfer amount I becomes I> I0, and the latent image potential V becomes V> V0. Therefore, the output of the recording head 1 is reduced so that I = I0. Adjust to At high humidity, I <I0, V <
Since it becomes V0, the output of the recording head 1 is increased so that I = I0. By performing feedback control in this way, a latent image having a uniform potential can be formed on the latent image carrier 2.

The electrostatic latent image formed on the latent image carrier 2 is made visible by a developing device or the like (not shown), and the development is recorded on recording paper through a transfer process and the recorded image is fixed in a fixing process.

In the present embodiment, the drive time of the area (monitor section) 1a and the other recording section areas are substantially the same so that the output from the predetermined area 1a of the recording head 1 becomes an average value of the output values in the recording section. Is set so that This setting is calculated in advance by the image signal source 7, and the calculated signal is input to the recording head 1 via the recording head drive circuit 6.

As described above, according to the present invention, the ion emission recording head is divided into the recording section and the detection output section, and the detection output section receives the drive signal that is the average pixel output of the ion output of the recording section. Since the ion output can be detected regardless of the recording pattern, a stable electrostatic latent image is formed on the latent image carrier without being affected by environmental changes such as humidity and temperature. be able to. Further, by setting the ion emission output of the detection output unit to be the pixel average output of the ion output of the recording unit, the life of the detection output unit can be made substantially equal to the average life of the recording unit, It is possible to prevent early deterioration of only the detection output unit.

On the other hand, since the ion emission recording head is divided into the recording section and the detection output section, the portion of the latent image carrier facing the recording section passes through the developing process, while the portion of the latent image carrier facing the detection output section is of the developing width. Can be located outside. According to this structure, ions are emitted from the detection output unit based on the drive signal which is the pixel average output of the recording unit which is calculated in advance prior to image recording, and the ions are detected by the recording head output detection unit to perform recording. The ion output from the recording unit can be adjusted prior to the output from the unit. As a result, good image recording can be performed from the top of the first recording sheet.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a graph showing the relationship between relative humidity and the current value of an electrode, FIG. 3 is a graph showing the relationship between relative humidity and latent image potential, and FIG. FIG. 5 is a schematic side view showing an embodiment of the present invention, and FIG. 5 is a circuit configuration diagram for explaining output control of a recording head in the embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Recording head, 2 ... Latent image carrier, 3 ... Recording head output detecting means, 4 ... Electrode, 5 ... Slip ring, 6 ... Recording head drive circuit, 7 ... Image signal source, 8 ...... Current-voltage converter, 10 …… Record head output adjusting means.

Claims (1)

[Claims] 1. A latent image carrier and an electrostatic latent image formed on the latent image carrier by being arranged so as to face the latent image carrier and emitting ions in pixel units toward the facing surface. In the electrostatic latent image forming apparatus, the ion-emission recording head includes: an ion-emission recording head and a driving unit that selectively drives the ion-emission recording head on a pixel-by-pixel basis. A recording head and a recording head output detection unit configured to detect an output of the detection output unit, which includes a recording unit and a detection output unit that emits ions for detecting an ion emission state based on a drive signal for the detection output unit, and the recording head. A recording head output adjusting means for outputting to the drive means a control signal for adjusting the amount of ions in the recording portion according to the output of the output detection means, and the detection output portion drive signal output In an electrostatic latent image forming apparatus in which the output of the pixel to be ion emission is characterized by being set so that the average output of the pixels ion emission at the recording portion.