JPS63289570A - Recorder - Google Patents

Abstract

PURPOSE:To enable dealing with a fluctuation in the quantity of light of a light source by providing a means for generating a developing bias voltage which generates the developing bias voltage corresponding to the detection signal of a quantity of light detector. CONSTITUTION:A recorder for forming a recording image on recording paper by an electrophotographic process is provided with the quantity of light detector 10 which detects the quantity of the output light of the light source 3a and the means for generating the developing bias voltage which generates the developing bias voltage corresponding to the detection signal of the detector 10. Namely, a bias voltage selecting part 13 sets a voltage VB4 at the developing bias voltage EB when decision is made that the quantity of light of a fluorescent lamp 3a is larger than L1 in accordance with the value of a digital signal CD. Said part sets a voltage V3 at the developing bias voltage EB when decision is made that the quantity of light is larger than L1 and below L2. The selecting part sets a voltage VB2 at the developing bias voltage EB when decision is made that the quantity of light is larger than L2 and below L3 and sets a voltage VB1 at the developing bias voltage EB when decision is made that the quantity of light is larger than L3. The fluctuation in the quantity of light of the light source is thereby dealt with and the running cost is reduced.

Description

[Detailed description of the invention] [Technical field] The present invention relates to a recording device.

[Prior Art] In recent years, with the spread of so-called office automation, various information processing devices have been introduced into office environments. Devices used in such environments are required to suppress elements such as noise and vibration that adversely affect the environment as much as possible.

By the way, dot impact printers have been widely used for printing documents created with Japanese word processors etc. as hard copies, but these dot impact printers produce a lot of printing noise and vibration. In particular, high-speed machines tended to have a strong tendency to do something, often interfering with the work of those around them.

To solve this problem, non-impact printers that form images using an electrophotographic process, such as laser beam printers, liquid crystal shutter printers, or LED printers, have been put into practical use.

Unlike the above-mentioned dot-impact printers, this printer produces very low printing noise because there is no part where the paper is struck when forming an image, and it is also a page printer that basically records images on a page-by-page basis. Therefore, high-speed recording is possible.

By the way, among such page printers, laser beam printers require a high-precision optical system such as a polygon mirror for the optical writing system, which is very costly, and LED printers require a high-precision optical system such as a polygon mirror for the optical writing system. L
Due to variations in the light emitting characteristics of EDs (light emitting diodes), it is difficult to obtain stable recorded images.

On the other hand, the liquid crystal shutter used in the optical writing system of liquid crystal shutter printers can integrate the light source, liquid crystal shutter, and imaging element that make up the optical system, and the optical system can be configured easily and compactly, resulting in an inexpensive device. can do.

An example of such a liquid crystal shutter printer is shown in FIG.

In the figure, the surface of a photoreceptor 1 is uniformly charged by a charger 2, and an optical writing device 3 exposes a light image corresponding to a recorded image to form an electrostatic latent image corresponding to the recorded image on its surface. be done.

The optical writing device 3 includes a fluorescent lamp 3a used as a light source.
, a liquid crystal micro shutter array (hereinafter simply referred to as a liquid crystal shutter) 3b that turns on and off the light from the fluorescent lamp 3a in pixel units corresponding to one line of recorded image; and an image light formed by the liquid crystal shutter 3b is transmitted to the photoreceptor It is composed of a homogeneous linear imaging element 3C made of a convergence fiber array, etc., which forms an image on one image and exposes it to light. Further, the cover 3d is provided to prevent light from the fluorescent lamp 3a from leaking to the outside.

The electrostatic latent image formed on the surface of the photoreceptor 1 is developed with toner by the developer 4, and the toner image thus formed on the surface of the photoreceptor 1 is transferred to a recording sheet conveyed by a paper feeding system (not shown). is transferred by the transfer charger 5.

The toner image transferred to the recording paper is then thermally fixed by the fixing device 6, thereby forming a recorded image on the recording paper.

Further, residual toner and residual charges on the photoreceptor 1 are removed by a cleaner 7.

Now, the potential of the electrostatic latent image formed on the surface of the photoreceptor 1 is determined by the amount of light exposed.

That is, as shown in FIG. 7(a), on the surface of the photoreceptor 1 charged to the surface potential vS by the charger 2,
Amount of light LVI that passed through the liquid crystal shutter 3b when the light was turned on
When the photoreceptor 1 is irradiated with light, an electric charge corresponding to the amount of light LVI is generated on the surface of the photoreceptor 1. As a result, the potential at the exposure position becomes the latent image potential VII, which is lower than the surface potential vS by a potential corresponding to the amount of generated charge.

On the other hand, a developing bias potential VB between the latent image potential VII and the surface potential vS is set in the developing device 4, and a potential difference VEI between the developing bias potential VB and the latent image potential 'VII is set.
An amount of toner TN corresponding to the amount adheres to the latent image portion, thereby making the electrostatic latent image visible.

Incidentally, the fluorescent lamp 3 used as a light source deteriorates over time, and as the period of use increases, its output view decreases as shown in FIG.

When the light source scene decreases in this way, the amount of light passing through the liquid crystal shutter 3b also decreases, as shown in FIG. 7(b), for example.

As a result, compared to the case shown in FIG. 7(a), the amount of charge generated at the exposure position of the photoreceptor 1 is reduced, and as a result, the latent image potential VI2 of the electrostatic latent image becomes the latent image potential VII. rises more than

As a result, the potential difference VIE2 between the development bias potential VB and the latent image potential VII becomes smaller than the potential difference VEI, and the amount of toner TN adhering to the latent image portion decreases.

Therefore, as the period of use becomes longer and the light intensity of the fluorescent lamp 3a decreases, the amount of toner that adheres to the electrostatic latent image on the photoreceptor l decreases, resulting in the density of the recorded image becoming thinner and thin lines becoming blurred. This results in a situation where the image quality deteriorates.

Further, the potential distribution in the electrostatic latent image of one dot is shown in FIG. 9, where the curve C1 shows the case where the amount of light from the light source is large, and the curve C2 shows the case when the amount of light from the light source is small. Further, VB is a developing bias potential.

In this way, when the amount of light from the light source is large, an electrostatic latent image is formed with a sufficient amount of light, so the area of the area where the potential is lower than the development pipe input potential VB, that is, the area where toner adheres, is large. The dot diameter after development also becomes sufficiently large.

On the other hand, when the amount of light from the light source is small, the amount of leaked light when the liquid crystal shutter 3b is turned off is small, so the potential of the portion other than the electrostatic latent image increases. On the other hand, since the potential of the electrostatic latent image portion increases, the area of the portion whose potential is lower than the developing bias potential VB decreases, and as a result, the dot diameter of the recorded image becomes smaller.

In this way, when the light intensity of the fluorescent lamp 3a decreases, the dot diameter of the recorded image becomes smaller.

For this reason, conventionally, the fluorescent lamp 3a as a light source whose light intensity has decreased to a certain extent must be replaced, resulting in the inconvenience that the fluorescent lamp 3a has to be replaced frequently and running costs increase.

[Objective] The present invention was made in order to eliminate the disadvantages of the prior art, and it is an object of the present invention to provide a recording device that can cope with fluctuations in the amount of light from a light source.

[Structure] In order to achieve this object, the present invention includes a light amount detector that detects the output light amount of a light source, and a developing bias voltage generating means that generates a developing bias voltage corresponding to a detection signal of the light amount detector. It is something that

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a liquid crystal shutter printer according to an embodiment of the present invention. In this figure, the same parts as those in FIG. 6 are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, a light amount sensor lO attached to the inside of the cover 3d of the fluorescent lamp 3a is for detecting the output light amount of the fluorescent lamp 3a.

As shown in FIG.
2 and is converted by this analog/digital converter 12 into a corresponding digital signal CD. The digital signal CD is applied to the bias voltage selection section 13.

The bias voltage selection section 13 includes the developing bias voltage generation section 1
Voltage applied from 4 VBI-VB4 (VBI<VB2
<Input digital signal CD among VB3 (VB4)
A value corresponding to the value of is selected and supplied to the developing device 4 as the developing bias voltage EB.

That is, as shown in FIG. 3, when the bias voltage selection unit 13 determines that the light amount of the fluorescent lamp 3a is larger than LL based on the value of the digital signal CD, it sets the voltage VB4 to the developing bias voltage EB. However, if the light amount is determined to be greater than Ll and less than L2, the voltage VB3 is set to the developing bias voltage EB, and if the light amount is determined to be greater than Ll and less than L3, the voltage VB2 is set to the developing bias voltage EB. However, if it is determined that the light amount is larger than L3, the voltage VBIt! - Set the developing bias voltage EB.

Therefore, as shown in FIGS. 4(a) and 4(b), when the light amount of the fluorescent lamp 3a is larger than L3, the voltage VB4 is selected as the developing bias voltage EB, and the light amount of the fluorescent lamp 3a is If the range is greater than Ll and less than L3, voltage VB3 is selected as developing bias voltage EB.

Here, in the former case, the amount of light transmitted through the liquid crystal shutter 3b L
The latent image potential VII of the electrostatic latent image on the photoconductor 1 when exposed at VI and the developing bias potential E corresponding to the voltage VB4
Let the potential difference of B4 be VEa, and in the latter case, the latent image potential VI2 of the electrostatic latent image on the photoreceptor 1 when exposed with the transmitted light 1LV2 of the liquid crystal shutter 3b, and the developing bias potential EB3 corresponding to the voltage VB3. Let the potential difference be VEb.

At this time, the potential difference between the developing bias potential EB4 and the developing bias potential EB3 is approximately equal to the potential difference between the latent image potential VII and the latent image potential VI2, so the potential difference VEa
and the potential difference VEb are almost equal.

As a result, the amount of toner TN that adheres to the latent image portion remains almost constant regardless of changes in exposure amount, so that the density of the recorded image can be maintained at a predetermined value even when the output light amount of the fluorescent lamp 3a decreases. Can be done.

Further, the potential distribution in the electrostatic latent image of one dot is shown in FIG. In FIG. 5, similarly to FIG. 9, the curve CI shows the case where the light source light amount is larger than the light amount L3, and the curve C2 shows the case where the light source light amount is one step smaller.

Therefore, the developing bias potential for curve C1 is 1E
At B4, the developing bias potential in the case of curve C2 becomes EB3.

As a result, in the case of curve C1, development bias potential EB4
The area of the part where toner adheres at a lower potential than curve C
In case 2, the area of the portion to which the toner adheres does not change much at a potential lower than the developing bias potential EB3.

That is, it is possible to suppress the change in the dot diameter when the output light amount of the fluorescent lamp 3a fluctuates, so that deterioration in image quality can be minimized.

As described above, in this embodiment, since the developing bias potential is changed in four stages according to the output light amount of the fluorescent lamp 3a, deterioration in the quality of recorded images is prevented when the output light amount of the fluorescent lamp 3a fluctuates. can.

Furthermore, even when the fluorescent lamp 3a deteriorates over time and its output light intensity decreases, the image quality of the recorded image can be maintained for the most part, so the period during which the fluorescent lamp 3a can be used can be extended, and running costs can be reduced. .

In the above embodiment, the developing bias voltage is changed in four steps, but it can also be changed in more steps. Further, the developing bias voltage can also be changed continuously instead of stepwise.

Further, in the embodiments described above, a drum-shaped photoreceptor is used, but the present invention can also be applied to an apparatus using a belt-shaped photoreceptor.

Further, in the embodiments described above, a fluorescent lamp is used as a light source, but the present invention can also be applied to a case where a linear light source other than that is used.

[Effects] As described above, according to the present invention, the present invention includes a light amount detector that detects the output light amount of the light source, and a developing bias voltage generating means that generates a developing bias voltage corresponding to the detection signal of the light amount detector. Therefore, it has the advantage of being able to cope with fluctuations in the amount of light from the light source.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a liquid crystal shutter printer according to an embodiment of the present invention, FIG. 2 is a block diagram illustrating a developing bias setting section, and FIG. 3 is a waveform showing an example of the operation of the bias voltage selection section. 4(a) is a schematic diagram showing how toner adheres when the amount of light is large, FIG. 4(b) is a schematic diagram showing how toner adheres when the amount of light is small, and FIG.
The figure is a graph for explaining changes in dot diameter, Figure 6 is a schematic diagram illustrating a conventional device, and Figure 7 (a) is a schematic diagram showing how toner adheres when the amount of light is large in the conventional example. Figure 9 (b) is a schematic diagram showing how toner adheres when the amount of light is small in a conventional example, Figure 8 is a graph to explain the aging of fluorescent lamps, and Figure 9 is a conventional example. FIG. 3 is a graph diagram for explaining changes in dot diameter in FIG. 10... Sight sensor, 11... Amplifier, 12...
Analog/digital converter, 13...bias voltage selection section, 14...development bias voltage generation section. Agent Patent Attorney Crest 1) Makoto 5・Fig. 1 Fig. 3 Yado B Akihir LI Lj TA1 Fig. 4 (a) (b) Fig. 5 Fig. 6 (a) (b) Fig. 8 η "1

Claims (2)

[Claims] (1) Light from a linear light source is focused on a photoreceptor through a liquid crystal micro shutter array that turns on and off in pixel units corresponding to one line of recorded image, and the recorded image is transferred onto recording paper using an electrophotographic process. In the recording device that forms
A recording apparatus comprising: a light quantity detector for detecting the output light quantity of the light source; and a developing bias voltage generating means for generating a developing bias voltage corresponding to a detection signal of the light quantity detector. (2) A recording apparatus according to claim 1, wherein the light source is a fluorescent lamp.