JPH08314209A - Recorder - Google Patents

Abstract

PURPOSE: To faithfully make the gradation of an image, in accordance with the quality of an image desired to print. CONSTITUTION: An image signal 15 and the signal of an input part 1 for selecting the quality of the image are transmitted to a control part 2. This control part 2 transmits the signal to a light quantity control part 5 for a long wavelength and a light quantity control part 7 for a short wavelength, in accordance with the density and gradation of the image. Further, the signal is transmitted to the electrostatic charge quantity control part 3 of a photoreceptor 14, to electrify it by an electrifier 4, in accordance with the density of the image. The signal is transmitted to an exposure light source 6 with the signal from the light quantity control part 5, to output light from the exposure light source 6. The signal is transmitted to an exposure light source 8 with the signal from the light quantity control part. 7 to output the light from the exposure light source 8. The light is reflected by a reflection mirror 10 and a dichroic mirror 9. The light from the exposure light source 6 passes through the dichroic mirror 9. At this time, as the light source for an exposure, either of the light sources is used. The light is made incident on a collimator lens 11 and scanned by a polygon mirror 12, to expose the surface of the photoreceptor 14. The light after being scanned passes through an image forming lens 13, to converge on the surface of the photoreceptor, so that it is exposed. Thus, the image is formed by the photoreceptor 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming system,
In particular, it relates to a recording device using an electrophotographic method.

[0002]

2. Description of the Related Art Since electrophotographic image formation using a single exposure light source as a first conventional example has been performed using one type of exposure light source, the obtained image is incident on a photoconductor. It largely depended on the intensity of the exposure light source and the characteristics indicating the charge amount of the photoconductor against it.

For this reason, for example, in the photoconductor having the characteristics shown in FIG. 10, the gradation of the characteristic curve is large even if it is possible to easily form the gradation of the image in which the gradation of the image is remarkable like the character image. There is a problem that the change of the charge amount is large with respect to the change of the exposure intensity, and it is difficult to form the gradation of the image having a gentle gradation.

A second conventional example disclosed in Japanese Patent Laid-Open No. 1-303467 has been proposed as a means for solving the above-mentioned drawbacks inherent in the first conventional technique.

The second conventional technique is based on a laser device for emitting a scanning beam, a laser wavelength control unit for varying the wavelength of the scanning beam from the laser device, and a wavelength of the irradiation light. An image forming apparatus comprising: a photoconductor having a photosensitivity characteristic; and a density control unit that operates the laser wavelength control unit according to the density of an image formed on the photoconductor to change the wavelength of a scanning beam. It is a halftone control device.

As a third conventional example, Japanese Patent Laid-Open No. 4-3137
The technique disclosed in Japanese Patent Publication No. 79 is cited.

In the third prior art, an exposure apparatus combining a light source, an ND filter, a bandpass filter, and a liquid crystal shutter forms a plurality of exposure lights having different light intensities and wavelengths, and the photosensitive material is charged in advance. It is characterized by irradiating the body and thus forming electrostatic latent images having different surface potentials on the photoreceptor. Then
Since it can express light and shade for each dot, it is excellent in gradation expression,
And the resolution is not reduced. In addition, a clear image without image blur can be obtained.

[0008]

However, in the first conventional technique, as described above, the change in the charge amount is large with respect to the change in the exposure intensity, and the gradation is large because of the large slope of the characteristic curve. There is a problem that it becomes difficult to form a gradation of a gentle image.

The second prior art has the drawbacks that the laser wavelength controller and the concentration controller are complicated, the control operation is not smooth, and good desired characteristics and effects cannot be obtained.

Furthermore, the third conventional technique has the drawback that the operability is poor and the desired effect cannot be obtained.

The present invention has been made in view of the above-mentioned conventional circumstances. Therefore, the object of the present invention is to solve the above-mentioned drawbacks inherent in the conventional art and to provide a relatively simple structure.
It is an object of the present invention to provide a novel recording device capable of faithfully expressing the gradation of an image.

[0012]

In order to achieve the above object, a recording apparatus using an electrophotographic system according to the present invention is provided with an image signal input means and an image quality based on the image signal. A means for exposing the photoconductor, a wavelength changing means for changing the wavelength of a light source for exposing the photoconductor on the basis of the image quality, and a light amount control for controlling the light amount of the light source for exposing the photoconductor on the basis of the image quality. Means, charging means for charging the photoconductor, charge amount changing means for changing the charge amount charged on the photoconductor based on the image quality,
And a means for developing the electrostatic latent image formed on the photoconductor.

The present invention further comprises means for inputting image quality based on the image signal.

In the present invention, the wavelength changing means has a first exposure light source that outputs a long wavelength light and a second exposure light source that outputs a short wavelength light. The feature is that the light source is switched and output according to the image quality.

Further, the light quantity control means in the present invention includes a first light quantity control section connected to a first exposure light source for outputting a long wavelength light and a second exposure light source for outputting a short wavelength light. A second light quantity control unit connected to the first light quantity control unit,
It is characterized in that the second light amount control unit is controlled according to the image quality.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the accompanying drawings with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a recording apparatus according to the present invention. However, this block configuration is merely an example for explaining the present invention, and does not limit the scope of the technique of the present invention.

In FIG. 1, an image signal is input to the input unit 1 from 15. The input unit 1 selects the image quality, that is, the density of the image and the gradation of the image from the image signal. The signal selected by the image quality input unit 1 is input to the control unit 2. The control unit 2 controls the light amount control unit 5 of the long-wavelength exposure light source 6 and the light amount control unit 7 of the short-wavelength exposure light source 8 according to the input contents of the image density and gradation input by the image quality input unit 1. To do.

The control unit 2 also sends an appropriate signal to be controlled to the charge amount control unit 3 in order to charge the photosensitive member 14,
The photoconductor 14 is charged by the charger 4. In addition, the control unit 2 also controls each unit that constitutes the recording device (not shown).

The light quantity control unit 5 changes the size of the exposure quantity according to the lightness and darkness of the image signal, and the long wavelength exposure light source 6 is used.
Signal to. The exposure light source 6 outputs light according to the signal. Similarly, the signal from the light amount control section 7 is transmitted so as to change the magnitude of the exposure amount of the short wavelength exposure light source 8 according to the contrast of the image signal. As a result, the exposure light source 6
Alternatively, the exposure light source 8 outputs light according to the type of image.

Light from the exposure light source 6 passes through the dichroic mirror 9 (TM). The light from the exposure light source 8 is reflected by the reflecting mirror 10 and is reflected by the dichroic mirror 9 (TM). At this time, dichroic mirror 9 (TM)
Light from the exposure light source 8 that reflects light and the dichroic mirror 9
The light of the exposure light source 6 that passes through (TM) enters the collimator lens 11 through the same optical path. At this time, the light source to be exposed is either the light source 6 or the light source 8. The incident light is scanned on the photoconductor 14 by the rotating polygon mirror 12. The scanned light is formed by the imaging lens 13
Is focused on the photoreceptor surface.

FIG. 2 shows the characteristics when the photosensitive member 14 is charged with a certain amount of charge and the exposure intensity is changed. The vertical axis represents the change in charge amount on the surface of the photoconductor (-V), and the horizontal axis represents the exposure intensity (H) for exposing the photoconductor.

Curves 21 and 22 in FIG. 2 are obtained when the photoconductor is charged at a relatively high potential (V-HI in FIG. 2) and the exposure intensity (H) incident on the photoconductor is changed. The change in the charge amount is shown. A curve 21 shows a change in charge amount when exposed by the exposure light source 6 (long wavelength), and a curve 22 shows a change in charge amount when exposed by the exposure light source 8 (short wavelength).

Curves 23 and 24 show changes in the amount of charge when charged at a relatively low potential (V-LO in FIG. 2) and the exposure intensity (H) incident on the photoconductor is changed. ing. The curve 23 is the curve 2 when exposed by the exposure light source 6.
Reference numeral 4 is a characteristic curve when exposed by the exposure light source 8.

FIG. 3 shows curves 21 and 22 in FIG.
The printing density (D) when the photoconductor is charged with the characteristics indicated by and the photoconductor is developed and transferred to paper or the like is shown. In FIG. 3, the horizontal axis represents the exposure intensity (H) with which the photoconductor is exposed, and the vertical axis represents the print density (D). Curve 21 'in FIG. 3 corresponds to curve 21 in FIG. 2, and curve 22' in FIG. 3 corresponds to curve 22 in FIG.

Comparing curves 21 and 22 in FIG.
In both cases, when the exposure intensity is 0, the charge amount is V-HI.
The print density obtained at this time is 0 in FIG. Curve 21 '
The point where the print density becomes 3 is point a, and the exposure intensity at this point is Ia. The point where the print density becomes 3 on the curve 22 'is point b, and the exposure intensity at this point is Ib. At this time, the slope of the change in the print density with respect to the exposure intensity is shown by the curve 2
1'is shown in FIG. 4 and curve 22 'is shown in FIG.

In FIGS. 4 and 5, the horizontal axis represents the exposure intensity (H), and the vertical axis represents the slope of change in the print density obtained at that time. This vertical axis represents so-called image γ. In order to perform high-quality image formation in FIGS. 4 and 5, when the exposure intensity changes at a constant rate according to the change of the image signal, the print density also increases at a constant rate according to the image signal. A range is used (IL-a in FIG. 4, IL-b in FIG. 5). Therefore, if an image is formed in this area, fine gradation is possible.

Similarly, FIG. 6 shows the print density (D) obtained from the curves 23 and 24 (the curve 23 'in FIG. 6 is shown in FIG. 2).
6 corresponds to the curve 23 of FIG.
4). The points at which the printing density becomes 2 on each curve are points c and d, and the exposure intensity at that time is I-c and I.
-D. At this time, the slope of the change in the print density with respect to the exposure intensity can be expressed in FIGS. 7 and 8. 7 and 8
The range in which fine gradation can be easily procured is IL-c in Fig. 7.
Exposure intensity of IL-d in FIG. 8.

As described above, from FIG. 4, FIG. 5, FIG. 7, and FIG. 8, the curve 24 'and the curve 2 can easily achieve the gradation of the image.
2 ', curve 23', curve 21 '(IL-d,
The value of γ with respect to the exposure intensity of IL-b, IL-c, and IL-a). Comparing the exposure intensity that can easily form gradation,
IL-b has an exposure intensity that is more than twice that of IL-a.
-D is an exposure intensity twice or more that of IL-c. An image with a gentle image density can be obtained by forming an image in a wide range of exposure intensity like IL-b and IL-d.

FIG. 9 is a flow chart showing how an image is specifically formed in the present invention.

In practicing the present invention, the quality of the image is first selected.

First, in Step 1, the quality of the image to be output is set and stored from the operation panel (operator panel) or the like. This operation corresponds to the input unit 1 in the block diagram of FIG. Here, when the image has a significant change in gradation such as characters, or an operation of forming the gradation of the image finely like a photographic image is stored.

As a result, the wavelength of the exposure light source is selected in order to select the image quality in Step 2 (the exposure light source 6 or the exposure light source 8 in FIG. 1 is selected). The long-wavelength exposure light source 6 is selected when the gradation of the image can be significantly changed, and the short-wavelength exposure light source 8 is selected when the gradation of the image is finely formed. If the exposure light source 6 has a long wavelength, the process proceeds to Step 3.

In Step 3, the print density of the image input in Step 1 is selected. If the print density is high, the process proceeds to Step 6 and the charge amount for charging the photoconductor 14 is set high (V-HI charge amount). On the other hand, if a relatively light image is acceptable, go to Step 5 and
The amount of charge that is charged to is set to a low value (V-LO charge amount). The exposure light source 6 in Step 9 and Step 10.
Is used to expose the photoconductor 14.

On the other hand, when the image is a photograph or the like, the exposure light source 8 of short wavelength is selected in Step 2 in order to form the gradation of the image finely. In Step 4, the print density of the image input in Step 1 is selected. If the print density is high, the process proceeds to Step 8 and the charge amount for charging the photoconductor 14 is set to be high (V-HI charge amount). On the other hand, if a relatively pale image is acceptable, proceed to Step 7,
The amount of charge on the photoconductor 14 is set low (VL
O charge amount). The photoreceptor 14 is exposed using the exposure light source 8 in Step 11 and Step 12. At this time, the exposure light source is controlled by the control unit 2 to form an image in the above-described exposure range.

As described above, when the photoconductor 14 is exposed, the photoconductor 1
An electrostatic latent image is formed on 4. Thereafter, in Step 13, the latent image on the photoconductor is developed by adding a latent image adhering material such as toner. The image of the electrostatic latent image formed on the photoconductor in Step 14 is transferred (fixed) by applying pressure to a print medium such as paper. As a result, a good quality image can be obtained by executing the present invention.

[0037]

As described above, according to the present invention, two or more types of exposure light sources are used as the exposure light sources incident on the photoconductor.
The characteristic curve obtained from the light source and the photoconductor is changed such that the exposure intensity is changed according to the target image, and an image having a lot of information on the shading of the image such as a photographic image can be faithfully expressed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a charge amount of a photoconductor according to exposure intensity when the exposure wavelength of exposure light according to the present invention is changed.

FIG. 3 is a diagram showing print density according to exposure intensity when the exposure wavelength of exposure light according to the present invention is changed.

FIG. 4 is a diagram showing a slope of change in exposure density when the exposure intensity is changed according to the present invention.

FIG. 5 is a diagram showing a slope of change in exposure density when the exposure intensity is changed according to the present invention.

FIG. 6 is a diagram showing print density according to exposure intensity when the exposure wavelength of the exposure light according to the present invention is changed.

FIG. 7 is a diagram showing a slope of change in print density when the exposure intensity is changed according to the present invention.

FIG. 8 is a diagram showing a slope of a change in print density when the exposure intensity is changed according to the present invention.

FIG. 9 is a flowchart illustrating a process of processing a photoconductor according to an exemplary embodiment of the present invention.

FIG. 10 is a diagram showing a change in print density when the exposure intensity according to the present invention is changed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input part 2 ... Control part 3 ... Charge amount control part 4 ... Charging part 5 ... Light amount control part 6 ... Exposure light source 7 ... Light amount control part 8 ... Exposure light source 9 ... Dichroic mirror 10 ... Reflected light 11 ... Collimator 12 ... Multi-sided Mirror 13 ... Imaging lens 14 ... Photoconductor 15 ... Image signal 21 ... Characteristic curve when the photoconductor is charged with V-HI and exposed at long wavelength 22 ... Photoconductor is charged with V-HI, and at short wavelength Characteristic curve when exposed to light 23 ... V-L0 to charge the photoreceptor, characteristic curve when exposed at long wavelength 24 ... Characteristic curve to charge at photoreceptor V-L0 and exposed at short wavelength

Claims (4)

[Claims] 1. A means for inputting an image signal, a means for exposing a photosensitive member according to image quality based on the image signal,
A wavelength changing unit that changes the wavelength of a light source that exposes the photoconductor based on the image quality, a light amount control unit that controls the light amount of the light source that exposes the photoconductor based on the image quality, and the photoconductor is charged. And a charge amount changing unit that changes a charge amount charged on the photoconductor based on the image quality, and a unit that develops an electrostatic latent image generated on the photoconductor. Recording device. 2. The recording apparatus according to claim 1, further comprising means for inputting image quality based on the image signal. 3. The wavelength changing means has a first exposure light source that outputs a long wavelength light and a second exposure light source that outputs a short wavelength light. The first and second exposure light sources are provided. The recording apparatus according to claim 1, further comprising switching and outputting according to image quality. 4. The light amount control means is connected to a first light amount control unit connected to a first exposure light source that outputs a long wavelength light and a second exposure light source that outputs a short wavelength light. The recording apparatus according to claim 1, further comprising a second light amount control unit, which controls the first and second light amount control units according to image quality.