JPS6223075A - Recorder - Google Patents

Abstract

PURPOSE:To decrease the consumption quantity of a toner in a recording device, and to obtain a high fixing strength by executing a fixation in a range in which a fixed image density after heating is higher than an unfixed image density before heating. CONSTITUTION:A case when an optical reflection density d1 of a toner image in an unfixed state before, heating, in which a fixing energy is a parameter is equal to an optical reflection density d2 of a fixed toner image after heating is shown by a broken line (d) in the figure. In this figure, for instance, a practical range of the fixed image density d2 is denoted by (a). In such a case, on the broken line (d) and in the upper side than the broken line (d), namely in a range where the unfixed image density d1 is equal to the fixed image density d2, or the fixed image density d2 is higher than the unfixed image density d1, the heating fixation is executed. In such a way, a high fixing strength can be obtained by executing the heating fixation so that the fixed image density d2 satisfies the practical range (a) in order to obtain a practical fixed image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a device that records an image using toner, such as a printer or a facsimile, and particularly to a recording device suitable for efficiently obtaining a good fixed toner image. Regarding equipment.

[Background of the invention]

This recording device is used in printers, facsimiles, etc., and uses toner powder for each image.

An electrostatic recording method is used for development, and a method of fixing the toner image on a recording medium such as recording paper in an unfixed state before heating using a heating body such as a heat roll or flash lamp is used for fixing. .

Incidentally, related recording methods of this type include, for example, Japanese Patent Application Laid-Open No. 57-54969 and U.S. Patent No. 2807.
No. 703 etc. are mentioned.

In this type of recording device, the strength and density of the image after fixing are sufficient, the amount of toner consumed by the recording device is low, and the fogging density in the non-image area of the recording medium such as recording paper after fixing is also low. required.

Therefore, it is desirable to keep the image density low in the unfixed state before heating during development. Here, the strength of the image after fixing refers to the degree of adhesion of the toner to the image after fixing.

However, conventional recording methods do not take into consideration the relationship between the density of an image in an unfixed state before heating and the density of an image in a fixed state after heating.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording device that can reduce the amount of toner consumed in the recording device and provide high image strength after fixing.

[Summary of the invention]

Therefore, the present invention aims at developing the toner image while maintaining the optical reflection density of the toner image in the unfixed state before heating to be equal to or lower than the optical reflection density of the toner image in the fixed state after heating.

The inventors of the present invention performed heat fixing while varying the unfixed image density before heating, and measured the image density after heating, and as a result, they discovered fixing characteristics 1 and 2 that provided the motivation for the present invention as described below.

The image density was measured using an optical reflection density using a perfect densitometer manufactured by Cosar. Optical reflection density is defined by the following equation.

OD=-tog to (I emu / I o )
Here, OD is the optical reflection density hIo is the amount of incident light, ■, 1,
indicates the amount of reflected light.

Fixing characteristics 1: As long as the fixing energy is the same,
Regarding the relationship between the unfixed image density before heating and the fixed image density after heating, when the unfixed image density is below a certain value, the fixed image density is higher than the unfixed image density. Above that value, the density of the fixed image becomes lower than the density of the unfixed image. In other words, when the unfixed image density is increased from zero, the fixed image density increases, but the rate of increase decreases, showing a saturation tendency. Eventually, even if the unfixed image density is increased, the fixed image density will no longer increase, and may decrease depending on the toner and fixing method.

The saturation tendency of the fixing characteristic 1 described above is more pronounced in a non-contact fixing method such as a fixing method using a flash lamp than in a contact fixing method such as a fixing method using a heat roll.

This fixing characteristic 1 was found to be due to the following reason from microscopic observation of the image. FIG. 4 schematically shows an enlarged view of the image before heating when the density of the unfixed image is low. (1
) is a diagram before heating (2) is a diagram after heating, the lower side is a plan view, and the upper side is a cross-sectional view. j indicates recording paper, and the hatched area indicates toner. If the unfixed image density is low, before heating (1
) As shown in (2), the toner is roughly distributed on the recording paper j, but it is melted by heating, and after heating, the toner is distributed on the recording paper j as shown in (2).
to expand its area and adhere to it. As a result, the recording paper
The area of the upper toner portion increases and the density increases.

FIG. 5 schematically shows enlarged views before and after heating when the unfixed image density is high. Symbols and other symbols are the same as in FIG. 4.

When the density of the unfixed image is high, as shown in (1) before heating, the toner is densely distributed on the recording paper j, and when heated, the toner melts and adjacent toners combine and flow.
After heating, large-scale holes exposing the recording paper appear as shown in (2). These vacancies cause the concentration to decrease.

When the unfixed image density is in the intermediate range, the phenomena shown in FIGS. 4 and 5 are present together, and the above-mentioned fixing characteristic 1 is observed.

Conventionally, the image density in an unfixed state before heating is in a range where the maximum value of the density setting of the recording apparatus is higher than the reflection density after heating. Therefore, there is a drawback that the amount of toner consumed in the recording apparatus is large.

Further, since the amount of toner adhering per unit area on the recording paper is large, and therefore the image requires a large amount of heat absorption, there is also a drawback that the strength of the image after fixing tends to be low. Furthermore, it is necessary to increase the amount of charge in the developing device to form an unfixed image, and the fogging density in the non-image area tends to be high. 7. In the fixing method using a lash lamp, toner tends to scatter during flash irradiation. The fixing method using a heat roll has various drawbacks such as the tendency to cause an offset phenomenon in which residual toner adheres to the surface of the heat roll after fixing.

Note that in this specification, an unfixed image refers to a toner image on a recording medium such as recording paper before heating, and a fixed image refers to a toner image on a recording medium such as recording paper after heating. .

From the fixing characteristic 1 described above, it is possible to obtain a fixing density within a practical range within a range where the fixed image density is higher than the unfixed image density and within a range where the unfixed image density is lower.

At that time, since the density of the unfixed image is low, the intensity of the image after fixing is higher than before.

Next, other fixing characteristics 2 will be described.

Fixing characteristic 2: As long as the unfixed image density is the same, the higher the fixing energy, the higher the fixed image density.

Fixing characteristic 2 is due to the fact that the higher the fixing energy, the fewer the pores shown in FIG. 5.

By using the fixing characteristic 2 and changing the fixing energy, it is possible to adjust the fixed image density.

[Embodiments of the invention]

In order to further explain the present invention in detail, embodiments will be described below with reference to the drawings.

FIG. 1 is a diagram showing the relationship between the optical reflection density of a toner image in an unfixed state before heating and the optical reflection density of a fixed toner image after heating, using fixing energy as a parameter. In the figure, d1 is the optical reflection density of the toner image in an unfixed state before heating, and d.

is the optical reflection density of the toner image in the fixed state after heating, a is the practical range of the fixed image density, b is the relationship between the unfixed image density and the fixed image density when the fixing energy is 1.12 J/cm'', C The fixing energy is 1.44J/cm”
The relationship between the unfixed image density and the fixed image density is shown.

The broken line d in the figure is the unfixed image density d, and the fixed image density d3.
Indicates the case where are equal. The fixing range of the present invention is located on this broken line d and above the broken line d.

FIG. 2 shows the relationship between the minimum energy required for fixing and the optical reflection density d1 of the toner image in an unfixed state before heating. The minimum energy required for fixing is determined by evaluating the peeling of the fixed toner image after heating using 3M 810 mending tape, and the ratio of optical reflection density after tape peeling and before peeling is 9.
Indicates the value of 0%. Hereinafter, this ratio will be referred to as the fixation rate. The fixation rate corresponds to the fixation strength. e shows the relationship between unfixed image density d1 and fixing energy when the fixing rate is 90%.

To obtain practical fixing strength, K requires a fixing rate of 90% or more.

The data shown in FIGS. 1 and 2 are based on actual measurements, and the toner used is an epoxy type toner. The fixing method used was a fixing method using a xenon flash lamp in which flash light was irradiated once. FIG. 3 is a diagram showing the experimental apparatus.

f is a xenon 7:7 lamp, g is a toner image formed on recording paper, h is a power meter, and i is a flash irradiation range.

The pattern of the toner image g used was one in which four 20×20 am peta black images were arranged in two rows, one above the other. The longitudinal direction of the image pattern g was aligned with the longitudinal direction of the xenon flash lamp f, and the center of the image pattern g was aligned with the center of the xenon flash lamp f, and heating was performed by causing the xenon flash lamp f to emit light. A perfect densitometer manufactured by Cosar was used for optical density measurement. For the fixing energy, a value obtained by dividing the amount of electric power supplied to the xenon flash lamp f by the flash irradiation area is used.

The present invention is applied to areas above the broken line d and above the broken line d in FIG. 1, that is, the unfixed image density dl and the fixed image density d! are equal or
Alternatively, heat fixing is performed in a range where the fixed image density d3 is higher than the unfixed image density d1. To obtain a practical fixed image within this range, the fixed image density d! satisfies practical range a.

Heat fixing may be performed under the condition that the fixing energy in FIG. 2 is above the curve e, which satisfies the minimum energy required for tomstick fixing. Here, fixed image density d
In the case of the toner image used in this experiment, if 2 is lower than 0.8, the image is thin, so the practical fixed image density is 0.
．． 8 or more is required.

For example, when heating is performed under conditions where the unfixed image density d1 is 0°62 and the fixing energy is 1.12 J/cIn, the first
According to the curve in the figure, the relationship between the unfixed image density and the fixed image density according to the present invention is satisfied. At that time, the fixed image density d
2 is 0.8, which satisfies the practical range a of fixed images. Furthermore, at the unfixed image density d1 under this condition, the curve e in FIG.
The minimum energy required for fixation is 0.95 J 7c
m", the fixing energy is sufficient. In other words, since the curve e in FIG. 2 indicates a fixing rate of 90%, it means that a high fixing strength with a fixing rate of 90% or more has been obtained. Next, when the unfixed image density d is 0.62 and the fixing energy is 1.44 J 7cm'', the unfixed image density and the fixed image density of the present invention are determined from curve C in FIG. The following relationship will be satisfied. At that time, the fixed image density d2 was 0.92, which is higher than the above example using the curved line. That is, by increasing the fixing energy, using the same unfixed image density d1, the fixed image density d! This means that we were able to increase the At that time, of course, the fixing strength is sufficient as in the case where the curved line was used as described above.

Next, as a comparative example, a case where fixing was performed under conditions other than the relationship between unfixed image density and fixed image density according to the present invention will be shown.

For example, under the conditions that the unfixed image density d1 is 124 and the fixing energy is 1.12 J 7 cm'', the relationship between the unfixed image density and the fixed image density of the present invention is not satisfied as shown by the curve in FIG.

In this case, the fixed image density d2 is 1.04, which satisfies the practical range of fixed images, but from FIG. 2, the minimum energy required is 1.12 J 7 cm'', which matches the conditions of this comparative example. That is, the fixing rate was 90%, and only the lowest value of the practical fixing strength was obtained.

According to the embodiments of the present invention, the density of an unfixed image can be significantly lower than that of the conventional method, so that the amount of toner consumed in the recording apparatus can be significantly reduced, and the density of a fixed image higher than that of the conventional method can be obtained.

Furthermore, since the amount of charge required to form an unfixed image in the developing area is reduced, the fogging density in the non-image area can also be reduced.

Fixing methods using flash lamps can reduce toner scattering during flash irradiation, while contact fixing methods such as fixing methods using heat rolls can reduce the offset phenomenon in which residual toner adheres to the surface of the heat roll after fixing. It also has the effect of preventing.

A second embodiment of the fixing device of the present invention will be described with reference to the drawings.

In this embodiment, in order to obtain a stable image without density unevenness within a range that satisfies the relationship between the density of an unfixed image and the density of a fixed image, a toner image on a latent image forming body made visible by toner or a record on a recording paper, etc. This method measures the density of the toner image on the body and controls the developing conditions of the printing system by applying feedback.

FIG. 6 is a diagram showing an embodiment of the second invention.

k is the photosensitive drum, t is the charger 1m is the charger application power source,
n is a densitometer, 0 is a print range, p is a solid black toner image for monitoring, q is a recording paper, r is a cleaner, and S is a sleeve.

In FIG. 6, the width of the photosensitive drum is wider than the width of the printing range O, and a solid black toner image P for monitoring is printed outside the printing range 0 at the same time as the toner image within the printing range O. Changes in the density of the solid black toner image p for monitoring are detected by a densitometer n, and, keeping in mind the increase or decrease in the density, the power supply m applied to the charger is applied in a direction that stabilizes the solid black toner image p for monitoring.
control the output of Therefore, the amount of charge on the photosensitive drum is controlled, and the toner image density in the printing range 0 is stabilized. After the monitor solid black toner image p is measured by a densitometer n, it is erased from the photoreceptor drum k by a cleaner r without being transferred to the recording paper q.

In order to obtain a practical fixed image under conditions where the fixed image density is higher than the unfixed image density, a stable developing method with no density unevenness is required under conditions where the unfixed image density is low, as shown in Figure 6. By setting the density of the monitor solid black toner image p to a low level using the above method, a stable unfixed image without desired density unevenness can be obtained.

In order to reduce the density of the unfixed image, in addition to the method of reducing the amount of charge on the photoreceptor drum of this embodiment, there is also the method of (1) widening the gap between the photoreceptor drum and the sleeve.

■ Decrease the amount of exposure during development.

■ Decrease the amount of charge of the developer.

The following methods can be mentioned.

〔Effect of the invention〕

As described above, according to the present invention, by performing fixing in a range where the fixed image density is higher than the unfixed image density, it is possible to perform fixing with a low unfixed image density.

High fixing strength can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the effects of the invention, Fig. 3 is a perspective view showing the experimental apparatus, and Fig. 4 is a diagram showing the phenomenon that motivated the present invention. FIG. 5 is another diagram showing the phenomenon that motivated the present invention, and FIG. 6 is a perspective view showing an embodiment of the invention as set forth in claim 5 of the present invention. b, c... Relationship between unfixed image density and fixed image density, d... Condition where unfixed image density and fixed image density are equal. dl: Optical reflection density of the toner image in an unfixed state before heating, d2: Optical reflection density of the toner image in a fixed state after heating, e: Unfixed image density and the minimum energy required for fixing. Relationship with, f...Flash lamp, g...Toner image, j...Recording paper, ratio of 3 figures to 5 figures

Claims (1)

[Claims] 1. Forming an electrostatic latent image on a latent image forming body, developing the latent image to form a toner image, transferring the toner image to a recording body, and unfixing it on the recording body. In an electrophotographic recording apparatus that forms a toner image in an unfixed state and then heats and fixes the unfixed toner image in a fixing device to obtain a toner image in a fixed state, optical reflection of the toner image in an unfixed state before heating is performed. The concentration is d_
1, the optical reflection density of the toner image in a fixed state after heating is d_2, and d_1/d_2 is developed to a value of 1 or higher than 1. 2. The recording apparatus according to claim 1, wherein the heating body of the fixing device is a non-contact heating body. 3. The recording apparatus according to claim 1, wherein the heating body of the fixing device comprises a flash lamp. 4. The recording apparatus according to claim 1, wherein the toner image is developed to have an optical reflection density of 0.8 or less in an unfixed state before heating. 5. Measure the density of the toner image on the latent image forming body visualized by the toner or the unfixed toner image on the recording medium before heating, feed it back to the charger application power source, and adjust the latent image according to the measured value. 5. A recording apparatus according to claim 1, which controls the amount of charge on the image forming member.