JPH086406A - Image recorder - Google Patents

Abstract

PURPOSE:To improve the reproducibility of half tone by setting the surface speed of a developed image carrier to be higher than the surface speed of a body to be transferred, enlarging and forming a developed image on the developed image carrier and reducing and transferring it on the body to be transferred. CONSTITUTION:The device is provided with developed image forming means 2 and 3 forming the developed image on the developed image carrier 1 and a transfer means transferring the developed image on the carrier 1 on the body to be transferred 4. Then, the surface speed v1 of the carrier 1 is set to be higher than the surface speed v2 of the body to be transferred 4 and the developed image formed on the carrier 1 by the forming means 2 and 3 is formed in a state where it is enlarged to be prescribed size. By transferring the developed image formed on the carrier 1 on the body to be transferred 4 in the state where it is reduced, an image is recorded. Therefore, a means such as a special developing device or a dielectric drum need not be disposed and developing technique or a photoreceptor drum generally used for the field of an electrophotographic recording system can be utilized as it is. Besides, the deterioration of resolution caused by the thickness of an electrostatic latent image is solved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording device such as a printer or a facsimile.

[0002]

2. Description of the Related Art Conventionally, an image recording apparatus using a so-called ion flow head as an electrostatic latent image forming means is disclosed in JP-A-59 / 59.
As disclosed in Japanese Patent Application Laid-Open No. 164154 and Japanese Patent Application Laid-Open No. 54-78134, a so-called irradiating an ion stream according to image information on a visible image carrier such as a photosensitive drum or a dielectric drum. After creating an electrostatic latent image using an ion flow head and visualizing this electrostatic latent image using developing means,
There is known a structure in which an image is recorded by transferring a visible image formed on a visible image carrier to a transfer target using a transfer means.

In these image recording apparatuses, an ion flow head is used to irradiate an ion flow according to image information on a visible image carrier to form an electrostatic latent image and record the image. , SPIE Vol. 1252 Ha
rd Copy Printing Technology
gies (1990) pp45-53 "Limitin
g Factors of High Resolute
Ion and Gray Scale Ionogr
apic Printing ", JP-A-1-127
As pointed out in Japanese Patent Application Laid-Open No. 366, JP-A-3-130174, etc., the repulsive electric field created by the electrostatic latent image thickens the latent image, making it difficult to perform high-resolution recording. ing. That is, in the above-mentioned image recording apparatus, an ion flow head is used to irradiate an ion flow in accordance with image information to create an electrostatic latent image and record an image. As the ions irradiated from the flow head accumulate on the surface of the image carrier, coulombs that act between the ions already deposited on the surface of the image carrier and the newly-deposited ions of the same polarity. The repulsive force of the force gradually increases, the electrostatic latent image expands in the direction along the surface of the image carrier, and the resolution of the electrostatic latent image formed on the image carrier is It is lower than expected from the arrangement density of the control electrodes and the like, and there is a problem that a predetermined resolution cannot be obtained.

By the way, the thickening of the electrostatic latent image formed on the visible image bearing member by using the ion flow head is substantially proportional to the contrast of the electrostatic latent image formed on the visible image bearing member. It is known that, as a measure to prevent the thickening of the electrostatic latent image, the electrostatic latent image is created on the visible image carrier with a low contrast such that the thickening of the electrostatic latent image does not matter, This electrostatic latent image can be developed by using a developing means capable of developing a low-contrast latent image with a sufficient image density, or an electrostatic latent image with a high charge density can be formed. In order to prevent high contrast from being induced, a dielectric drum with a large capacitance is used as the image carrier, or an electric field formed between the ion flow head and the image carrier that acts to attract the ion flow. To an extremely high electric field Means which prevents thickening of the electrostatic latent image has been proposed by.

[0005]

However, the above-mentioned prior art has the following problems. That is, in the case of the image recording apparatus according to the above proposal, in order to prevent the electrostatic latent image formed on the image bearing member from being thickened by using the ion flow head, a special developing device or a dielectric drum is used. Etc., and the structure of the device becomes complicated and high cost by that amount, and by combining the developing device for electrophotographic method and the photoconductor drum which are generally widely researched and developed with the ion flow head. There is a problem that it is difficult to construct an image recording device. In addition, an image recording apparatus configured to prevent the electrostatic latent image from becoming thick by forming an extremely high electric field that is formed between the ion flow head and the image bearing member and that acts to attract the ion flow. In this case, in order to form a high electric field between the ion flow head and the image carrier, the gap between the ion flow head and the image carrier must be kept narrow and highly accurate. A new problem arises that the processing accuracy of the head and the mounting accuracy of the ion flow head and the image bearing member must be increased.

Further, as a problem having a commonality in a sense with the problem that the electrostatic latent image formed on the image bearing member becomes thick by using the ion flow head as described above,
As shown below, there is one relating to the recording width of the image.

That is, in various image recording systems such as thermal transfer recording, multi-stylus electrostatic recording, and laser xerography, various area modulation type gradation reproducing methods by a sub-scanning division system have been proposed. For example,
"Reproduction of halftone by thermal fusion transfer method" Saito et al. IEICE technical report IE93-61, pp31-
The area 37 is an area modulation type which uses a thermal head having a heating element having a narrow width in the sub-scanning direction, and finely controls the transfer area of the recording paper by finely controlling the transfer of the recording paper. A key expression method is disclosed.

Further, Japanese Patent Laid-Open No. 3-33874 discloses that
In a multi-stylus type electrostatic recording device, an image is recorded by dividing it in the sub-scanning direction.
Japanese Unexamined Patent Publication No. 2-3006 discloses a technique relating to sub-scan division in the ionography system, and further discloses a technique relating to sub-scan division in the laser xerography system.

A problem common to these techniques is that the minimum print size must be made smaller and smaller in order to increase the number of gradations of halftone expression. Now, if the pixel density is 200 dpi and one pixel is divided into 256 levels by sub-scanning, the minimum print size is 0.5 μm.
(Sub scanning direction) × 127 μm (main scanning direction), which requires a very small print size in the sub scanning direction. In order to realize such minute size printing, the size of the heating element of the thermal head and the electrode size of the multi-stylus must be made to be about 0.5 μm (sub scanning direction) × 127 μm (main scanning direction). However, it is difficult to realize in consideration of manufacturing problems, reliability, and stability in manufacturing a heating element of a thermal head or a multi-stylus electrode whose size in the sub-scanning direction is very small. However, there is also a problem in that it is not possible to increase the number of halftone expression gradations by implementing the technique related to sub-scanning division.

Therefore, the present invention has been made in order to solve the above-mentioned problems of the prior art. The object of the present invention is not to use a special developing device, a dielectric drum, or the like, but to generally use an electronic device. The development technology and photoconductor drums used in the field of photographic recording system can be used as they are, and further, it is possible to solve the problems such as resolution reduction due to the thickening of the electrostatic latent image, and the thermal head. Another object of the present invention is to provide an image recording apparatus capable of improving the reproducibility of halftones by realizing a technique related to sub-scanning division without making the recording elements such as the heat generating element and the electrodes of the multi-stylus finer.

[0011]

As shown in FIG. 1, an image recording apparatus according to the present invention includes a visible image forming means 2 and 3 for forming a visible image on a visible image carrier 1, and the visible image carrier. In an image recording apparatus having a transfer means for transferring the visible image on the body 1 to the transferred body 4, the surface speed v1 of the visible image carrier 1 is set higher than the surface speed v2 of the transferred body 4, and The image forming means 2 and 3 form a visible image on the visible image bearing member 1 in a state of being enlarged to a predetermined size, and the visible image formed on the visible image bearing member 1 is transferred onto the transferred material 4. An image is recorded by transferring in a reduced state.

As the above-mentioned visible image forming means, for example, one comprising an electrostatic latent image forming means 2 and a developing means 3 is used, but it is not limited to this and other visible image forming means may be used. Of course, it is also good.

That is, as the visible image forming means, for example, a device for forming an electrostatic latent image by using an ion stream and developing the electrostatic latent image to form a visible image is used. In addition, using a multi-stylus or a device that irradiates light from a laser beam or LED on the photosensitive drum to form an electrostatic latent image and develops the electrostatic latent image to form a visible image. The electrostatic latent image is formed and the electrostatic latent image is developed to form a visible image, or a latent image is directly formed by using a thermal head like a thermal transfer system.

As the electrostatic latent image forming means, for example, an ion head is used as described above.

Further, the image density of the visible image on the visible image carrier is set to, for example, not more than the image density of the visible image on the transferred body.

FIG. 2 shows a visible image 5 formed on the visible image carrier 1.
And the appearance of the visible image 6 transferred onto the transfer-receiving member 4 are schematically shown. On the visible image carrier 1, a visible image 5 stretched by v1 / v2 times along the process direction than a desired image size is formed as an image having a lower density than the desired image density. . Then, the visible image 5 formed on the visible image bearing member 1 is transferred onto the transferred member 4 by the transfer portion 7 having a surface speed difference, so that the size is v2 / v1.
The image density is also increased at the same time, and a visible image 6 having a desired size and a desired density can be obtained on the transferred body 4.

As the above-mentioned image bearing member, for example, one made of a dielectric material having a volume resistivity of 10 ¹² Ωcm or more is used. Further, as the visible image bearing member, a member made of a photoconductive member having photoconductivity used in a normal electrophotographic copying machine or the like may be used. Further, the shape of the image bearing member is not limited to the drum shape, and may be a belt shape or a plate shape.

The transfer target may be any one that transfers and holds a visible image from a visible image carrier, and a recording paper or the like is adsorbed and held on the surface by electrostatic force, adhesive force, mechanical force or the like. Alternatively, the material to be transferred itself may temporarily hold a visible image and then be secondarily transferred to a recording sheet or the like.

Further, the transfer portion may be such that the image bearing member and the transferred object are in contact with each other or may be in contact therewith.
When the image bearing member and the transferred object are brought into contact with each other, since the transfer is performed in a state where the visible image bearing member and the transferred object rotate while slipping, fluororesin or the like is used as at least one surface material. It is more preferable to use a material that has abrasion resistance and a small friction coefficient.

[0020]

In the above image recording apparatus, the density of the visible image 6 is increased by reducing the image at the transfer portion 7,
The visible image on the visible image carrier 1 may be formed at a low density.
That is, the electrostatic latent image is formed on the image bearing member 1 by the electrostatic latent image forming means with a low contrast, and the electrostatic latent image may be developed by a general standard developing means. Even when a means for forming an electrostatic latent image by irradiating an ion stream according to image information is used as the latent image forming means 2, it is possible to prevent the electrostatic latent image from becoming thick and to achieve high resolution. Of course, it does not require a special developing device or a means such as a dielectric drum, and it does not require a developing technique or a photosensitive drum that is generally used in the field of electrophotographic recording. It can be used as it is.

Further, in the above image recording apparatus, since the size of the visible image 6 in the sub-scanning direction is reduced by reducing the image in the transfer section 7, sub-pixels in the sub-scanning direction are finely divided. Even when the scanning division technique is applied, since the visible image on the visible image carrier 1 may be formed in a relatively large size, the heating elements of the thermal head and the recording elements such as the electrodes of the multi-stylus are miniaturized. It is possible to provide an image recording apparatus that can realize the technique related to sub-scanning division and improve the reproduction of halftones.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 3 shows an embodiment of the image recording apparatus according to the present invention.

In FIG. 3, reference numeral 11 is a photoconductor drum using an organic photoconductor (OPC) as a visible image carrier,
The photosensitive drum 11 is the same as the photosensitive drum used in a normal electrophotographic copying machine. Further, the photosensitive drum 11 is rotationally driven by a driving unit (not shown) along a direction of an arrow at a predetermined rotational speed, for example, a surface speed v1 = 75 mm / sec. Reference numeral 12 denotes a bias charge roll (BC) which charges by contacting the surface of the photosensitive drum 11.
R), the surface of the photosensitive drum 11 is previously charged to a predetermined potential (for example, −60) by the charger 12 including the bias charge roll (BCR).
It is uniformly charged to 0 V). As the charger 12, a normal scorotron or corotron charger may be used, of course. Reference numeral 13 denotes an ion flow head as an electrostatic latent image forming means for forming an electrostatic latent image on the surface of the photoconductor drum 11 which is uniformly charged to a predetermined potential by the charger 12. For example, the head disclosed in JP-A-59-164154 is used.

This ion flow head 13 is shown in FIGS.
As shown in, the dielectric interface plate 22 is interposed between the ion generating unit 20 and the ion modulating unit 21. A transfer fluid passage 23 is formed in the ion generating portion 20, the ion modulating portion 21, and the dielectric interface plate 22 in a penetrating state as a predetermined pitch or a continuous passage along a direction perpendicular to the drawing. A suitable device 24 for introducing the transfer fluid A into the transfer fluid passage 23 is arranged above the fluid passage 23. Further, the electric field electrode 26 is arranged on the upper end surface of the dielectric 25 constituting the ion generating section 20 and on one end side of the transfer fluid passage 23, and in the dielectric 25, the transfer fluid is provided. A wire-shaped RF (radio frequency) electrode 27 is embedded in the passage 23 on the same side as the electric field electrode 26 by a dielectric 28. A positive voltage is applied to the electric field electrode 26 of the ion generating section 20 by a reference potential source 29, and an RF voltage source 30 is connected to the RF electrode 27. The RF arc discharge between the electric field electrodes 26 causes the positive and negative ions to be directly generated in the transfer fluid A introduced into the passage 23 by the device 24.

On the other hand, in the ion modulation section 21, a conductive modulation plate 32 connected to a reference potential source 31 which can be grounded is arranged at one end side of the transfer fluid passage 23, as shown in the figure. On the opposite side of the passage 23, several individually spaced addressable modulation electrodes 33 are arranged, which are in the form of conductive strips and are not shown in the insulating region. Are spaced apart from each other. In the figure, one modulation electrode 3 is provided on the insulating plate 34.
Although only 3 is mounted, the long side of each conductive piece extends in the direction of the moving fluid passage 23 and is 50.8 to 76.2 μm.
The short side of the m width extends in the direction perpendicular to the drawing. A modulation bias source 3 having a direct current of about 5 to 10 V is applied to the modulation electrode 33.
If the switch 36 connected to 5 is grounded (FIG. 4), positive and negative ions are free to escape from the passage. When the ions approach the open end of the passage 23, either outflowing positive or negative ions can be attracted to the surface of the photoconductor drum 11 according to the electric field on the photoconductor drum 11. In the illustrated form, a negative bias is attracted to the conductive substrate 11a of the photosensitive drum 11. Thus
An image pattern of positive ions is formed on the photosensitive drum 11 according to the image signal.

Reference numeral 14 denotes a developing means for developing the electrostatic latent image formed on the photosensitive drum 11, and the developing means 14 is a magnetic material used in a general electrophotographic copying machine. The same one-component developing means is used.

Reference numeral 15 is a transferred material to which the visible image formed on the photosensitive drum 11 is transferred.
Is composed of a transfer roll 17 that electrostatically adsorbs the recording paper 16 onto which the visible image is transferred and holds it in a wound state. Further, a high DC voltage for forming an electric field for transferring a visible image is applied to the transfer roll 17 by a high voltage power supply 18.

Reference numeral 19 denotes a cleaner for cleaning the surface of the photosensitive drum 11.

By the way, in this embodiment, the surface speed of the image bearing member is different from the surface speed of the transferred material. That is, in this embodiment, the surface velocity v1 of the photosensitive drum 11 is 75 mm / se as described above.
While the surface velocity v2 of the transfer roll 17 is
25 mm, which is significantly slower than the surface speed v1 of the photosensitive drum 11 and is 1/3 of the surface speed v1 of the photosensitive drum 11.
/ Sec is set.

With the above arrangement, the image recording apparatus according to this embodiment records an image in the following manner while preventing a decrease in resolution due to the thickening of the electrostatic latent image.
That is, in the image recording apparatus, as shown in FIG.
After cleaning the surface of the photosensitive drum 11 with the cleaner 19, as shown in FIGS. 3 and 6, the surface of the photosensitive drum 11 is charged by the charger 12 to a predetermined potential (for example, −60).
It is uniformly charged to 0 V). Next, as shown in FIG. 6, on the surface of the photoconductor drum 11 uniformly charged by the charger 12, as shown in FIG. The electrostatic latent image doubled is formed so that the latent image has a contrast of 150V. Here, an electrostatic latent image of 400 dpi (do) is formed on the photoconductor drum 11.
In order to form a 1-bit line corresponding to the resolution of t / inch), the target value of the line width of the recorded image is set to 63.5 μm corresponding to the 1-bit line, and 63 corresponding to the 1-bit line on the photosensitive drum 11. 3 times the size of 0.5 μm (190.5 μm
When the electrostatic latent image of (m) was formed, the line width after development was 215 μm due to the effect of a slight thickening of the latent image. As described above, in order to form an electrostatic latent image on the photosensitive drum 11 which is stretched three times in the process direction and has a predetermined low contrast, the surface velocity v1 of the photosensitive drum 11 is set.
So that a normal electrostatic latent image is formed at a speed of 1/3 of
An image signal is applied to the ion flow head 12, and the RF wire 27 and the modulation electrode 33 of the ion flow head 13 are applied.
It is sufficient to set the voltage to be applied to, etc., the flow rate of the transfer fluid, or the like to a voltage or pressure lower than that in the case of forming a normal electrostatic latent image.

The image density of the 1-bit line image thus developed on the photosensitive drum 11 was 0.6 (FIG. 7). Further, at the transfer portion, the visible image formed on the photosensitive drum 1 is transferred to the transfer roll 17 side by the transfer bais voltage while the photosensitive drum 11 slides at a surface speed three times that of the transfer roll 17. Transfer roll 17
As shown in FIG. 7, the visible image on the recording paper 16 held above is reduced in size to about 1/3, and the image density is 1.
Rose to 3. When the line width of the image formed on the recording paper 16 is accurately measured, it is 73 μm, which is +9.5 μm thicker than the initially targeted value of 63.5 μm, and there is no problem in image quality. Is a level,
It turns out that high resolution images can be recorded.

Comparative Example With the same configuration as in Example 1 above, the difference is that the surface velocity v1 of the photoconductor drum 11 is 25 mm / sec, and the line width formed on the photoconductor drum 11 is 63.5 μm, which is the same size. The latent image contrast is 450 V as a contrast at which sufficient image density can be obtained by magnetic one-component development. FIG. 5 is a schematic view showing the image recording process of this comparative example.

In this comparative example, the line width of the visible image on the photosensitive drum 11 was 135 μm, which was +71.5 μm thicker than the target value of 63.5 μm. This is a line width of almost 2 bit lines or more, and it cannot be said that the resolution of 400 dpi is reproduced.

By the way, according to the present invention, as the electrostatic latent image forming means, a means for forming an electrostatic latent image by irradiating an ion stream according to image information is used, and the electrostatic latent image forming means is used. An electrostatic latent image is formed on the image bearing member with low contrast and magnified to a predetermined size, and the visualized image formed on the image bearing member by the developing means is It is characterized in that an image is recorded by transferring the image on a transfer target which is rotationally driven at a speed lower than the surface speed of the image carrier.

In such an image recording apparatus, as shown in FIG. 1, the factors that determine the proper latent image contrast and the speed ratio between the image bearing member 1 and the transferred member 4 in terms of the image quality of the recorded image. The following is a consideration.

Looking at the image forming process in the image recording apparatus, as shown in FIG. 8, the latent image contrast V and the image thickening Δ are formed on the visible image carrier 11 by using the ion flow head 13.
A latent image of S is formed, and the latent image is subjected to magnetic one-component development using the developing means 14, so that a developed image having a toner weight M per unit area and an image thick ΔS ′ is obtained. This developed image shows the speed ratio v1 / v of the visible image carrier 11 and the transferred material 15.
By being transferred at 2, the transfer image has a toner weight M ′ per unit area and an image thickening ΔS ″. Since the image density D after transfer depends on the toner weight M ′ per unit area, the image density D can be expressed as D = f (M ′) as a function of the toner weight M ′ per area.

Here, there is the following relationship between the image thickening ΔS of the electrostatic latent image formed on the visible image carrier 11 and the image thickening ΔS ′ after development. ΔS ″ ≈ΔS ′ · v2 / v1≈ΔS · v2 / v1 = g (V) v2 / v1 (1) That is, the post-transfer fat ΔS ″ is the speed ratio v1 / v
By the transfer of 2, it becomes almost equal to ΔS ′ · v1 / v2. Further, ΔS ′ varies depending on the developing conditions and is not always equal to ΔS, but in obtaining the proper latent image contrast V and the speed ratio v1 / v2, it can be treated as almost equal and there is no problem. Here, the latent image thickening ΔS depends on the latent image contrast V when the electric field applied between the ion flow head 13 and the visible image carrier 11 is constant. Therefore, the image density D after transfer and the toner weight M ′ per area of the developed image can be expressed as follows.

D = f (M ') M'.apprxeq.M.v1 / v2 = h (V) v1 / v2 Since the developed image is not always 100% transferred, M'.noteq.M.v1 / Although it is v2, there is no problem assuming that both sides are almost equal. The toner weight M per unit area depends on the latent image contrast.

By the way, FIG. 9 qualitatively shows the relationship ΔS = g (V) between the latent image thickening ΔS and the latent image contrast V. Further, FIG. 10 qualitatively shows the relationship D = f (M ′) between the image density D and the toner weight M ′ per unit area of the transferred image. Further, FIG. 11 qualitatively shows the relationship M = h (V) between the toner weight M per unit area of the developed image and the latent image contrast V.

Assuming that the image thickening and the image density are ΔS ″ ≦ S ₀ and D ≧ D ₀ , respectively, as the allowable values of the image quality, appropriate values of V and v1 / v2 satisfying the conditions are given above. You can select based on relationships. That is, for the latent image thickening S ₀ that satisfies the image thickening tolerance,
From FIG. 9, an appropriate value range V ≦ V _{0 of the} latent image contrast can be obtained. Further, FIG. 10 shows that the toner weight M ′ ≧ M ′ ₀ per unit area of the transferred image that satisfies the allowable value D _{0 of the} image density is satisfied.

On the other hand, the toner weight M ₀ per unit area of the developed image at the latent image contrast V ₀ can be known from FIG. 11, and therefore v1 / v2 so that M ₀ · v1 / v2 ≧ M ′ ₀ is satisfied. Will be selected.

In the above embodiment, the image quality allowable value is 400d.
Considering the resolution of pi, half of 1 bit pitch Δ
S ″ ≦ 31.8 μm (≈S ₀ · v1 / v2), D ≧
It was set to 1.3 (= D ₀ ). Under the condition that the photosensitive drum 1 is uniformly charged = −600V, and the distance between the ion flow head and the photosensitive drum is 200 μm, the latent image contrast satisfying ΔS ″ ≦ 31.8 μm is V ≦ 200 · v1 / v2.
Met. Here, since v1 / v2> 1, v1 /
A large value of V can be selected depending on the setting of v2, but in that case, the weight of the developing toner per unit area becomes large, and further, it increases v1 / v2 times in transfer, which causes image deterioration in transfer and fixing. Not preferable. In order to secure a margin for maintaining image quality, the latent image contrast V is selected to be a low value, and the decrease in the toner weight per unit area of the developed image due to the low latent image contrast is compensated by the transfer with a speed difference. preferable.

Therefore, by selecting latent image contrast = 200 V, the toner weight per unit area of the developed image by magnetic one-component development is M0 = 0.45 mg / cm ^2.
Met. On the other hand, it was confirmed that the toner weight per unit area of the transferred image satisfying D ≧ 1.3 was M ′ ≧ 1.1 mg / cm ² . It was also confirmed that when the toner weight per unit area of the transferred image exceeds 1.8 mg / cm ² , the image deterioration during fixing becomes remarkable. Therefore, the speed ratio between the photosensitive drum and the transfer target is 2.44 ≦ v1 / v2 ≦
It may be selected in the range of 4.0.

In the case of the above embodiment, the latent image contrast was 150 V, and the toner weight per unit area of the developed image at this time was M0 = 0.4 mg / cm ² . Therefore,
The speed ratio between the photosensitive drum and the transferred material is 2.75 ≦ v1
It is selected from the range of /v2≦4.5, and is performed with v1 / v2 = 3.

As a comparative example, latent image contrast = 400
The case of V is shown. Toner weight per unit area of the developed image at latent image contrast = 400V is 1.0 mg / cm ^2.
Is. On the other hand, from the relationship of V ≦ 200 · v1 / v2, the speed ratio must satisfy v1 / v2 ≧ 2. However, under this condition, the toner weight per unit area of the transferred image is 2.0 mg / cm ² or more, and the resolution of 400 dpi cannot be satisfied in the image that has passed through fixing.

As described above, according to the present invention, since the image thickening which has been a problem in the related art is dramatically improved, the latent image contrast V is selected to be a low value within the range permitted by the performance of the recording apparatus. It is preferable that the decrease in toner weight per unit area of the developed image due to the low latent image contrast is compensated by the transfer with a speed difference. As this speed ratio, v1 / v2 =
A sufficient effect cannot be expected with a setting of about 1.01 to 1.1.

Second Embodiment FIG. 13 shows a second embodiment of the present invention. The same parts as those of the above-mentioned embodiment are designated by the same reference numerals, and a description will be given.
In the second embodiment, 1 formed on the photosensitive drum 11
As shown in FIG. 13, one pixel is divided into a large number of areas along the sub-scanning direction, and the time for irradiating the one pixel on the photosensitive drum 11 with the ion current head 13 is changed. By this, area gradation is performed.

In the image recording apparatus according to the second embodiment, as shown in FIG. 14, the size of the visible image 6 in the sub-scanning direction is reduced by reducing the image at the transfer portion. Even when the sub-scanning division technique in which the pixels in the direction are finely divided is applied, since the visible image on the visible image carrier 1 may be formed in a relatively large size, one pixel of the ion flow head 13 is of course required. Therefore, it is possible to provide an image recording apparatus capable of improving the reproducibility of halftones by realizing the technique related to sub-scanning division without making the recording elements such as the heating element of the thermal head and the electrodes of the multi-stylus fine. it can.

The other structure and operation are the same as those of the above-mentioned embodiment, and the description thereof will be omitted.

[0051]

The present invention, which has the above-described structure and operation, does not require a special developing device or means such as a dielectric drum, and can be used in a developing technique generally used in the field of electrophotographic recording systems. It is possible to use the photoconductor drum etc. as it is, and it is possible to solve the problem of resolution deterioration due to the thickening of the electrostatic latent image, and to use the recording elements such as the heating element of the thermal head and the electrodes of the multi-stylus. An object of the present invention is to provide an image recording apparatus capable of improving the reproducibility of halftones by realizing the technique related to sub-scanning division without making the device finer.

[Brief description of drawings]

FIG. 1 is a conceptual block diagram showing an image recording apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing the operation of the image recording apparatus according to the present invention.

FIG. 3 is a configuration diagram showing an embodiment of an image recording apparatus according to the present invention.

FIG. 4 is a cross-sectional configuration diagram showing an ion flow head.

FIG. 5 is a sectional view showing an ion flow head of the same.

FIG. 6 is an explanatory diagram showing an image recording process of the image recording apparatus according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an image transfer state.

FIG. 8 is an explanatory diagram showing an image recording process of the image recording apparatus according to the embodiment of the present invention.

FIG. 9 is a graph showing the relationship between the latent image contrast and the thickening of the latent image.

FIG. 10 is a graph showing the relationship between the toner weight per unit area of the transferred image and the image density.

FIG. 11 is a graph showing the relationship between the latent image contrast, the toner weight per unit area of the developed image, and the image density.

FIG. 12 is an explanatory diagram showing an image recording process in a comparative example.

FIG. 13 is an explanatory diagram showing pixels on a photosensitive drum according to a second embodiment of the present invention.

FIG. 14 is an explanatory diagram showing pixels on a photosensitive drum according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Visual image carrier, 2, 3 Visual image creation means, 4 Transferred object, v1 Surface speed of the visual image carrier 1, v2 Transferred object 4
Surface speed.

Claims (6)

[Claims] 1. An image recording apparatus comprising: a visible image creating means for creating a visible image on a visible image carrier; and a transfer means for transferring the visible image on the visible image carrier to a transfer target. Set the surface speed of the carrier faster than the surface speed of the transferred material,
A state in which a visible image is formed on the visible image carrier in a state of being magnified to a predetermined size by the visible image creating means, and the visible image formed on the visible image carrier is reduced on the transfer target. An image recording apparatus characterized in that an image is recorded by transferring the image. 2. The image recording apparatus according to claim 1, wherein the visible image forming means includes an electrostatic latent image forming means and a developing means. 3. The image recording apparatus according to claim 2, wherein the electrostatic latent image forming means is an ion head. 4. The volume bearing has a volume resistivity of 10 ¹² Ω.multidot.
A dielectric material having a size of cm or more.
The image recording apparatus according to any one of items 1 to 3. 5. The image recording apparatus according to claim 1, wherein the image bearing member is made of a photoconductor having photoconductivity. 6. The image density of the visible image on the visible image bearing member is equal to or lower than the image density of the visible image on the transfer-receiving member. Image recording device.