JPH086180A - Image forming method - Google Patents

Abstract

(57) [Summary] [Object] To provide an image forming method capable of forming an image without density unevenness. In an image forming method of forming an image by exposing and heating a heat-developable photoreceptor, a step of forming a test image, a step of measuring an optical density of the test image, A step of correcting the exposure energy based on a measurement result to form an image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming an image by performing imagewise exposure on a heat-developable photosensitive member, and then developing the image. The present invention relates to an image forming method in which no occurrence occurs.

[0002]

2. Description of the Related Art The silver salt photography method using silver halide is a recording technology that has been widely used from the past because of its excellent sensitivity and gradation. However, since processing such as development, stopping, and fixing is performed by a wet method after image exposure, workability, convenience, and safety are poor, and it has been a problem until now. On the other hand, research has been conducted on dry materials that have eliminated these wet treatments, and are disclosed in Japanese Patent Publication Nos. 43-4921 and 43-4924. These use a photosensitive silver halide in a catalytic amount and a non-photosensitive organic silver salt as an image forming material. The organic silver salt functions as an image forming material according to the following mechanism. That is, (1) silver nuclei are generated from a catalytic amount of photosensitive silver halide by imagewise exposure, and this forms a latent image. (2) The silver nuclei serve as a catalyst, and the photoreceptor is heated to cause an oxidation-reduction reaction between the organic silver salt and the reducing agent to reduce the organic silver salt to silver, which forms an image.

The heat-developable photoconductor has the advantage that image formation is performed by a dry process instead of a wet process, so that image communication,
It is used as a photosensitive material for various industries such as medical field and computer output.

Various methods have been proposed in the past for thermally developing an imagewise exposed photothermographic material. Among them, a typical thermal development method is, for example, a method of heating the photoreceptor by a heating heater. A heating method by radiant heat using infrared rays or microwaves, a method in which a carbon conductive layer is provided on the back surface of the photoconductor and heat is generated by energizing this layer, and the like can be mentioned. The most common one is a heat-generating heater. As a typical proposal of a heating method using a heating heater, for example, Japanese Patent Application Laid-Open No. 61-134761.
JP-A-61-137152 and JP-A-61-11-1
34761, JP-A-54-130025,
54-154326, 59-104648, JP-A-60-135947, and 60-14.
3338 and 61-173230.

[0005]

Since the image density of the heat-developable photoreceptor greatly changes depending on the heat-development temperature, a temperature sensor is usually provided near the heat source to control the temperature so that the heat-development temperature does not fluctuate. .

However, since it takes a certain time from when the sensor detects the temperature until the heat source reaches the set temperature, it is very important to control the heat source temperature so that the image density does not change. was difficult.

An object of the present invention is to provide an image forming method capable of forming an image without density unevenness.

[0008]

The image forming method of the present invention forms an image by exposing and heating a heat-developable photoconductor, and the step of forming a test image and the test image It comprises a step of measuring an optical density and a step of forming an image by correcting the exposure energy based on the measurement result of the optical density.

In the image forming method of the present invention, an image is formed by exposing a heat-developable photoconductor to light and then heating (heat-developing) the image. An image corresponding to an exposure pattern can be obtained.

In the image forming method of the present invention, the heat-developable photoconductor is exposed with uniform intensity and further heated to form a test image. This test image ideally has no uneven optical density. However, density unevenness usually occurs in the test image due to factors such as a change in heating temperature during heat development.

Next, the optical density of the test image is measured with a densitometer to detect density unevenness on the test image.

Finally, the exposure intensity of the light source is corrected by the detected density unevenness to form a desired image without density unevenness. That is, the exposure energy is increased in the portion where the optical density is expected to decrease due to the detected density unevenness.
On the contrary, the exposure energy is lowered in the portion where the optical density is expected to increase.

The test image may be an image obtained by imagewise exposing the entire image area (area where an image can be formed) and then heating, but as shown in FIG. 2, the image is formed only on the portion where the optical density is measured. It may be one. It is preferable that the test image has regularity so that density unevenness in the image area can be easily detected. Here, the regularity means that certain patterns are arranged at equal intervals in the vertical direction or the horizontal direction. The repeated pattern preferably has the same shape. The test image shown in FIG. 2 has 5 × 5 = 25 quadrangles (7 m
m × 7 mm) to form a test image.
By measuring the optical density of each square in this test image, it is possible to know the density unevenness that occurs in the image area. By increasing the number of squares, it is possible to detect density unevenness more accurately, but it is meaningless if there are too many. The optical density measurement points are preferably 2 to 15 points in each of the vertical and horizontal directions in the image area, and more preferably 3 to 10 points.

The image forming method of the present invention will be described below using the image forming apparatus of FIG.

The heat-developable photoreceptor 11 is housed in a detachable cassette 12 and set in the image forming apparatus.

The heat-developable photoreceptor 11 contains an organic silver salt, a reducing agent and silver halide in the photosensitive layer, as described in detail later. When a heat-developable photoreceptor is imagewise exposed, silver nuclei are produced from silver halide to form a latent image. In the portion where the latent image is formed, the organic silver salt and the reducing agent undergo a redox reaction by heating to reduce the organic silver salt to silver, which becomes an image, at which time the silver nuclei act as a catalyst.

The inside of the cassette 12 is shielded from light by a shutter 13 until it is set in the apparatus. Cassette 1
When No. 2 is set in the apparatus, the shutter 13 opens and the supply roller 14 comes down onto the photoconductor 11 in the cassette.
The drive of the image forming apparatus is controlled by the controller 15.

The supply roller 14 rotates to send out the photosensitive member 11. The photoconductor 11 pulled out from the cassette 12 is
It is guided to the image exposure unit along the transport guide 16. Further, the transport rollers 17a and 17b of the exposure unit also start to rotate and transport the photoconductor 11 to a predetermined position (image exposure start position). After that, the paper feed roller 14 and the transport rollers 17a and 17b are stopped.

In the image exposure section, the photoreceptor 11 is imagewise exposed by a semiconductor laser scanner exposure device 19 including a semiconductor laser (not shown), a polygon mirror 18, and the like.

The transport rollers 17a and 17b rotate in synchronization with the light emission of the semiconductor laser scanner exposure device 19,
Imagewise exposure is performed while the photoconductor 11 is being conveyed.

The semiconductor laser includes a laser driver 2
0 and the image signal generator 21.

As the exposure device, any device other than the above-mentioned semiconductor laser scanner exposure device 19 can be used as long as it can be written according to an image signal, and specifically, a CRT, FOT, LED, LED array, An LCD or PLZT shutter array, a fluorescent lamp, or the like can be used.

The photoconductor 11 imagewise exposed in this manner
Is conveyed to the heating and developing section by the conveying rollers 17a and 17b and is heated and developed.

The heating / developing section includes heating rollers 22a and 22a.
b, transport guides 23a, 23b, heating elements 24a, 24
b, cooling rollers 25a and 25b, and a heat insulator 26. The heating rollers 22a and 22b are made of, for example, silicone rubber. A halogen lamp is provided as a heater at the center of the heating rollers 22a and 22b.
The heating rollers 22a and 22b are the transport rollers 1 of the image exposure unit.
It rotates at the same speed as 7a and 17b, and
And carrying out heat development. The photoconductor 11 is further guided to the conveyance guides 23a and 23b in the heating and developing section and reaches the cooling rollers 25a and 25b. Transport guides 23a, 2
Heating elements 24a and 24b (silicon rubber sheet heating elements) are provided on 3b, respectively, and heat development is performed at the same time when the photoconductor 11 is conveyed. The heat development of the photoconductor 11 is stopped by being cooled by the cooling rollers 25a and 25b.

The cooling rollers 25a and 25b are heating rollers 2.
It rotates at the same speed as 2a and 22b and is discharged to the outside of the photoconductor 11.

Thus, first, test images a _{1 to} a ₂₅ as shown in FIG. 2, for example, are formed on the photothermographic material. Next, the optical densities of the test images a _{1 to} a ₂₅ are measured. In the present invention, the optical density was measured using an optical densitometer NLM-STD-Tr manufactured by Narumi Trading Co., Ltd.

From the optical densities of the test images a _{1 to} a ₂₅ thus measured, it is possible to predict how density unevenness will occur when an image is formed by this image forming apparatus.

According to the present invention, a desired image is formed by the same steps as the above-mentioned test image formation, but when the image formation is carried out, the image exposure is carried out based on the respective optical densities of the test images a _{1 to} a _25. The light energy at that time is corrected so that density unevenness does not occur in the formed image. That is, the light energy at the time of image exposure is increased at the portion where the density is expected to decrease due to the test image. On the contrary, the light energy at the time of image exposure is lowered in the portion where the increase in density is expected.

The correction amount of the image exposure energy is determined depending on how much the optical density of the test image is deviated from the reference optical density (desired optical density). The graph of 3 is used.

The graph shown in FIG. 3 is a graph showing the relationship between the light energy E and the optical density (OD) at the time of image exposure, and the heat development temperatures are 114.0 ° C., 114.5 ° C. and 11 ° C.
The graphs at 5.0 ° C., 115.5 ° C. and 116.0 ° C. are illustrated. The graph shown in FIG. 3 is determined by the type of heat-developable photoconductor used. Therefore, in carrying out the present invention, a graph is prepared according to the type of the photoconductor to be used. The graph of FIG. 3 can be easily prepared by forming an image by changing the image exposure energy and the heat development temperature and measuring the optical density.

According to FIG. 3, for example, the image exposure energy E
₀ , when the image is formed at a heat development temperature of 115.0 ° C.
D. An image of = 0.7 should be obtained. However, in the heat development step, heat is taken by the photoconductor as the photoconductor progresses, so that the heating temperature tends to decrease. As a result, the image density is reduced. For example, in FIG. 2, the test image a ₁₈ O. D. = 0.6 is assumed. still,
The arrow A in FIG. 2 indicates the traveling direction of the photoconductor.

The test image a ₁₈ was O.I. D. = 0.6, it can be seen from FIG. 3 that the heat development temperature of the test image a ₁₈ is 114.5 ° C. Furthermore, even if the heat development temperature reaches 114.5 ° C., the original O. D. = 0.7
It can be seen from FIG. 3 that the image exposure energy can be set to E ₁ in order to obtain Eq. Or heat development temperature is 114.5 ° C
When O. D. It can be seen from FIG. 3 that the image exposure energy can be set to E ₂ in order to obtain = 0.4.

Therefore, in the next image formation, the exposure energy is corrected to E ₁ or E ₂ when the position corresponding to the test image a ₁₈ is image-exposed. By doing so, it is possible to prevent a decrease in image density and obtain a desired optical density.

The above correction operation is performed for all test images a ₁
Image is obtained with excellent free of density reduction by performing the ~a _25. If the heat development temperature T is finely changed and the number of graphs in FIG. 3 is increased, more accurate correction can be made.
There is a limit to increasing the number of graphs. Actually, the approximate value of the correction amount is obtained from the graph of about 5 lines shown in FIG.

The approximation of the correction amount is, for example, as follows.

In FIG. 3, when the point obtained as the intersection of the measured value of the optical density and the exposure energy E ₀ before correction does not come on the five graphs in FIG. 3, the graph closest to this point. The above-described correction operation is performed by using to obtain the correction amount.

In order to perform the approximation of the correction amount more accurately, a graph passing through the above point obtained from the measured value of the optical density and the exposure energy E ₀ is obtained from two graphs narrowing this point and the position of the above point. It is advisable to add in a linear proportional calculation and to perform the above correction operation using this added graph to obtain the correction amount.

In the apparatus shown in FIG. 1, the heating roller 22a,
Temperature sensors 27a, 27b, 28a, and 28b are attached to the heating elements 22a, 27b, 28a, and 28b, respectively, and the outputs of the temperature sensors 27a, 27b, 28a, and 28b are fed back to the temperature control unit 29 to heat the heating roller 22a. , 22b and the heating elements 24a, 24b are controlled to be constant.

The control for feeding back the detection result of the temperature sensor to keep the heating and developing temperature constant is that the temperature of the heating roller and the heating element changes irregularly around a constant value in a very detailed manner. . Although this irregular temperature change is a very delicate change, it may cause density unevenness in the image.

In such a case, it is preferable that the temperature control for keeping the heating and developing temperature constant by feedback is stopped and the heating and developing temperature is controlled to decrease or rise with a certain regularity over time. In particular, it is preferable to lower the heat development temperature with a certain regularity. Specifically, when the photoconductor is not in the heat development step, heat development means (heating rollers 22a, 22b, heating element 24a,
24b) is kept at a constant temperature, and immediately before the photosensitive member enters the heating and developing step, the energy supply to the heating and developing means is stopped so that the heating and developing temperature is naturally lowered, that is, regularly lowered. Then, the photosensitive member is heated with the residual heat in the process in which the heating and developing temperature naturally decreases.

Alternatively, energy may be applied to the heating and developing means by a repeating pulse having a constant cycle. in this case,
The pulse cycle is 0.1 to 100 Hz, further 0.5 to 5
0 Hz is preferred. The pulse duty is 10
It is preferably 75%, more preferably 20 to 50%.

As a light source for image exposure, a gas laser or an LED can be used in addition to a semiconductor laser.
The image exposure energy is 0.5 to 20 μJ on the surface of the photoconductor.
/ Cm ² , and more preferably 1.0 to 10 μJ / cm ² .

The heat development temperature is 60 to 200 ° C., and further 70
The temperature is preferably ~ 150 ° C. The heating time for heat development is 1 second
It is preferably 3 minutes, more preferably 3 seconds to 60 seconds.

The heat-developable photosensitive material used in the present invention has a photosensitive layer on a support, and the photosensitive layer contains at least an organic silver salt, a reducing agent and silver halide.

The organic silver salt is preferably a silver salt of an organic acid, a silver salt of an acetylene derivative, a silver salt of an organic compound having an imino group or a mercapto group. In particular, those that do not undergo changes such as coloring at room temperature or under room light are preferable. As the silver salt of an organic acid, silver behenate is particularly preferable.

As the reducing agent, a phenol compound, a hydrazine compound, a naphthol compound, a pyrazolidone compound or the like is used. As a phenol compound, aminophenol, 2.6-dichloroaminophenol, 4.4 '
-Dihydroxy-3.3'-di-t-butyl-5.5 '
-Dimethylbiphenyl, 2.2'-dihydroxy-
3.3'5.5'-tetrakis-t-butylbiphenyl, 2.2'-dihydroxy-3.3'-dichlorobiphenol, 2.2'-methylenebis (6-t-butyl-
4-methylphenol), 2.2'-propylenebis (6-t-butyl-4-ethylphenol), 4.4 '
-Butylidene bis (2-t-butyl-6-methylphenol), 4.4'-thiobis (2-t-butyl-6-ethylphenol), 2.6-dichloro-4-benzenesulfonamidephenol and the like.

Examples of the hydrazine compound include β-acetylphenylhydrazine and β-acetyltolylhydrazine.

As the naphthol compound, 4-methoxynaphthol, 4-chloronaphthol, 4.4'-methylenebis (2-methylnaphthol), 4- (2.6dimethyl-4-hydroxybenzyl) -2-methylnaphthol, 4- (2-t-butyl-6-ethyl-4-hydroxybenzyl) -2-methylnaphthol and the like.

Examples of the pyrazolidone compound include 1-phenyl-3-pyrazolidone.

Examples of the silver halide include silver chloride, silver bromide, silver chlorobromide, silver chlorobromide, silver chlorobromide, and silver chlorobromide. Further, such a silver salt may be doped with an Ir compound. The silver halide is particularly preferably in the form of fine particles, and a cubic crystal of 0.01 to 0.2 μm is effective. As a method of adjusting fine silver halide, a method of halogenating an organic silver salt with a silver halide-forming component such as ammonium bromide, lithium bromide, sodium chloride, N-bromosuccinimide and the like can be mentioned.

The silver halide is sensitized by sulfur, noble metals and
Processing such as reduction sensitization may be performed. Various sensitizing dyes are used for spectral sensitization. As a sensitizing dye,
For example, a cyanine dye, a merocyanine dye, etc. can be mentioned. Specific examples include the following.

[0052]

[Outer 1]

The photosensitive layer is formed by mixing the above components in a binder. As the binder, a hydrophobic or hydrophilic polymer is preferable, and a transparent or translucent one is used. A hydrophobic material is particularly preferable as the binder. Preferable examples of the binder include polyvinyl butyral, cellulose acetate butyrate, polymethyl methacrylate, polyester, polyvinyl chloride, and copolymers thereof.

Examples of the support include polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, paper, synthetic paper, photographic bariter paper, art paper and the like.

The preferred blending ratio of the above components in the photosensitive layer is as follows.

The reducing agent is preferably contained in an amount of 0.05 to 3 mol, more preferably 0.2 to 1.3 mol, per mol of the organic silver salt.

The amount of the organic silver salt contained is 0.3 to 30.
g / m ² , particularly 0.7 to 15 g / m, and further 1.2 to 8
g / m ² is preferred.

The silver halide is preferably contained in an amount of 0.001 to 2 mol, more preferably 0.05 to 1 mol, based on 1 mol of the organic silver salt. Further, when a color tone agent is used, the color tone agent is contained in an amount of 0.01 to 5 mol, preferably 0.05 to 2 mol, and more preferably 0.08 to 1 mol per mol of the organic silver salt. desirable.

If necessary, the amount of the binder to be contained is
0 to 10 parts by weight, more preferably 0.
A ratio of 5 to 5 parts by weight is preferable.

The thickness of the photosensitive layer is preferably 0.5 to 30 μm, more preferably 2 to 17 μm.

Further, in order to improve the color tone of the image and the stability after image formation, an organic acid, an antifoggant in the photosensitive layer, an anticoloring agent, an antistatic agent, an ultraviolet absorber, an anti-irradiation dye, a fluorescent agent A whitening agent, a filter dye or the like may be contained.

A protective layer may be provided on the photosensitive layer, if desired. The protective layer is formed by using various binders as main components. As the binder used,
Water-soluble resins such as polyvinyl alcohol, casein, gelatin, and ethylene-maleic anhydride copolymer are preferable. Colloidal silica, an anti-irradiation dye or the like may be added to the protective layer. The thickness of the protective layer is 0.
It is preferably 1 μm to 7 μm, more preferably 0.5 μm to 5 μm.

[0063]

EXAMPLES The present invention will be specifically described below based on examples. In addition, "parts" shown below means "parts by weight".

Example 1 A photothermographic material was prepared by the following method.

A 100 μm thick polyethylene terephthalate (PET) film was coated with the following photosensitive solution A so as to have a dry film thickness of 13 μm to form a photosensitive layer, and then dried with the following protective solution B. A protective layer was formed to a film thickness of 2 μm to obtain a photoreceptor of the present invention.

[Photosensitive solution A] Silver behenate 25.0 parts Silver bromide 2.5 parts Polyvinyl butyral 30.0 parts Behenic acid 11.0 parts Homophthalic acid 0.1 parts α, α, p-tribromoacetonephenone 0.1 part Phthalazinone 3.0 part 2,2'-methylenebis (4-t-butyl-6-methylphenol) 11.0 part 2-mercaptobenzoxazole 0.08 part Dye of the following structural formula (1) 01 parts Xylene 200.0 parts n-Butanol 180.0 parts Dimethyl sulfoxide 5.0 parts

[0067]

[Outside 2]

[Protective liquid B] Polyvinyl alcohol 5 parts Colloidal silica 5 parts Water 70 parts

The photoconductor thus obtained is 210 mm × 290
After being processed into a size of mm, it was set in the image forming apparatus of FIG. 1 to form an image. The spectral sensitivity of this photoconductor is 68
It had a spectral absorption maximum near 0 nm.

In this example, a semiconductor laser having an oscillation wavelength of 680 nm and a maximum output of 30 mW was used as a light source. Exposure energy is 3.3 μJ / cm on the photoconductor surface.
^{Was 2} . The heat development temperature is the PID temperature control device (E4
The temperature was set to 115.0 ° C. using E5 type, manufactured by OMRON Corporation. The heat development time was 15 seconds.

Thus, first, the test image shown in FIG. 2 was prepared. Optical densities of the obtained test images a _{1 to} a ₂₅ were measured. The measurement effects are shown below. a ₁ = 0.70 a ₂ = 0.70 a ₃ = 0.70 a
_{4 = 0.70 a 5 = 0.68 a} 6 = 0.68 a 7 = 0.69 a 8 = 0.70 a
_{9 = 0.68 a 10 = 0.66 a} 11 = 0.65 a 12 = 0.66 a 13 = 0.67 a
_{14 = 0.66 a 15 = 0.64 a} 16 = 0.63 a 17 = 0.64 a 18 = 0.65 a
₁₉ = 0.64 a ₂₀ = 0.62 a ₂₁ = 0.60 a ₂₂ = 0.61 a ₂₃ = 0.63 a
₂₄ = 0.60 a ₂₅ = 0.60

The heat development temperature actually applied was calculated from the above measurement results and the linear proportional calculation described above, and the result was as follows. a ₁ = 115.0 a ₂ = 115.0 a ₃ = 115.
0 a ₄ = 115.0 a ₅ = 114.90 a ₆ = 114.90 a ₇ = 114.95 a ₈ = 11
5.0 a ₉ = 114.90 a ₁₀ = 114.80 a ₁₁ = 114.75 a ₁₂ = 114.80 a ₁₃ = 11
4.85 a ₁₄ = 114.80 a ₁₅ = 114.70 a ₁₆ = 114.65 a ₁₇ = 114.70 a ₁₈ = 11
4.75 a ₁₉ = 114.70 a ₂₀ = 114.60 a ₂₁ = 114.50 a ₂₂ = 114.55 a ₂₃ = 11
4.65 a ₂₄ = 114.50 a ₂₅ = 114.50

The exposure energy in the next image formation was determined from the above results, the graph of FIG. 3 and the linear proportional calculation described above.

Image exposure was carried out with the exposure energy thus corrected, and otherwise, images were formed on 60 photoconductors at intervals of 1 minute in the same manner as in the test image formation.

As a result, density unevenness was slightly generated on the 50th and 54th photoconductors, but this was not a problem in practical use.

Example 2 Images were formed using the photoreceptor and image forming apparatus of Example 1. However, in this embodiment, the photosensitive member is the heating roller 22.
Immediately before being heated by a, 22b, the heating roller 22a,
22b and the heating elements 24a and 24b are stopped from supplying energy, and immediately after the photoconductor is separated from the heating elements 24a and 24b, the heating rollers 22a and 22b and the heating element 24 are re-energized.
A and 24b were energized to maintain them at 115 ° C. When the energy supply to the heating roller and the heating element was stopped, the heat development temperature was 4 ° C./min. Fell at a rate of.

In this way, first, the test image shown in FIG. 2 was created. Optical densities of the obtained test images a _{1 to} a ₂₅ were measured. The measurement results are shown below. a ₁ = 0.68 a ₂ = 0.69 a ₃ = 0.70 a
_{4 = 0.70 a 5 = 0.68 a} 6 = 0.67 a 7 = 0.67 a 8 = 0.67 a
_{9 = 0.66 a 10 = 0.66 a} 11 = 0.62 a 12 = 0.63 a 13 = 0.63 a
_{14 = 0.62 a 15 = 0.61 a} 16 = 0.57 a 17 = 0.58 a 18 = 0.60 a
_{19 = 0.58 a 20 = 0.56 a} 21 = 0.51 a 22 = 0.54 a 23 = 0.55 a
₂₄ = 0.53 a ₂₅ = 0.50

The heat development temperature actually applied was calculated from the above measurement results and the linear proportional calculation described above, and the result was as follows. a ₁ = 114.9 a ₂ = 114.95 a ₃ = 11
5.0 a ₄ = 115.0 a ₅ = 114.90 a ₆ = 114.85 a ₇ = 114.85 a ₈ = 11
4.85 a ₉ = 114.80 a ₁₀ = 114.80 a ₁₁ = 114.60 a ₁₂ = 114.65 a ₁₃ = 11
4.65 a ₁₄ = 114.60 a ₁₅ = 114.55 a ₁₆ = 114.35 a ₁₇ = 114.40 a ₁₈ = 11
4.50 a ₁₉ = 114.40 a ₂₀ = 114.30 a ₂₁ = 114.05 a ₂₂ = 114.20 a ₂₃ = 11
4.25 a ₂₄ = 114.15 a ₂₅ = 114.0

The exposure energy in the next image formation was determined from the above results, the graph of FIG. 3 and the linear proportional calculation described above.

Image exposure was carried out with the exposure energy thus corrected, and otherwise the image was formed on 60 photoconductors at intervals of 1 minute in the same manner as in the test image formation.

As a result, all the formed images were clear with no density unevenness.

Example 3 Images were formed using the photoreceptor and image forming apparatus of Example 1. However, in this embodiment, the photosensitive member is the heating roller 22.
Immediately before being heated by a, 22b, heating rollers 22a, 2
The feedback control for maintaining 2b and the heating elements 24a and 24b at 115 ° C. was stopped, and energy was supplied to the heating roller and the heating element by repeating pulses of 1 Hz.
The duty of the repeating pulse was 25%. As a result, the heat development temperature was 1 ° C./min. Fell at a rate of. After the photoconductors passed through the heating elements 24a and 24b, the heating rollers 22a and 22b and the heating elements 24a and 24b were feedback-controlled again and maintained at 115 ° C.

Thus, first, the test image shown in FIG. 2 was prepared. Optical densities of the obtained test images a _{1 to} a ₂₅ were measured. The measurement results are shown below. a ₁ = 0.69 a ₂ = 0.70 a ₃ = 0.70 a
_{4 = 0.70 a 5 = 0.68 a} 6 = 0.68 a 7 = 0.69 a 8 = 0.70 a
_{9 = 0.68 a 10 = 0.66 a} 11 = 0.65 a 12 = 0.66 a 13 = 0.67 a
_{14 = 0.65 a 15 = 0.64 a} 16 = 0.63 a 17 = 0.65 a 18 = 0.65 a
₁₉ = 0.64 a ₂₀ = 0.62 a ₂₁ = 0.60 a ₂₂ = 0.61 a ₂₃ = 0.63 a
₂₄ = 0.60 a ₂₅ = 0.60

From the above measurement results and the linear proportional calculation described above, the actually applied heat development temperature was obtained as follows. a ₁ = 114.95 a ₂ = 115.0 a ₃ = 11
5.0 a ₄ = 115.0 a ₅ = 114.90 a ₆ = 114.90 a ₇ = 114.95 a ₈ = 11
5.0 a ₉ = 114.90 a ₁₀ = 114.80 a ₁₁ = 114.75 a ₁₂ = 114.80 a ₁₃ = 11
4.85 a ₁₄ = 114.75 a ₁₅ = 114.70 a ₁₆ = 114.65 a ₁₇ = 114.75 a ₁₈ = 11
4.75 a ₁₉ = 114.70 a ₂₀ = 114.60 a ₂₁ = 114.50 a ₂₂ = 114.55 a ₂₃ = 11
4.65 a ₂₄ = 114.50 a ₂₅ = 114.50

The exposure energy for the next image formation was determined from the above results, the graph of FIG. 3 and the linear proportional calculation described above.

Image exposure was carried out with the exposure energy thus corrected, and otherwise, images were formed on 60 photoconductors at intervals of 30 seconds in the same manner as in the test image formation.

As a result, the formed images were clear with no density unevenness. In this embodiment, the image forming speed could be made faster than in the second embodiment.

Comparative Example 1 Images were formed on 60 photoconductors in the same manner as in Example 1 except that the image exposure energy was not corrected.

As a result, the formed images were all uneven in density.

[0090]

According to the present invention, since the exposure energy is corrected, it is possible to form a clear image without density unevenness.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an image forming apparatus that carries out an image forming method of the present invention.

FIG. 2 is a plan view showing an example of a test image formed by the image forming method of the present invention.

FIG. 3 is an example of a graph used to determine a correction amount of exposure energy in the image forming method of the present invention.

[Explanation of symbols]

 Reference Signs List 11 heat-developable photoconductor 12 cassette 13 shutter 15 controller 18 polygon mirror 19 semiconductor laser scanner exposure device 20 laser driver 21 image signal generator 22a, 22b heating rollers 24a, 24b heat generator 29 temperature controller

Claims (8)

[Claims] 1. An image forming method for forming an image by exposing and heating a heat-developable photosensitive material, the step of forming a test image, the step of measuring the optical density of the test image, and the optical density. And a step of forming an image by correcting the energy of the exposure based on the measurement result. 2. The image forming method according to claim 1, wherein the test image has regularity. 3. The image forming method according to claim 1, wherein the heating temperature is feedback-controlled. 4. The image forming method according to claim 1, wherein the heating temperature is controlled so as to decrease or increase with a certain regularity over time. 5. The image forming method according to claim 4, wherein the heating temperature is lowered by not applying energy to the heating and developing means for heating. 6. The image forming method according to claim 4, wherein energy is applied to the heating and developing means that performs the heating with a repeating pulse having a constant cycle. 7. The pulse has a cycle of 0.1 to 100 Hz.
The image forming method according to claim 6, wherein 8. The image forming method according to claim 7, wherein the cycle is 0.5 to 50 Hz.