JP3493478B2 - Organic semiconductor gas sensor and electrophotographic apparatus having the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic semiconductor gas sensor and an electrophotographic apparatus having the same.

[0002]

2. Description of the Related Art Some organic photo-semiconductors used in electrophotographic devices have their charging characteristics deteriorated by exposure to gases such as ozone, NOx, ammonia, etc., resulting in a decrease in density (positive / positive) on an image and background stain ( Some may cause an abnormal image such as negative / positive). However, such anomalous images can also be caused by causes other than gas exposure.Therefore, the operator assuming the electrophotography should judge from the anomalous images whether or not this is due to the gas exposure. Is virtually impossible. However, if found to be due to gas exposure, this is a recoverable deterioration and can be recovered by appropriate means. Therefore, it is necessary to provide a means for knowing whether or not the electrophotographic apparatus has deteriorated due to gas exposure, and it is desired to mount a gas sensor that meets such a purpose.

In general, as a method of measuring the gas concentration, in the case of ozone, a method of irradiating ultraviolet rays to measure the change in the amount of transmitted light of the ultraviolet rays depending on the ozone concentration is adopted, and in the case of NOx, light emission due to a complicated photochemical reaction is also taken. It is performed by measuring, and therefore these devices tend to be large and expensive.

Further, although the gas concentration in the atmosphere can be known by using these conventional gas densitometers, the deterioration of the organic optical semiconductor due to the above gases differs depending on the gas concentration gas and the exposure period. However, even if it is exposed to a high-concentration gas, it does not immediately deteriorate, and on the contrary, even if it is a low-concentration gas, deterioration may occur if it is exposed for a long period of time. For the above-mentioned reason, it is not possible to know how much the deterioration of the photoconductor has progressed, just by knowing the gas concentration. If you try to know the deterioration of an object using a gas sensor for concentration measurement that is currently known,
Deterioration pattern of organic photo-semiconductor due to gas (gas concentration,
Gas exposure period is used as a parameter), and the gas concentration and gas concentration duration in the atmosphere during actual use are monitored and stored, and the deterioration of the organic optical semiconductor due to the gas is estimated from these data. Become. In addition, the gas concentration in the atmosphere during actual use may not be constant, which makes the gas sensor (densitometer) large and expensive, making such a sensor system complicated and economically costly. It becomes high. Therefore, it is needless to say that a gas sensor (system) that is small and inexpensive and that can easily detect gas concentration and that can detect the deterioration of an object is desired.

It is already known that an electrophotographic apparatus is equipped with a gas sensor, for example, JP-A-59-1.
No. 47354 can be mentioned. However, the gas sensor described here uses a phthalocyanine-based material and detects the gas concentration by the change in the surface resistivity (which may also be called conductivity) of the sensor. There are some drawbacks. In other words, as a gas sensor, the phthalocyanine-based material does not have sufficient sensitivity for gas detection, and since the surface resistivity changes according to the concentration of the ozone atmosphere and the ozone concentration can be known, the effect of ozone is transient. It can be understood that the effect of ozone can be prevented by setting the ozone concentration below a certain value for a photoconductor made of the same material, but the effect of ozone accumulates due to ozone exposure. It is not enough for the photoconductor to know the density. Further, in this specification, there is a description that "ozone is adsorbed on phthalocyanine to increase its electrical conductivity", but in this case,
Since there is no means for desorbing the adsorbed gas, it becomes a one-time concentration sensor and is functionally insufficient. For this reason, the degree of progress of the deterioration of the electrophotographic photosensitive member pointed out above cannot be properly or almost properly known. Also, the gas sensor described here appears to be for ozone only.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to mount on an electrophotographic apparatus using an organic photosemiconductor (photoreceptor) in which the influence of gas is accumulated and to determine the degree of deterioration of the organic photosemiconductor due to gas exposure. An organic semiconductor gas sensor capable of displaying and an electrophotographic apparatus including the same are provided. Another object of the present invention is to provide an electrophotographic apparatus in which the characteristics of the photoconductor deteriorated by gas exposure can be easily recovered.

[0007]

SUMMARY OF THE INVENTION The present inventor
About the degree of deterioration of the true photoconductor and recovery from the deterioration
We examined from various angles. As a result, (i) Ozo
To produce abnormal images when exposed to NOx
The deteriorated charging characteristics of the organic photo-semiconductor
As a result, this deterioration of the charging characteristics affects the so-called "rising potential".
And / or treated as a decrease in “saturation potential”, but other
In addition, the characteristic of "delay of charging" as shown in FIG.
Degradation is shown, but these degradations are not irreversible.
And (ii) in (i) above
Azo pigment material is used as charge generation material for deterioration and recovery
Are notable when exposed to ozone, NOx, etc.
In addition, deterioration progresses depending on the length of exposure time.
And still, as a gas sensor, phthalocyanine-based material
Is not enough gas detection sensitivity, (iii) photoconductor
The method of recovering the deterioration of
Heat at 130 ° C may be applied for a short time (0.1 to 3 minutes)
I found that.

Therefore, a gas sensor is made of the same material and formulation as the organic optical semiconductor mounted on the electrophotographic apparatus, and the characteristic deterioration phenomenon due to gas exposure is utilized to know whether or not the photoreceptor is deteriorated due to gas exposure. By doing so, quick response is possible. It is also possible to provide an appropriate recovery means in the electrophotographic apparatus through this detection means and automatically operate the recovery means from the detection means. The present invention has been made based on these findings.

Therefore, according to the present invention, (1) a photosensitive layer comprising a charge generating material and a charge transfer material, which are organic semiconductors, and a polymer binder resin is formed on a conductive substrate. Uses an azo pigment, and a metal electrode is formed on the upper surface of the photosensitive layer, and lead wires are connected to the metal electrode and the end of the conductive substrate, respectively, and the conductive material is connected through the lead wire. A closed circuit is formed by the substrate and a voltage generator capable of applying a DC voltage in the thickness direction of the metal electrode, and current detection means is provided between the lead wire from the conductive substrate and the voltage generator. Further, there is provided an organic semiconductor gas sensor characterized in that means for heating the photosensitive layer is provided in the vicinity of the photosensitive layer, and (2) the photosensitive layer has a charge generation layer and a charge transfer layer on a conductive substrate. Characterized by being laminated in this order (1) The organic semiconductor gas sensor according to (1) above is provided, and (3) when a direct current voltage is applied to the photosensitive layer, the current detecting means detects and integrates the value of the current flowing through the photosensitive layer, and holds it in a storage device in advance. There is provided an organic semiconductor gas sensor according to the above (1) or (2), characterized in that the organic semiconductor gas sensor has means for comparing with an integrated calculation value of the current before the start of gas exposure. The heating means is provided in the vicinity of, and the heating means heats the sensor in the range of 100 to 130 ° C. for 0.1 to 3 minutes, (1) or (2) above. A sensor center is provided, and (5) an electrophotographic photoconductor in which an azo-based pigment charge generation layer and an organic charge transfer layer are sequentially laminated on the conductive substrate, and the same charge generation material, charge transfer material as the photoconductor, Polymer binding There is provided an electrophotographic apparatus characterized in that the organic semiconductor gas sensor (3) made of fat is arranged, and (6) gas exposure deterioration of an organic photoconductor is detected from the output of the organic semiconductor gas sensor. Means for heating the photosensitive member in the range of 100 to 130 ° C. for 0.1 to 3 minutes after a cleaning cycle in which the organic photosensitive member rotates once or more while the cleaning member is in contact with the organic photosensitive member The electrophotographic apparatus according to (5) above is provided.

The present invention will be described in more detail below. As a principle of operation of the gas sensor, a method of observing a change in electrical conductivity by utilizing a change in weight due to adsorption of an inorganic gas or a semiconductor characteristic can be considered. The principle of the gas sensor according to the present invention utilizes the change in conductivity due to the adsorption of gas, but more accurately, it utilizes the change in the integral value of the so-called charging current flowing into the sensor immediately after the electric field is applied to the sensor. It is a thing. Here, the reason for using the integrated value of the charging current is that the charging current in the initial stage of the electric field application due to the adsorption of gas is extremely short, but it becomes a large current as if the electrodes were short-circuited. This is because it is suitable as a substitute characteristic for deterioration to be regarded as a charge.

To explain this more clearly, the polymer binder resin has voids after the solvent has escaped, and most of the organic photo-semiconductors are molecular crystals, and the inorganic particles of low molecular weight are present in the crystal particles. There is a space where gas can enter. The change in conductivity caused by the adsorption of the gas diffusing into this space provides information on the gas concentration or deterioration due to gas exposure. However, for repeated use as a gas sensor, it is necessary to promptly desorb the adsorbed gas. Therefore, in the present invention, the organic photoconductor is 0.1 to 3 in the range of 100 to 130 ° C. It is desirable to heat for a minute.

As described above, the gas sensor used here may be made of the same material and formulation as the organic optical semiconductor mounted on the electrophotographic apparatus. As a material, a material using an azo pigment is preferable to a material using a phthalocyanine pigment because the sensitivity as a gas sensor is higher. The thinner the film thickness of the gas sensor is, the higher the sensitivity as a sensor is, which is preferable. However, for the purpose of the present invention, the one installed in the electrophotographic apparatus may have the same or more characteristics as the mounted photoconductor, and therefore the same. It may be a film thickness or less.

As a gas sensor system, in order to obtain conductivity (integral value of charging current when voltage is applied), the value of the current detecting section is changed to voltage, this voltage signal is amplified, and then AD converted, A calculation unit that accumulates a product with time to obtain an integrated value, and a storage unit that holds the conductivity before starting gas exposure,
This value is compared with the value of conductivity after the start of gas exposure, and a signal output unit for notifying that there is deterioration when the difference (or ratio) is a certain value or more. further,
In order to repeatedly use the gas sensor, it is necessary to install a sheet heating element or a small dryer directly or in the vicinity of the sensor as a means for heating the sensor at a high temperature (Fig. 2).

When the photoconductor heating means is incorporated in the electrophotographic apparatus, the heater may be any of a nichrome heater, an infrared lamp, a combination of a nichrome heater and a fan, etc., but the heat source is set so as to suppress the temperature rise of units other than the photoconductor. It is preferable to use one having a good temperature rise or one having a heat insulating treatment applied to the surroundings. Further, since the photoconductor is heated to a high temperature, the residual toner on the photoconductor needs to be sufficiently cleaned. This is because the residual toner adheres to the surface of the photoconductor due to heat, which may cause a new image defect. This photoconductor heating means has a mechanism for displaying that there is gas exposure deterioration by the signal output from the gas sensor system, and the operator of the electrophotographic apparatus turns on the power SW of the heating means and turns it off by a timer that operates at the same time. Alternatively, the SW may be automatically turned on (FIG. 8). When the heat treatment is not performed automatically, the photoconductor high temperature heating means does not necessarily have to be incorporated in the electrophotographic apparatus.

Next, an example of the organic optical semiconductor mounted on the electrophotographic apparatus will be described, and at the same time, a sensor having the same prescription and a sensor system will be described.

The organic photoreceptor used in the present invention generally has a constitution in which an undercoat layer, a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate, and the photosensitive layer has such a functional separation. Not only the mold but also a single layer type may be used. Aluminum is usually used for the conductive substrate.

The undercoat layer contains a conventionally used binder (low resistance resin). The binder that may be used here depends on the material forming the undercoat layer,
When the conductive polymer is contained, it is preferably water-soluble or alcohol-soluble in consideration of the condition that it is also soluble in the solvent for dissolving it and is not immersed in the photosensitive layer liquid coated on the undercoat layer. Specifically, polyvinyl alcohol, sodium polyacrylate, CMC, casein, sodium alginate,
Examples include nylon, copolymerized nylon, and alkoxymethylated nylon. As the conductive polymer, an anionic conductive polymer represented by a polymer containing a sodium sulfonate group, a polymer containing an ammonium sulfonate group, and a cationic system represented by a polymer containing a quaternary ammonium group. Examples include conductive polymers.

The undercoat layer may contain an inorganic pigment. Examples of the inorganic pigment include titanium dioxide, zinc oxide, zinc white, lead white, lithopone, calcium carbonate, alumina, barium sulfate, and white carbon, and the refractive index in visible light or near infrared light is preferably 1.9 or more. It is an inorganic white pigment having a relatively high value of. In particular, the addition of an inorganic white pigment is effective in preventing moire in an electrophotographic apparatus using laser light. The undercoat layer may contain an electrolyte-based substance, and examples of the electrolyte-based substance include sodium sulfonate (—Na ₂ SO ₃ ) -containing substances and lithium sulfate (Li ₂ SO ₄ ).

To form an undercoat layer from these materials, a conductive polymer, a solvent, an electrolyte-based additive, an inorganic pigment, etc. are added, and if necessary, the binder is placed in a ball mill or the like to disperse the pigment well. The obtained dispersion liquid may be applied onto a conductive substrate and dried. The thickness of the undercoat layer is 0.
3 to 20 μm is suitable. When a conductive polymer is used, the ratio of this to the inorganic pigment and the binder varies depending on the materials used, so it cannot be uniformly determined, but when the total amount of the conductive polymer and the binder is 1 part The weight ratio of the inorganic pigment is 10 parts or less, preferably about 0.05 to 10 parts. Further, the ratio of the conductive polymer to the binder cannot be uniformly determined, but when the conductive polymer is 1 part, the binder is 0 to 200 parts by weight, preferably 10 to 200 parts by weight. is there.

The organic photosensitive layer comprises (1) a charge-transporting complex formed by a combination of an electron-donating compound and an electron-accepting compound (described in US Pat. No. 3,484,237), and (2) a dye added to an organic photoconductor to increase the organic photosensitive layer. What I felt (Japanese Patent Sho 48
No. 25658), and (3) one in which a pigment is dispersed in a positive hole or electron active matrix (JP-A-47-47).
No. 30328, JP-A-47-18547 and the like), (4) A charge-generating layer and a charge-transporting layer which are functionally separated (described in JP-A-49-105537),
(5) A compound containing a eutectic complex composed of a dye and a resin as a main component (described in JP-A-47-10785), and (6) a compound in which an organic pigment or an inorganic charge generating material is added to a charge transport complex ( It may be formed of any of conventionally known organic photoconductors such as JP-A-49-91648). However, among these, the laminated type photoreceptor of the type (4) has high sensitivity, and
It is widely used because various materials can be selected according to the function and it is more effective when a high electric field is applied.

The charge generating layer is a charge generating substance such as azo pigment, phthalocyanine pigment, indigo pigment, perylene pigment, square pigment, selenium powder, selenium alloy powder, amorphous silicon powder, zinc oxide powder, cadmium sulfide powder. The polyester, polycarbonate,
It is formed by dispersing it in a binder resin solution such as polyvinyl bitillal or acrylic resin, and coating this on the undercoat layer. However, as described above, it is particularly advantageous to use the azo pigment among the charge generating substances. The suitable thickness of the charge generation layer is about 0.01 to 2 μm.

The charge transport layer comprises an α-phenylstilbene compound (described in JP-A-58-198043) and a hydrazone compound (described in JP-A-55-46760).
A charge-transporting substance such as is dissolved in a film-forming resin such as polyester, polysulfone, polycarbonate, polymethacrylic acid ester, polystyrene, etc., and this is applied to the charge-generating layer to a thickness of about 10 to 30 μm. . The film-forming resin is used here because the charge-transporting substance generally has a low molecular weight and is poor in film-forming property by itself.

An example of the production of the organic photoconductor will be described below. Alcohol-soluble copolymer nylon (Toray Industries, CM-8000) 200 g methanol 2
It was dissolved in 000 g. To this, 20 g of a conductive polymer (Chemist 6120 manufactured by Sanyo Kasei Co., Ltd.) and 100 g of titanium oxide powder (A-100 manufactured by Ishihara Sangyo Co., Ltd.) were added, and 1.6 g of Li ₂ SO ₄ was further added, followed by dispersion in a ball mill for 12 hours. I went. The obtained coating liquid was applied by dipping onto the surface of an aluminum drum (conductive substrate) having a diameter of 80 mm and a height of 340 mm and then dried at 110 ° C. for 10 minutes to form an undercoat layer having a thickness of about 2 μm. Next, 10 g of butyral resin (Sekisui Chemical Co., Ltd., S-REC BL-S) was added to cyclohexanone 3
20 g of the trisazo pigment represented by the following structural formula was added, and the mixture was dispersed in a ball mill for 48 hours.

[0024]

[Chemical 1]

To this, 420 g of cyclohexanone was added and dispersed for 3 hours, then taken out into a container and the solid content was 1.
A charge generation layer forming liquid was prepared by diluting with cyclohexanone while stirring so as to be 5% by weight. This solution was applied onto the undercoat layer by dip coating and dried at 120 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.3 μm. Furthermore, polycarbonate resin (Panlite K-130 manufactured by Teijin Chemicals Ltd.
0) 240 g of tetrahydrofuran was dissolved in 1800 g of tetrahydrofuran, and the charge-transporting substance 14 represented by the following structural formula was added to the solution.
What melt | dissolved 0 g was apply | coated by dip coating on the said charge generation layer,
It was dried at 120 ° C. for 10 minutes to form a charge transport layer having a thickness of about 22 μm to prepare a laminated electrophotographic photoreceptor.

[0026]

[Chemical 2]

Regarding the charging characteristics of this electrophotographic photosensitive member,
Photoconductor drum evaluation device manufactured by Ricoh Co., Ltd. (JP-A-60-10)
No. 0167). In particular, in order to evaluate the rising state of charging, the photosensitive member is 1500
r.p.m. It was a high speed rotation. The discharge voltage is -5.
It was set to 5 kv. A representative example of the characteristics obtained by the photoconductor drum evaluation device is shown in FIG.

[0028]

EXAMPLES Next, the present invention will be described more specifically with reference to examples.

Example 1 (Example of gas sensor) The same coating liquid and coating conditions as those shown in the above-mentioned photosensitive member preparation example were used, except that a conductive film obtained by aluminum vapor deposition on a polyester film was used as the conductive substrate. A photoconductor was created. Next, it is cut into a size of 50 mm x 50 mm, and the film thickness is approximately 200 Å and the size is 35 mm x 3 on the surface of the photoconductor using a vacuum vapor deposition device.
A 5 mm semi-transparent comb-shaped gold (Au) electrode was attached. Vacuum equipment is Edwards vacuum equipment, vacuum degree is 7x1E-3
Pa or less, molybdenum boat (Furuuchi Chemical Co., B
V-107) was used. A thin copper wire was attached to the obtained electrode with silver paste to form a lead wire. On the other hand, the end of the photoconductor was wiped with a solvent (tetrahydrofuran) to expose the conductive substrate, and a thin copper wire was attached to the conductive substrate to form a lead wire (FIG. 1). Using this, a sensor system was constructed as shown in the block diagram of FIG.

A direct current voltage of -800 V is applied to the sensor (photoreceptor), and the initial conductivity (the current (charging current) flowing into the photosensitive layer immediately after the application of the electric field is changed to a voltage value by the current detector).
After the amplified value was digitized by an A / D converter, it was converted to an integral value by a calculation unit (CPU) and used as a substitute characteristic). FIG. 3 shows a typical example of current data flowing through the sensor (photoconductor).

Here, first, the initial charging characteristics of the produced photoconductor are evaluated, and then -800 V is applied to the sensor (photoconductor).
DC voltage is applied to measure the initial conductivity (the above charging current), and then an ozone exposure tester (manufactured by Dylec Corporation) is used to force the photoconductor and the sensor section at an ozone concentration of 5 ppm for 5 days. Exposed and deteriorated. The photoconductor and the sensor were taken out every day on the way, and the characteristics were evaluated. With respect to the photosensitive drum, image evaluation was also performed with MF530 (a copying machine manufactured by Ricoh Co., Ltd.). The image quality was evaluated by the degree of "background stain". Deterioration of charging characteristics is called "rising potential",
Although it also appears as a decrease in "saturation potential", here is the characteristic of deterioration due to exposure to ozone and NOx, "charging delay" (shown in Fig. 4 (b)) that does not charge momentarily even when subjected to corona discharge. It was used as a substitute characteristic for deterioration. FIG. 4B shows that charging is delayed in the portion B of FIG. 4A. The horizontal axis of FIG. 4 (b) is shown in FIG. 4 (a).
The horizontal axis (time) of is converted into the amount of charge passing through the sample. The results are summarized in Table 1.

[0032]

[Table 1] ×: Large degree of background stain, Δ: Small degree of background stain, ◯: Same as initial image

From Table 1, as the ozone exposure period becomes longer, the charging characteristics of the photoconductor deteriorate, and the image quality becomes unacceptable. Along with this, the indicated value of the gas sensor placed in the same environment also increased (initial 2
It is clear that it is possible to know the deterioration of the photoreceptor due to gas exposure with a gas sensor. FIG. 8 shows an example in which this sensor system is mounted on an electrophotographic apparatus.

Example 2 (Recovery Example of Photoreceptor) Eight photoconductor drums shown in Example 1 were prepared. First,
The initial characteristics of the photoconductor were evaluated, and then an ozone exposure tester (manufactured by Dylec Corporation) was used to measure ozone concentration of 5 ppm and 5
It was forcibly degraded by exposure for one day. 60 for each
℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 1
It was put into a dryer (manufactured by Isuzu Co.) at 20 ° C., 130 ° C. and 140 ° C. and taken out at an arbitrary time, and the recovery state was evaluated by the above-mentioned drum evaluation device. Those which had not been recovered were put in the dryer again, heat-treated, taken out, and evaluated again. Then, the above heat treatment was repeated until it was sufficiently recovered. FIG. 5 shows the relationship between the cumulative heat treatment time at 60 ° C., 80 ° C. and 100 ° C. and the recovery. The results at each temperature are shown in Table 2. (The definition of the deterioration of the charging characteristics is described in Example 1.
Is the same as In addition, this “delay of charging” is 5 × 10 ⁻⁹
The time required for recovery was defined as the time when (C / cm ² ) or less-the initial state-was reached. ) The photoconductor drum was equipped with a thermocouple inside, and the time the drum itself was at each temperature was observed.

[0035]

[Table 2] From the data in Table 2, the relationship between the heat treatment temperature and the recovery time is shown in FIG.
It was shown to. It can be seen that it takes a long time to recover the deterioration of the charging characteristics at a temperature lower than 100 ° C.

Example 3 (Recovery Example of Photoreceptor) The four photoconductor drums shown in Example 1 were placed in the above-mentioned image tester to perform image formation. Then, using a NOx exposure tester (manufactured by Dairec), NO 25ppm, NO
₂ 5 in a mixed atmosphere of 25 ppm (NOx 50 ppm)
It was exposed to NOx for a day and forcedly deteriorated. When this drum was put in an image tester and an image was printed, an image with background stain was formed. This is because the copying machine has a reversal development process, which has an effect of lowering the charging potential due to NOx exposure.

Next, these photoconductor drums are put in an image tester, and the photoconductor drums are idled several times for sufficient cleaning with only the cleaning blades in contact with each other, and then the cleaning blades are released and developed. While the device is not in contact with the photoconductor, the heating heater installed near the surface of the photoconductor is turned on while the photoconductor drum is rotating, and the temperature of the photoconductor surface in the vicinity of the heater is locally set to 8
The temperature was 0 ° C. The temperature was measured with a non-contact thermometer (manufactured by Everest). The temperature control was based on the preset power condition. 0.5 minutes, 1 minute, 3 minutes, 5 minutes, 10
After 15 minutes, 15 minutes, 30 minutes, 45 minutes, 60 minutes, and 90 minutes, the heater was turned off, and images were displayed. Note that the time here is the time when the photoconductor is at a predetermined temperature, but the photoconductor is rotating and the same point on the surface of the photoconductor is continuously at the predetermined temperature for this time. Not a thing. The result is 9
After 0 minutes, an image close to the initial image was obtained, but there was scumming and the recovery was not sufficient. Further, since it took a long time to reach this point, the temperature of the periphery of the photoconductor increased to around 70 ° C. even if the heat insulation treatment was performed around the photoconductor, so the experiment was terminated. Another photoconductor drum exposed to NOx was prepared, and the photoconductor temperature was set to 110 ° C. in the same manner as described above. As a result of the image display, the image returned to the initial one after 1 minute of heating. The temperature around the photoreceptor was also 40 to 50 ° C. The photoconductor temperature was set to 140 ° C. in the same manner as using another photoconductor drum exposed to NOx. As a result of image output,
An image close to the initial image was obtained in 0.5 minutes. The ambient temperature of the photoreceptor was also around 50 ° C. After 3 minutes, the coating film was swollen on a part of the surface of the photoreceptor. In the above, the evaluation was performed in the same manner except that several cleaning steps before the heat treatment were omitted. The result is warming 1
The image returned to the initial image after a minute, but white dots were missing in the solid black portion on the image, and the toner adhered to the surface when the photoreceptor was observed. The above results are summarized in Table 3.

[0038]

[Table 3]

As shown in Examples 2 and 3, ozone, NO
It takes a long time to recover the deterioration of the charging characteristics due to exposure to x and the like at 100 ° C. or lower, and there is a problem with the side effect that the ambient temperature of the photoconductor rises in order to perform this in an electrophotographic apparatus. Also, above 140 ° C, "partial blistering" on the surface coating of the photoconductor
It was found that such defects may occur, which is not preferable.

Example 4 (Example of Repeated Use of Organic Gas Sensor) A similar sensor was prepared in the gas sensor system of Example 1 except that the film thickness of the sensor was set to about 5 μm, and a small nichrome was provided near this gas sensor. A heater (with a fan) was installed, and these sets were put in a NOx exposure tester. The concentration in the NOx exposure tester is NOx (N
O: NO ₂ = 1: 1) is 10 ppm, 20 ppm, 30
The concentration was adjusted to ppm, 40 ppm, and 50 ppm, and each concentration was exposed for 5 minutes. The heater was set so as to heat at 110 ° C. for 1 minute at the time when the integrated measurement of the charging current by the sensor was completed. The same sensor was used to find the relationship between each concentration and the sensor conductivity (charging current integrated value). The results are shown in FIG. 7 (the integrated value of the charging current is normalized by the value of 10 ppm). It was confirmed that the gas concentration can be measured as a gas sensor and that it can be used repeatedly.

Example 5 (Electrophotographic apparatus equipped with an organic gas sensor) An image testing machine was modified to prepare an apparatus equipped with a gas sensor and a photosensitive member heating means as shown in FIG. The photoconductor drum shown in the example was inserted and a test for image output was conducted. (In FIG. 8, the photoconductor heating means and the gas sensor system are interfaced by a mechanism (not shown), the timer SW for the heater is turned on by the signal output of the gas sensor system, and is turned off after the set time elapses.
To be done. ) The test condition was to intermittently output 200 images per day, turn off the power at the end, and repeat the next day. The gas sensor system was set to output a signal notifying that there was deterioration when a value more than doubled was detected by comparing the data before gas exposure. The photoconductor heating means was adapted to perform heating at 110 ° C. for 1 minute. In addition, the environment is 20 ℃
28 degreeC and relative humidity were 40% -65%. Image evaluation was timely performed during the test period. After the start of the test,
From around the 3rd month, scumming began to stand out gradually, and an unacceptable image appeared around the 4th month, but the gas sensor system was activated and immediately returned to the initial image level. Further, no abnormal image due to toner sticking appeared.

[0042]

According to the present invention, the same material as the organic photoconductor (organic optical semiconductor) mounted in the electrophotographic apparatus,
By installing the organic gas sensor made by the prescription in the vicinity of the organic photoconductor, it becomes possible to know that the organic photoconductor has been deteriorated by the gas such as ozone, NOx, etc. It can be dealt with quickly. When the coping means (heating means) is mounted on the electrophotographic apparatus,
By cleaning the surface of the photoconductor and then heating it, it is possible to recover the photoconductor from deterioration due to gas exposure without causing problems such as toner adhesion on the surface of the photoconductor. Moreover,
Since the sensor system is installed, careless heating is eliminated, and the effect of high temperature heating on the photoconductor can be minimized.

[Brief description of drawings]

FIG. 1 is a diagram in which lead wires are provided on a surface of a photoconductor and a conductive base for supplying a charging current.

FIG. 2 is a diagram for explaining a system using the gas sensor of the present invention.

FIG. 3 is a view showing an example of current data flowing through a gas sensor.

FIG. 4 is a diagram showing an example of characteristics of a photoconductor obtained by a photoconductor evaluation apparatus.

FIG. 5 is a diagram showing that charging characteristics are changed by heating a photosensitive member.

FIG. 6 is a diagram showing the relationship between the recovery time of the photoconductor and the temperature.

FIG. 7 is a diagram showing the relationship between the electrical conductivity of the photoconductor and the gas concentration.

FIG. 8 is a schematic view of an electrophotographic apparatus of the present invention.

[Explanation of symbols]

1 photoconductor (1a photoconductor surface) 2 electrodes 3 lead wire 4 DC voltage power supply 5 heater 6 gas sensor 11 Conductive substrate 12 Undercoat layer 13 Charge generation layer 14 Charge transfer layer 71 Charger 72 Developing device 73 Transcription Charger 74 cleaning 75 Static eliminator 76 fixing roller

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Claims (6)

(57) [Claims] 1. A photosensitive layer comprising a charge generation material and a charge transfer material which are organic semiconductors, and a polymer binder resin is formed on a conductive substrate, and an azo pigment is used as the charge generation material. , And a metal electrode is formed on the upper surface of the photosensitive layer, and lead wires are connected to the metal electrode and the end of the conductive substrate, respectively, and the conductive substrate and the metal electrode are arranged in the thickness direction through the lead wire. A closed circuit is formed by a voltage generator capable of applying a DC voltage, a current detecting means is provided between the lead wire from the conductive substrate and the voltage generator, and the photosensitive layer is further provided in the vicinity of the photosensitive layer. An organic semiconductor gas sensor, characterized in that means for heating the layer are provided. 2. The photosensitive layer is a charge generating layer on a conductive substrate,
The organic semiconductor gas sensor according to claim 1, wherein the charge transfer layers are laminated in this order. 3. A current value flowing through the photosensitive layer is detected and integrated by the current detecting means when a DC voltage is applied to the photosensitive layer, and an integral operation of a current held in a storage device before starting gas exposure is performed. The organic semiconductor gas sensor according to claim 1 or 2, further comprising a means for comparing with a value. 4. A heating means is provided in the vicinity of the organic semiconductor gas sensor, and the heating means places the sensor in a range of 100 to 130.
3. The organic semiconductor gas sensor according to claim 1, wherein the organic semiconductor gas sensor is heated in the range of 0.degree. C. for 0.1 to 3 minutes.
-. 5. An electrophotographic photosensitive member in which a charge generating layer and an organic charge transfer layer are sequentially laminated on the conductive substrate, and the same charge generating material, charge transfer material, and polymer binder resin as the photosensitive member. An electrophotographic apparatus comprising the organic semiconductor gas sensor according to claim 3. 6. A cleaning cycle in which deterioration of the organic photoreceptor due to gas exposure is detected from the output of the organic semiconductor gas sensor, and the organic photoreceptor rotates one or more revolutions with the cleaning member being in contact with the organic photoreceptor. 6. An electrophotographic apparatus according to claim 5, further comprising means for heating the photosensitive member in the range of 100 to 130 [deg.] C. for 0.1 to 3 minutes after the passage.