JPS6250782A - Electrophotographic recording device - Google Patents

Abstract

PURPOSE:To obtain an excellent image record at any time by detecting the wet state of recording paper from its resistance value directly and setting the quantity of transfer corona charging properly according to the detected state. CONSTITUTION:A recording device applies a specific level voltage between electrodes 6a and 6b by a power source 13 in synchronism with a start signal for recording. Consequently, a current flows in the surface of the recording paper 3a at the uppermost part used for the recording and the level of the current is detected by a current value detecting means 14. Consequently, the resistance value, i.e. wet state of the recording paper 3a is detected. Then the detection signal from the detecting means 14 is compared by a comparing circuit 15 with data on the correlation between the current value and the proper quantity of corona charging which are stored in a storage circuit 15A previously and a signal indicating the proper quantity of transfer corona charging is inputted to a transfer corona quantity control circuit 16 to set the voltage value or current value of a high voltage power source 17 for transfer corona to proper value. Thus, an excellent image record is obtained at any time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an electronic device that develops an electrostatic latent image formed on the surface of an image carrier by adsorbing toner, and then transfers the toner image onto recording paper for recording. 0 Related to Photographic Recording Apparatus Conventionally, an electrophotographic recording apparatus shown in FIG. 9 has been widely known. Here, 1oo is a photosensitive drum, 1o2 is an initial corona charger, 103 is an exposure device, 104 is a developing device composed of a sleeve and a magnetic material inside it, and 105 is a developer (
107 is a recording paper, 109 is a transfer corona charger, and 110 is a peeling charger. To briefly explain the recording operation in the above apparatus, while the photosensitive drum 100 is rotating in the direction of the arrow, the photoconductive layer (not shown) on the drum surface is first charged entirely by the initial corona charger 102, and then exposed to light. A developing device 103 performs selective exposure according to the image or image signal to form an electrostatic latent image, and then a developing device 104
The developer 105 is supplied and a toner image is formed. Next, a sheet of recording paper is placed on the surface of the drum holding this toner image.
07 is supplied, and the toner image is transferred to the recording paper 107 (J
The recording paper 107 carrying the toner image is separated from the photosensitive drum 100 by a peeling charger 110, and sent to a fixing device (not shown) where it is fixed. In this way, an image is formed on the recording paper 107.6 Problems to be Solved by the Invention However, in the electrophotographic recording apparatus described above, the transfer characteristics deteriorate and the image density decreases at high humidity. There was a problem in that the degraded image was distorted.The inventor of the present invention investigated the cause of the above-mentioned problem and found the following matter. In other words, the transfer of toner to recording paper is carried out by the close contact between the photosensitive drum, which has toner on its surface, and the recording paper, which has been charged with opposite characteristics by a transfer corona charger. However, under high humidity conditions, The resistance value of the recording paper decreases, and the charge given by the transfer corona charger leaks, so the potential on the recording paper side decreases.
The toner transfer characteristics had deteriorated.

In order to prevent deterioration of transfer characteristics under high humidity conditions, it is sufficient to maintain the charge retention ability, or resistance value, of the recording paper under high humidity conditions to the same level as under normal humidity conditions. One possible method is to provide a heat roller in the paper feed section, dry the recording paper by passing it through it, and restore the resistance value to a normal level before using it for recording. However, according to such a method, a start-up time is required, and if the device were to heat up all the time, problems such as energy loss and danger due to overheating would occur. Also,
Another possible method is to monitor the humidity inside the apparatus and increase the amount of transfer corona charge as the humidity increases to compensate for the amount of charge leaked from the recording paper due to the influence of humidity. However, with this method, when recording continuously under high humidity conditions, for example, the amount of paper that is stacked at the bottom is too high for normal paper that is virtually unaffected by humidity. This results in excessive transfer corona charging, which on the contrary causes disturbances in the recorded image.

The present invention was devised in view of the above-mentioned problems, and does not require a large device for drying recording paper, and is an electronic device that can perform recording well even under high humidity conditions. An object of the present invention is to provide a photographic recording device. Means for solving the problems In order to solve the above-mentioned problems, the present invention provides a dampness detection means for detecting the dampness of the recording paper itself, and The apparatus is equipped with a control means for controlling the transfer corona charge amount based on the output signal from the detection means.

Function Since the present invention has the above-described structure, the resistance value of the recording paper itself can be detected by detecting the wet state of the recording paper itself, and the state of the recording paper itself can be detected even under a wide variety of environmental conditions and usage conditions. Since it is possible to accurately judge the amount of transfer corona charge and change the amount of transfer corona charge according to the state, it is possible to always obtain a good recorded image.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
The figure shows a schematic configuration of main parts of an electrophotographic recording apparatus according to an embodiment of the present invention, in which 1 is a photosensitive drum which is an image bearing member, 2 is a developing device, 3 is a cut paper-like recording paper, 32L
is the recording paper located at the top of the stacked recording papers 3,
4 is a recording paper cassette. The recording paper cassette 4 has a top lid 5
A pair of electrodes 6N and 8b are arranged on the back surface of the upper lid 5 so as to be in contact with the uppermost recording paper 3a.

As shown in Fig. 2, the pair of electrodes 6&, 6b are attached in parallel with each other with an appropriate distance between them, and as will be described later, a predetermined voltage is applied between the two electrodes, and the recording paper between the electrodes is It is used to measure electrical resistance. A pair of electrodes 6a
, 6b each have a cable 12. When f2 is in contact with the cable 12, an appropriate connector is arranged at the end of the cable 12, and when the cassette 4 is attached to the recording device main body 11, it is automatically connected to the control circuit in the recording device main body 11. The configuration is as follows. At the bottom of the recording paper cassette 4 or the portion of the recording apparatus main body 11 equipped with the recording paper cassette 4 facing the bottom of the cassette, the uppermost recording paper 3a is in contact with the electrodes ea and ab at least before being used for recording. A spring (not shown) is arranged to push the recording paper 3 upward.

In FIG. 1, 7 is a paper feed roller that pulls out the recording paper in the cassette 4, 82L is a pair of timing rollers, 9 is a transfer corona charger, and 10 is a running path for the recording paper. It should be noted that various other parts constituting the electrophotographic recording apparatus are arranged around the photosensitive drum, but since these are the same as conventional ones, illustrations and explanations thereof will be omitted.

FIG. 3 is a block diagram showing a control circuit for controlling the transfer corona charger 9 in the above device.

The configuration of this block diagram will be explained together with the following operation.

Next, the operation of the above device will be explained. The recording paper 3 is stored in a cassette 4 as shown in FIG. 2, and is supplied by mounting the cassette 4 at a predetermined position on the main body 11 of the recording apparatus. During recording, the electrode 61 is activated in synchronization with the recording start signal.
A voltage of a predetermined magnitude is applied between L and 6b by the power supply 13. For this reason, the top recording paper 31L used for recording
Since a current flows through the surface of the current, the current value detection means 14 detects the magnitude of the current. As a result, the resistance value, ie, the wet state, of the uppermost recording paper 3& is detected.

By the way, when the recording paper 3 is used under normal humidity conditions, that is, in a dry state, the weaker the corona discharge, the better the image quality within the range in which corona discharge is generally performed stably. On the other hand, if it is too strong, it becomes a cause of image disturbance. On the other hand, when the paper becomes wet under high humidity conditions, the resistance value of the recording paper 3 decreases, and the charge given by the transfer corona charger 9 leaks, resulting in a decrease in transfer efficiency. The image may become distorted. Therefore, in order to immediately compensate for the leaked charge, it is necessary to increase the intensity of the transfer corona to increase the amount of charge applied.

The relationship between the wet state of the recording paper 3 and the appropriate amount of transferred corona charge can be expressed as the resistance value of the recording paper 3 (actually, when a predetermined voltage is applied, the flow that flows between the electrodes 6 and 6b through the surface of the recording paper 3a) Measure in advance by replacing the current value) with the characteristics of the current flowing into the transfer corona charger 9, etc., and use the current value ~ as data.
This is stored in the appropriate corona charge amount correlation data storage circuit 15m.

The detection signal from the current value detection means 14 is compared with the current value-appropriate corona charge amount correlation data stored in advance in the storage circuit 16m in the comparison circuit 16, and the transfer corona amount control circuit 16 determines the appropriate transfer corona. A signal indicating the amount of charge is input, and the voltage value or current value of the transfer corona high voltage power source 17 at the final stage is set to an appropriate value.

The recording paper 3a on which the transferred corona charge amount is used as described above.
At the same time, the recording paper 3 & is pulled out from the cassette 4 by the paper feed roller 7.
It passes between the timing rollers 88L and 81L, travels along the path shown by the arrow 1o, and is transferred to the photosensitive drum 1 at the transfer section.
The toner image is transferred in good condition.

In the above explanation, when the uppermost recording paper 3a is in the stored position, the electrodes ea and ebic voltages are applied and the resistance value is measured.
, eb are in close contact with each other, that part is less susceptible to humidity and may cause malfunctions. Therefore, it is desirable to extend the edge of the recording paper 31L by a predetermined amount and apply a voltage while changing the portion that contacts the electrode 61.6b to detect the resistance.

By checking the dampness of each recording paper as described above immediately before using it for recording, the condition of the recording paper can always be accurately determined even under a wide variety of environmental conditions and usage conditions. It becomes possible to always set an appropriate transfer corona charge amount. For example, when recording at short time intervals under high humidity conditions,
Even if the first recording paper becomes damp due to the effects of humidity, subsequent recording papers are not as affected by humidity, so
There is no need to increase the amount of transfer corona charge, and in the above embodiment, appropriate control is performed depending on the humidity of each recording paper. It is impossible to perform such precise control.

Note that the detection of the wet state of the recording paper does not need to be performed for all recording papers, and can be omitted as appropriate. For example, among the recording papers 3 stacked in the recording paper cassette 4, those located at the bottom are less likely to become damp than those located at the top and directly exposed to environmental conditions. . Therefore, in each series of records, at least the first one should be checked for wetness, and if it is at a normal level, subsequent records should not be checked. Virtually no problems occur.

Although the above embodiments are for the case where the recording paper is cut paper, the present invention is not limited to such a case. FIG. 4 shows a schematic configuration of an electrophotographic recording apparatus which is an embodiment in which roll paper is used instead of cut paper as the recording paper. Here, 30 is a recording paper roll, 30a is a recording paper that is fed out from the recording paper roll, and 60a and 60b are electrodes that sandwich the recording paper 30 & from both sides, and there are electrodes that are in contact with the recording paper and at a distance. It can be moved to different positions. 8b is a pair of timing rollers,
18 is a cutter for the recording paper 30&. Other configurations are first
This is the same as the case shown in the figure.

Next, the operation will be explained. Normally, in a recording device that uses roll paper in this way, the recording paper 302L fed out from the recording paper roll 3° passes between the timing rollers 8b, 8b, reaches the transfer section, and transfers toner from the photosensitive drum 1. The image is transferred and recorded, and cut into a predetermined length by a cutter 18. The remaining recording paper 3ON is then fed out to the vicinity of the cutter 18, timing roller 8b, and sb and stands by in preparation for the next recording.

Therefore, in the case of the above-mentioned cut paper, the paper located near the top of the paper stacked in the paper cassette is easily affected by humidity; The portion fed out from the paper roll 3o and the surface portion of the recording paper roll 30 following it are most susceptible to the influence of humidity.

Therefore, in this embodiment, the resistance value (current value) of the recording paper 30& fed out from the recording paper roll 30 is measured by sandwiching it from above and below until it reaches the timing rollers 8b, 8b. electrode 602L for,
sob is provided. When the apparatus is in standby mode, this electrode is separated from the recording paper 30 by a predetermined distance, but during recording, it is placed in close contact with the recording paper 30a' (i-) in synchronization with the recording start signal. At the same time, a predetermined voltage is applied through the cable 12.The subsequent operation is similar to the embodiment using cut paper described above.

In all of the above embodiments, electrodes for measuring the resistance value of the recording paper are provided separately from the conventional structural members. It is also possible to incorporate it into one, and in that configuration,
This is advantageous in terms of installation space and cost.

Figures 5 and 6 show timing rollers incorporating electrodes.
Fig. 5 is a perspective view of the entire structure, and Fig. 6 is a perspective view of the entire structure.
It is a sectional view of the timing roller 8C of the book. Here, 1
9 is a metal roller that also serves as an electrode; 20 is an insulating coating; 21
is a flange made of conductive metal material that also serves as a shaft. A pair of timing rollers 8C98c rotate and come into close contact with each other to the extent that the recording paper passes through them, and both are insulated from the apparatus by appropriate means (not shown). As a method for insulating, for example, there is a method in which the bearing that receives the shaft portion of the flange 21 is supported by a hanging made of an insulating material. Further, the width of the metal roller 19 exposed to the surface in the axial direction (2 in the figure) shall not exceed the width of the recording paper at most. Timing roller 8C configured as above
, 8C are used in place of the timing rollers 8a, 8b in the embodiment of FIG. 1 and the embodiment of FIG. 4, and the electrodes in each embodiment are omitted. This timing roller s
A voltage is applied to c and sc through the shaft portion of the flange 21 at a predetermined timing while the recording paper is present between them, and the resistance value of the recording paper is measured in the same way as in each of the above embodiments, and the transfer corona charge is measured. The amount is controlled.

7 and 8 show other modified examples of timing rollers used as electrodes, FIG. 7 is a sectional view thereof, and FIG.
This figure is a side view showing the timing roller of FIG. 7 in use. The timing roller 8d of this embodiment has a shaft 24 made of metal, a conductive rubber 22 and an insulating rubber 2.
This is a roller formed by providing 3. By configuring the roller surface with an elastic material such as rubber, the contact surface with the recording paper 3 is deformed into a flattened shape, as shown exaggeratedly in FIG. 8, and the contact area with the recording paper 3 is greatly increased. This makes it easy to measure resistance values and improves accuracy. However, in this case, the elastic body undergoes plastic deformation due to changes over time, etc., and the recording paper 3
The contact area may change, causing an error in the measured value.

Therefore, in such a case, for example, when replenishing recording paper, the resistance value of the recording paper that has not yet been affected by humidity is used as the new reference value, and the difference from the previous reference value is reset. This allows you to continue using it without any problems.

Effects of the Invention As explained above, the present invention improves the dampness of recording paper by
By measuring its resistance value, it can be directly detected, and the amount of transfer corona charge can be appropriately set according to the state, and the effect is that good image recording can always be obtained even under various environmental conditions. It has the following.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the main parts of an electrophotographic recording apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view of a recording paper cassette used in FIG. 1, and FIG. 3 is a transfer corona charger in the above embodiment. FIG. 4 is a block diagram of a quantity control circuit system, and FIG. 5 is a schematic diagram of the main part of an electrophotographic recording apparatus of another embodiment different from the above embodiment. FIG. 6 is a perspective view and a sectional view of a timing roller that functions as an electrode, FIGS. 7 and 8 are a sectional view and a side view showing modified examples of the timing roller, and FIG. 9 is a conventional electrophotographic recording device. FIG. 1...Photosensitive drum, 2...°Developer, 3
, 311°3'0, 30'lL...Recording paper,
4...Cassette, 5...Top lid, 61L
, 6b , 60& , 60b-, -・electrode, sa, s
b, sc, sa...timing roller, 9...
...Transfer corona charger. Name of agent: Patent attorney Toshio Nakao and 1 other person 20
- Dark blue color yI arrogance Fig. 6 Fig. 7 δd --- Gumi〉7° roller 23 --- color separation half 1]"mu Fig. 8

Claims (2)

[Claims] (1) An electrophotographic recording apparatus characterized by having a wetness detection means for detecting a wet state of recording paper, and a control means for controlling the transfer corona charge amount based on an output signal from the wetness detection means. (2) The electrophotographic recording apparatus according to claim 1, wherein the wetness detection means is a resistance measuring means for measuring the resistance value of the recording paper.