JP2008281888A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage of a cleaning means downstream of the moving direction of an image carrier by securely cleaning off a toner image on the image carrier of an image forming apparatus. <P>SOLUTION: A photoreceptor cleaning device 100 includes a first cleaning blade 101 and a second cleaning blade 102 located downstream and upstream of the direction of rotation, respectively. A contact/separation means 105b slides and thus the second cleaning blade 102 comes into contact with the photoreceptor 1 or separates therefrom. For cleaning, the photoreceptor cleaning device 100 is configured taking into consideration the contacting/separating timing, contacting width, contacting conditions, etc., of the second cleaning blade 102 in an extremely short section through which a reference pattern image passes during a cleaning step. This suppresses wear of the first cleaning blade 101 that is constantly in contact with the photoreceptor. This also prevents cleaning failure that may occur immediately after the first cleaning blade 101 is passed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and an image forming method using an electrophotographic system such as a copying machine, a printer, a facsimile, or a multifunction machine thereof.

  In an image forming apparatus using an electrophotographic system, in order to stabilize an image density, an image is formed under certain image forming conditions (conditions such as a toner density of a developer, a potential on an image carrier and a bias applied to a developing sleeve). A reference pattern is created on the carrier, its image density is detected by an optical sensor, and this is fed back to image forming conditions and developer toner density to stabilize the image density. Usually, the optical sensor is fixed at a certain position with respect to the longitudinal direction of the image forming apparatus, and the reference pattern is created at a position corresponding to the optical sensor. Then, when performing repeated image forming operations, a reference pattern is created between the transfer paper P1 and the transfer paper P2 (between paper) (see FIG. 7), and the image density of the reference pattern is detected by the optical image density sensor. The image density is controlled to be constant by feeding back the image forming conditions and the toner density of the developer according to the magnitude of the detected value.

  This reference pattern passes through the transfer nip with no paper in the transfer portion of the image forming apparatus. If no transfer current is applied, most of the toner on the pattern portion on the image carrier moves directly to the cleaning portion on the image carrier, and a small portion moves to the transfer roller and transfer conveyance belt. It will be collected by the cleaning unit. Conversely, if a transfer current is applied, a very small portion of the toner on the pattern portion on the image carrier moves directly to the cleaning portion on the image carrier, and most of the toner moves to the transfer roller or transfer conveyor belt. It is collected by the cleaning unit of the conveyor belt.

  The amount of toner per unit area collected by the cleaning unit is about 5 to 10 times that of a normal image forming operation, which is a burden on the cleaning unit. In addition, as shown in FIG. 6, the edge portion of the reference pattern adheres more strongly to the image carrier than the inside of the pattern due to a high potential due to the edge effect, and is difficult to clean. When the reference pattern is imaged at the same position in the main scanning direction, toner that is difficult to clean between the sheets is input at the position corresponding to the edge of the pattern of the cleaning device, which exceeds the limit. Sometimes the toner slips through, resulting in poor cleaning.

  Further, in recent years, a toner having a particle size smaller than that of a conventional toner, such as a small particle size polymerized toner, has been used in order to cope with high image quality. This toner has a lower cleaning margin than a conventional pulverized toner with a relatively large angle and has a characteristic of easily passing through the cleaning blade. The conventional method (cleaning blade material, contact conditions, toner) It is becoming difficult to respond by improving external additives.

  As a technique that can solve this problem, a technique has been proposed in which two cleaning blades are brought into contact with the image carrier to improve the cleaning performance in order to improve the margin of cleaning performance. There are the following three representative examples.

  The technique of Patent Document 1 is intended to prevent the occurrence of various abnormal images when performing roller charging in the charging process of image exposure and reversal development image forming processes, and rotates in contact with the photosensitive drum and its surface. A charging roller that performs image exposure on the surface of the photosensitive member charged thereby, a developing unit that converts the electrostatic latent image formed by the exposure into a visible image by reversal development, and a formed visible image In an image forming apparatus, comprising: a transfer unit that transfers to paper; a cleaning unit that cleans the surface of the photoconductor with a blade after the transfer by the transfer unit; and a quenching unit that photodischarges residual charges on the photoconductor The cleaning means has a first stage blade and a second stage blade.

  The technology of Patent Document 2 aims to provide a good color electrophotographic image using an image forming apparatus and an image forming method using an intermediate transfer member. In an image forming apparatus for forming a color image, The body is a spherical toner in which the surface layer contains fluororesin fine particles, the contact angle with water is 90 ° or more, and the shape index (SF) of each colored toner used in the developing means is less than 140. At least one of the toners contains an inorganic external additive having a number average primary particle size of 0.1 to 1.0 μm, and the transfer residual toner remaining on the intermediate transfer member is removed by a plurality of cleaning blades. It has a cleaning means.

  The technique of Patent Document 3 aims to maintain a high removal efficiency of the residue remaining on the surface of the toner image carrier while adopting a toner image carrier having high wear resistance. A toner image carrier whose surface is constituted by a surface layer including the toner image carrier, and each of which is a plate-like member extending in the extending direction of the rotation axis of the toner image carrier, and the toner image carrier has a toner on the surface to be transferred A plurality of cleaning blades arranged side by side in the rotation direction of the toner image bearing member and having a contact portion extending in the extending direction that is in contact with the surface after the image is transferred.

  In any of these three techniques, two blades are constantly in contact with the surface of the image carrier. The upstream blade in the image carrier rotation direction is constantly supplied with toner (transfer residual toner and scumming toner), but the downstream blade is insufficiently supplied with toner, and the cleaning blade abutted by the counter method There is a problem of drowning downstream.

JP 9-265250 A Japanese Patent Laid-Open No. 2005-234082 JP 2005-352310 A

  In view of the above-described conventional problems, the present invention creates a reference pattern on the image carrier to adjust the image density, and brings the first cleaning means and the second cleaning means into contact with the image carrier. In an electrophotographic image forming apparatus for cleaning toner on an image carrier, an apparatus and method capable of reliably cleaning a toner image on an image carrier and preventing damage to cleaning means downstream in the image carrier movement direction The purpose is to provide.

  The image forming apparatus according to the first aspect of the present invention includes a reference pattern creating unit on the image carrier, an image density detecting unit for detecting an optical density of the reference pattern on the image carrier, and a transfer A first cleaning means for removing residues on the image carrier after the process, and the image carrier can be brought into contact with and separated from the image carrier, and the image carrier is more than the first cleaning means on the image carrier. In the image forming apparatus, the image forming apparatus includes a second cleaning unit that is provided upstream in the moving direction of the body and removes the residue on the image carrier after the transfer step. When the reference pattern on the carrier is cleaned, the reference pattern abuts on the image carrier, and otherwise it is separated.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a contact width in the longitudinal direction of the second cleaning unit is longer than a width in the longitudinal direction of the reference pattern, and the first cleaning unit. Is shorter than the contact width in the longitudinal direction of the member for removing the residue on the image bearing member.

  According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect, the cleaning capability of the second cleaning unit is larger than that of the first cleaning unit.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, each of the first cleaning unit and the second cleaning unit removes the residue on the image carrier. A plate-like elastic member is included, and the linear pressure of contact of the plate-like elastic member of the second cleaning unit with the image carrier is higher than the linear pressure of contact of the plate-like elastic member of the first cleaning unit with the image carrier. Characterized by being enlarged.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, each of the first cleaning unit and the second cleaning unit removes the residue on the image carrier. The plate-like elastic member of the second cleaning unit is larger than the plate-like elastic member of the first cleaning unit, the cleaning angle that includes the plate-like elastic member and contacts the image carrier. .

The image forming method according to claim 6 includes a reference pattern creating step on an image carrier, an image density detecting step for detecting an optical density of the reference pattern on the image carrier, and the image after the transfer step. A first cleaning step for removing the residue on the carrier, and the image carrier can be moved toward and away from the image carrier, and the image carrier may be moved further than the first cleaning step execution position on the image carrier. A second cleaning step for removing residues on the image carrier after the transfer step on the upstream side in the moving direction;
In the image forming method, the member for removing the residue on the image carrier at the time of performing the second cleaning step contacts the image carrier at the time of cleaning the reference pattern on the image carrier, and the others In the case of, it is characterized by being separated.

  According to the seventh aspect of the present invention, in the image forming method of the sixth aspect, a member that removes the residue on the image carrier when the second cleaning step is performed contacts the longitudinal direction of the image carrier. The width is longer than the width in the longitudinal direction of the reference pattern and shorter than the contact width in the longitudinal direction of the member for removing the residue on the image carrier used when the first cleaning process is performed. It is characterized by.

  According to an eighth aspect of the present invention, in the image forming method of the sixth or seventh aspect, the cleaning ability of the first cleaning unit is made larger than that of the second cleaning unit.

  According to the ninth aspect of the present invention, in the image forming method according to any one of the sixth to eighth aspects, the first cleaning unit and the second cleaning unit remove the residue on the image carrier. The contact line pressure of the plate-like elastic member of the second cleaning unit to the image carrier is determined by the line pressure of contact of the plate-like elastic member of the first cleaning unit to the image carrier. It is also characterized by a larger size.

  According to a tenth aspect of the present invention, there is provided the image forming method according to any one of the sixth to eighth aspects, wherein each of the first cleaning unit and the second cleaning unit removes the residue on the image carrier. The plate-like elastic member of the second cleaning unit is larger than the plate-like elastic member of the first cleaning unit, the cleaning angle that includes the plate-like elastic member and contacts the image carrier. .

  The present invention relates to an electrophotographic method in which a reference pattern is formed on an image carrier to adjust image density, and toner on the image carrier is cleaned by contacting a first cleaning unit and a second cleaning unit on the image carrier. In the image forming apparatus of the type, it is possible to reliably clean the toner image on the image carrier and to prevent the cleaning means on the downstream side in the moving direction of the image carrier from being damaged.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings. In the following embodiments, a photoconductor on a roller is used as an image carrier, but the present invention is not limited to this, and the present invention can also be applied to one using an endless belt. Also, an apparatus using an intermediate transfer member as an image carrier may be used.

  FIG. 1 is a diagram showing a main part of an image forming apparatus for explaining the configuration of the first embodiment of the present invention. In Example 1, as described later, the contact width of the second blade is the same as that of the first blade, the linear pressure of the second blade is the same as that of the first blade, and the cleaning angle of the second blade is the same as that of the first blade. It is.

  A charging device 2, an exposure device 3, a developing device 4, a transfer roller 7, and a photoconductor cleaning device 100 are sequentially arranged around the photoconductor 1 that is an image carrier and rotates clockwise in the drawing. A toner image is formed on the transfer paper 9 by performing charging, exposure, development, transfer, and cleaning processes on the photoreceptor 1 by these apparatuses. The toner container 12 contains toner 13, and the toner replenishing device 11 can replenish the developer in the developing device 4. The transfer paper 9 on which the toner image is formed passes through the nip between the photosensitive member 1 and the transfer roller 7 that rotate in the forward direction, and is then conveyed to the fixing device 8 to fix the toner image. The transfer residual toner on the photoreceptor 1 after the transfer is cleaned by the photoreceptor cleaning device 100. This operation is continuously performed to form an image on one or a plurality of transfer sheets. Further, an optical image density sensor 5 for detecting the image density of the reference pattern is installed at a position facing the photoreceptor 1 downstream of the developing device 4 and upstream of the transfer roller 7 in the rotation direction of the photoreceptor 1. .

  In this embodiment, a reference pattern (see FIG. 7) is created between the sheets on the photoreceptor 1 (between the transfer sheet and the transfer sheet). After the image density is detected by the image density sensor 5, the reference pattern enters the transfer process (the portion where the photoconductor 1 and the transfer roller 7 are in contact) with the rotation of the photoconductor 1. In the transfer process, when the reference pattern passes, no transfer bias is applied to the transfer roller 7, and most of the toner image remains on the photoconductor 1 as it is and is cleaned by the photoconductor cleaning device 100. Further, a very small part of the toner image moves onto the transfer roller 7 and is scraped off and cleaned by the cleaning blade 201 of the transfer cleaning device 200. In the figure, 203 is a brush, and 204 is a waste toner conveying screw.

  In this embodiment, toner density control is performed based on the detection result of the image density of the reference pattern created on the photosensitive member 1 by the image density sensor 5. The toner density sensor (not shown) attached to the developing device 4 detects the carrier density using the magnetic permeability of each developer (carrier), and controls the toner replenishment amount so that the value becomes a certain target value. To do. However, since the developing ability of the developer changes as the charging ability changes due to environmental fluctuations or deterioration with time, the image density changes as a result under constant image forming conditions. Therefore, for each image formed on the transfer paper, the image density is detected and corrected to the target value of the carrier density described above, and an appropriate toner replenishment amount is set with respect to the change range of the image density (sensor output). decide. At the time of the next image forming operation on the transfer paper, the toner replenishing device 11 can replenish the toner 13 to the developing device 4 by the determined toner replenishment amount. In this embodiment, the image density is controlled to be constant by such a configuration operation.

  The photoconductor cleaning device 100 includes a first cleaning blade 101, a second cleaning blade 102, a brush 103, a waste toner conveying screw 104, and second cleaning blade contacting / separating means 105a and 105b. The toner image adhered by the brush 103 is disturbed, the toner adhered by the first cleaning blade 101 and the second cleaning blade 102 is scraped off, and the scraped toner is disposed in a waste toner bottle (see FIG. (Not shown). Further, when the contact / separation means 105a rotates in the forward and reverse directions, the contact / separation means 105b slides and the second cleaning blade 102 attached to the contact / separation means 105b contacts and separates from the photosensitive member 1. ing. As shown in FIG. 2, the first cleaning blade 101 is always in contact with the photosensitive member at the blade edge portion over a width that covers the entire image area in the main scanning direction (the contact condition is, for example, Contact linear pressure: 20 g / cm, cleaning angle: 75 °). Further, the second cleaning blade 102 can also come into contact with the photosensitive member at the blade edge portion over the width that covers the image area in the main scanning direction. Tangential pressure: 20 g / cm, cleaning angle: 75 °). Here, the cleaning angle is an angle θ shown in FIG.

As shown in FIG. 4, the second cleaning blade 102
(1) When the reference pattern and the transfer residue before and after the reference pattern pass through the cleaning device 100, the edge of the second cleaning blade 102 is brought into contact with the photosensitive member 1,
(2) The other portions (the image transfer residue on the transfer paper or the portion where there is no reference pattern between the paper) are kept apart.

  Compared to the conventional example, the normal cleaning device has a small amount of scumming toner adhered to the transfer portion in the image portion and a developing portion in the non-image portion (the scumming toner is hardly transferred to the transfer paper in the transfer portion). The toner acts as a lubricant at the blade edge portion, and the cleaning blade abutted by the counter method is kept in a state where it does not fall downstream. However, when this background toner is used up, the cleaning blade is drowned on the downstream side, and the transfer residual toner and the reference pattern image, which are the original functions, cannot be cleaned. Similarly, when two blades are in constant contact as in the series of inventions listed as the prior art, the transfer residual toner image on the photoreceptor 1 can be completely cleaned with the blade on the upstream side under normal conditions. As a result, the toner is not supplied to the blade edge on the downstream side, and the cleaning blade is rolled. On the other hand, in the present embodiment, the second cleaning blade 102 is brought into contact with and cleaned only in a very short section in which the reference pattern image passes through the cleaning process (the above (1)). The time required for the surface of the photoconductor to pass through the blade edge of one cleaning blade 101 without any toner adhering is extremely short, and the scumming toner immediately adhering to the section ((2) above) is immediately removed from the first cleaning blade 101. Therefore, the first cleaning blade 101 is not rolled up.

  Further, in the configuration of only one conventional cleaning blade, which is a conventional general method, wear of the blade edge is promoted at a position corresponding to the reference pattern over time, and cleaning failure occurs at that portion. On the other hand, in the present embodiment, the second cleaning blade 102 is brought into contact with and cleaned only in a very short section in which the reference pattern image passes through the cleaning process in the above-described configuration (described above (1)). At this position, the wear of the first cleaning blade 101 is not promoted, and the occurrence of defective cleaning immediately after passing through the first cleaning blade 101 is eliminated.

  In this embodiment, the contact time of the second cleaning blade 102 is short, but the cleaning of the blade is accelerated because only the reference pattern is cleaned, and cleaning failure occurs immediately after passing through the second cleaning blade. The life of the second cleaning blade may be reached. However, at that time, the first cleaning blade 101 is not accelerated to be worn, so that the toner remaining after cleaning by the second cleaning blade 102 can be cleaned by the first cleaning blade 101.

  Next, a second embodiment of the present invention will be described. In Example 2, the contact width of the second blade is 1.5 times the reference pattern, the linear pressure of the second blade is higher than that of the first blade, and the cleaning angle of the second blade is wider than that of the first blade. The schematic configuration of this embodiment, reference pattern cleaning, image density sensor detection and toner density control, and photoconductor cleaning device configuration / operation are substantially the same as those of the first embodiment, and therefore, overlapping description is omitted. .

  When this second embodiment is compared with the first embodiment, the basic configuration / operation is almost the same as that of the first embodiment. However, in the first embodiment, as described above, the second cleaning blade 102 is arranged in the longitudinal direction. Since there is only a width corresponding to the length of the reference pattern + α, the dirt toner is continuously supplied to the first cleaning blade 101 in other portions, so that the first cleaning blade 101 is drowned more than in the first embodiment. It becomes difficult. Further, in the configuration of only one conventional cleaning blade, which is a conventional general method, wear of the blade edge is promoted at a position corresponding to the reference pattern over time, and cleaning failure occurs at that portion. On the other hand, in the second embodiment, the second cleaning blade 102 is brought into contact with and cleaned only in a very short section in which the reference pattern image passes the cleaning process (described in (1)). The wear of the first cleaning blade is not promoted at the corresponding position, and the occurrence of defective cleaning immediately after passing through the first cleaning blade 101 is also eliminated.

  In the second embodiment, the contact time of the second cleaning blade 102 is short. However, since only the reference pattern is cleaned, the wear of the second cleaning blade is accelerated, and immediately after passing through the second cleaning blade 102 over time. In some cases, a cleaning failure occurs and the life of the second cleaning blade is reached. However, since the wear of the first cleaning blade 101 is not promoted at that time, the toner remaining after being cleaned by the second cleaning blade 102 can be cleaned by the first cleaning blade 101.

  The contact condition of the second cleaning blade 102 is set so that the cleaning power is stronger than that of the first cleaning blade 101, and the toner of the reference pattern that is difficult to clean is more reliably cleaned than in the first embodiment. It becomes possible.

  Although not shown in the drawings, as another example, a cleaning blade that is a plate-like elastic member is not used as a cleaning member as in the first and second examples. For example, a rotating brush or roller is used as an example. Can be mentioned. In the case of a rotating brush or roller, when any of these is used as the second cleaning means, a contact / separation mechanism is mounted so that the width of contact with the image carrier is about 1.5 times the reference pattern. Configure.

  In the case of a rotating brush, the relative rotation speed of the brush used as the second cleaning unit relative to the image carrier is set higher than the brush used as the first cleaning unit, or the brush density is increased. A configuration may be adopted in which the cleaning capability of the second cleaning unit is set higher than that of the first cleaning unit.

  That is, in any of the embodiments of the present invention, an electronic device that creates a reference pattern, adjusts the image density, and contacts the first cleaning unit and the second cleaning unit on the image carrier to clean the toner on the image carrier. In a photographic image forming apparatus, the toner image on the image carrier can be reliably cleaned, and damage to the downstream cleaning means can be prevented. In addition, in an electrophotographic image forming apparatus that creates a reference pattern, adjusts the image density, and contacts the first cleaning unit and the second cleaning unit on the image carrier to clean the toner on the image carrier. It is possible to surely clean the toner image on the image carrier, and more reliably prevent the downstream cleaning unit from being damaged.

The figure which shows the principal part of the image forming apparatus for demonstrating the structure of the 1st Example of this invention. FIG. 3 is a diagram showing a relationship between a reference pattern creation position of the image forming apparatus shown in FIG. FIG. 3 is a diagram showing the relationship between the reference pattern creation position of the image forming apparatus shown in FIG. Explanatory diagram of contact / separation conditions for the second cleaning blade Diagram showing cleaning angle Diagram showing that the potential of the edge of the reference pattern increases Diagram of a conventional example in which a reference pattern is created between transfer sheets (between sheets) during repeated image forming operations

Explanation of symbols

1: Photoconductor 2: Charging device 3: Exposure device 4: Developing device 5: Image density sensor 7: Transfer roller 8: Fixing device 9: Transfer paper 11: Toner replenishing device 12: Toner container 13: Toner 100: Photoconductor cleaning Device 101: First cleaning blade 102: Second cleaning blade 103: Brush 104: Waste toner transport screw 105a, 105b: Second cleaning blade contact / separation means 200: Transfer cleaning device 201: Cleaning blade 203: Brush 204: Waste toner transport Screw θ: Cleaning angle

Claims (10)

Means for creating a reference pattern on the image carrier;
Image density detection means for detecting the optical density of the reference pattern on the image carrier;
First cleaning means for removing residues on the image carrier after the transfer step;
The image carrier that can be moved toward and away from the image carrier, and is provided upstream of the first cleaning unit on the image carrier in the moving direction of the image carrier, and after the transfer step. A second cleaning means for removing the residue on the top;
In an image forming apparatus comprising:
2. The image forming apparatus according to claim 1, wherein the second cleaning unit abuts on the image carrier when cleaning the reference pattern on the image carrier, and is separated at other times.   2. The image forming apparatus according to claim 1, wherein a contact width in the longitudinal direction of the second cleaning unit is longer than a width in the longitudinal direction of the reference pattern, and the residual on the image carrier that the first cleaning unit has. An image forming apparatus characterized by being shorter than a contact width in a longitudinal direction of a member for removing an object.   3. The image forming apparatus according to claim 1, wherein a cleaning capability of the second cleaning unit is larger than that of the first cleaning unit.   4. The image forming apparatus according to claim 1, wherein each of the first cleaning unit and the second cleaning unit includes a plate-like elastic member for removing a residue on the image carrier. (2) An image formation characterized in that the contact linear pressure of the plate-like elastic member of the cleaning means to the image carrier is larger than the contact linear pressure of the plate-like elastic member of the first cleaning means to the image carrier. apparatus.   4. The image forming apparatus according to claim 1, wherein each of the first cleaning unit and the second cleaning unit includes a plate-like elastic member for removing a residue on the image carrier. 2. An image forming apparatus according to claim 1, wherein the plate-like elastic member of the second cleaning unit is set to have a larger cleaning angle that contacts the carrier than the plate-like elastic member of the first cleaning unit. Creating a reference pattern on the image carrier;
An image density detection step for detecting an optical density of the reference pattern on the image carrier;
A first cleaning step for removing residues on the image carrier after the transfer step;
The image carrier after the transfer step, which is capable of coming into contact with and separated from the image carrier and upstream of the position of the first image carrier on the image carrier in the moving direction of the image carrier. A second cleaning step for removing residues on the body;
In an image forming method comprising:
The member for removing the residue on the image carrier when the second cleaning process is performed contacts the image carrier when cleaning the reference pattern on the image carrier, and is separated at other times. An image forming method.   7. The image forming method according to claim 6, wherein a contact width in a longitudinal direction of the image carrier of a member for removing a residue on the image carrier when the second cleaning step is performed is a longitudinal direction of the reference pattern. An image forming method characterized in that the width is longer than the width of the member, and is shorter than the contact width in the longitudinal direction of the member for removing the residue on the image carrier used when the first cleaning step is performed.   8. The image forming method according to claim 6, wherein a cleaning capability of the first cleaning unit is larger than that of the second cleaning unit.   9. The image forming method according to claim 6, wherein each of the first cleaning unit and the second cleaning unit includes a plate-like elastic member for removing residues on the image carrier, An image in which the contact linear pressure of the plate-like elastic member of the second cleaning means to the image carrier is made larger than the contact linear pressure of the plate-like elastic member of the first cleaning means to the image carrier. Forming method. 9. The image forming method according to claim 6, wherein each of the first cleaning unit and the second cleaning unit includes a plate-like elastic member for removing a residue on the image carrier. The image forming method according to claim 1, wherein a cleaning angle that contacts the carrier is larger for the plate-like elastic member of the second cleaning means than for the plate-like elastic member of the first cleaning means.