Printer

Abstract

A printer comprises a toner cartridge and a de-energizing lamp, the toner cartridge comprises a toner cartridge box, a developing roller, a charging roller and a photosensitive drum, the developing roller, the charging roller and the photosensitive drum are all installed on the toner cartridge box, the charging roller and the developing roller are arranged in the circumferential direction of the photosensitive drum at intervals, the charging roller charges the photosensitive drum, and the developing roller transmits carbon powder in the toner cartridge to the surface of the photosensitive drum. At least part of the photosensitive drum is exposed out of the drum powder box; and the light emitted by the de-lamp irradiates the photosensitive drum exposed outside the drum powder box so as to eliminate charges of residual carbon powder on the photosensitive drum. According to the application, the electric discharge lamp is arranged in the printer, and the photoelectric effect of the photosensitive drum is utilized, so that after the potential on the surface of the photosensitive drum after transfer printing is cleared and the residual potential is eliminated, waste carbon powder can be well absorbed by the developing roller, and the problem of residual images on printing paper is reduced. The residual carbon powder on the photosensitive drum can be directly rotated back to the developing roller and recovered to the powder bin, so that the problems of large occupied space, high cost and non-environment-friendly waste powder treatment of a waste powder bin are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of printing equipment, in particular to a printer. BACKGROUND

[0002] With the continuous development of printer technology, the structure design and working principle of the selenium drum, as the core component of the printer, are also constantly optimized and improved. The selenium drum usually includes a photosensitive drum, a developing roller, a charging roller and other core components, which work together to complete the imaging and developing functions in the printing process.

[0003] In the traditional structure of the selenium drum, a cleaning blade is usually used to remove the residual waste toner on the surface of the photosensitive drum. However, this structure of using a cleaning blade to remove waste toner has some problems. First, the cleaning blade structure needs to be equipped with a waste powder bin to collect the removed waste toner, which increases the volume and complexity of the selenium drum. Second, the contact between the cleaning blade and the surface of the photosensitive drum can cause wear and tear to the photosensitive drum, reducing the service life of the selenium drum. In addition, improper handling of the waste toner collected in the waste powder bin can pollute the environment.

[0004] Therefore, an improved structure of the selenium drum is proposed: a selenium drum without a waste powder structure, which cancels the cleaning blade and allows the residual toner on the surface of the photosensitive drum to be adsorbed by the developing roller and recycled into the powder bin. When the waste powder bin and the cleaning blade structure are cancelled, the residual toner on the surface of the photosensitive drum cannot be completely adsorbed by the developing roller due to the electric charge, and part of the charged toner will continue to adhere to the surface of the photosensitive drum. These residual charged toner will be transferred to the paper during the next printing process, forming a residual image, which seriously affects the printing quality. CONTENT OF THE UTILITY MODEL

[0005] The purpose of the present application is to provide a printer that solves the problem of residual toner on the surface of the photosensitive drum and poor printing quality.

[0006] To achieve the purpose of the present application, the present application provides the following technical solution:

[0007] In a first aspect, the present application provides a printer, comprising:

[0008] A selenium drum, the selenium drum comprising a drum powder box, a developing roller, a charging roller, a photosensitive drum and a discharge lamp, the developing roller, the charging roller and the photosensitive drum being mounted on the drum powder box, the charging roller and the developing roller being arranged at intervals in the circumferential direction of the photosensitive drum, the charging roller charging the photosensitive drum with a charging voltage, forming an electrostatic latent image on the surface of the photosensitive drum after laser exposure, the developing roller transmitting the toner in the drum powder box to the surface of the photosensitive drum, at least part of the photosensitive drum being exposed outside the drum powder box;

[0009] The electric discharge lamp is arranged on the mounting frame, and light emitted by the electric discharge lamp irradiates the surface of the photosensitive drum through the opening.

[0010] In one embodiment, the printer further comprises a mounting frame, and the toner cartridge further comprises a housing connected with the toner cartridge to form a containing cavity with an opening, and the photosensitive drum is arranged in the containing cavity.

[0011] The electric discharge lamp is arranged on the mounting frame, and light emitted by the electric discharge lamp irradiates the surface of the photosensitive drum through the opening.

[0012] In one embodiment, the mounting frame is provided with a first clamping groove, and the electric discharge lamp is clamped in the first clamping groove.

[0013] In one embodiment, the mounting frame is provided with a mounting hole, the first clamping groove is provided in plurality, and the mounting hole is arranged between two adjacent first clamping grooves, and the electric discharge lamp is arranged in the mounting hole.

[0014] In one embodiment, the printer further comprises a wiring holder and a wire, and a clamping block is arranged on the surface of the mounting frame close to the housing, and the clamping block and the surface of the mounting frame form a second clamping groove, and the wiring holder is clamped in the second clamping groove, and one end of the wire is fixed to the wiring holder and connected with the electric discharge lamp.

[0015] In one embodiment, the wiring holder is provided with a third clamping groove, and the wire is provided with a first connector and a second connector at two ends respectively, and the first connector is clamped in the third clamping groove.

[0016] In one embodiment, the electric discharge lamp is a lamp strip, and the electric discharge lamp extends along the axial direction of the photosensitive drum.

[0017] In one embodiment, the electric discharge lamp is an LED lamp.

[0018] In one embodiment, the printer further comprises a laser scanner and a transfer roller, and the transfer roller, the developing roller and the charging roller are arranged in sequence and at intervals in the circumferential direction of the photosensitive drum, the laser beam emitted by the laser scanner irradiates the surface of the photosensitive drum between the developing roller and the charging roller, and the light emitted by the electric discharge lamp irradiates the surface of the photosensitive drum between the charging roller and the transfer roller.

[0019] In one embodiment, the charging roller, the developing roller, the transfer roller and the electric discharge lamp are arranged in sequence and at intervals in the circumferential direction of the photosensitive drum.

[0020] The charging roller uniformly charges the surface of the photosensitive drum, the laser beam emitted by the laser scanner irradiates the surface of the photosensitive drum to form an electrostatic latent image, the developing roller transfers the toner in the drum cartridge to the electrostatic latent image to form a visible toner image, the transfer roller transfers the toner image to the paper, and the light emitted by the discharge lamp irradiates the surface of the photosensitive drum to eliminate the charge of the residual toner after transfer.

[0021] Compared with the prior art, the present application has at least the following beneficial effects:

[0022] 1. In the present application, by providing a discharge lamp in the printer, using the photoelectric effect of the photosensitive drum, the potential of the surface of the photosensitive drum after transfer is cleared, and after the residual potential is eliminated, the waste toner can be well absorbed by the developing roller, greatly improving the image quality and effectively reducing the residual image problem on the printed paper.

[0023] 2. In the present application, the selenium drum cancels the waste powder bin module, so that the residual toner on the photosensitive drum is directly transferred back to the developing roller and recycled to the drum cartridge, solving the problems of large space occupation, high cost and non-environmental protection of waste powder treatment of the waste powder bin.

[0024] 3. In the present application, the selenium drum directly eliminates the charge of the residual toner on the photosensitive drum through the discharge lamp, further simplifying the structure of the selenium drum, and the discharge lamp is clamped on the mounting seat, facilitating the installation and disassembly of the discharge lamp. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] Figure 1 is a perspective view of part of the structure of the printer of an embodiment of the present application;

[0027] Figure 2 is a front view of part of the structure of the printer of an embodiment of the present application;

[0028] Figure 3 is Figure 2 is an A-A sectional view in the middle;

[0029] Figure 4 is an exploded view of part of the structure of the printer of an embodiment of the present application;

[0030] Figure 5 is a perspective view of the drum cartridge and the shell of an embodiment of the present application;

[0031] Figure 6 Figure 1 is a perspective view of a charging lamp and a mounting frame according to an embodiment of the present application;

[0032] Figure 7 Figure 2 is an exploded view of the structure in Figure 1 ; Figure 6

[0033] Figure 8 Figure 3 is a perspective view of a printer according to an embodiment of the present application;

[0034] Figure 9 Figure 4 is a sectional view of the printer in Figure 3.

[0035] Explanation of Reference Signs:

[0036] 100, toner cartridge; 110, toner cartridge; 120, developing roller; 130, charging roller; 140, photosensitive drum; 150, charging lamp; 160, housing; 161, accommodating cavity; 162, opening; 170, mounting frame; 171, first clamping slot; 172, mounting hole; 173, clamping block; 174, second clamping slot; 180, wiring seat; 181, third clamping slot; 190, wire; 191, first joint; 192, second joint; 200, laser scanner; 300, transfer roller. DETAILED DESCRIPTION

[0037] The following is a specific embodiment of the present application and further describes the technical solution of the present application in conjunction with the accompanying drawings, but the present application is not limited to these embodiments.

[0038] With reference to Figure 1 , Figure 2 and Figure 3 , the present application provides a printer, which comprises a toner cartridge 100 and a charging lamp 150. The toner cartridge 100 comprises a toner cartridge 110, a developing roller 120, a charging roller 130 and a photosensitive drum 140. The developing roller 120, the charging roller 130 and the photosensitive drum 140 are all mounted on the toner cartridge 110, and the developing roller 120 and the charging roller 130 are arranged at intervals in the circumferential direction of the photosensitive drum 140. The charging roller 130 charges the photosensitive drum 140 to a voltage, and forms an electrostatic latent image on the surface of the photosensitive drum 140 after exposure by laser irradiation. The developing roller 120 transfers the toner in the toner cartridge 110 to the surface of the photosensitive drum 140. At least part of the photosensitive drum 140 is exposed outside the toner cartridge 110, and the light emitted by the charging lamp 150 irradiates the photosensitive drum 140 exposed outside the toner cartridge 110 to eliminate the charge of the residual toner on the photosensitive drum 140.

[0039] ​Specifically, the toner cartridge 110 is used to store toner, and the toner cartridge 110 is internally provided with a channel for supplying toner, so that the toner can be uniformly supplied to the surface of the developing roller 120. The toner cartridge 110 is made of plastic material and has certain strength and rigidity, which can withstand various pressures and vibrations of the selenium drum 100 during use.

[0040] The charging roller 130 is installed on the toner cartridge 110 and is arranged in the circumferential direction of the photosensitive drum 140 and is spaced apart from the developing roller 120. The surface of the charging roller 130 is coated with a conductive material and can apply a uniform voltage to the photosensitive drum 140.

[0041] The developing roller 120 is installed at the front end of the toner cartridge 110 by a bearing and can rotate around its axis. The surface of the developing roller 120 is coated with a special material that can adsorb toner and transfer it to the surface of the photosensitive drum 140. The charging roller 130 is installed on the toner cartridge 110 and is arranged in the circumferential direction of the photosensitive drum 140 and is spaced apart from the developing roller 120. The surface of the charging roller 130 is coated with a conductive material and can apply a uniform voltage to the photosensitive drum 140.

[0042] The photosensitive drum 140 is installed on the toner cartridge 110 and can rotate around its axis. The surface of the photosensitive drum 140 is coated with a photoconductive material that can change its charge state after being irradiated by a laser. At least a portion of the photosensitive drum 140 is exposed outside the toner cartridge 110, which is usually located at the opening 162 of the toner cartridge 110, so that the photosensitive drum 140 can contact other components in the printer.

[0043] The light emitted by the discharge lamp 150 can irradiate the surface of the photosensitive drum 140 exposed outside the toner cartridge 110. After the light emitted by the discharge lamp 150 irradiates the surface of the photosensitive drum 140, it can eliminate the charge of residual toner on the photosensitive drum 140, prevent toner from remaining on the surface of the photosensitive drum 140 due to static electricity, thereby improving the printing quality and prolonging the service life of the photosensitive drum 140.

[0044] In this application, by providing a discharge lamp 150 in the printer, using the photoelectric effect of the photosensitive drum 140, the potential on the surface of the photosensitive drum 140 after transfer is zeroed, and after eliminating the residual potential, the waste toner can be well absorbed by the developing roller 120, greatly improving the image quality and effectively reducing the residual image problem on the printing paper. The selenium drum 100 cancels the waste toner cartridge module, so that the residual toner on the photosensitive drum 140 is directly transferred back to the developing roller 120 and recycled to the toner cartridge 110, solving the problems of large space occupation, high cost and non-environmental protection of waste toner treatment.

[0045] Reference Figure 4 , Figure 5 and Figure 6The printer further comprises a mounting rack 170, and the toner cartridge 100 further comprises a housing 160. The housing 160 is connected with the drum cartridge 110, and the two together enclose a containing cavity 161 with an opening 162. The housing 160 is made of plastic material and has sufficient strength and rigidity. The shape of the housing 160 is matched with the drum cartridge 110 and can protect the photosensitive drum 140 and other components inside. The housing 160 is provided with the opening 162, so that part of the surface of the photosensitive drum 140 can be exposed outside and contact other components in the printer. The photosensitive drum 140 is arranged in the containing cavity 161 and can rotate around its axis by bearing support.

[0046] The mounting rack 170 is connected with the drum cartridge 110 and is used for supporting and fixing the discharge lamp 150. The mounting rack 170 is made of plastic material and has sufficient strength and rigidity. The shape of the mounting rack 170 is matched with the drum cartridge 110 and the housing 160 and can stably support the discharge lamp 150. The discharge lamp 150 is arranged on the mounting rack 170, and its position is accurately designed so that the light emitted by the discharge lamp 150 can directly or indirectly pass through the opening 162 on the housing 160 and irradiate the surface of the photosensitive drum 140.

[0047] Referring to Figure 6 , Figure 7 and Figure 8 , the mounting rack 170 is provided with a first clamping groove 171 for fixing the discharge lamp 150. The shape of the first clamping groove 171 is matched with the discharge lamp 150 and can firmly fix the discharge lamp 150 to prevent it from loosening or falling off during use. The discharge lamp 150 is clamped in the first clamping groove 171, and the installation and disassembly are convenient, which facilitates maintenance and replacement.

[0048] The mounting rack 170 is further provided with a mounting hole 172 for penetrating part of the structure or connecting wire of the discharge lamp 150. The first clamping groove 171 is provided with a plurality of first clamping grooves 171, and the plurality of first clamping grooves 171 are arranged at intervals in the axial direction of the photosensitive drum 140 and can support different parts of the discharge lamp 150. The mounting hole 172 is arranged between two adjacent first clamping grooves 171 and forms a complete support structure. The discharge lamp 150 is penetrated in the mounting hole 172 and fixes the discharge lamp 150 together with the first clamping groove 171, which further guarantees the firmness of the installation of the discharge lamp 150.

[0049] The printer further comprises a terminal 180 and a wire 190 for providing power supply and control signals for the discharge lamp 150. The mounting frame 170 is provided with a clamping block 173 protruding from the surface of the mounting frame 170 and surrounding a second clamping groove 174. The clamping block 173 can firmly fix the terminal 180. The terminal 180 is clamped in the second clamping groove 174, and thus is easy to install and disassemble. One end of the wire 190 is fixed to the terminal 180, and the other end is connected to the discharge lamp 150 to provide power supply and control signals for the discharge lamp 150.

[0050] The terminal 180 is provided with a third clamping groove 181 for fixing the joint of the wire 190. The wire 190 is provided with a first joint 191 and a second joint 192 at two ends respectively. The first joint 191 is clamped in the third clamping groove 181, and the second joint 192 is connected to the discharge lamp 150. The first joint 191 and the second joint 192 facilitate the wiring of the wire 190 and make the connection of the wire 190 more reliable and less likely to be loosened or detached.

[0051] The light emitted by the discharge lamp 150 can be white light. The light quantity of the discharge lamp 150 can be appropriately increased or decreased according to the physical properties of the photosensitive drum 140.

[0052] The wavelength range of the light emitted by the discharge lamp 150 is 650nm-780nm. The light with this wavelength range can match the properties of the photosensitive drum 140 to effectively eliminate the charge of residual toner on the photosensitive drum 140, and will not cause damage to the photoconductive material of the photosensitive drum 140. In actual application, the most suitable wavelength can be selected within the range of 650nm-780nm according to the material properties and use environment of the photosensitive drum 140.

[0053] The discharge lamp 150 is a lamp strip extending along the axial direction of the photosensitive drum 140. The length of the lamp strip is adapted to the length of the photosensitive drum 140, and can irradiate the entire surface of the photosensitive drum 140. The lamp strip can be a plastic light strip.

[0054] The discharge lamp 150 is an LED lamp, which has the advantages of small size, low power consumption, and long service life. The number and arrangement of the LED lamps are determined according to the model and use environment of the toner cartridge 100, and the brightness of the LED lamps can be adjusted as needed to adapt to different discharge conditions.

[0055] Reference Figure 8 and Figure 9The printer further comprises a laser scanner 200 and a transfer roller 300. The transfer roller 300, the developing roller 120 and the charging roller 130 are arranged in sequence and at intervals in the circumferential direction of the photosensitive drum 140. The laser beam emitted by the laser scanner 200 irradiates the surface of the photosensitive drum 140 between the developing roller 120 and the charging roller 130, and the light emitted by the erasing lamp 150 irradiates the surface of the photosensitive drum 140 between the charging roller 130 and the transfer roller 300.

[0056] Specifically, the laser scanner 200 is used to emit a laser beam to expose the surface of the photosensitive drum 140 and form an electrostatic latent image. The laser scanner 200 comprises a laser diode, a focusing lens, a multi-faceted rotating mirror and a scanning lens, etc. The transfer roller 300 is used to transfer the toner image on the photosensitive drum 140 to a paper sheet. The transfer roller 300 is usually composed of a metal shaft and a conductive rubber layer, and can apply a proper voltage to transfer the toner from the photosensitive drum 140 to the paper sheet.

[0057] The transfer roller 300, the developing roller 120 and the charging roller 130 are arranged in sequence and at intervals in the circumferential direction of the photosensitive drum 140. This arrangement allows the photosensitive drum 140 to pass through the charging, exposing, developing and transferring work areas in sequence during rotation, thereby forming a complete printing process.

[0058] In one embodiment, the charging roller 130, the developing roller 120, the transfer roller 300 and the erasing lamp 150 are arranged in sequence and at intervals in the circumferential direction of the photosensitive drum 140, and the light emitted by the erasing lamp 150 can directly irradiate the surface of the photosensitive drum 140 to eliminate the charge of residual toner after transfer.

[0059] During the printing process, first, the charging roller 130 uniformly charges the surface of the photosensitive drum 140; then, the laser beam emitted by the laser scanner 200 irradiates the surface of the photosensitive drum 140 to form an electrostatic latent image; next, the developing roller 120 transfers toner to the electrostatic latent image to form a visible toner image; subsequently, the transfer roller 300 transfers the toner image to a paper sheet; finally, the light emitted by the erasing lamp 150 irradiates the surface of the photosensitive drum 140 to eliminate the charge of residual toner, thereby preparing for the next printing.

[0060] The printer provided in the application charges the photosensitive drum 140 with a voltage to form a uniform charge distribution on the surface of the photosensitive drum 140, and the developing roller 120 transfers the toner in the drum cartridge 110 to the surface of the photosensitive drum 140. When the photosensitive drum 140 rotates to the position of the laser scanner 200 of the printer, a laser beam irradiates the surface of the photosensitive drum 140 to change the charge state of the irradiated area and form an electrostatic latent image. As the photosensitive drum 140 continues to rotate, the electrostatic latent image passes the position of the developing roller 120, and the toner is adsorbed onto the electrostatic latent image to form a visible toner image. When the photosensitive drum 140 continues to rotate to the position of the transfer roller 300, the toner image is transferred to the paper. After the transfer is completed, a small amount of toner and charge may still remain on the surface of the photosensitive drum 140, and at this time, the light emitted by the electric lamp 150 irradiates the surface of the photosensitive drum 140 to eliminate the charge of the residual toner, so that it is easily removed by the cleaning device, thereby keeping the surface of the photosensitive drum 140 clean, improving the printing quality and prolonging the service life of the photosensitive drum 140.

[0061] It should be noted that all the direction indications (such as up, down, left, right, front, back, etc.) in the embodiments of the application are only used to explain the relative position relationship, movement condition, etc. between the components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the direction indications also change accordingly.

[0062] In addition, the descriptions such as “first”, “second”, “one”, etc. in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as “first” and “second” can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of “plurality” is at least two, such as two, three, etc., unless otherwise specifically limited.

[0063] In the present application, unless otherwise specifically defined and limited, the terms “connection”, “fixation”, etc. should be understood in a broad sense, for example, “fixation” can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through an intermediate medium; can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0064] In addition, the technical solutions of various embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor is it within the scope of protection claimed by the present application.

Claims

1. A printer characterized by comprising: The printer comprises: a selenium drum, which comprises a drum powder box, a developing roller, a charging roller and a photosensitive drum, the developing roller, the charging roller and the photosensitive drum are all mounted on the drum powder box, the charging roller and the developing roller are arranged at intervals in the circumferential direction of the photosensitive drum, the charging roller charges the photosensitive drum with a charging voltage, and an electrostatic latent image is formed on the surface of the photosensitive drum after laser exposure, the developing roller transmits the carbon powder in the drum powder box to the surface of the photosensitive drum, and at least part of the photosensitive drum is exposed outside the drum powder box; a de-electrification lamp, which emits light to irradiate the exposed part of the photosensitive drum outside the drum powder box to eliminate the charge of residual carbon powder on the photosensitive drum.

2. The printer of claim 1, wherein, The printer further comprises a mounting rack, and the selenium drum further comprises a shell connected with the drum powder box to form a containing cavity with an opening, and the photosensitive drum is arranged in the containing cavity. The de-electrification lamp is arranged on the mounting rack, and the light emitted by the de-electrification lamp irradiates the surface of the photosensitive drum through the opening.

3. The printer of claim 2, wherein, A first clamping groove is arranged on the mounting rack, and the de-electrification lamp is clamped in the first clamping groove.

4. The printer of claim 3, wherein, A plurality of first clamping grooves are arranged on the mounting rack, and a mounting hole is arranged between two adjacent first clamping grooves, and the de-electrification lamp is arranged in the mounting hole.

5. The printer of claim 2, wherein, The printer further comprises a terminal seat and a wire, a clamping block is protruded from the surface of the mounting rack close to the shell, a second clamping groove is formed between the surface of the mounting rack and the clamping block, the terminal seat is clamped in the second clamping groove, and one end of the wire is fixed to the terminal seat and connected with the de-electrification lamp.

6. The printer of claim 5, wherein, A third clamping groove is arranged on the terminal seat, and first and second connectors are arranged at two ends of the wire respectively, and the first connector is clamped in the third clamping groove.

7. The printer of claim 1, wherein, The de-electrification lamp is a lamp strip, and the de-electrification lamp extends along the axial direction of the photosensitive drum.

8. The printer of claim 1, wherein, The de-electrification lamp is an LED lamp.

9. The printer of claim 1, wherein, The printer further comprises a laser scanner and a transfer roller, the transfer roller, the developing roller and the charging roller are arranged at intervals in the circumferential direction of the photosensitive drum, a laser beam emitted by the laser scanner irradiates the surface of the photosensitive drum between the developing roller and the charging roller, and the light emitted by the de-electrification lamp irradiates the surface of the photosensitive drum between the charging roller and the transfer roller.

10. The printer of claim 9, wherein, The charging roller, the developing roller, the transfer roller and the de-electrification lamp are arranged at intervals in the circumferential direction of the photosensitive drum. The charging roller uniformly charges the surface of the photosensitive drum, the laser beam emitted by the laser scanner irradiates the surface of the photosensitive drum to form an electrostatic latent image, the developing roller transmits the carbon powder in the drum powder box to the electrostatic latent image to form a visible carbon powder image, the transfer roller transfers the carbon powder image to a paper sheet, and the light emitted by the de-electrification lamp irradiates the surface of the photosensitive drum to eliminate the charge of residual carbon powder after transfer.

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