JP7098965B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

The technique described in Patent Document 1 below is known as a technique for adjusting the density of an image when continuous paper is used in an image forming apparatus.

In Japanese Patent No. 6098454 as Patent Document 1, before forming an image on continuous paper, a density adjusting toner image is formed on the image holder with the image holder and the continuous paper separated from each other, and a density sensor ( A technique for controlling the concentration based on the detection result of 48) is described. Further, in the technique described in Patent Document 1, during image formation on continuous paper, the toner concentration in the predictive control (ICDC) or the developing device (36) based on the print history in a state where the image holder and the continuous paper are in contact with each other. Predictive control (ATC) is performed based on.

Japanese Patent No. 6098454 ("0058"-"0080", FIG. 4, FIG. 6-8).

INDUSTRIAL APPLICABILITY In an image forming apparatus using continuous paper, the present invention stabilizes the image quality as compared with the case where the deteriorated developer is discharged or a new developer is replenished in response to the deterioration of the developer during image formation. That is a technical issue.

In order to solve the technical problem, the image forming apparatus of the invention according to claim 1 is used.
An image forming means having an image holding means and forming an image on a continuous medium,
Before forming an image on the continuous medium, a density adjusting means for adjusting the density of the image based on the density adjusting image formed on the image holding means with the image holding means and the continuous medium separated from each other.
Humidity acquisition means to acquire humidity and
During image formation on the continuous medium, it is a changing means for changing the image forming conditions by the image forming means based on the density of the image , and the range of the density for changing the image forming conditions based on the humidity is changed. At the same time, when the humidity does not reach the predetermined low humidity threshold, the image formation conditions are changed for the image portion having at least a higher density than the predetermined medium density, and the humidity is predetermined. When the threshold value for high humidity is reached, at least the above-mentioned changing means for changing the image forming conditions for a predetermined high-density image portion, and the above-mentioned changing means.
It is characterized by being equipped with.

The invention according to claim 2 is the image forming apparatus according to claim 1.
The image-holding means having a photoconductor on which an image is formed on the surface and an intermediate transfer body in which an image on the surface of the photoconductor is transferred and the transferred image is transferred to a continuous medium.
The image forming means having a writing means for irradiating the charged photoconductor with light for writing an image to form a latent image, and the image forming means.
The changing means for changing the image forming conditions by changing the amount of the writing light, and the changing means.
It is characterized by being equipped with.

The invention according to claim 3 is the image forming apparatus according to claim 2.
The changing means for changing the image forming conditions by increasing the amount of light of the writing light when the density of the formed image does not reach a predetermined low density value.
It is characterized by being equipped with.

The invention according to claim 4 is the image forming apparatus according to claim 2.
The changing means for changing the image forming conditions by reducing the amount of light of the writing light when the density of the formed image reaches a predetermined value for high density.
It is characterized by being equipped with.

The invention according to claim 5 is the image forming apparatus according to any one of claims 1 to 4.
The changing means for changing the image forming conditions by making a correction to increase the density of the formed image when the density of the image reaches a preset value.
It is characterized by being equipped with.

The invention according to claim 6 is the image forming apparatus according to any one of claims 1 to 4.
The changing means for changing the image forming conditions by making a correction to reduce the density of the formed image when the density of the image does not reach a preset value.
It is characterized by being equipped with.

According to the first aspect of the present invention, in an image forming apparatus using continuous paper, when the deteriorated developer is discharged or a new developer is replenished in response to the deterioration of the developer during image formation. In comparison, the image quality can be stabilized. Further, according to the first aspect of the present invention, the image quality can be stabilized according to the humidity as compared with the case where the humidity is not taken into consideration. Further, according to the invention of claim 1, it is possible to suppress an increase in the density of a low-density image in a low-humidity environment. Further, according to the invention of claim 1, it is possible to suppress an increase in the density of a low to medium density image in a high humidity environment.
According to the second aspect of the present invention, the image quality can be adjusted by adjusting the potential of the portion irradiated with the writing light.
According to the third aspect of the present invention, when low-density image formation continues, the amount of light can be increased to adjust the image quality.
According to the fourth aspect of the present invention, when the image formation with high image density continues, the amount of light can be reduced to adjust the image quality.

According to the inventions of claims 5 and 6, the density of the image can be corrected and the image quality can be quickly stabilized as compared with the case of controlling by replenishing the developer .

FIG. 1 is an overall explanatory view of the image forming apparatus of the first embodiment. FIG. 2 is a block diagram showing each function provided in the control unit of the image forming apparatus of the first embodiment. FIG. 3 is an explanatory diagram of a flowchart of the control process of the image formation condition of the first embodiment. FIG. 4 is an explanatory diagram of the relationship between the image density and the density change when no correction is made, and is a graph in which the print amount is taken on the horizontal axis and the image density is taken on the vertical axis. FIG. 5 is a block diagram of the second embodiment and corresponds to FIG. 2 of the first embodiment. FIG. 6 is an explanatory diagram of correction of image formation conditions according to humidity when the image density is low. The horizontal axis is gradation, and the vertical axis is the corrected potential (development contrast setting and gradation correction). It is a graph which took the average potential) which combined. FIG. 7 is an explanatory diagram of correction of image formation conditions according to humidity when the image density is high. The horizontal axis is gradation, and the vertical axis is the corrected potential (development contrast setting and gradation correction). It is a graph which took the average potential) which combined. FIG. 8 is a flowchart of the image formation condition control process of the second embodiment, and is a diagram corresponding to FIG. 3 of the first embodiment.

Next, an embodiment as a specific example of the embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate the understanding of the following explanations, in the drawings, the front-back direction is the X-axis direction, the left-right direction is the Y-axis direction, and the up-down direction is the Z-axis direction. The directions indicated by Z and −Z or the indicated sides are referred to as anterior, posterior, right, left, upward, downward, or anterior, posterior, right, left, upper, and inferior, respectively.
In addition, in the figure, the one with "・" in "○" means the arrow from the back of the paper to the front, and the one with "×" in "○" is the front of the paper. It shall mean an arrow pointing from to the back.
In addition, in the explanation using the following drawings, the illustrations other than the members necessary for the explanation are omitted as appropriate for the sake of easy understanding.

(Explanation of the overall configuration of the printer U of the first embodiment)
FIG. 1 is an overall explanatory view of the image forming apparatus of the first embodiment.
In FIG. 1, the printer U as an example of the image forming apparatus of the first embodiment of the present invention includes a printer main body U1, a feeder unit U2 as an example of a supply means for supplying a medium to the printer main body U1, and an image. It has a recovery unit U3 as an example of a recovery means in which the recorded medium is recovered.

(Explanation of Marking Configuration of Example 1)
In FIG. 1, the main body U1 of the printer is a print image server COM as an example of a control unit C that controls the printer U and an information transmission device connected to the outside of the printer U via a dedicated cable (not shown). It has a communication unit (not shown) for receiving image information transmitted from the printer, a marking unit U1a as an example of an image forming means for recording an image on a medium, and the like. A personal computer PC as an example of an image transmission device connected to the print image server COM via a wired or wireless communication line and to which information on an image printed by the printer U is transmitted is connected to the print image server COM.
The marking portion U1a prints photoconductors Py, Pm, Pc, Pk for each color of Y: yellow, M: magenta, C: cyan, K: black as an example of image holding means, and a photographic image or the like as an example. It has a photoconductor Po for forming an image using a glossy toner that gives a gloss to the image in some cases.

In FIG. 1, around the black photoconductor Pk, along the rotation direction of the photoconductor Pk, a charger CCk as an example of charging means, an exposure machine ROSk as an example of writing means, and an example of developing means. The developer Gk, the primary transfer roll T1k as an example of the primary transfer means, and the photoconductor cleaner CLk as an example of the cleaning means for the image holder are arranged.
Similarly, around the other photoconductors Py, Pm, Pc, Po, the charger CCy, CCm, CCc, CCo, the exposure machine ROSy, ROSm, ROSc, ROSo, the developer Gy, Gm, Gc, Go, primary Transfer rolls T1y, T1m, T1c, T1o, and photoconductor cleaners CLy, CLm, CLc, and CLo are arranged.
As an example of the container, a toner cartridge (not shown) containing the developer to be replenished in the developing units Gy to Go is detachably supported on the upper portion of the marking portion U1a.

Below each of the photoconductors Py to Po, an intermediate transfer belt B, which is an example of the intermediate transfer means and is an example of the image holding means, is arranged, and the intermediate transfer belts B are 1 with the photoconductors Py to Po. It is sandwiched between the next transfer rolls T1y to T1o. The back surface of the intermediate transfer belt B includes a drive roll Rd as an example of a drive member, a tension roll Rt as an example of a tension applying member, a walking roll Rw as an example of a meandering prevention member, and a plurality of driven members. It is supported by the idler roll Rf, the backup roll T2a as an example of the facing member for the secondary transfer, the plurality of retract rolls R0 as an example of the movable member, and the primary transfer rolls T1y to T1o.
On the surface of the intermediate transfer belt B, a belt cleaner CLB as an example of the cleaning means of the intermediate transfer means is arranged in the vicinity of the drive roll Rd.

A secondary transfer roll T2b, which is an example of an opposing member, an example of a transfer means, and an example of a secondary transfer means, is arranged on the backup roll T2a so as to sandwich the intermediate transfer belt B. .. The secondary transfer roll T2b of Example 1 comes into contact with the lower end, which is the center of the winding of the intermediate transfer belt B around the backup roll T2a, at a position shifted to the upstream side in the rotational direction of the intermediate transfer belt B. It is configured as follows. Further, the secondary transfer roll T2b of the first embodiment is pressed against the backup roll T2a by a spring (not shown) as an example of the urging member.

Further, in order to apply a voltage to the backup roll T2a having a polarity opposite to the charging polarity of the developer, the contact roll T2c, which is an example of the feeding means and is an example of the contact means, comes into contact with the backup roll T2a. There is.
The backup roll T2a, the secondary transfer roll T2b, and the contact roll T2c constitute the secondary transfer device T2 of Example 1 as an example of the transfer device, and the primary transfer rolls T1y to T1o, the intermediate transfer belt B, and the like. The transfer devices T1, B, and T2 of the first embodiment are configured by the secondary transfer device T2 and the like.

The feeder unit U2 is rotatably supported by a paper feed member U2a in which continuous paper S as an example of a continuous medium is wound up in a roll shape. The continuous paper S extending from the paper feed member U2a is sent to the first tension adjusting mechanism U2b. The first tension adjusting mechanism U2b has a guide roll R1 as an example of the guide member. A pair of guide rolls R1 are arranged along the transport direction of the continuous paper S. A dancer roll R2 as an example of the tension applying member is arranged between the guide rolls R1. The dancer roll R2 is in contact with the surface of the continuous paper S and is supported in a state of being free to move up and down. Therefore, the dancer roll R2 applies tension to the continuous paper S by the weight of the dancer roll R2. The paper feed member U2a of the first embodiment feeds out the continuous paper S when the height of the dancer roll R2 becomes higher than the preset feed height, and the height of the dancer roll R2 is higher than the preset stop height. When it becomes low, the rotation is controlled so as to stop the feeding of the continuous paper S.

A paper feed mechanism U2c as an example of the means for transporting the continuous paper S is arranged on the downstream side of the first tension adjusting mechanism U2b with respect to the transport direction of the continuous paper S. The paper feeding mechanism U2c has a plurality of guide rolls R3 as an example of the guide member. On the downstream side of the guide roll R3, a paper feed roll R4, which is an example of a first transport member, an example of a drive member, and an example of a paper feed member, is arranged. On the paper feed roll R4, a sandwiching roll R5 as an example of the facing member is arranged so as to sandwich the continuous paper S. The paper feed roll R4 feeds the continuous paper S at a preset transport speed of the continuous paper S. The sandwiching roll R5 sandwiches the continuous paper S between the paper feed roll R4 and the continuous paper S at a preset pressure in order to reduce the occurrence of slippage between the paper feed roll R4 and the continuous paper S. Further, in the guide roll R3, in order to reduce the occurrence of slippage between the paper feed roll R4 and the continuous paper S, the continuous paper S has a large area around which the continuous paper S is wound around the paper feed roll R4. It guides the route of.

The continuous paper S sent out from the paper feeding mechanism U2c is sandwiched between the transport roll Ra as an example of the transport member arranged at the inlet of the main body U1 of the printer. A plurality of guide rolls Rb are arranged on the right side of the transport roll Ra as an example of the guide member. The guide roll Rb of the first embodiment is configured in a rotatable roll shape.
An idler roll R6 as an example of the guide member is arranged on the downstream side of the continuous paper S in the transport direction with respect to the secondary transfer roll T2b. The idler roll R6 is arranged so as to be in contact with the lower surface of the continuous paper S, that is, the surface opposite to the surface on which the image is transferred. The idler roll R6 is configured to be rotatable while supporting the continuous paper S.

A fixing device F as an example of the fixing means is arranged on the downstream side of the idler roll R6. The fixing device F is an example of a first fixing member, a heating roll Fh as an example of a heating member, and an example of a second fixing member, a pressure roll Fp as an example of a pressure member. Has. Inside the heating roll Fh, a heater h as an example of a heat source is housed.

A recovery unit U3 is arranged on the downstream side of the fixing device F. The recovery unit U3 has a cooling mechanism U3a as an example of the cooling means. The cooling mechanism U3a has a first cooling roll R11 as an example of the first medium cooling member and a second cooling roll R12 as an example of the second medium cooling member. The second cooling roll R12 is arranged on the downstream side of the continuous paper S in the transport direction with respect to the first cooling roll R11. The continuous paper S is wound around the cooling rolls R11 and R12 so as to be in contact with each other.

A transport roll R13 as an example of a transport member is arranged on the downstream side of the cooling mechanism U3a with respect to the transport direction of the continuous paper S via the guide roll Rb. The transport roll R13 transports the continuous paper S to the downstream side.
A second tension adjusting mechanism U3b is arranged on the downstream side of the transport roll R13 with respect to the transport direction of the continuous paper S. The second tension adjusting mechanism U3b is configured in the same manner as the first tension adjusting mechanism U2b. Therefore, it has a pair of guide rolls R14 and a dancer roll R15.

A take-up roll U3c as an example of the recovery member is arranged on the downstream side of the second tension adjusting mechanism U3b with respect to the transport direction of the continuous paper S. The continuous paper S is wound on the take-up roll U3c. The take-up roll U3c winds up the continuous paper S when the height of the dancer roll R15 becomes lower than the preset take-up height, and the height of the dancer roll R15 becomes higher than the preset stop height. Stop winding the continuous paper S.

(Marking operation)
In the printer U, when the image information transmitted from the personal computer PC is received via the print image server COM, a job which is an image forming operation is started. When the job is started, the photoconductors Py to Po, the intermediate transfer belt B, and the like rotate.
The photoconductors Py to Po are rotationally driven by a drive source (not shown).
A preset voltage is applied to the chargers CCy to CCo to charge the surface of the photoconductors Py to Po.
The exposure machines ROSy to ROSo output laser light Ly, Lm, Lc, Lk, Lo as an example of light for writing a latent image in response to a control signal from the control unit C, and charge the photoconductors Py to Po. An electrostatic latent image is written on the surface.
The developers Gy to Go develop an electrostatic latent image on the surface of the photoconductors Py to Po into a visible image.

A primary transfer voltage having a polarity opposite to the charging polarity of the developer is applied to the primary transfer rolls T1y to T1o, and the visible image on the surface of the photoconductors Py to Po is transferred to the surface of the intermediate transfer belt B.
The photoconductor cleaners CLi to CLo are cleaned by removing the developer remaining on the surface of the photoconductors Py to Po after the primary transfer.
When the intermediate transfer belt B passes through the primary transfer region facing the photoconductors Py to Po, images are transferred and laminated in the order of O, Y, M, C, and K, and the intermediate transfer belt B is laminated on the secondary transfer device T2. It passes through the opposite secondary transfer region Q4. In the case of a monochromatic image, an image of only one color is transferred and sent to the secondary transfer region Q4.

The transport roll Ra transports the continuous paper S extending from the feeder unit U2 to the downstream side. The guide roll Rb guides the continuous paper S to the secondary transfer region Q4.
In the secondary transfer device T2, a secondary transfer voltage having the same polarity as the charging polarity of the developer preset on the backup roll T2a is applied via the contact roll T2c, and the image of the intermediate transfer belt B is transferred to the continuous paper S. do.
The fixing device F heats the continuous paper S passing through the fixing region Q5 where the heating roll Fh and the pressure roll Fp come into contact with each other while pressurizing the continuous paper S to fix the unfixed image on the surface of the continuous paper S.
In the recovery unit U3, the continuous paper S is cooled by the cooling rolls R11 and R12, and then the take-up roll U3c winds up the continuous paper S.

(Explanation of Control Unit of Example 1)
FIG. 2 is a block diagram showing each function provided in the control unit of the image forming apparatus of the first embodiment.
In FIG. 2, the control unit C of the printer U has an input / output interface I / O for inputting / outputting signals to / from the outside. Further, the control unit C has a ROM: read-only memory in which a program, information, and the like for performing necessary processing are stored. Further, the control unit C has a RAM: random access memory for temporarily storing necessary data. Further, the control unit C has a CPU: a central processing unit that performs processing according to a program stored in a ROM or the like. Therefore, the control unit C of the first embodiment is configured by a small information processing device, a so-called microcomputer. Therefore, the control unit C can realize various functions by executing the program stored in the ROM or the like.

(Signal output element connected to control unit C)
The control unit C is input with an output signal from a signal output element such as the operation unit UI.
The operation unit UI has an input button UIa for inputting an arrow key or the like as an example of an input member.

(Controlled element connected to control unit C)
The control unit C is connected to a drive circuit D1 of the main drive source, a contact / separation circuit D2 of the secondary transfer roll, a power supply circuit E, and other control elements (not shown). The control unit C outputs those control signals to the circuits D1, D2, E and the like.
D1: Drive circuit of the main drive source The drive circuit D1 of the main drive source rotationally drives the photoconductors Py to Po, the intermediate transfer belt B, and the like via the main motor M1 as an example of the main drive source.
D2: Contact / separation circuit of the secondary transfer roll The contact / separation circuit D2 of the secondary transfer roll approaches the secondary transfer roll T2b with respect to the intermediate transfer belt B via the motor M2 as an example of the drive source. By moving in the direction of separation, the secondary transfer roll T2b is moved in the direction of contact / separation with respect to the continuous paper S.

E: Power supply circuit The power supply circuit E includes a power supply circuit Ea for development, a power supply circuit Eb for charging, a power supply circuit Ec for transfer, a power supply circuit Ed for fixing, and the like.
Ea: Power supply circuit for development The power supply circuit Ea for development applies a development voltage to the development rolls of the developers Gy to Go. In the first embodiment, as the development voltage as an example of the discharge bias, a voltage in which the AC voltage as an example of the alternating voltage is superimposed on the DC voltage is applied.
Eb: Power supply circuit for charging The power supply circuit Eb for charging applies a charging voltage for charging the surfaces of the photoconductors Py to Po to each of the charging devices CCy to CCo. In the first embodiment, as the charging voltage as an example of the discharge bias, a voltage in which the AC voltage as an example of the alternating voltage is superimposed on the DC voltage is applied. Further, in the first embodiment, as the charging devices CCy to CCo, a charging roll is used as an example of a contact-type discharging means that contacts and charges the photoconductors Py to Po.

Ec: Power supply circuit for transfer The power supply circuit Ec for transfer applies a transfer voltage to the primary transfer rolls T1y to T1o and the backup roll T2a. In the first embodiment, as the transfer voltage as an example of the discharge bias, a voltage in which the AC voltage as an example of the alternating voltage is superimposed on the DC voltage is applied.
Ed: Power supply circuit for fixing The power supply circuit Ed for fixing supplies electric power to the heater of the heating roll Fh of the fixing device F.

(Function of control unit C)
The control unit C has a function of executing processing according to an input signal from the signal output element and outputting a control signal to each of the control elements. That is, the control unit C has the following functions.
C1: Image formation control means The image formation control means C1 drives each member of the printer main body U1 and charges each voltage in response to an input to the operation unit UI or an input of image information from an external personal computer or the like. The job, which is an image forming operation, is executed by controlling the application timing and the like.

C2: Drive source control means The drive source control means C2 controls the drive of the main motor M1 via the drive circuit D1 of the main drive source, and controls the drive of the photoconductors Py to Po and the like.
C3: Power supply circuit control means The power supply circuit control means C3 controls each power supply circuit Ea to Ed to control the voltage applied to each member and the electric power supplied to each member.

C4: Contact / separation control means for the secondary transfer roll The contact / separation control means C4 for the secondary transfer roll controls the drive of the motor M2 to bring the secondary transfer roll T2b into contact with and separate from the continuous paper S. .. The contact / separation control means C4 for the secondary transfer roll of Example 1 brings the secondary transfer roll T2b into contact with the continuous paper S when the image formation on the continuous paper S is started. Then, when the image formation is completed, the secondary transfer roll T2b is separated from the continuous paper S.

C5: Density adjusting means The density adjusting means C5 has a density adjusting time determining means C5a and a patch forming means C5b as an example of a density adjusting image forming means. The density adjusting means C5 causes the intermediate transfer belt B to form a patch image as an example of the density adjusting image in a state where the intermediate transfer belt B and the secondary transfer roll T2b are separated from each other before forming an image on the continuous paper S. .. Then, the density of the patch image is read by a density sensor (density reading member, not shown), and the density of the image is adjusted based on the density difference between the formed patch image density and the read density. The concentration adjusting means C5 is, for example, the same as the first concentration control process described in Patent Document 1, and is known, so detailed description thereof will be omitted.

C5a: Concentration adjustment timing determination means The concentration adjustment timing determination means C5a determines whether or not it is time to adjust the density using a patch image. As an example, the density adjustment time determination means C5a determines that the density adjustment time has come when a new continuous paper S is loaded or when 1000 pages of printing have been performed since the previous density adjustment. do.
C5b: Patch forming means The patch forming means C5b controls each member of the marking portion U1a to form a patch image having a predetermined density on the photoconductors Py to Po, and first transfers the patch image to the intermediate transfer belt B. The density of the patch image is read on the intermediate transfer belt B, is not transferred to the continuous paper S, and is removed by the belt cleaner CLB.

C6: Changing means The changing means C6 changes the image forming conditions based on the density of the image during the image forming on the continuous paper S. The changing means C6 of the first embodiment includes a changing time determining means C6a, an image density determining means C6b, and a developing potential setting means C6c.
C6a: Change time determination means The change time determination means C6a determines whether or not it is time to change the image formation conditions during image formation. As an example, the change time determination means C6a of the first embodiment determines that the change time has come every time 100 pages are printed.

C6b: Image density discriminating means The image density discriminating means C6b discriminates the image density. The image density determination means C6b of the first embodiment determines the image density Cn based on the image information of the image to be formed from the image density C6b. As an example, the image density Cn is an image density between the first discrimination density Ca and the second discrimination density Cb, or an image density equal to or higher than the second discrimination density Cb. Determine if it exists. In Example 1, the first discrimination density Ca = 4% and the second discrimination density Cb = 15% are predetermined, but can be arbitrarily changed depending on the design, specifications, and the like. Further, the image density Cn of the image to be formed can be, for example, the density of the next one page or the average density of 20 pages.

C6c: Development potential setting means The development potential setting means C6c sets the development potential as an example of image formation conditions. In the first embodiment, the development potential is adjusted by adjusting the potential of the exposed portion by controlling the amount of light of the exposure machines ROSy to ROSo. Therefore, in the first embodiment, the image formation conditions are adjusted by adjusting the potential difference between the voltage applied to the developers Gy to Go and the exposed portion, that is, the development contrast (development potential). The developing potential setting means C6c of Example 1 is set to increase the developing potential when the image density is smaller than the first discrimination density Ca (when the density is low). Therefore, in order to increase the development contrast, the light amount of the exposure machines ROSy to ROSo is set to a high light amount. Further, the developing potential setting means C6c of Example 1 is set to lower the developing potential when the image density Cn is larger than the second discrimination density Cb (in the case of high density). Therefore, in order to reduce the development contrast, the light amount of the exposure machines ROSy to ROSo is set to a low light amount. When the image density Cn is between the first discrimination density Ca and the second discrimination density Cb (medium density), the development potential is not changed from the standard setting. The amount of light is adjusted based on the image density Cin = 100% so that the image density Cin = 100% is matched.

(Explanation of Flow Chart of Example 1)
Next, the flow of control in the printer U of the first embodiment will be described using a flow chart, a so-called flowchart.
(Explanation of the flowchart of the image formation condition adjustment process)
FIG. 3 is an explanatory diagram of a flowchart of the control process of the image formation condition of the first embodiment.
The processing of each step ST in the flowchart of FIG. 3 is performed according to the program stored in the control unit C of the printer U. Further, this process is executed in parallel with other various processes of the printer U.
The flowchart shown in FIG. 3 is started by turning on the power of the printer U.

In ST1 of FIG. 3, it is determined whether or not the job has been started. If no (N), proceed to ST2, and if yes (Y), proceed to ST7.
In ST2, it is determined whether or not it is time to adjust the image density using the patch image. If yes (Y), proceed to ST3, and if no (N), return to ST1.
In ST3, the photoconductors Py to Po, the intermediate transfer belt B, and the like are driven. At this time, the secondary transfer roll T2b is separated from the intermediate transfer belt B and the continuous paper S, and the continuous paper S is also separated from the intermediate transfer belt B. Then proceed to ST4.

In ST4, a patch image is formed and the process proceeds to ST5.
In ST5, the image density is controlled based on the density of the read patch image. Then, proceed to ST6.
In ST6, the driving of the photoconductors Py to Po and the like is stopped, and the adjustment of the image density using the patch image is completed. Then, it returns to ST1.

In ST7, the secondary transfer roll T2b is moved to the transfer position. That is, the continuous paper S is sandwiched between the secondary transfer roll T2b and the intermediate transfer belt B. That is, the secondary transfer roll T2b is in contact with the continuous paper S. Then, proceed to ST8.
In ST8, it is determined whether or not it is time to change the image formation conditions during image formation. If yes (Y), proceed to ST9, and if no (N), proceed to ST13.
In ST9, it is determined whether or not the image density Cn is equal to or less than the first discrimination density Ca. If yes (Y), proceed to ST10, and if no (N), proceed to ST11.
In ST10, the setting is changed to increase the development potential. Then, proceed to ST13.

In ST11, it is determined whether or not the image density Cn is equal to or higher than the second discrimination density Cb. If yes (Y), proceed to ST12, and if no (N), proceed to ST13.
In ST12, the setting is changed to lower the development potential. Then, proceed to ST13.
Image formation is performed in ST13. Then, proceed to ST14.
In ST14, it is determined whether or not the job is completed. If no (N), the process returns to ST8, and if yes (Y), the process proceeds to ST15.
In ST15, the secondary transfer roll T2b is moved to a separated position. That is, the secondary transfer roll T2b is separated from the continuous paper S, and the continuous paper S is separated from the intermediate transfer belt B. Then, it returns to ST1.

(Action of Example 1)
In the printer U of the first embodiment having the above configuration, the continuous paper S is separated from the intermediate transfer belt B before image formation (state in which image formation is not performed). Therefore, it is possible to adjust the image density by forming a patch image on the photoconductors Py to Po and the intermediate transfer belt B without transferring the image to the continuous paper S. Therefore, it is possible to suppress the generation of waste paper and waste paper when adjusting the image density.

FIG. 4 is an explanatory diagram of the relationship between the image density and the density change when no correction is made, and is a graph in which the print amount is taken on the horizontal axis and the image density is taken on the vertical axis.
In Example 1, during image formation, the image formation conditions are changed based on the image density Cn of the image to be formed. In FIG. 4, if the image density is not corrected during image formation, the image density may fluctuate with the image formation depending on the image density Cn. Specifically, when image formation with a low image density Cn is continued, the consumption of the developer in the developing devices Gy to Go continues to be low. If the consumption of the developer continues to be low, the developer inside the developing units Gy to Go deteriorates. When the developer deteriorates, the amount of the toner's external additive decreases and the amount of charge in the toner increases. Therefore, in the developing region, the toner that moves is likely to decrease due to being electrically saturated with respect to the potential difference between the photoconductors Py to Po and the developing units Gy to Go. Therefore, there is a problem that the amount of toner developed on the Py to Po side of the photoconductor is reduced and the image density is lowered, resulting in deterioration of image quality.
Further, in the printer U in which the continuous paper S is used, there are many situations in which 1000 copies of the same image are printed when printing a label or the like to be attached to the product, and when the image density Cn is high, the image density Cn is high. There is also a problem that the amount of toner to be developed increases and the density tends to increase as the amount of charge of the toner decreases.

On the other hand, in the first embodiment, the image forming conditions are adjusted according to the image density Cn during the image forming. Therefore, the change in image density during image formation is suppressed, and the image quality is likely to be stable. In particular, in the technique of increasing the toner concentration in the developing apparatus such as the technique described in Patent Document 1, a new developing agent is replenished or the developing agent is discharged from the developing apparatus even if the toner concentration is changed. There is a problem that it takes a long time to be processed and the image quality formed by that time is difficult to stabilize. On the other hand, in the first embodiment, the light amounts of the exposure machines ROSy to ROSo are adjusted to adjust the image formation conditions. Therefore, the responsiveness is good and the image quality is easily stabilized as compared with the technique of replenishing and discharging the developer.

When adjusting the light intensity of the exposure machines ROSy to ROSo, it is not necessary to change the charging voltage, the developing voltage, and the transfer voltage, and the influence on other parts is reduced as compared with the case where the power supply circuit E is adjusted. Therefore, adjustment can be easily performed. Although the configuration for adjusting the amount of light is illustrated in Example 1, a configuration for adjusting the charging voltage, the developing voltage, and the transfer voltage as an example of the image forming conditions is also possible.
It is also possible to perform gradation correction instead of adjusting the amount of light. That is, it is also possible to correct the density to be written by the exposure machines ROSy to ROSo based on the density Cin of the image to be formed.

Next, a second embodiment of the present invention will be described. In the second embodiment, the components corresponding to the components of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. do.
This embodiment differs from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other respects.
FIG. 5 is a block diagram of the second embodiment and corresponds to FIG. 2 of the first embodiment.

In FIG. 5, in the control unit C of the printer U of the second embodiment, the developing potential setting means C6c', the humidity acquiring means C6d, and the humidity are replaced with the developing potential setting means C6c of the changing means C6 of the first embodiment. It has a discriminating means C6e and a gradation setting means C6f.
The humidity acquisition means C6d acquires the environmental humidity from a hygrometer (not shown) installed in the printer U.
The humidity determination means C6e determines whether it is a low humidity environment, a medium humidity environment, or a high humidity environment based on the environmental humidity acquired by the humidity acquisition means C6d. In Example 2, as an example, a humidity of 30% (threshold value Ha for low humidity) or less is determined as a low humidity environment, and a humidity of 70% (threshold value Hb for high humidity) or more is determined as a high humidity environment. It can be changed arbitrarily according to the situation.

The developing potential setting means C6c'sets the developing potential as an example of the image forming conditions. The developing potential setting means C6c'of Example 2 changes the light amount setting of the exposure machines ROSy to ROSo based on the image density Cn of the formed image. In Example 2, the amount of light is set so that the density of the formed image matches when the image density Cn is low density or high density and the image density Cin is 100%. The adjustment of the light amount itself increases the light amount when the density is low and decreases the light amount when the density is high, as in the first embodiment.

The gradation setting means C6f sets the gradation of an image as an example of image formation conditions. The gradation setting means C6f of the second embodiment changes the gradation setting based on the image density Cn of the formed image and the environmental humidity. In Example 2, when the image density is low and the environment is low in humidity, when Cin = 20%, the gradation is adjusted so as to cancel the development contrast increased by the adjustment of the amount of light. Further, even when Cin = 60%, the gradation is adjusted so as to reduce the development contrast increased by adjusting the amount of light. That is, when Cin = 60%, the correction amount is adjusted to be smaller than that when Cin = 20%. In addition, when Cin = 100%, it is compared with the standard before adjusting the amount of light (initial stage of running. Potential correction is necessary when running at low image density. At the initial stage of running, the image density is almost the same as the middle). The potential is adjusted so that the development contrast is high, and the gradation is not corrected.
Further, in Example 2, when the image density is low and the environment is high in humidity, the gradation is lowered at Cin = 20% and Cin = 60% so as to cancel the development contrast increased by adjusting the amount of light. Further, when Cin = 100%, the potential is adjusted so that the development contrast is higher than the reference before the light amount adjustment (initial stage of running) and the development contrast is lower than in the low humidity environment.

Further, in Example 2, when the image density is high and the humidity is low, the gradation is increased so as to cancel the development contrast decreased by adjusting the amount of light at Cin = 20% and Cin = 60%. When Cin = 100%, the potential is adjusted so that the development contrast is lower than the reference before the light amount adjustment (initial stage of running).
Further, in the case of a high density and high humidity environment, at Cin = 20% and Cin = 60%, the gradation is increased so as to cancel the development contrast reduced by adjusting the amount of light. When Cin = 100%, the potential is adjusted so that the development contrast is lower than the reference before the light amount adjustment (initial stage of running) and the development contrast is lower than in the low humidity environment.
Further, in the halftone (60%), the case where the correction is not performed in the high humidity environment is illustrated, but it is also possible to make the correction even in the high humidity environment.

FIG. 6 is an explanatory diagram of correction of image formation conditions according to humidity when the image density is low. The horizontal axis is gradation, and the vertical axis is the corrected potential (development contrast setting and gradation correction). It is a graph which took the average potential) which combined.
Therefore, in Example 2, when the image density is low, when both the light amount adjustment and the gradation adjustment are performed, as shown in FIG. 6, the corrected potential is 60% Cin in a low humidity environment. At 100%, it becomes higher than the standard (initial stage of running), and the high humidity environment becomes higher when Cin is 100%. Therefore, as a whole, the image formation conditions (light amount and gradation) are corrected so that the density of Cin = 100% is higher than that of the medium-humidity environment. Further, in the case of a low image density and a high humidity environment, the development contrast is not adjusted at Cin = 20% and Cin = 60%, and Cin = 100% has a higher density and a lower humidity environment than the medium humidity environment. The image formation conditions are corrected so that the density is lower than in the case.

FIG. 7 is an explanatory diagram of correction of image formation conditions according to humidity when the image density is high. The horizontal axis is gradation, and the vertical axis is the corrected potential (development contrast setting and gradation correction). It is a graph which took the average potential) which combined.
Further, when the image density is high, when both the light amount adjustment and the gradation adjustment are performed, as shown in FIG. 7, the corrected potential is lowered by the light amount adjustment, but Cin is generated in a low humidity environment. It is lower than the standard at 100% (initial stage of running. When running at high image density, it is necessary to lower the potential as opposed to running at low image density. At the initial stage of running, the image density is almost the same as the middle). Therefore, the high humidity environment becomes low when Cin is 60% and 100%.
That is, in the present application, the deviation when traveling under severe conditions (structural density, low image density) with respect to the change from the initial stage is corrected by the potential.

(Explanation of Flow Chart of Example 2)
Next, the flow of control in the printer U of the second embodiment will be described using a flow chart, a so-called flowchart.
(Explanation of the flowchart of the image formation condition adjustment process)
FIG. 8 is a flowchart of the image formation condition control process of the second embodiment, and is a diagram corresponding to FIG. 3 of the first embodiment.
The processing of each step ST in the flowchart of FIG. 8 is performed according to the program stored in the control unit C of the printer U. Further, this process is executed in parallel with other various processes of the printer U. In the flowchart of FIG. 6, the same ST numbers are assigned to the same processes as those of FIG. 3 of the first embodiment, and the description thereof will be omitted.

In ST9 of FIG. 8, if yes (Y), the process proceeds to ST21.
In ST21, it is determined whether or not the environmental humidity is equal to or less than the threshold value Ha for low humidity. If yes (Y), proceed to ST22, and if no (N), proceed to ST23.
In ST22, the following processes (1) and (2) are executed, and the process proceeds to ST13.
(1) Use the light intensity setting for low density. That is, the amount of light of the exposure machines ROSy to ROSo is increased.
(2) Use the gradation setting for low humidity. That is, correction is performed so that the density becomes high in halftones and high gradations.

In ST23, it is determined whether or not the environmental humidity is equal to or higher than the threshold value Hb for high humidity. If yes (Y), proceed to ST24, and if no (N), proceed to ST25.
In ST24, the following processes (1) and (2) are executed, and the process proceeds to ST13.
(1) Use the light intensity setting for low density. That is, the amount of light of the exposure machines ROSy to ROSo is increased.
(2) Use the gradation setting for high humidity. That is, the correction is performed so that the density becomes high at high gradation.
In ST25, the following processes (1) and (2) are executed, and the process proceeds to ST13.
(1) Use the light intensity setting for low density. That is, the amount of light of the exposure machines ROSy to ROSo is increased.
(2) Use standard gradation settings.

In ST11 of FIG. 8, if yes (Y), the process proceeds to ST26, and if no (N), the process proceeds to ST31.
In ST26, it is determined whether or not the environmental humidity is equal to or less than the threshold value Ha for low humidity. If yes (Y), proceed to ST27, and if no (N), proceed to ST28.
In ST27, the following processes (1) and (2) are executed, and the process proceeds to ST13.
(1) Use the light intensity setting for high density. That is, the amount of light of the exposure machines ROSy to ROSo is increased.
(2) Use the gradation setting for low humidity. That is, correction is performed so that the density becomes high in halftones and high gradations.

In ST28, it is determined whether or not the environmental humidity is equal to or higher than the threshold value Hb for high humidity. If yes (Y), proceed to ST29, and if no (N), proceed to ST30.
In ST29, the following processes (1) and (2) are executed, and the process proceeds to ST13.
(1) Use the light intensity setting for high density. That is, the amount of light of the exposure machines ROSy to ROSo is increased.
(2) Use the gradation setting for high humidity. That is, the correction is performed so that the density becomes high at high gradation.

In ST30, the following processes (1) and (2) are executed, and the process proceeds to ST13.
(1) Use the light intensity setting for high density. That is, the amount of light of the exposure machines ROSy to ROSo is increased.
(2) Use standard gradation settings.
In ST31, standard settings are used for both the light intensity setting and the gradation setting. Then, proceed to ST13.

(Action of Example 2)
In the printer U of the second embodiment having the above configuration, the image formation conditions during image formation are set in consideration of humidity in addition to the image density Cn. That is, the development contrast and the gradation are adjusted as image formation conditions.
In a low humidity environment, if image formation is continued at a low image density, the image of the overall gradation becomes lighter. In particular, the influence is greater in midtones and high gradations than in low gradations. Here, if the amount of light is adjusted to increase the density of Cin = 100%, there is a problem that the density of low gradation (Cin = 20%) becomes too high. Therefore, in the second embodiment, not only the amount of light but also the gradation is adjusted to improve the reproducibility of the density in the low density to high density region as compared with the case where the adjustment is performed only by the amount of light.

Further, in a high-humidity environment, if image formation is continued at a low image density, the density becomes low, but the toner is less likely to be overcharged and the influence on the density is small as compared with the low-humidity environment. Therefore, if the amount of light is adjusted to increase the density of Cin = 100%, there is a problem that low gradation to halftone (about 20% to 80% of Cin) becomes dark. On the other hand, in the second embodiment, the gradation correction of the low gradation and the halftone is made larger than that in the low humidity environment, and the deterioration of the image quality is suppressed as compared with the case where only the light amount is adjusted.

Even in an environment with a high image density, if the amount of light is reduced with Cin = 100% as a reference, the density is too low in low gradation to halftone. Therefore, in the second embodiment, the gradation is corrected to suppress the density decrease in the low gradation to the halftone. It should be noted that the toner is more likely to be charged in the low humidity environment than in the high humidity environment. Therefore, the correction amount in gradation is set larger in the low humidity environment than in the high humidity environment. Therefore, the image quality tends to be stable even if the humidity changes.

(Change example)
Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications are made within the scope of the gist of the present invention described in the claims. It is possible. Examples of modifications (H01) to (H06) of the present invention are illustrated below.

(H01) In the above embodiment, the printer U as an example of the image forming apparatus has been exemplified, but the present invention is not limited to this, and the printer U is composed of, for example, a copying machine, a fax machine, or a multifunction device having a plurality or all of these functions. It is also possible to do.
(H02) In the above embodiment, a configuration in which a five-color developer is used as the printer U has been exemplified, but the present invention is not limited to this, and for example, a monochromatic image forming apparatus, four colors or less, or six or more colors or more. It can also be applied to a multicolor image forming apparatus.

(H03) In the above embodiment, the case where the development contrast is adjusted and the gradation is adjusted is exemplified as the change of the image forming condition, but any image forming condition in which the image density can be adjusted can be used. be. For example, it is possible to control the transfer efficiency as an example of the image formation conditions by changing the contact pressures of the transfer rolls T1y to T1o and T2b.
(H04) In the above embodiment, Example 1 in which only the development contrast is adjusted and Example 2 in which the development contrast and the gradation are adjusted are exemplified, but the present invention is not limited thereto. It is also possible to adjust only the gradation.

(H05) In the above embodiment, the configuration in which the image formation conditions are adjusted based on the image density of the image to be formed is exemplified, but the present invention is not limited thereto. It is also possible to adjust the image formation conditions based on the history of the image density of the images formed in the past.
(H06) The specific numerical values exemplified in the above embodiment can be arbitrarily changed according to the design, specifications, and the like.

B ... Image holding means,
C5 ... Concentration adjusting means,
C6 ... Change means,
C6d ... Humidity acquisition means,
Ca ... Value for low concentration,
Cb ... Value for high concentration,
Cn ... Image density,
Ha ... Threshold for low humidity,
Hb ... Threshold for high humidity,
ROSy-ROSo ... Writing means,
S ... Continuous medium,
U ... Image forming device,
U1a ... Image forming means.

Claims (6)

An image forming means having an image holding means and forming an image on a continuous medium,
Before forming an image on the continuous medium, a density adjusting means for adjusting the density of the image based on the density adjusting image formed on the image holding means with the image holding means and the continuous medium separated from each other.
Humidity acquisition means to acquire humidity and
During image formation on the continuous medium, it is a changing means for changing the image forming conditions by the image forming means based on the density of the image , and the range of the density for changing the image forming conditions based on the humidity is changed. At the same time, when the humidity does not reach the predetermined low humidity threshold, the image formation conditions are changed for the image portion having at least a higher density than the predetermined medium density, and the humidity is predetermined. When the threshold value for high humidity is reached, at least the above-mentioned changing means for changing the image forming conditions for a predetermined high-density image portion, and the above-mentioned changing means.
An image forming apparatus characterized by being equipped with. The image-holding means having a photoconductor on which an image is formed on the surface and an intermediate transfer body in which an image on the surface of the photoconductor is transferred and the transferred image is transferred to a continuous medium.
The image forming means having a writing means for irradiating the charged photoconductor with light for writing an image to form a latent image, and the image forming means.
The changing means for changing the image forming conditions by changing the amount of the writing light, and the changing means.
The image forming apparatus according to claim 1, wherein the image forming apparatus is provided. The changing means for changing the image forming conditions by increasing the amount of light of the writing light when the density of the formed image does not reach a predetermined low density value.
The image forming apparatus according to claim 2, wherein the image forming apparatus is provided. The changing means for changing the image forming conditions by reducing the amount of light of the writing light when the density of the formed image reaches a predetermined value for high density.
The image forming apparatus according to claim 2, wherein the image forming apparatus is provided. The changing means for changing the image forming conditions by making a correction to increase the density of the formed image when the density of the image reaches a preset value.
The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus is provided. The changing means for changing the image forming conditions by making a correction to reduce the density of the formed image when the density of the image does not reach a preset value.
The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus is provided.

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