JP6784060B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus capable of performing a patch forming process for forming a patch, which is a toner image for testing, on a transfer object.

Conventionally, as an image forming apparatus, in order to correct a change in density or misalignment of an image, when the number of printed sheets exceeds a predetermined value or when there is a temperature change of more than a predetermined value, for example, a paper transport belt or the like. Some form a patch (pattern image for testing) and make corrections based on the density and position of this patch. As a device that executes such correction, a device that prohibits patch formation when the remaining amount of toner is low and suppresses toner consumption is known (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-245646 (see paragraph 0021, FIG. 4, etc.)

By the way, the density change and the misalignment of the image due to the temperature change are more noticeable than the density change and the misalignment due to the deterioration of the toner as the number of printed sheets increases. Therefore, if the correction according to the temperature change is prohibited when the remaining amount of toner is lowered, the print quality may be significantly deteriorated.

Therefore, an object of the present invention is to achieve both suppression of toner consumption by patch formation when the remaining amount of toner is low and suppression of deterioration of print quality.

In order to solve the above problems, the image forming apparatus according to the present invention includes an image forming unit for forming a toner image on a transfer target object and a control unit.
The control unit can execute a patch forming process for forming a patch, which is a toner image for testing, on the transfer object.
When the remaining amount of toner is more than a predetermined value, the control unit executes the patch forming process when the print amount condition such that the print amount from the previous patch formation is equal to or more than the print amount threshold is satisfied, and the toner is executed. If the remaining amount of toner is less than or equal to a predetermined value, the patch forming process is not executed even if the printing amount condition is satisfied, and the temperature difference between the time of the previous patch forming and the time of receiving the printing command is equal to or greater than the temperature threshold. When a certain temperature condition is satisfied, the patch forming process is executed regardless of the remaining amount of toner.

According to this configuration, when the remaining amount of toner is as small as a predetermined value or less, the patch forming process is not executed even if the print amount condition is satisfied, so that the consumption of toner can be suppressed. Further, even when the remaining amount of toner is as low as a predetermined value or less, the patch forming process is executed when the temperature condition is satisfied, so that it is possible to correct a remarkable density change or misalignment of the image due to the temperature change, and printing. Deterioration of quality can be suppressed.

Further, the image forming apparatus according to the present invention includes an image forming unit for forming a toner image on a transfer target object and a control unit.
The control unit can execute a patch forming process for forming a patch, which is a toner image for testing, on the transfer object.
When the remaining amount of toner is more than a predetermined value, the control unit executes the patch forming process and executes the toner when a printing amount condition such that the printing amount from the previous patch formation is equal to or more than the printing amount threshold is satisfied. When the remaining amount of toner is equal to or less than the predetermined value, the process of increasing the print amount threshold and the patch forming process executed based on the print amount condition are performed as compared with the case where the remaining amount of toner is larger than the predetermined value. If at least one of the processes for reducing the amount of toner used in the above is executed and a temperature condition such that the temperature difference between the time of the previous patch formation and the time of receiving the print command is equal to or greater than the temperature threshold is satisfied, the toner remains. The patch forming process is executed regardless of the amount.

According to this configuration, when the remaining amount of toner is as low as a predetermined value or less, the print amount threshold is increased, that is, the print amount condition is tightened, or the patch forming process is executed based on the print amount condition. Since the amount of toner used is reduced, the frequency of the patch forming process started based on the print amount condition can be reduced, the amount of toner used can be reduced, and the consumption of toner can be suppressed. Further, even when the remaining amount of toner is as low as a predetermined value or less, the patch forming process is executed when the temperature condition is satisfied, so that it is possible to correct a remarkable density change or misalignment of the image due to the temperature change, and printing. Deterioration of quality can be suppressed.

Further, the image forming apparatus according to the present invention includes an image forming unit for forming a toner image on a transfer target object and a control unit.
The control unit performs a first patch forming process for forming a patch, which is a test toner image for correcting a development bias, on the transfer object, and an image pattern and the image pattern on the transfer object. It is possible to carry out a second patch forming process for forming a patch, which is a toner image for testing for correcting the relationship with the density corresponding to.
The control unit has a first print amount condition such that the first print amount, which is the print amount from the previous first patch forming process, is equal to or higher than the first print amount threshold, and the previous first print amount, regardless of the remaining amount of toner. The first patch forming process is executed when at least one of the first temperature conditions such that the temperature difference between the patch forming process and the reception of the print command is equal to or greater than the first temperature threshold is satisfied.
The control unit satisfies the second print amount condition that the second print amount, which is the print amount from the previous second patch forming process, is equal to or larger than the second print amount threshold, and the remaining amount of toner is a predetermined value. If the amount is larger, the second patch forming process is executed, and if the remaining amount of toner is equal to or less than a predetermined value, the second patch forming process is executed even if the second print amount condition is satisfied. However, when the second temperature condition such that the temperature difference between the time of the previous second patch forming process and the time of receiving the print command is equal to or greater than the second temperature threshold is satisfied, the second is not limited to the remaining amount of toner. Execute the patch formation process.

According to this configuration, when the remaining amount of toner is as small as a predetermined value or less, the second patch forming process is not executed even if the second print amount condition is satisfied, so that the consumption of toner can be suppressed. Further, even when the remaining amount of toner is as small as a predetermined value or less, the first patch forming process or the second patch forming process is executed when the first temperature condition or the second temperature condition is satisfied, so that the image due to the temperature change is remarkable. It is possible to correct various changes in density and suppress deterioration of print quality.

According to the present invention, it is possible to suppress both the consumption of toner by forming a patch when the remaining amount of toner is low and the deterioration of print quality.

It is a figure which shows the schematic structure of the color printer as an example of the image forming apparatus which concerns on 1st Embodiment of this invention. It is a block diagram which shows the control part and the like. It is a figure which shows the linear function for setting the reference value of development bias. It is a flowchart which shows the operation of a control part. It is a flowchart which shows the 1st development bias correction processing. It is a flowchart which shows the image formation process. It is a flowchart which shows the operation of the control part which concerns on 2nd Embodiment. It is a flowchart which shows the 2nd development bias correction processing. It is a flowchart which shows the operation of the control part which concerns on 3rd Embodiment. It is a flowchart which shows the operation of the control part which concerns on 4th Embodiment. It is a flowchart which shows the operation of the control part which concerns on 5th Embodiment.

[First Embodiment]
Next, the color printer 1 as an example of the image forming apparatus according to the first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the direction will be described in the direction shown in FIG. That is, the left side in FIG. 1 is "front", the right side is "rear", the front side is "right", and the back side is "left". Further, the vertical direction in FIG. 1 is defined as "up and down".

As shown in FIG. 1, the color printer 1 mainly includes a paper feeding unit 20, an image forming unit 30, and a control unit 100 in the main body housing 10. On the upper side of the main body housing 10, an upper cover 12 that opens and closes the upper part of the main body housing 10 is provided so as to be rotatable up and down with the rear side as a fulcrum. Inside the main body housing 10, a temperature sensor 103 for detecting the temperature inside the main body housing 10 and four toner remaining amount sensors 104 for detecting the remaining amount of toner in each of the four process cartridges 50 described later are provided. Has been done. The toner remaining amount sensor 104 is, for example, an optical sensor including a light emitting element and a light receiving element, and detects the remaining amount of toner in the process cartridge 50 by passing light through a transmission window (not shown) of the process cartridge 50. ing.

The paper feed unit 20 is provided in the lower part of the main body housing 10 and includes a paper feed tray 21 for accommodating the paper S and a supply mechanism 22 for supplying the paper S from the paper feed tray 21 to the image forming unit 30. There is. The supply mechanism 22 includes a pickup roller 23, a separation roller 24, a separation pad 25, a paper dust removing roller 26, and a resist roller 27.

In the paper feed unit 20, after the paper S in the paper feed tray 21 is sent out by the pickup roller 23, the paper S is separated one by one between the separation roller 24 and the separation pad 25. After that, the paper S is supplied to the image forming unit 30 by rotating the resist roller 27 after the paper dust is removed by the paper dust removing roller 26 and the tip position is regulated by the resist roller 27 in a state where the rotation is stopped. Will be done.

The image forming unit 30 includes four LED units 40, four process cartridges 50, a transfer unit 70, and a fixing unit 80.

The LED unit 40 is arranged above the photoconductor drum 51 so as to face each other, and includes a plurality of LEDs (Light Emitting Diodes) (not shown) arranged in the left-right direction at the lower end thereof. The LED unit 40 exposes the surface of the photoconductor drum 51 by blinking the light emitting portion based on the image data.

The process cartridges 50 are arranged side by side in the front-rear direction between the upper cover 12 and the paper feed tray 21, and are detachably attached to the main body housing 10 with the upper cover 12 open. It has become. Each process cartridge 50 includes a photoconductor drum 51, a charger 52 for charging the photoconductor drum 51, a developing roller 53 for supplying toner to the photoconductor drum 51, a supply roller 54, and a layer thickness regulation. It includes a blade 55 and a toner accommodating portion 56 for accommodating toner.

The transfer unit 70 is provided between the paper feed unit 20 and the process cartridge 50, and includes a drive roller 71, a driven roller 72, a transport belt 73 composed of an endless belt, four transfer rollers 74, and patch detection. It is equipped with a sensor 75. The transport belt 73 is stretched between the drive roller 71 and the driven roller 72, and the outer surface is arranged to face each photoconductor drum 51, and each transfer roller 74 is placed inside each photoconductor drum 51. It is arranged so as to sandwich the transport belt 73 with and.

The patch detection sensor 75 is a sensor that detects a toner image (hereinafter, also referred to as “patch”) for testing, specifically for density measurement, formed on the transport belt 73, and faces the rear portion of the transport belt 73. Is arranged. As such a patch detection sensor 75, for example, a light reflection type sensor including a light emitting element and a light receiving element can be adopted.

The fixing unit 80 is provided behind the process cartridge 50 and the transfer unit 70, and includes a heating roller 81 and a pressure roller 82 that is arranged to face the heating roller 81 and presses the heating roller 81.

In the image forming unit 30 configured in this way, first, the surface of each photoconductor drum 51 is uniformly charged by the charger 52, and then exposed by the light emitted from each LED unit 40. As a result, an electrostatic latent image based on the image data is formed on each photoconductor drum 51.

Further, the toner in the toner accommodating portion 56 is supplied to the developing roller 53 by the rotation of the supply roller 54, and enters between the developing roller 53 and the layer thickness regulating blade 55 by the rotation of the developing roller 53 to have a constant thickness. It is supported on the developing roller 53 as a thin layer.

The toner supported on the developing roller 53 is supplied to the electrostatic latent image formed on the photoconductor drum 51 when the developing roller 53 faces the photoconductor drum 51 and comes into contact with it. As a result, the toner is selectively supported on the photoconductor drum 51 to visualize the electrostatic latent image, and the toner image is formed by reverse development.

Next, the paper S supplied on the transport belt 73 passes between the photoconductor drums 51 and the transfer rollers 74, so that the toner image formed on the photoconductor drums 51 is formed on the paper S. Transcribed. Then, as the paper S passes between the heating roller 81 and the pressure roller 82, the toner image transferred onto the paper S is heat-fixed.

When detecting the density of the patch, after an electrostatic latent image for density measurement is formed on the surface of the photoconductor drum 51, toner is supplied from the developing roller 53 to the electrostatic latent image for density measurement. By doing so, a patch is formed on the photoconductor drum 51. The patch formed on the photoconductor drum 51 is transferred onto the transport belt 73 by the transfer roller 74, and then the density is detected by the patch detection sensor 75.

That is, the image forming unit 30 can form a toner image on the transfer target such as the photoconductor drum 51, the paper S, and the transport belt 73.

A transport roller 15 is provided behind the fixing unit 80, and a discharge roller 16 is provided above the fixing unit 80. The paper S discharged from the fixing unit 80 is discharged to the outside of the main body housing 10 by the transport roller 15 and the discharge roller 16 and accumulated in the paper discharge tray 13.

Next, the control unit 100 will be described in detail.
As shown in FIG. 2, the control unit 100 includes a CPU, RAM, ROM, and an input / output circuit, and is output from a print command output from an external computer PC and output from the sensors 103, 75, 104. Control is executed by performing various arithmetic processes based on the incoming information and the programs and data stored in the ROM or the like. Specifically, the control unit 100 includes a patch forming means 101, a density detecting means 110, a reference value setting means 120, a first correction value setting means 130, a second correction value setting means 140, and a printing means 150. The storage means 160 composed of the above-mentioned RAM, ROM, and the like is provided. In other words, the control unit 100 operates based on the program stored in the storage means 160, so that the patch forming means 101, the concentration detecting means 110, the reference value setting means 120, the first correction value setting means 130, and the first correction value setting means 130 are used. 2 It functions as a correction value setting means 140 and a printing means 150.

The patch forming means 101 has a function of executing a patch forming process (patch forming step) for forming a patch on the transport belt 73. Specifically, the patch forming means 101 forms two patches having a predetermined concentration (for example, 100%) on the transport belt 73 with different development biases Vn1 and Vn2 in the patch forming process. That is, the patch forming means 101 forms the first patch with the development bias Vn1 and forms the second patch with the development bias Vn2. The parameters other than the development bias such as the charging bias and the transfer bias may be set in any way, and may be the same values as those at the time of image formation, for example.

The development biases Vn1 and Vn2 are set to values obtained by adding / subtracting a predetermined value Vα to the current development bias Vn as shown in the following equations (1-1) and (1-2).
Vn1 = Vn + Vα ... (1-1)
Vn2 = Vn-Vα ... (1-2)
Then, the patch forming means 101 executes (starts) the patch forming process when various conditions shown below are satisfied.

The patch forming means 101 executes a patch forming process (hereinafter, also referred to as an initial patch forming process) on condition that a new process cartridge 50 is mounted on the main body housing 10. Further, the patch forming means 101 has a print amount condition that the print amount Pn from the previous patch formation is equal to or higher than the print amount threshold Pth1 after the first patch formation process is executed, and the previous patch formation and the print command. The patch forming process is performed based on the temperature condition that the absolute value of the temperature difference ΔT1 at the time of reception is equal to or higher than the temperature threshold Tth1 and the remaining amount condition regarding the remaining amount of toner measured (detected) by the toner remaining amount sensor 104. Judging whether to execute.

Here, the print amount Pn means the print amount between the time when the patch forming process was performed last time and the time when the patch formation process is performed this time. As the print amount Pn, for example, the number of prints, the number of rotations of the photoconductor drum 51, the number of rotations of the pickup roller 23, and the like can be used, but in the present embodiment, the number of prints will be described. Further, the print amount Pn is counted by a counter (not shown). The print amount Pn counted by the counter is reset every time the patch forming process is performed. Further, the temperature threshold value Tth1 can be set to, for example, 10 ° C.

When the temperature condition is satisfied, the patch forming means 101 executes the patch forming process regardless of the remaining amount of toner (that is, the remaining amount condition). In the present embodiment, the temperature condition is the same regardless of the remaining amount of toner. Further, when the remaining amount of toner (hereinafter, also referred to as "remaining amount of toner Q") is larger than the predetermined value Qth1, the patch forming means 101 executes the patch forming process when the print amount condition is satisfied, and the toner. When the remaining amount Q is equal to or less than the predetermined value Qth1, the patch forming process is not executed even if the print amount condition is satisfied.

The concentration detecting means 110 has a function of executing a concentration detecting process (concentration detecting step) for detecting the densities of the two patches on the transport belt 73 by the patch detecting sensor 75. When the concentration detecting means 110 detects the densities of the two patches, the detected densities C1 and C2 (hereinafter, also referred to as “detection densities”) are used as a reference together with the development biases Vn1 and Vn2 applied at that time. Output to the value setting means 120.

The reference value setting means 120 has a function of executing a reference value setting process (reference value setting step) for setting a reference value Va of the development bias Vn based on the detection concentrations C1 and C2 and the development biases Vn1 and Vn2 described above. have. Specifically, the reference value setting means 120 shows the relationship between the development bias and the density as shown in FIG. 3 based on each detection density C1 and C2 and each development bias Vn1 and Vn2 in the reference value setting process. Find the linear function. Then, the reference value setting means 120 sets the reference value Va of the development bias Vn based on this linear function and the target density Ct.

When the reference value Va is set, the reference value setting means 120 stores the set reference value Va in the storage means 160. When the new process cartridge 50 is mounted on the main body housing 10, the reference value setting means 120 sets the initial value V0 as the reference value Va. That is, when the concentration detection process has not been performed even once since the new process cartridge 50 is mounted on the main body housing 10, the initial value V0 is set as the reference value Va.

The first correction value setting means 130 sets the first correction value α after the reference value setting process when the patch forming process, the density detection process, and the reference value setting process are performed due to the establishment of the print amount condition. It has a function of executing the first correction value setting process (first correction value setting step). Specifically, the first correction value setting means 130 sets the first correction value α based on the print amount Pn and the difference between the previous value Vap of the reference value Va and the current value Van. Specifically, the first correction value setting means 130 sets the first correction value α by the following equation (2).
α = (Van-Vap) / Pn ・ ・ ・ (2)

The print amount Pn in the formula (2) is the print amount when the patch formation process, the density detection process, and the reference value setting process are performed due to the condition of the print amount. In other words, it is the total amount of the print amount from the previous time when the patch forming process is performed until the present time, and is the same value as the print amount threshold value Pth1. Therefore, the denominator on the right side of the equation (2) may be replaced from Pn to Pth1.

Further, the first correction value setting means 130 sets the first correction value α to the initial value α0 when the new process cartridge 50 is mounted on the main body housing 10. That is, if the first correction value setting process has not been performed even once after the new process cartridge 50 is mounted on the main body housing 10, the initial value α0 is set as the first correction value α.

When the first correction value α is set, the first correction value setting means 130 stores the set first correction value α in the storage means 160.

The second correction value setting means 140 sets the second correction value β after the reference value setting process when the patch forming process, the concentration detection process, and the reference value setting process are performed due to the establishment of the temperature condition. 2 It has a function to execute a correction value setting process (second correction value setting step). Specifically, the second correction value setting means 140 has a temperature change amount ΔT2 which is a temperature difference between the previous patch forming process and the current patch forming process, and the previous value Vap and the current value Van of the reference value Va. The second correction value β is set based on the difference. Specifically, the second correction value setting means 140 sets the second correction value β by the following equation (3).
β = | Van-Vap | / | ΔT2 | ... (3)

The second correction value setting means 140 sets the second correction value β to the initial value β0 when the new process cartridge 50 is mounted on the main body housing 10. That is, if the second correction value setting process has not been performed even once after the new process cartridge 50 is mounted on the main body housing 10, the initial value β0 is set as the second correction value β.

When the second correction value β is set, the second correction value setting means 140 stores the set second correction value β in the storage means 160.

The printing means 150 has a function of executing a development bias setting process (development bias setting process) and a printing process (printing process) when a printing command is received. In the development bias setting process, the printing means 150 sets the development bias Vn based on the development bias reference value Va, the first correction value α, the print amount Pn, the temperature difference ΔT1, and the second correction value β. doing. Specifically, the printing means 150 sets the development bias Vn by the following formula (4). In the equation (4), the temperature difference ΔT1 is represented by a value (Tn−Tp) obtained by subtracting the temperature Tp at the time of the previous patch forming process from the temperature Tn at the time of receiving the print command.
Vn = Va + α ・ Pn + β ・ (Tn-Tp) ・ ・ ・ (4)

When the new process cartridge 50 is mounted on the main body housing 10, the printing means 150 sets the temperature Tp at the time of the previous patch forming process to the initial value T0. That is, if the development bias setting process has not been performed even once since the new process cartridge 50 was mounted on the main body housing 10, the initial value T0 is set as the temperature Tp at the time of the previous patch formation process. There is.

In addition to controlling the LED unit 40 and the like in the printing process, the printing means 150 forms a toner image on the photoconductor drum 51 by applying the development bias Vn set in the development bias setting process to the developing roller 53. ing. Further, the printing means 150 counts the above-mentioned print amount Pn when the printing process is being executed.

The storage means 160 stores the above-mentioned correction values α and β, the history of the reference value Va, the print amount Pn, the temperature Tp at the time of the previous patch forming process, and the like.

Next, the operation (control method) of the control unit 100 will be described in detail. Upon receiving the print command, the control unit 100 executes the process shown in FIG. In FIG. 4, the first development bias correction process shows a process including the patch formation process, the density detection process, the reference value setting process, the first correction value setting process, and the second correction value setting process described above. ..

Here, the processes shown in FIG. 4 are performed for each of the four process cartridges 50, that is, for each toner color. The first development bias correction process may be performed for four colors at the same time, or may be performed separately for each toner color. Specifically, for example, when the start condition of the first development bias correction process is satisfied in any one of the four colors, the first development bias correction process for the four colors may be executed at the same time. Further, for example, when the start condition of the first development bias correction process is satisfied in a predetermined color among the four colors, the first development bias correction process is executed only for the predetermined color, and the start condition is not satisfied. It is not necessary to perform the first development bias correction process for the other three colors. Further, the first development bias correction process including the initial patch forming process performed when the new process cartridge 50 is mounted may be performed simultaneously for four colors or separately for each toner color.

As shown in FIG. 4, when the control unit 100 receives the print command (START), the control unit 100 first measures the current temperature Tn by the temperature sensor 103 (S1). After step S1, the control unit 100 measures the current toner remaining amount Q by the toner remaining amount sensor 104 (S2).

After step S2, the control unit 100 determines whether or not the remaining amount of toner Q is greater than the predetermined value Qth1 (S3). If it is determined in step S3 that Q> Qth1 (Yes), the control unit 100 determines whether or not the absolute value of the temperature difference ΔT1 is equal to or greater than the temperature threshold Tth1 (S4).

If it is determined in step S4 that ΔT1 ≧ Tth1 (Yes), the control unit 100 executes the first development bias correction process (S6). The first development bias correction process will be described in detail later.

If it is determined in step S4 that ΔT1 <Tth1 (No), the control unit 100 determines whether or not the print amount Pn is equal to or greater than the print amount threshold Pth1 (S5). If it is determined in step S5 that Pn ≧ Pth1 (Yes), the control unit 100 executes the first development bias correction process (S6). That is, when the toner remaining amount Q is larger than the predetermined value Qth1, the control unit 100 executes the first development bias correction process when either the temperature condition (S4) or the print amount condition (S5) is satisfied.

After step S6 or when it is determined as No in step S5, the control unit 100 executes the image forming process (S9). The image forming process will be described in detail later.

If it is determined in step S3 that Q ≦ Qth1 (No), the control unit 100 determines whether or not the absolute value of the temperature difference ΔT1 is equal to or greater than the temperature threshold value Tth1 (S7). If it is determined in step S7 that ΔT1 ≧ Tth1 or more (Yes), the control unit 100 executes the first development bias correction process (S8). Here, the first development bias correction process in step S8 and the first development bias correction process in step S6 are the same process.

After step S8 or when it is determined as No in step S7, the control unit 100 executes the image forming process (S9). That is, whether or not the control unit 100 executes the first development bias correction process by looking only at the temperature condition without looking at the print amount condition when the toner remaining amount Q is equal to or less than the predetermined value Qth1. Is judging. Therefore, when the remaining amount of toner Q is equal to or less than the predetermined value Qth1, the first development bias correction process is not executed even if the print amount condition is satisfied.

As shown in FIG. 5, when the control unit 100 starts the first development bias correction process (START), first, two types of development biases are added or subtracted from the current development bias Vn by adding or subtracting a predetermined value Vα. Vn1 and Vn2 are set (S21). After step S21, the control unit 100 forms two patches on the transport belt 73 by the set two types of development biases Vn1 and Vn2 (S22).

After step S22, the control unit 100 measures the concentrations C1 and C2 of the two patches on the transport belt 73 by the patch detection sensor 75, respectively (S23). After step S23, the control unit 100 calculates a linear function shown in FIG. 3 using two types of development biases Vn1 and Vn2 and densities C1 and C2, and based on the linear function and the target density Ct, the development bias Vn The reference value Va is set (S24).

After step S24, the control unit 100 sets the first correction value α or the second correction value β according to the condition (printing amount condition or temperature condition) that triggered the start of the first development bias correction processing this time. Set (S25). Specifically, in step S25, when the control unit 100 determines that the current first development bias correction process has been started depending on the print amount condition, the control unit 100 sets the first correction value α by the above-mentioned equation (2). Further, in step S25, when the control unit 100 determines that the first development bias correction process of this time has been started depending on the temperature condition, the control unit 100 sets the second correction value β by the above-mentioned equation (3).

After step S25, the control unit 100 resets the counter that counts the print amount Pn to set the print amount Pn to 0 (S26), and ends the first development bias correction process.

As shown in FIG. 6, when the control unit 100 starts the image forming process (START), first, the development bias Vn is set by the above-mentioned equation (4) (S31). After step S31, the control unit 100 controls image formation on one sheet of paper S (S32).

After step S32, the control unit 100 counts up the print amount Pn by the counter that counts the print amount Pn (S33). Specifically, the print amount Pn is counted up by adding 1 to the previous value Pn'of the print amount Pn.

After step S33, the control unit 100 determines whether or not the print data has been lost (S34). If it is determined in step S34 that the print data still remains (No), the control unit 100 returns to the process of step S31. If it is determined in step S34 that all the print data has disappeared (Yes), the control unit 100 ends the image forming process.

Based on the above, the following effects can be obtained in the present embodiment.
When the remaining amount of toner Q is as small as the predetermined value Qth1 or less, the patch forming process (first development bias correction process) is not executed even if the print amount condition is satisfied, so that the toner consumption can be suppressed. Further, even when the remaining toner Q is as small as the predetermined value Qth1 or less, the patch formation process is executed when the temperature condition is satisfied, so that it is possible to correct a remarkable density change of the image due to the temperature change, and the print quality can be improved. The decrease can be suppressed.

Even if the remaining toner Q is as small as the predetermined value Qth1 or less, the temperature condition is the same as in the normal state (when the remaining amount of toner is large), so the frequency of the patch forming process started based on the temperature condition is equivalent to the normal time. It is possible to satisfactorily correct the remarkable density change of the image due to the temperature change.

In the first embodiment, the correction process performed based on the patch formed by the patch forming process is the first development bias correction process, but the present invention is not limited to this, and for example, gamma correction as described later. It may be processing, position correction processing, or the like.

[Second Embodiment]
Next, the second embodiment of the present invention will be described in detail with reference to the drawings as appropriate. Since the control of the control unit 100 according to the first embodiment described above is partially modified in this embodiment, the members and processes (steps) having substantially the same structure as those in the first embodiment are the same. Is added, and the description thereof will be omitted.

In the first embodiment, the temperature condition is the same regardless of the toner remaining amount Q (see steps S4 and S7), and the amount of toner used in the patch forming process executed based on the temperature condition is the same (step S6). , See step S22 in the first development bias correction process executed in S8), but in the second embodiment, the temperature condition and the amount of toner used are changed according to the remaining amount of toner Q. Specifically, in the second embodiment, when the toner remaining amount Q becomes the predetermined value Qth1 or less, the control unit 100 sets the temperature threshold value as compared with the case where the toner remaining amount Q is larger than the predetermined value Qth1. It's getting bigger. Further, when the toner remaining amount Q becomes the predetermined value Qth1 or less, the control unit 100 performs the patch forming process based on the temperature condition as compared with the case where the toner remaining amount Q is larger than the predetermined value Qth1. The amount of toner used is reduced.

Specifically, in the second embodiment, the control unit 100 is configured to perform control according to the flowcharts shown in FIGS. 7 and 8. The flowchart shown in FIG. 7 includes the same steps S1 to S6 and S9 as the flowchart shown in FIG. 4, and has a configuration in which new steps S41 and S42 are provided instead of steps S7 and S8 of FIG.

In step S41, the control unit 100 determines whether or not the temperature difference ΔT1 is equal to or greater than the temperature threshold Tth2, which is larger than the temperature threshold Tth1. If it is determined in step S41 that ΔT1 <Tth2 (No), the control unit 100 executes the image forming process (S9).

When it is determined in step S41 that ΔT1 ≧ Tth2, the control unit 100 executes a second development bias correction process different from the first development bias correction process (S42). The second development bias correction process is the process shown in the flowchart of FIG. 8, and includes the same steps S21, S25, and S26 as the flowchart shown in FIG. 5, and new steps S51 to S51 instead of steps S22 to S24 of FIG. It has a configuration in which S53 is provided.

In step S51, the control unit 100 forms one patch on the transport belt 73 by the development bias Vn set in step S21. That is, the number of patches (that is, the amount of toner used) in the patch forming process (S51) in the second development bias correction process is smaller than the number of patches in the patch forming process (S22) in the first development bias correction process. It has become.

After step S51, the control unit 100 measures the concentration of one patch on the transport belt 73 by the patch detection sensor 75 (S52). After step S52, the control unit 100 determines the development bias based on the development bias Vn when the patch is formed and the development bias ΔVa corresponding to the difference between the density (detection density) measured in step S52 and the target density. The reference value Va of is set (S53). That is, the control unit 100 (reference value setting means 120) executes the reference value setting process (S24) when the toner remaining amount Q is equal to or less than the predetermined value Qth1 and the toner remaining amount Q is larger than the predetermined value Qth1. ), A reference value setting process (reference value setting process) is executed. Specifically, the reference value setting means 120 sets the reference value Va by the following equation (5).
Va = Vn−ΔVa ・ ・ ・ (5)

Here, the development bias ΔVa is the difference between the development bias Vn at the time of the patch forming process this time and the ideal development bias with respect to the target density. The reference value setting means 120 obtains the development bias ΔVa based on, for example, a map showing the relationship between the development bias ΔVa and the difference between the detected density and the target density.

As described above, according to the second embodiment, when the remaining amount of toner Q is as small as the predetermined value Qth1 or less, the temperature threshold value is increased, so that the frequency of the patch forming process started based on the temperature condition is reduced. It is possible to suppress the consumption of toner. Further, when the remaining amount of toner Q is as small as the predetermined value Qth1 or less, the amount of toner used in the patch forming process executed based on the temperature condition is reduced, so that the consumption of toner can be suppressed.

In the second embodiment, when the second development bias correction process is performed on a predetermined color among the four colors, the second development bias correction process may be performed on the other three colors in the same manner.

Further, in the second embodiment, the number of patches is reduced from two to one in order to reduce the amount of toner used in the patch forming process, but the present invention is not limited to this. For example, when the remaining amount of toner Q is more than the predetermined value Qth1, a predetermined number of patches are formed at a predetermined first density, and when the remaining amount of toner Q is less than or equal to the predetermined value Qth1, it is smaller than the first concentration. A predetermined number of patches may be formed at the second concentration.

[Third Embodiment]
Next, the third embodiment of the present invention will be described in detail with reference to the drawings as appropriate. Since the control of the control unit 100 according to the second embodiment described above is partially modified in this embodiment, the members and processes (steps) having substantially the same structure as those in the second embodiment are the same. Is added, and the description thereof will be omitted.

In the first embodiment and the second embodiment, when the toner remaining amount Q is equal to or less than the predetermined value Qth1, the patch forming process based on the print amount condition is not executed by not looking at the print amount condition. However, in the third embodiment, even when the remaining toner Q is equal to or less than the predetermined value Qth1, the patch forming process is executed based on the print amount condition, but the print amount condition at this time is made strict and printing is performed. The amount of toner used in the patch forming process based on the amount condition is reduced. Further, in the third embodiment, as the remaining amount of toner Q gradually decreases, the frequency of executing the patch forming process based on the print amount condition and the amount of toner used in the patch forming process gradually decrease. It is configured as follows.

Specifically, in the third embodiment, the control unit 100 is configured to perform control according to the flowchart shown in FIG. The flowchart shown in FIG. 9 includes the same steps S1 to S6, S9, S41, and S42 as the flowchart shown in FIG. 7, and also includes new steps S61 to S65.

The process of step S61 is executed when it is determined in step S3 that Q ≦ Qth1 (No). In step S61, the control unit 100 determines whether or not the remaining amount of toner Q is larger than the predetermined value Qth2, which is smaller than the predetermined value Qth1. If it is determined in step S61 that Q> Qth2 (Yes), the control unit 100 executes the process of step S41 described above.

When it is determined in step S41 that ΔT1 <Tth2 (No), the control unit 100 determines whether or not the print amount Pn is equal to or greater than the print amount threshold Pth2 larger than the print amount threshold Pth1 (S64). ). That is, when the toner remaining amount Q is equal to or less than the predetermined value Qth1, the print amount threshold value (Pth1 <Pth2) is larger than when the toner remaining amount Q is larger than the predetermined value Qth1.

If it is determined in step S64 that Pn ≧ Pth2 (Yes), the control unit 100 executes the second development bias correction process (S65). Here, the second development bias correction process is a process including a patch formation process in which the number of patches is smaller than the patch formation process in the first development bias correction process, as described in the second embodiment (. (See FIG. 8). As a result, when the remaining amount of toner Q is equal to or less than the predetermined value Qth1, the amount of toner used in the patch forming process executed based on the print amount condition is compared with the case where the remaining amount of toner Q is larger than the predetermined value Qth1. Is decreasing.

If it is determined in step S64 that Pn <Pth2 (No), the control unit 100 executes the image forming process (S9). If it is determined in step S61 that Q ≦ Qth2 (No), the control unit 100 executes the same process as in step S41 (S62). If it is determined in step S62 that ΔT1 ≧ Tth2 (Yes), the control unit 100 executes the same process as in step S42 (S63). After step S63, or when it is determined as No in step S62, the control unit 100 executes the image forming process (S9). That is, when the remaining amount of toner Q is the predetermined value Qth2 or less, the patch forming process based on the print amount condition is not executed by not looking at the print amount condition.

As described above, according to the third embodiment, the following effects can be obtained.
When the remaining toner Q is as low as the predetermined value Qth1 or less, the print amount threshold is increased, that is, the print amount condition is tightened to reduce the frequency of the patch forming process started based on the print amount condition. Therefore, toner consumption can be suppressed. Further, when the remaining amount of toner Q is as small as the predetermined value Qth1 or less, the amount of toner used in the patch forming process executed based on the print amount condition is reduced, so that the consumption of toner can be suppressed.

Further, when the remaining amount of toner Q is further reduced to a predetermined value Qth2 or less, the patch forming process based on the print amount condition is not executed, so that the consumption of toner is further suppressed when the remaining amount of toner Q is extremely low. be able to.

Even when the remaining toner Q is as small as the predetermined values Qth1 and Qth2 or less, the patch formation process is executed when the temperature condition is satisfied, so that it is possible to correct a remarkable density change of the image due to the temperature change, and the print quality can be improved. The decrease can be suppressed.

When the remaining toner Q is as small as the predetermined values Qth1 and Qth2 or less, the frequency of the patch forming process started based on the temperature condition can be reduced by increasing the temperature threshold value (Tth1 <Tth2). Therefore, toner consumption can be suppressed.

When the remaining amount of toner Q is as small as the predetermined values Qth1 and Qth2 or less, the amount of toner used in the patch forming process executed based on the temperature condition is reduced (S42, S63), so that the toner consumption is suppressed. be able to.

In the third embodiment, when the remaining amount of toner Q is the predetermined value Qth1 or less (specifically, when Qth1 ≧ Q> Qth2), the print amount condition is strict and the patch is formed based on the print amount condition. Although the amount of toner used in the treatment is reduced, the present invention is not limited to this. For example, when the remaining amount of toner Q is equal to or less than the predetermined value Qth1, the print amount condition is strict, but the amount of toner used in the patch forming process based on the print amount condition is the same as when Q> Qth1. May be good. Further, for example, when the remaining amount of toner Q is equal to or less than the predetermined value Qth1, the amount of toner used in the patch forming process based on the print amount condition is reduced, but the print amount condition is the same as in the case of Q> Qth1. May be. Specifically, in FIG. 9, the print amount threshold value in step S64 may be changed from Pth2 to Pth1, and the correction process in step S65 may be the first development bias correction process.

[Fourth Embodiment]
Next, the fourth embodiment of the present invention will be described in detail with reference to the drawings as appropriate. Since the control of the control unit 100 according to the first embodiment described above is partially modified in this embodiment, the members and processes (steps) having substantially the same structure as those in the first embodiment are the same. Is added, and the description thereof will be omitted.

As shown in FIG. 10, the control unit 100 according to the fourth embodiment executes the same first development bias correction process (S72) as in the first embodiment, as well as the gamma correction process (S76) and the position correction process (S76). S80) and is executed. In the following description, for convenience, the patch forming process in the first development bias correction process described above is referred to as a "first patch forming process" to distinguish it from the patch forming process in each correction process.

In the gamma correction processing, in order to correct the deviation between the indicated density (indicated gradation) by the external computer PC and the output density of the color printer 1 itself, the image pattern (dither pattern) and the indicated density corresponding to the image pattern are corrected. It is a process to correct the relationship with. That is, when the control unit 100 receives the indicated density from the computer PC, the control unit 100 selects an image pattern corresponding to the indicated density and forms an image with the image pattern, whereby the image has an output density corresponding to the indicated density. Is displayed. The relationship between the indicated density and the output density may be disrupted due to toner deterioration or temperature change. In this case, the control unit 100 executes gamma correction.

In the gamma correction process, the control unit 100 conveys a plurality of patches having different densities in a plurality of image patterns according to a plurality of densities (for example, 20%, 40%, 60%, 80%, 100%) for each color. A second patch forming process such as forming on 73 is executed. That is, in the second patch forming process, the control unit 100 forms a test patch on the transport belt 73 for correcting the relationship between the image pattern and the indicated density corresponding to the image pattern.

After that, the control unit 100 reads these patches with the patch detection sensor 75, calculates the actual density based on the amount of received light, and identifies the change characteristic of the density of each color from the relative relationship of the density between the patches. Then, a relative relationship table between the change characteristic and the indicated concentration of the external computer PC is created. After that, the control unit 100 corrects the relationship between the indicated density and the image pattern based on the relative relationship table. For example, when the first image pattern is set corresponding to the indicated density of 20%, when the gamma correction process is performed and the actual output density is detected at a value deviating from 20%, the control unit 100 replaces the image pattern corresponding to the indicated density 20% with a second image pattern different from the first image pattern based on the relative relationship table. That is, in the gamma correction process, the gradation instructed by the external computer PC is replaced with another gradation based on the relative relationship table, thereby eliminating the shortage or excess of the density for each gradation.

The position correction process is a process for correcting the deviation of the image on the paper S in the sub-scanning direction. The position correction process includes dynamic position shift correction and static position shift correction, but only one of them may be corrected or both may be performed.

The dynamic position shift correction is for adjusting the shift of the dynamic image position having a specific period due to the eccentricity of the roller member such as the photoconductor drum 51 and the deviation of the pitch of the gear that rotationally drives them. This is a process for acquiring a correction value (position shift amount). When the control unit 100 acquires the correction value, the control unit 100 corrects the exposure timing (timing of emitting light) of the LED unit 40 based on the correction value, thereby correcting the dynamic image position deviation.

In the dynamic position shift correction, the control unit 100 forms a row of a plurality of patches for each color on the transport belt 73 so that a plurality of patches long in the left-right direction are lined up at intervals in the transport direction. The fourth patch forming process as an example of the three patch forming process is executed. That is, in the fourth patch forming process, the control unit 100 forms a test patch for correcting the exposure timing on the transport belt 73. After that, the control unit 100 reads these patches with the patch detection sensor 75, calculates the interval between each patch, and acquires a periodic misalignment amount (correction value).

The static misalignment correction is a correction value (position misalignment amount) for adjusting a static image position misalignment that does not have a specific period due to a misalignment of the mounting position of the photoconductor drum 51 or the LED unit 40. It is a process for acquiring. When the control unit 100 acquires the correction value, the control unit 100 corrects the exposure timing of the LED unit 40 based on the correction value to correct the static image position deviation.

In the static misalignment correction, in the control unit 100, patches of four colors long in the left-right direction are alternately arranged at intervals in the transport direction, and a group of patches of four colors arranged alternately are spaced in the transport direction. The fifth patch forming process as an example of the third patch forming process, such as forming each patch on the transport belt 73 so as to be lined up in a space, is executed. That is, in the fifth patch forming process, the control unit 100 forms a test patch for correcting the exposure timing on the transport belt 73. After that, the control unit 100 reads these patches with the patch detection sensor 75, calculates the interval between the patches, and acquires the amount of misalignment (correction value) between the colors.

Then, the gamma correction process and the position correction process described above are started based on the print amount condition and the temperature condition as in the first development bias process. The print amount condition and the temperature condition in each correction process may be set to the same condition or different conditions.

Hereinafter, the operation of the control unit 100 according to the fourth embodiment will be described in detail with reference to FIG. The flowchart shown in FIG. 10 includes the same steps S1, S2, and S9 as the flowchart shown in FIG. 4, and also includes new steps S71 to S80.

After step S2, the control unit 100 has a first temperature condition such that the first temperature difference ΔT11, which is the temperature difference between the previous first patch forming process and the reception of the print command, is equal to or higher than the first temperature threshold Tth11. It is determined whether or not the first print amount condition such that the first print amount Pn11, which is the print amount from the previous first patch formation process, is equal to or higher than the first print amount threshold Pth11 is satisfied (S71). If it is determined in step S71 that ΔT11 ≧ Tth11 or Pn11 ≧ Pth11 (Yes), the control unit 100 executes the first development bias correction process (first patch forming process) (S72). That is, the control unit 100 does not see the condition of the remaining amount of toner Q as a condition for starting the first development bias correction process, and when the first temperature condition or the first print amount condition is satisfied, the toner The first development bias correction process is executed regardless of the remaining amount Q.

After step S72, or when it is determined as No in step S71, the control unit 100 has a second temperature difference ΔT21 which is a temperature difference between the time of the previous second patch forming process and the time of receiving the print command. It is determined whether or not the second temperature condition such as the temperature threshold value Tth21 or more is satisfied (S73). If it is determined in step S73 that ΔT21 ≧ Tth21 (Yes), the control unit 100 executes the gamma correction process (second patch forming process) (S76). That is, when the second temperature condition is satisfied, the control unit 100 executes the gamma correction process without looking at other conditions (second print amount condition and toner remaining amount Q condition), so that the print amount Pn And the gamma correction process is executed regardless of the toner remaining amount Q. After step S76, the control unit 100 shifts to the process of step S77.

When it is determined in step S73 that ΔT21 <Tth21 (No), the control unit 100 prints the second print amount Pn21, which is the print amount from the previous gamma correction process (second patch formation process), as the second print. It is determined whether or not the second print amount condition such as the amount threshold value Pth21 or more is satisfied (S74). When it is determined in step S74 that Pn21 ≧ Pth21 (Yes), the control unit 100 determines whether or not the toner remaining amount Q is greater than the predetermined value Qth1 (S75).

If it is determined in step S75 that Q> Qth1 (Yes), the control unit 100 executes the gamma correction process (S76). That is, when the second print amount condition is satisfied (S74: Yes) and the toner remaining amount Q is larger than the predetermined value Qth1 (S75: Yes), the control unit 100 executes the gamma correction process.

If No is determined in step S74 or step S75, the control unit 100 shifts to the process of step S77 without executing the gamma correction process. That is, the control unit 100 does not execute the gamma correction process even if the second print amount condition is satisfied (S74: Yes) even if the toner remaining amount Q is equal to or less than the predetermined value Qth1 (S75: No).

In step S77, the control unit 100 satisfies the third temperature condition that the third temperature difference ΔT31, which is the temperature difference between the time of the previous third patch forming process and the time of receiving the print command, is equal to or higher than the third temperature threshold value Tth31. Judge whether or not. If it is determined in step S77 that ΔT31 ≧ Tth31 (Yes), the control unit 100 executes a position correction process (fourth or fifth patch forming process as the third patch forming process) (S80). That is, when the third temperature condition is satisfied, the control unit 100 executes the position correction process without looking at other conditions (second print amount condition and toner remaining amount Q condition), so that the print amount Pn And the position correction process is executed regardless of the toner remaining amount Q. After step S80, the control unit 100 shifts to the process of step S9.

When it is determined in step S77 that ΔT31 <Tth31 (No), the control unit 100 determines the amount of printing from the previous position correction process (fourth or fifth patch forming process as the third patch forming process). It is determined whether or not the third print amount condition such that a certain third print amount Pn31 is equal to or higher than the third print amount threshold Pth31 is satisfied (S78). When it is determined in step S78 that Pn31 ≧ Pth31 (Yes), the control unit 100 determines whether or not the toner remaining amount Q is greater than the predetermined value Qth1 (S79).

If it is determined in step S79 that Q> Qth1 (Yes), the control unit 100 executes the position correction process (S80). That is, when the third print amount condition is satisfied (S78: Yes) and the toner remaining amount Q is larger than the predetermined value Qth1 (S79: Yes), the control unit 100 executes the position correction process.

If No is determined in step S78 or S79, the control unit 100 shifts to the process of step S9 without executing the position correction process. That is, when the toner remaining amount Q is equal to or less than the predetermined value Qth1 (S79: No), the control unit 100 does not execute the position correction process even if the third print amount condition is satisfied (S78: Yes).

As described above, according to the fourth embodiment, the following effects can be obtained.
When the remaining toner Q is as low as the predetermined value Qth1 or less, the gamma correction processing or the position correction processing is not executed even if the second print amount condition or the third print amount condition is satisfied, so that the toner consumption is suppressed. be able to. Further, even when the remaining toner Q is as small as the predetermined value Qth1 or less, the gamma correction process or the position correction process is executed when the second temperature condition or the third temperature condition is satisfied, so that the remarkable density of the image due to the temperature change is executed. Changes or misalignments can be corrected, and deterioration of print quality can be suppressed.

Regardless of the remaining amount of toner, when the first print amount condition or the first temperature condition is satisfied, the first development bias correction process (first patch forming process) is executed, so that the remaining amount of toner Q is as small as a predetermined value Qth1 or less. Even so, the development bias can be satisfactorily corrected.

In the fourth embodiment, the first patch forming process is executed when either the first print amount condition or the first temperature condition is satisfied, but the present invention is not limited to this, and the first print The first patch forming process may be executed when at least one of the quantity condition and the first temperature condition is satisfied. In this case, for example, when both the first print amount condition and the first temperature condition are satisfied at the same time, the first patch forming process corresponding to either condition (for example, the first temperature condition) may be executed.

[Fifth Embodiment]
Next, the fifth embodiment of the present invention will be described in detail with reference to the drawings as appropriate. Since the control of the control unit 100 according to the fourth embodiment described above is partially modified in this embodiment, the members and processes (steps) having substantially the same structure as those in the fourth embodiment are the same. Is added, and the description thereof will be omitted.

The fifth embodiment is a form in which the condition of the remaining amount of toner Q is added to the start condition of the first development bias correction process in the fourth embodiment. Specifically, in the fifth embodiment, the control unit 100 is configured to perform control according to the flowchart shown in FIG. The flowchart shown in FIG. 11 includes all the steps of the flowchart shown in FIG. 10, and also includes new steps S91 to S95.

As shown in FIG. 11, after step S2, the control unit 100 determines whether or not the remaining amount of toner Q is greater than the predetermined value Qth1 (S91). If it is determined in step S91 that Q> Qth1 (Yes), the control unit 100 shifts to the process of step S71.

If it is determined in step S91 that Q ≦ Qth1 (No), the control unit 100 determines whether or not the first temperature difference ΔT11 is equal to or greater than the first temperature threshold Tth11 (S92). If it is determined in step S92 that ΔT11 ≧ Tth11 (Yes), the control unit 100 executes the first development bias correction process (S93).

When it is determined in step S92 that ΔT11 <Tth11 (No), the control unit 100 determines whether or not the first print amount Pn11 is equal to or greater than the first print amount threshold Pth12, which is larger than the first print amount threshold Pth11. Is determined (S94). That is, when the toner remaining amount Q becomes the predetermined value Qth1 or less (S91: No), the control unit 100 sets the first print amount threshold value as compared with the case where the toner remaining amount Q is larger than the predetermined value Qth1. It is made larger (Pth11 <Pth12).

If it is determined in step S94 that Pn11 ≧ Pth12 (Yes), the control unit 100 executes the second development bias correction process (S95). That is, when the toner remaining amount Q becomes the predetermined value Qth1 or less (S91: No), the control unit 100 sets the first print amount condition as compared with the case where the toner remaining amount Q is larger than the predetermined value Qth1. The amount of toner used in the first patch forming process to be executed based on this is reduced (2 patches → 1 patch).

After step S93 and S95, or when it is determined as No in step S94, the control unit 100 shifts to the process of step S73.

As described above, according to the fifth embodiment, the following effects can be obtained.
When the remaining toner Q is as small as the predetermined value Qth1 or less, the first print amount threshold value is increased (Pth11 <Pth12), so that the frequency of the first patch forming process can be reduced and the toner consumption is suppressed. be able to.

When the remaining amount of toner Q is as small as the predetermined value Qth1 or less, the amount of toner used in the first patch forming process executed based on the first print amount condition is reduced, so that toner consumption can be suppressed. ..

In the above embodiment, the patch formed on the transport belt 73 is detected by the patch detection sensor 75, but the present invention is not limited to this, and for example, the patch formed on the paper is detected by the patch detection sensor. You may.

In the above embodiment, the remaining amount of toner is detected by the remaining amount of toner sensor 104, but the present invention is not limited thereto. For example, the toner consumption amount may be calculated based on the image data, and the toner remaining amount may be obtained by subtracting the toner consumption amount from the toner amount in the process cartridge 50 in a new state.

In the above embodiment, the present invention is applied to the color printer 1, but the present invention is not limited to this, and the present invention may be applied to other image forming devices such as a monochrome printer, a copying machine, and a multifunction device. .. Further, the image forming unit can also adopt various structures. For example, the image forming unit may be an image forming unit provided with an exposure device different from the above embodiment such as a scanner unit that emits a laser, or a belt-shaped image forming unit. The image forming unit may be provided with a photoconductor such as a photoconductor, which is different from the above-described embodiment.

1 Color printer 30 Image forming unit 73 Conveying belt 100 Control unit

Claims (12)

An image forming unit that forms a toner image on the transfer target,
With a control unit
The control unit
It is possible to perform a patch forming process for forming a patch, which is a toner image for testing, on the transfer object.
When the remaining amount of toner is more than a predetermined value and the print amount condition such that the print amount from the previous patch formation is equal to or more than the print amount threshold value is satisfied, the patch formation process is executed.
When the remaining amount of toner is equal to or less than a predetermined value, the patch forming process is not executed even if the print amount condition is satisfied.
When a temperature condition such that the temperature difference between the time of the previous patch formation and the time of receiving the print command is equal to or higher than the temperature threshold value is satisfied, the patch formation process is executed regardless of the remaining amount of toner and the print amount. A featured image forming apparatus. The control unit is characterized in that when the remaining amount of toner becomes equal to or less than the predetermined value, the temperature threshold value is increased as compared with the case where the remaining amount of toner is larger than the predetermined value. The image forming apparatus according to 1. When the remaining amount of toner is equal to or less than the predetermined value, the control unit performs the patch forming process based on the temperature condition as compared with the case where the remaining amount of toner is larger than the predetermined value. The image forming apparatus according to claim 1 or 2, wherein the amount of toner used is reduced. The image forming apparatus according to claim 1, wherein the temperature condition is the same regardless of the remaining amount of the toner. An image forming unit that forms a toner image on the transfer target,
With a control unit
The control unit
It is possible to perform a patch forming process for forming a patch, which is a toner image for testing, on the transfer object.
When the remaining amount of toner is more than the first predetermined value and the print amount condition such that the print amount from the previous patch formation is equal to or more than the print amount threshold value is satisfied, the patch formation process is executed.
When the remaining amount of toner is equal to or less than the second predetermined value smaller than the first predetermined value, the patch forming process is not executed even if the print amount condition is satisfied.
When the remaining amount of toner is equal to or less than the first predetermined value and more than the second predetermined value , the print amount threshold value is set as compared with the case where the remaining amount of toner is larger than the first predetermined value. At least one of the process of increasing the amount and the process of reducing the amount of toner used in the patch forming process executed based on the print amount condition is executed.
When a temperature condition such that the temperature difference between the time of the previous patch formation and the time of receiving the print command is equal to or higher than the temperature threshold value is satisfied, the patch formation process is executed regardless of the remaining amount of toner and the print amount. A featured image forming apparatus. When the remaining amount of toner is equal to or less than the first predetermined value and more than the second predetermined value , the control unit has a comparison with a case where the remaining amount of toner is larger than the first predetermined value. The image forming apparatus according to claim 5, wherein the printing amount threshold value is increased and the amount of toner used in the patch forming process executed based on the printing amount condition is reduced. Wherein, when the remaining amount of toner is equal to or less than the first predetermined value, characterized in that as compared with the case the remaining amount of toner is larger than the first predetermined value, to increase the temperature threshold The image forming apparatus according to claim 6. When the remaining amount of toner is equal to or less than the first predetermined value, the control unit executes a patch based on the temperature condition as compared with the case where the remaining amount of toner is larger than the first predetermined value. The image forming apparatus according to claim 6, wherein the amount of toner used in the forming process is reduced. An image forming unit that forms a toner image on the transfer target,
With a control unit
The control unit
A first patch forming process for forming a patch, which is a test toner image for correcting a development bias, on the transfer object,
It is possible to perform a second patch forming process of forming a patch, which is a toner image for testing, on the transfer object to correct the relationship between the image pattern and the density corresponding to the image pattern.
Regardless of the remaining amount of toner, the first print amount condition that the first print amount, which is the print amount from the previous first patch formation process, is equal to or more than the first print amount threshold, and the time of the previous first patch formation process. When at least one of the first temperature conditions such that the temperature difference at the time of receiving the print command is equal to or higher than the first temperature threshold is satisfied, the first patch forming process is executed.
When the second print amount condition such that the second print amount, which is the print amount from the previous second patch formation process, is equal to or more than the second print amount threshold value is satisfied, and the remaining amount of toner is larger than the predetermined value. , The second patch forming process is executed,
When the remaining amount of toner is equal to or less than a predetermined value, the second patch forming process is not executed even if the second print amount condition is satisfied.
When the second temperature condition such that the temperature difference between the time of the previous second patch forming process and the time of receiving the print command is equal to or greater than the second temperature threshold value is satisfied, the first is irrespective of the remaining amount of toner and the print amount . 2 An image forming apparatus characterized by executing a patch forming process. The control unit
It is possible to execute a third patch forming process for forming a patch, which is a test toner image for correcting the exposure timing, on the transfer object.
When the third print amount condition such that the third print amount, which is the print amount from the previous third patch formation process, is equal to or more than the third print amount threshold value is satisfied, and the remaining amount of toner is larger than the predetermined value. , The third patch forming process is executed,
When the remaining amount of toner is equal to or less than a predetermined value, the third patch forming process is not executed even if the third print amount condition is satisfied.
When the third temperature condition such that the temperature difference between the time of the previous third patch forming process and the time of receiving the printing command is equal to or greater than the third temperature threshold is satisfied, the third temperature condition is irrespective of the remaining amount of toner and the printing amount . 3. The image forming apparatus according to claim 9, wherein the patch forming process is executed. The control unit is characterized in that when the remaining amount of toner becomes equal to or less than a predetermined value, the first print amount threshold value is increased as compared with the case where the remaining amount of toner is larger than the predetermined value. The image forming apparatus according to claim 9 or 10. When the remaining amount of toner is equal to or less than a predetermined value, the control unit executes the first patch based on the first print amount condition as compared with the case where the remaining amount of toner is larger than the predetermined value. The image forming apparatus according to any one of claims 9 to 11, wherein the amount of toner used in the forming process is reduced.

Images