JP2008164972A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device for surely determining a degree of soiling of a lens face of an LED print head. <P>SOLUTION: The image forming device makes the LED print head emit light for a prescribed exposure time T1 after a photoreceptor drum is put in a rotating state and in an electrification state, if a test sequence program (steps 101-104) is started. The image forming device measures surface potential Vs of a region irradiated with light when a time T2 until the region irradiated with the light from the LED print head reaches the position of a surface electrometer elapses, determines whether the absolute value of detected surface potential Vs is smaller than a reference value Vth when power source voltage is normal, and displays that the lens face of the LED print head has soiling on an operation panel display part when the absolute value of the surface potential Vs is larger than the reference value Vth (steps 105-109). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus in which a lens surface of an LED print head is opposed to a photoreceptor.

  In general, in an image forming apparatus such as a copying machine or a printer that performs electrophotographic recording, an image is formed by each recording process of charging, exposure, development, transfer, fixing, and cleaning. Some image forming apparatuses use an LED print head configured by combining an LED light source and a SELFOC (registered trademark) lens as an exposure apparatus in order to reduce the size of the apparatus.

  The LED print head has an LED array in which a plurality of light emitting portions are arranged in a long manner on an LED substrate, and a SELFOC (registered trademark) lens is disposed on the LED array, and is set in parallel with the long LED array. An image of the LED array is formed by a SELFOC (registered trademark) lens array on a photosensitive drum that rotates about the axis.

  In such an image forming apparatus using an LED print head, the lens surface of the SELFOC (registered trademark) lens array and the photosensitive surface of the photosensitive drum are formed in order to form an image of light emitted from the LED array on the photosensitive drum. Because of the close proximity, paper dust, floating toner, and floating carrier adhere to the lens surface of the SELFOC (registered trademark) lens array from the photosensitive surface of the photosensitive drum, and the light that reaches the photosensitive member by the adhered toner. Is weakened, resulting in a problem that the density of the printed image is lowered.

For this reason, it has been proposed to provide a mechanism for cleaning the surface of the SELFOC (registered trademark) lens array in order to remove paper dust, floating toner, carrier, etc. adhering to the surface of the LED print head (for example, Patent Documents). 1).
In addition, in order to remove stains attached to the surface of the LED print head, a transparent film is closely attached to the surface of the SELFOC (registered trademark) lens array, and the transparent film is placed every predetermined number of prints or every predetermined print time. A method of taking up a fixed amount has also been proposed (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 2006-218656 Japanese Patent Laid-Open No. 2005-14281

As described above, it has been proposed to provide a mechanism for cleaning the surface of the SELFOC (registered trademark) lens array. However, it is up to the user to determine when to perform cleaning using this mechanism. Therefore, there arises a problem that cleaning is often performed after the print is thinned.
On the other hand, a method of winding a predetermined amount of a transparent film after printing for a predetermined number of sheets or for a predetermined time has been proposed, but the amount of toner, carrier, and paper dust adhering to the transparent film surface changes depending on environmental conditions such as temperature and humidity. Therefore, simply measuring the number of prints and the print time causes a problem that the print density is lowered before the transparent film is wound up when foreign matter rapidly adheres to the transparent film surface.

  The present invention has been made in view of the above problems, and provides an image forming apparatus capable of reliably determining the degree of contamination of the lens surface of an LED print head and cleaning the print head at an early stage of contamination. The purpose is to do.

  In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention is an image forming apparatus in which a lens surface of an LED print head is opposed to a photosensitive member, and charging means for charging the photosensitive member; Driving means for driving an LED print head for irradiating a predetermined area on the surface of the photosensitive member charged by the means; potential measuring means for measuring a potential of the predetermined area irradiated with light from the LED print head; Determining means for determining the degree of contamination of the LED print head lens surface based on the potential measured by the means.

  According to a second aspect of the present invention, there is provided an image forming apparatus comprising: a charging unit that charges the photosensitive member; and the photosensitive member charged by the charging unit. Driving means for driving an LED print head that irradiates light to a predetermined area on the surface, developing means for attaching toner to the predetermined area irradiated with light from the LED print head, and density of the area developed by the developing means A density measuring means for measuring the density of the LED print head lens surface based on the density measured by the density measuring means.

  Furthermore, an image forming apparatus according to a third aspect of the present invention is the image forming apparatus in which the lens surface of the LED print head is opposed to the photosensitive member, the environment detecting means for detecting the operating environment, and the counting means for counting the number of printed sheets. And adding the weight according to the operating environment detected by the environment detection means to the number of prints by the counting means, and the degree of contamination of the lens surface of the LED print head based on the weighted and added total number of prints. And determining means for determining.

  The image forming apparatus according to the first aspect of the invention detects a change in the photoreceptor potential due to light irradiation from the LED print head. However, if the LED print head is dirty, the light is weakened and the potential of the photoreceptor is reduced. Since the change is reduced, it is possible to reliably determine the degree of contamination of the lens surface of the LED print head by detecting the change in the photoreceptor potential. The print head can be cleaned by the cleaning mechanism.

  The image forming apparatus of the invention according to claim 2 measures the density when the toner is adhered, but if the lens surface of the LED print head is dirty, the light is weakened and the potential of the photoconductor changes. , The potential difference with the developing device decreases, and the amount of toner adhesion decreases, so the degree of contamination of the lens surface of the LED print head is reliably determined by measuring the density when the toner is adhered, Similarly to the above, it is possible to notify the user at the initial stage of the head contamination, or to clean the print head by an automatic cleaning mechanism.

  Furthermore, when the humidity and temperature are low, static electricity is likely to be generated on the lens surface of the LED print head, and toner and the like are likely to adhere to the lens surface. Therefore, it is possible to determine the degree of contamination of the lens surface of the LED print head with higher accuracy than simply determining from the number of prints and the print time.

  Hereinafter, an embodiment in which the image forming apparatus of the present invention is applied to a digital multifunction machine having a copying function, a facsimile function, a printing function, a scanner function, and the like will be described. FIG. 1 is a schematic block diagram showing the hardware configuration of a digital multi-function peripheral. As shown in the figure, the digital multi-function peripheral has an MPU (Micro Processing Unit) 1, ROM (Read Only Memory) 2, SRAM (Static Random Access Memory). 3) Memory controller 4, image memory 5, codec 6, modem 7, network control unit NCU8, scanner 9, operation panel 10, printer image processing circuit 11, printer mechanism control circuit 12, LAN interface (I / F) 13 Etc., and each part is connected via a bus 14.

  The MPU 1 controls each part of the hardware of the digital multi-function peripheral via the bus 14 and executes various programs based on the programs stored in the ROM 2. The ROM 2 stores various programs necessary for the operation of the digital multi-function peripheral. Operation messages are stored. The SRAM 13 stores temporary data generated when the program is executed, and includes a print number storage area 15 for storing the number of prints.

  The memory controller 4 controls writing and reading of image signals to and from the image memory 5, and the image memory 5 is configured using SDRAM or the like, and stores image data to be transmitted, received image data, or read image data, The codec 6 encodes and decodes in accordance with a predetermined protocol, encodes the read original image data by the MH, MR, or MMR method, and decodes the image data received from the outside.

  The modem 7 is connected to the bus 14 and functions as a fax modem capable of facsimile communication. The modem 7 is also connected to the NCU 8 connected to the bus 14. The NCU 8 is hardware for closing and opening an analog line, and connects the modem 7 to the public switched telephone network (PSTN) as necessary.

  The scanner 9 includes a reading document placing table such as an auto document feeder (ADF) or a flatbed scanner (FBS), reads a document using a CCD or the like, and outputs dot image data. The operation panel 10 includes a display unit that displays an operation state of the digital multifunction peripheral or displays an operation screen for various functions, and a plurality of keys for operating the digital multifunction peripheral.

Further, the printer image processing circuit 11 processes the print image signal and inputs it to the LED print head 16, and the printer mechanism control circuit 12 controls the printer engine 17 to print the received data, copy original data, and the like. Out. The printer mechanism control circuit 12 receives the outputs of the environmental temperature sensor 18 and the environmental humidity sensor 19 that measure the temperature and humidity in the digital multifunction peripheral.
The LAN interface 13 is connected to a LAN (not shown) and receives signals from the Internet network, while transmitting signals and data to the LAN, and performs interface processing such as signal conversion and protocol conversion. Execute.

  The digital multi-function peripheral has the above-described configuration. When sending a facsimile, the image data of the original is read by the scanner 9, and the read image signal is compressed by the codec 6 and is sent to the image memory 5 via the memory controller 4. Accumulated in. The compressed image data is read from the image memory 5, modulated by the modem 7, and transmitted from the NCU 8 to the communication partner through the PSTN. At the time of facsimile reception, the received image data is demodulated by the modem 7, stored in the image memory 5 via the memory controller 4, then decoded by the codec 6, and the printer image processing circuit 11 is connected to the LED print head 16. Printing is performed by supplying a print image signal.

Next, details of the structure of the printer engine 17 will be described with reference to FIG.
The printer engine 17 includes a photosensitive drum 21 as an image carrier that is rotationally driven at a predetermined speed. The transfer roller 22 and the photosensitive drum are sequentially arranged around the photosensitive drum 21 in the rotation direction (the arrow direction in the drawing). A memory removing brush 23 for removing the electric potential 20; a charging corona charger 24 which is a charger for uniformly charging the surface of the photosensitive drum 21; and an image for exposing the surface of the photosensitive drum 21 to form an electrostatic latent image. An LED print head 16 as an exposure device, a surface potential meter 25 for measuring the potential of a predetermined area of the photosensitive drum 21, and a developer 26 for developing the electrostatic latent image formed on the photosensitive drum 21 with toner are provided. Further, a fixing device 27 is provided on the sheet discharge side of the photosensitive drum 21.

The developing device 26 agitates a developer composed of a developing roller 28, a supply roller 29 for supplying toner to the developing roller 28, and toner and a carrier replenished from a toner replenishing portion (not shown) along the bottom thereof. In addition, a stirring paddle 30 is provided to be supplied to the surface of the developing roller 28.
Further, the transfer roller 22, the memory removal brush 23, the charging corona charger 24, the transfer bias high voltage generator 31 that supplies a high voltage to the developing roller 28, the memory removal brush high voltage generator 32, and the charging bias high voltage, respectively. The generator 33 and the development bias high voltage generator 34 are controlled by the printer mechanism control circuit 12 to generate respective high voltages, and the current detection resistor 35 detects the supply current to the charging corona charger 24 to detect the printer mechanism. Input to the control circuit 12.

On the other hand, the fixing device 27 includes a heat roller 36 and a nip roller 37 that is pressed against the heat roller 36 and rotates. A halogen lamp 38 disposed on the central axis of the heat roller 36 is driven by a commercial AC power supply AC. The printer mechanism control circuit 12 to which the output of the temperature sensor 40 provided in contact with the heat roller 36 is input controls the fixing device heating on / off switch 41 based on the output of the temperature sensor 40, thereby The temperature of the roller 36 is controlled to a standby temperature, a fixing temperature, and the like.
The motor 42 is a motor for rotating each rotating portion of the printer mechanism, and is controlled by the printer mechanism control circuit 12 via the motor driver 43.

When an image is formed by this printer engine, the surface of the photosensitive drum 21 is uniformly charged by the charging corona charger 24, and then the charged surface of the photosensitive drum 21 is converted from the LED print head 16 into a print image signal. An electrostatic latent image is formed by exposure with the image forming light emitted accordingly. The electrostatic latent image thus formed on the photosensitive drum 21 is developed into a visible toner image by the developing device 26 with toner. These visible toner images are sequentially transferred onto a sheet by the charging action of the transfer roller 22, and then the sheet onto which the toner image has been transferred is heated and pressed by a fixing device 27 to fix the toner image. The paper is guided to be discharged by a paper portion (not shown).
In this printer engine, residual toner, paper dust, and the like are removed from the surface of the photosensitive drum 21 after the transfer process of each toner image by the memory removal brush 23, and the charge is removed to obtain the next image. Prepare for the formation process.

The printer engine is configured as described above. Next, the operation of the MPU 1 during the test sequence for determining the degree of contamination of the lens surface of the LED print head will be described with reference to the flowchart of FIG.
The MPU 1 starts a test sequence program shown in the flowchart of FIG. 3 at regular intervals. When this program is started, the photosensitive drum 21 is rotated via the printer mechanism control circuit 12 and each high voltage generator is turned on. After being driven to be charged (step 101), the timers T1 and T2 are started to measure time (step 102).
Note that the timer T1 is a timer for measuring the exposure time of the LED print head 16, and the timer T2 is a timer for measuring the time for the region exposed by the LED print head 16 to move to the position of the surface electrometer 25.

Next, the MPU 1 drives the printer image processing circuit 11 to cause the LED print head 16 to emit light (step 103), and then determines whether or not the timer T1 has expired (step 104).
When the predetermined exposure time T1 has not elapsed, the MPU 1 continues to emit light from the LED print head 16, and when the predetermined exposure time T1 has elapsed, the light emission of the LED print head 16 is stopped and the timer T2 has timed up. Whether or not (step 105).

When the time T2 until the region irradiated with the light from the LED print head 16 reaches the position of the surface electrometer 25 has elapsed, the MPU 1 outputs the output of the surface electrometer 25 via the printer mechanism control circuit 12. By taking in, the surface potential Vs of the region irradiated with the light of the photosensitive drum 21 is measured (step 106).
Next, the MPU 1 acquires the supply current to the charging corona charger 24 detected by the printer mechanism control circuit 12 via the current detection resistor 35, and determines whether or not the power supply voltage is normal (step 107). If it is determined that the power supply voltage is not normal, the program is terminated.

If it is determined in step 107 that the power supply voltage is normal, the MPU 1 determines whether or not the detected absolute value of the surface potential Vs is smaller than the reference value Vth (step 108), and the detected absolute value of the surface potential Vs. Is smaller than the reference value Vth, it is determined that the lens surface of the LED print head 16 is not dirty, and the program ends.
On the other hand, when it is determined in step 108 that the absolute value of the surface potential Vs is larger than the reference value Vth, the MPU 1 displays that the lens surface of the LED print head is dirty on the display unit of the operation panel 10 (step 109). .

  That is, as shown in FIG. 4, when the light from the LED print head 16 is irradiated on the surface of the photosensitive drum 21 charged to −750 V by the charging corona charger 24, the lens surface of the LED print head 16 is not soiled. In the case (a), when the absolute value of the potential on the surface of the photosensitive drum 21 is small and the lens surface is dirty (b), the light is weakened and the absolute value of the potential on the surface of the photosensitive drum 21 is increased. Based on the potential Vs, it is possible to detect contamination on the lens surface of the LED print head 16.

As described above, it is possible to determine the degree of contamination of the lens surface of the LED print head and notify the user by detecting a change in the photoreceptor potential due to light irradiation from the LED print head. Knowing that the lens surface of the print head is dirty, the lens surface of the LED print head can be cleaned at an early stage of the head contamination.
In the above embodiment, the operation panel displays that the lens surface of the LED print head is dirty. However, when the cleaning mechanism is provided and the lens surface of the LED print head is determined to be dirty, the cleaning mechanism is automatically activated. It is also possible to drive them.

In the above embodiment, the degree of contamination of the lens surface of the LED print head was determined by detecting a change in the photoreceptor potential due to the light irradiation from the LED print head, but the light from the LED print head was irradiated. By measuring the density of the region, the degree of contamination of the lens surface of the LED print head can also be determined. Hereinafter, the contamination of the lens surface of the print head is determined based on the concentration of the region irradiated with light from the LED print head. An embodiment for determining the degree will be described.
The hardware configuration of the digital multi-function peripheral is the same as the schematic block diagram of FIG. 1, and the printer engine is provided with a light reflection type density sensor 44 instead of the surface electrometer 25 as shown in FIG. Except for this point, the printer engine is the same as that shown in FIG.

Hereinafter, the operation of the MPU 1 during the test sequence for determining the degree of contamination of the lens surface of the LED print head will be described with reference to the flowchart of FIG.
Similar to the above, the MPU 1 starts a test sequence program shown in the flowchart of FIG. 6 at regular intervals, and when this program is started, the photosensitive drum 21 is rotated through the printer mechanism control circuit 12 and After the high voltage generator is driven to be in a charged state (step 201), time measurement of the timers T1 and T3 is started (step 202).
The timer T1 is a timer for measuring the exposure time of the LED print head 16 as described above, and the timer T3 is a timer for measuring the time required for the region exposed by the LED print head 16 to move to the position of the density sensor 44. is there.

Next, the MPU 1 drives the printer image processing circuit 11 to cause the LED print head 16 to emit light (step 203), and then determines whether or not the timer T1 has expired (step 204).
When the predetermined exposure time T1 has not elapsed, the MPU 1 continues to emit light from the LED print head 16, and when the predetermined exposure time T1 has elapsed, the light emission of the LED print head 16 is stopped and the timer T3 has timed out. Whether or not (step 205).

When the time T3 until the region irradiated with light from the LED print head 16 reaches the position of the density sensor 44 has elapsed, the MPU 1 takes in the output of the density sensor 44 via the printer mechanism control circuit 12. Thus, the density D of the region irradiated with light from the photosensitive drum 21 is measured (step 206).
Next, the MPU 1 acquires the supply current to the charging corona charger 24 detected by the printer mechanism control circuit 12 through the current detection resistor 35, and determines whether or not the power supply voltage is normal (step 207). If it is determined that the power supply voltage is not normal, the program is terminated.

  If it is determined in step 207 that the power supply voltage is normal, the MPU 1 determines whether or not the detected concentration D is smaller than the reference value Dth (step 208). If the detected concentration D is larger than the reference value Dth, It is determined that the lens surface of the LED print head 16 is not dirty, and the program ends.

On the other hand, when it is determined in step 208 that the density D is smaller than the reference value Dth, the MPU 1 displays on the display unit of the operation panel 10 that the lens surface of the LED print head is dirty (step 209).
That is, as shown in FIG. 4, when the lens surface is not soiled when light is emitted from the LED print head (a), the potential difference between the surface potential of the photosensitive drum 21 and the developing bias is large, and the amount of toner attached is large. When the detected density D becomes high but the lens surface is dirty (b), the light is weakened and the potential difference between the surface potential of the photosensitive drum 21 and the developing bias is small, so that the amount of toner adhesion is small and detection is performed. Since the density D is low, the contamination of the lens surface can be detected based on the detected density D.

  As described above, it is possible to reliably determine the degree of contamination of the lens surface of the LED print head by measuring the density when the toner is adhered, so that the user is notified at an early stage of head contamination. The print head can be cleaned by an automatic cleaning mechanism.

In the above embodiment, the contamination of the lens surface of the LED print head is determined based on the potential and density of the photosensitive member at the time of exposure, but the contamination of the lens surface can also be determined based on the environmental conditions and the number of prints. An embodiment in which the contamination of the lens surface is determined based on the environmental conditions and the number of prints will be described.
The hardware configuration of the digital multifunction peripheral is the same as the schematic block diagram of FIG. 1, and the printer engine is the same except that the surface electrometer 25 is removed from the configuration of FIG. .

In this embodiment, the degree of contamination of the lens surface of the LED print head is determined according to the number of prints, but the weight of the number of prints is changed according to environmental conditions.
In other words, when the humidity and temperature are low, static electricity is likely to be generated on the lens surface, and toner and the like are likely to adhere. Therefore, as shown in FIG. The region below t1 and the relative humidity h1 is regarded as the LL environment, the region above the temperature t2 and the region above the humidity h2 as the HH environment, the range from the temperature t1 to t2 and the humidity h1 to h2 as the NN environment, and the remaining region as the NN environment. .
For example, the weight of the number of prints in the LL environment, that is, the weight is set to 2, the weight of the number of prints in the NN environment is set to 1.5, and the weight of the number of prints in the HH environment is set to 1.

Next, the operation of the program for determining the dirt on the lens surface of the LED print head will be described with reference to the flowchart of FIG.
In the digital multi-function peripheral, when printing is executed, the MPU 1 starts a lens surface dirt determination program shown in the flowchart of FIG. 8 to determine whether or not printing is completed (step 301). A count value of a counter (not shown) that counts the number of printed sheets is acquired (step 302), and the outputs of the environmental temperature sensor 18 and the environmental humidity sensor 19 are acquired via the printer mechanism control circuit 12, so that the temperature and Relative humidity is detected (step 303).

Thereafter, the MPU 1 determines in which environment in FIG. 7 the environmental conditions during printing are based on the detected temperature and relative humidity. For example, if it is determined that the environment is an LL environment, the MPU 1 determines the number of prints acquired in step 302. The weight 2 is multiplied (step 304).
Next, the MPU 1 calculates the converted print number by adding the past converted print number stored in the print number storage area 15 of the SRAM 3 and the weighted print number in step 304 (step 305), and then obtaining it. The converted print number is stored in the print number storage area 15 of the SRAM 3 (step 306).
For example, as shown in FIG. 9, if the number of prints in the HH environment is 240, the number of prints in the NN environment is 560, and the number of prints in the LL environment is 170, the total converted print number is 1920. Become.

After storing the converted print number, the MPU 1 determines whether or not the converted print number exceeds a predetermined value, for example, 5000 sheets (step 307), and determines that the converted print number exceeds the predetermined value The display unit of the operation panel 10 displays that the lens surface of the LED print head is dirty (step 308).
Thereby, since the user can know that the lens surface of the LED print head is dirty, the lens surface of the LED print head can be cleaned before the print becomes thin. When the user performs cleaning, the user manually resets the past converted print number stored in the print number storage area 15 of the SRAM 3.

In the above embodiment, the operation panel displays that the lens surface of the LED print head is dirty. However, as in the other embodiments, a cleaning mechanism is provided to determine whether the lens surface of the LED print head is dirty. It is also possible to drive the cleaning mechanism. In this case, after the cleaning mechanism is driven, the past converted print number stored in the print number storage area 15 of the SRAM 3 is automatically set to 0. Reset to.
In the above embodiment, the environmental conditions are divided into three environments such as the LL environment. However, a finer area can be set and the weight value can be changed as appropriate.

  As described above, in this embodiment, the contamination of the lens surface is determined based on the environmental conditions and the number of prints. Therefore, the degree of contamination of the lens surface of the LED print head can be determined with higher accuracy than the determination based solely on the number of prints and the print time. Can be determined.

  In the above embodiment, the case where the image forming apparatus of the present invention is applied to a digital multi-function peripheral has been described. However, the image forming apparatus of the present invention is also applicable to other image forming apparatuses such as a facsimile machine and a copying machine. can do.

It is a schematic block diagram which shows the hardware constitutions of a digital multi-function peripheral. It is a figure which shows the detail of the structure of a printer engine. It is a flowchart which shows the effect | action at the time of the test sequence which determines the stain | pollution | contamination degree of the lens surface of a LED print head. It is a figure which shows an electrical potential change when light is irradiated to the photosensitive drum surface. It is a figure which shows the detail of the structure of the printer engine of another Example. It is a flowchart which shows the effect | action at the time of the test sequence which determines the stain | pollution | contamination degree of the lens surface of the LED print head of another Example. It is an example when the area | region within an operation | movement guarantee range is divided according to environmental conditions. It is a flowchart which shows the effect | action of the program which determines the stain | pollution | contamination of the lens surface of the LED print head of another Example. It is an example of calculation of the number of converted prints weighted to the number of prints.

Explanation of symbols

1 MPU
2 ROM
3 SRAM
4 Memory controller 5 Image memory 6 Codec 7 Modem 8 NCU
9 Scanner 10 Operation Panel 11 Image Processing Circuit for Printer 12 Printer Mechanism Control Circuit 13 LAN I / F
14 Bus 15 Print number storage area 16 LED print head 17 Printer engine 18 Environmental temperature sensor 19 Environmental humidity sensor

Claims (3)

In the image forming apparatus in which the lens surface of the LED print head is opposed to the photoreceptor,
Charging means for charging the photosensitive member, driving means for driving an LED print head for irradiating light on a predetermined area on the surface of the photosensitive member charged by the charging means, and potential in a predetermined area irradiated with light from the LED print head An image forming apparatus comprising: a potential measuring unit that measures the degree of contamination of the LED print head lens surface based on the potential measured by the potential measuring unit. In the image forming apparatus in which the lens surface of the LED print head is opposed to the photoreceptor,
A charging unit for charging the photosensitive member; a driving unit for driving an LED print head for irradiating light on a predetermined region of the surface of the photosensitive member charged by the charging unit; and a toner for a predetermined region irradiated with light from the LED print head A developing means for adhering, a density measuring means for measuring the density of an area developed by the developing means, and a judging means for determining the degree of contamination of the LED print head lens surface based on the density measured by the density measuring means; An image forming apparatus comprising: In the image forming apparatus in which the lens surface of the LED print head is opposed to the photoreceptor,
Environment detecting means for detecting the operating environment, counting means for counting the number of printed sheets, and adding the number of printed sheets by the counting means by applying a weight according to the operating environment detected by the environment detecting means. An image forming apparatus comprising: a determination unit that determines a degree of contamination of a lens surface of an LED print head based on a total number of prints.

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