Image forming apparatus, medium discrimination method and program

Abstract

To provide an image formation device which enables efficient discrimination while preventing an envelope that is a special medium from being discriminated as a different medium by erroneous detection, when detecting the medium by a plurality of detection means.SOLUTION: An image formation device includes: image formation means 10 for forming an image on a medium S; first detection means 91 for detecting a basis weight of the medium S; second detection means 92 for detecting that the kind of the medium is an envelope; and determination means 101 for determining whether or not the basis weight of the medium is detected by the first detection means 91 or the detection result by the first detection means 91 is applied to a printing condition in the image formation means 10, on the basis of the detection result of the second detection means 92.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, or a multifunction digital multifunction machine called an MFP (Multifunction Peripheral), and a medium discrimination method and program executed in the image forming apparatus. [Background technology]

[0002] There is known a technology for automatically determining the type of medium, such as paper, on which an image is formed using the above-mentioned image forming apparatus, by using a sensor as a detection means. Meanwhile, in recent years, the number of special media, such as envelopes and overhead projectors, has been increasing.

[0003] Therefore, Patent Document 1 discloses a method for comprehensively determining the type of recording material from the detection results of a CMOS area sensor that detects the surface condition of the recording material and an ultrasonic sensor that detects the basis weight of the recording material, in order to accurately determine the type of recording material when multiple recording material discrimination methods are used to discriminate the type of recording material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-29622 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a special medium such as an envelope is identified comprehensively based on the detection results of a plurality of sensors, as described in Patent Document 1, there is a risk of erroneous detection resulting in identification of a different medium.

[0006] The present invention has been made in view of this technical background. , special For envelopes, which are a special medium, a false positive occurred. Image formation forPrevent Stop The present invention aims to provide an image forming apparatus, a medium discrimination image forming method, and a program therefor. [Means for solving the problem]

[0007] The above object can be achieved by the following means. (1) an image forming means for forming an image on a medium; The amount of light that passes through the medium out of the light irradiated onto the medium is detected. No. 1 A sensor; The above No. 1 A first control means for controlling the image forming means based on a detection result of the sensor; a second sensor for detecting a different media characteristic than the first sensor; The second sensor detects an envelope characteristic of the medium. a second control means for performing control for envelopes without performing control by the first control means in the above case; An image forming apparatus comprising: (2) The first control means No. 1 2. The image forming apparatus according to claim 1, further comprising a means for determining a basis weight of the medium based on an amount of transmitted light detected by a sensor, and controlling the image forming means under conditions corresponding to the basis weight. (3) The image forming apparatus according to (2), wherein the second control means stops the determination of basis weight by the first control means and performs control for an envelope. (4) The image forming apparatus according to the above item 2, wherein the second control means performs control for an envelope without using a result of determination of basis weight by the first control means. (5) The second sensor is An ultrasonic sensor that detects ultrasonic waves transmitted through a medium among ultrasonic waves emitted to the medium and , Based on the detection result by the ultrasonic sensor, For envelope Characteristics of the case were found A judgement call that determines Step Has The second control means determines whether the medium For envelope Characteristics of the case were found5. The image forming apparatus according to any one of claims 1 to 4, wherein when it is determined that the first control means does not perform control, but performs control for an envelope. (6) The second control means For For envelopes If the characteristic of An image forming device as described in any one of items 1 to 5 above, which notifies a user that an envelope has been fed from a paper feed port that cannot feed envelopes, if the medium has been fed from a paper feed port that cannot feed envelopes. (7) A fixing unit for fixing a medium between a pair of heating and pressing bodies that can be adjusted in the contact and separation direction, The second control means For For envelopes If the characteristic of 7. The image forming apparatus according to any one of items 1 to 6, further comprising control for adjusting the position of the heating and pressing member of the fixing unit in the separating direction. (8) an image forming means for forming an image on a medium; an optical sensor that detects an amount of transmitted light that passes through the medium out of the light irradiated onto the medium; an ultrasonic sensor that detects ultrasonic waves transmitted through the medium among ultrasonic waves transmitted to the medium; a second control means for not performing control based on the detection result of the optical sensor when an attenuation amount of the ultrasonic wave is equal to or greater than a predetermined amount, and for performing control based on the detection result of the optical sensor when the attenuation amount is equal to or less than the predetermined amount, based on the detection result of the ultrasonic sensor; An image forming apparatus comprising: ( 9 ) 9. The image forming apparatus according to item 8, wherein the second control means stops detection by the optical sensor and performs control for an envelope when an amount of attenuation of the ultrasonic wave is equal to or greater than a predetermined amount. ( 10 ) 9. The image forming apparatus according to item 8, wherein the second control means performs control for an envelope without using a detection result by the optical sensor when an attenuation amount of the ultrasonic wave is equal to or greater than a predetermined amount. ( 11 ) The image forming device described in any of paragraphs 8 to 10 above, wherein the second control means, when the attenuation of the ultrasonic wave is greater than or equal to a predetermined value, notifies a user that the envelope has been fed from a paper feed port that cannot feed envelopes, if the medium has been fed from a paper feed port that cannot feed envelopes. ( 12 ) The fixing unit has a pair of heating and pressing bodies that can be adjusted in the contact and separation direction, and fixes the medium between the heating and pressing bodies. 11. The image forming apparatus according to any one of items 8 to 10, wherein the second control means performs control to adjust the position of the heating and pressing body of the fixing unit in a separating direction when an attenuation amount of the ultrasonic wave is equal to or greater than a predetermined value. (13) An image forming step of forming an image on a medium; The amount of light that passes through the medium out of the light irradiated onto the medium is No. 1 detecting by a sensor; The above No. 1 a first control step of controlling the image forming step based on a detection result of the sensor; detecting a medium characteristic with a second sensor different from the first sensor; The second sensor detects an envelope characteristic of the medium. a second control step of performing envelope control without performing control according to the first control step when the envelope is not being fed; The image forming method is carried out by the image forming apparatus. (14) An image forming step of forming an image on a medium; detecting an amount of light transmitted through the medium out of the light irradiated onto the medium by an optical sensor; detecting, by an ultrasonic sensor, ultrasonic waves transmitted through the medium among the ultrasonic waves transmitted to the medium; a second control step of not performing control based on the detection result of the optical sensor when an attenuation amount of the ultrasonic wave is equal to or greater than a predetermined amount based on the detection result of the ultrasonic sensor, and performing control based on the detection result of the optical sensor when the attenuation amount is equal to or less than the predetermined amount based on the detection result of the ultrasonic sensor; The image forming method is carried out by the image forming apparatus. (15) An image forming step of forming an image on a medium; The amount of light that passes through the medium out of the light irradiated onto the medium is No. 1 detecting by a sensor; The above No. 1 a first control step of controlling the image forming step based on a detection result of the sensor; detecting a medium characteristic with a second sensor different from the first sensor; The second sensor detects an envelope characteristic of the medium. a second control step of performing envelope control without performing control according to the first control step when the envelope is not being fed; A program for causing a computer of an image forming apparatus to execute the above. (16) An image forming step of forming an image on a medium; detecting an amount of light transmitted through the medium out of the light irradiated onto the medium by an optical sensor; detecting, by an ultrasonic sensor, ultrasonic waves transmitted through the medium among the ultrasonic waves transmitted to the medium; a second control step of not performing control based on the detection result of the optical sensor when an attenuation amount of the ultrasonic wave is equal to or greater than a predetermined amount based on the detection result of the ultrasonic sensor, and performing control based on the detection result of the optical sensor when the attenuation amount is equal to or less than the predetermined amount based on the detection result of the ultrasonic sensor; A program for causing a computer of an image forming apparatus to execute the above. Effect of the Invention

[0008] According to the image forming apparatus and medium discrimination method of the present invention, the detection result of the second detection means is first obtained, and based on that detection result, a determination is made as to whether or not to detect the basis weight of the medium using the first detection means, or whether or not to apply the detection result of the first detection means to the printing conditions. This makes it possible to perform processing such as not performing detection using the first detection means depending on the detection result of the second detection means, thereby enabling efficient discrimination.

[0009] According to the program of the present invention, the computer of the image forming device can be caused to execute a process of first obtaining the detection result of the second detection means, and then determining, based on the detection result, whether to detect the basis weight of the medium using the first detection means, or whether to apply the detection result of the first detection means to the printing conditions. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus. [Diagram 3] FIG. 4 is an explanatory diagram of an arrangement state of an optical sensor. [Figure 4] FIG. 2 is an explanatory diagram of an ultrasonic sensor and its arrangement; [Diagram 5]FIG. 1A is a diagram showing the positions of the optical sensor and the ultrasonic sensor, FIG. 1B is a diagram showing the detection voltage (output voltage) of the sensor after the leading edge of the medium reaches the timing roller, and FIG. 1C is a diagram showing the detection voltage of the sensor before the leading edge of the medium reaches the timing roller. [Figure 6] 1 is a table showing characteristics of an optical sensor and an ultrasonic sensor. [Figure 7] 4 is a flowchart showing an example of a medium discrimination process executed by the image forming apparatus of FIG. 1. [Figure 8] 13 is a flowchart showing another example of the medium discrimination process executed by the image forming apparatus of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] 1 is a schematic diagram of an image forming apparatus 1 according to an embodiment of the present invention. In this example, a tandem type color printer is used as the image forming apparatus 1.

[0013] 1, the image forming apparatus 1 is configured with a paper feed section 20 disposed at the bottom of an apparatus main body 1A, an image forming section 10 disposed in the center, and a paper discharge section 60 disposed at the top. A medium transport path 22 is formed between the paper feed section 20 and the paper discharge section 60, for transporting media S, such as paper or envelopes, fed from the paper feed section 20 upward.

[0014] The image forming section 10 includes a drive roller 16 and a driven roller 15 disposed approximately in the vertical center of the device main body 1A, an intermediate transfer belt 14 horizontally suspended between the drive and driven rollers 16, 15 and running in the direction of the arrow, and photosensitive units 12Y, 12M, 12C, and 12K which are image forming units for each color of yellow (Y), magenta (M), cyan (C), and black (K) arranged along this running direction.

[0015] The toner images created by each photosensitive unit 12Y, 12M, 12C, and 12K are superimposed and transferred to the transfer belt 14, and a secondary transfer is performed on the medium S transported along the medium transport path 22 by a transfer roller (corresponding to a transfer means) 17 at the transport end (right end in the figure) of the transfer belt 14, and the paper S is sent to the fixing unit 30 to fix the toner image.

[0016] In this embodiment, the fixing unit 30 includes a heating roller 31 equipped with a heater (not shown), and a pressure roller 32 arranged in contact with the heating roller 31, and the medium S is passed through a nip portion formed between the heating roller 31 and the pressure roller 32 to be heated and pressurized, thereby fixing a toner image onto the medium S. Furthermore, in this embodiment, at least one of the heating roller 31 and the pressure roller 32 can be moved in a direction toward or away from the medium S in order to adjust the pressure according to the thickness of the medium S. Note that the movement in the direction toward or away from the medium is not limited to a movement that allows the user to visually confirm that they are separated. It is sufficient if the nip pressure weakens and an envelope can be passed through.

[0017] Each of the photoconductor units 12Y, 12M, 12C, and 12K forms an image by electrostatic copying, and includes a charger disposed around the photoconductor unit, developing units 11Y, 11M, 11C, and 11K, photoconductor drums 13Y, 13M, 13C, and 13K, a transfer unit, etc. The surfaces of the photoconductor drums 13Y, 13M, 13C, and 13K charged by the charger are exposed to light by the laser diodes of an exposure unit 40 including a print head 41 having four laser diodes, a polygon mirror, and a scanning lens, etc., and four reflecting mirrors 42, etc., so that an electrostatic latent image is formed on the surface.

[0018] In addition, toner cartridges 70Y, 70M, 70C, 70K and sub-hoppers 80Y, 80M, 80C, 80K are disposed above the photosensitive units 12Y, 12M, 12C, 12K as supply mechanisms for supplying toner to the developers 11Y, 11M, 11C, 11K of each photosensitive unit 12Y, 12M, 12C, 12K.

[0019] In FIG. 1, reference numeral 50 denotes an operation panel unit equipped with a key section and a display section.

[0020] The paper feed section 20 includes one or more (two in the example of FIG. 1) paper feed cassettes 21. A paper feed roller 23 is provided on the outlet side of each paper feed cassette 21, and the medium S stored in each paper feed cassette 21 is pulled out by the paper feed roller 23 and transported to a secondary transfer position by the secondary transfer roller 17 by one or more pairs of transport rollers 24, 25 provided along the transport path 22. Note that the image forming apparatus 1 may be provided with a manual feed tray. In this embodiment, the paper feed roller 23, the transport rollers 24, 25, etc. constitute a transport means for transporting the medium S. In this embodiment, the transport roller 25 near the secondary transfer roller 17 also serves as a timing roller for adjusting the timing for transporting the medium S to the transfer roller 17 in accordance with the transfer timing of the toner image to the medium S by the secondary transfer roller 17.

[0021] A plurality of sensors 91, 92 for detecting paper types are arranged on the conveying path 22 between the lower conveying roller 24 and the upper conveying roller (timing roller) 25. In this embodiment, an optical sensor 91 is arranged on the lower side as a first detection means, and an ultrasonic sensor 92 is arranged above the optical sensor 91, in other words, between the timing roller 25 and the optical sensor 91. Note that, between the secondary transfer roller 17 and the timing roller 25, the optical sensor 91 may be arranged on the upstream side and the ultrasonic sensor 92 on the downstream side. The optical sensor 91 and the ultrasonic sensor 92 will be described later.

[0022] Fig. 2 is a block diagram showing the electrical configuration of the image forming apparatus 1. As shown in Fig. 2, the image forming apparatus 1 includes the above-mentioned operation panel unit 50, image forming unit 10, paper feed unit 20, optical sensor 91, ultrasonic sensor 92, printer controller 150, network interface (network I / F) 160, etc., in addition to control unit 100, fixed storage device 110, and image reading device 120, which are connected to each other via a system bus 175.

[0023] The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, an S-RAM (Static Random Access Memory) 103, an NV-RAM (Non Volatile RAM) 104, and a clock IC 105.

[0024] The CPU 101 executes operation programs stored in the ROM 102 or the like to centrally control the entire image forming apparatus 1. For example, in addition to controlling functions such as copy function, printer function, and scan function to be executable, in this embodiment in particular, the CPU 101 controls the printing by automatically setting an output mode (print mode) suitable for the paper type based on the result of detection of the paper type of the paper S by the paper type detection sensor 90 at the time of printing, and the like, which will be described in detail later.

[0025] The ROM 102 stores the programs executed by the CPU 101 and other data.

[0026] The S-RAM 103 serves as a working area when the CPU 101 executes a program, and temporarily stores the program, data used when the program is executed, and the like.

[0027] The NV-RAM 104 is a non-volatile memory backed up by a battery, and stores various settings relating to image formation, the number of pixels of the display unit 54, data of various screens displayed on the display unit 54, and the like.

[0028] The clock IC 105 keeps time and also functions as an internal timer to measure processing times, etc.

[0029] The fixed storage device 110 is made up of a hard disk or the like, and stores programs, various data, and the like.

[0030] The image reading device 120 includes a scanner and the like, and reads an original document set on a platen glass by scanning it, and converts the read original document into image data.

[0031] The operation panel unit 50 is used when the user instructs the image forming apparatus 1 to issue a job or other instructions or to make various settings, and includes a reset key 51, a start key 52, a stop key 53, a display unit 54, a touch panel 55, and the like.

[0032] The reset key 51 is used to reset settings, the start key 52 is used to start operations such as scanning, and the stop key 53 is pressed to interrupt an operation, etc.

[0033] The display unit 54 is, for example, a liquid crystal display device, and displays messages and various operation screens, etc., and the touch panel 55 is formed on the screen of the display unit 54 and detects touch operations by the user.

[0034] The image forming unit 10 prints on paper image data of an original read by the image reading device 120 or a copy image generated from print data transmitted from an external terminal device, etc., and is equipped with a print engine 18 and the fixing unit 30 mentioned above, etc.

[0035] The print engine 18 refers to the hardware parts involved in image formation, and is composed of, for example, photosensitive units 12Y, 12M, 12C, 12K, developers 11Y, 11M, 11C, 11K, photosensitive drums 13Y, 13M, 13C, 13K, chargers, transfer devices, laser diodes, polygon mirrors, print head 41, and motors that drive these.

[0036] The printer controller 150 generates a reproduced image from the print data received by the network interface 160 .

[0037] A network interface (network I / F) 160 functions as a communication means for transmitting and receiving data to and from an external terminal device or the like.

[0038] FIG. 3 is an explanatory diagram of the optical sensor 91 and its arrangement. The optical sensor 91 includes a pair of light-emitting section 91a and light-receiving section 91b arranged opposite to each other across the medium transport path 22. The light-emitting section 91a is provided with a light-emitting element (not shown) made of a light source such as a light-emitting diode (LED), and the light-receiving section 91b is provided with a light-receiving element (not shown) made of a photodiode or the like. The medium S pulled out from the paper feed cassette 21 by the paper feed roller 23 is passed from below to above while the gap between the rollers 24a and guides 24b constituting the transport roller 24 is regulated so that there is no variation in the transport position. The rollers 24a and guides 24b are provided in a plurality of pairs (two pairs in FIG. 3) in a direction perpendicular to the transport direction (width direction of the medium), and the light-emitting section 91a and the light-receiving section 91b are installed at a position between the adjacent rollers 24a and guides 24b immediately after the leading edge of the medium S passes through the rollers 24a and guides 24b. There are no limitations on the placement requirements for the optical sensor 91, but in order to suppress a decrease in sensitivity due to fluttering of the medium S, it is desirable to set the distance from the medium S to the light-emitting portion 91a and the distance from the medium S to the light-receiving portion 91b to approximately 6:4, and to set the paper passing width within ±1 to 2 mm.

[0039] The optical sensor 91 is a known sensor that irradiates light from a light-emitting element of a light-emitting section 91a onto the medium S passing through the optical sensor 91, detects the transmitted light with a light-receiving element of a light-receiving section 91b, and measures the basis weight of the medium S based on the detected amount of light, in other words, the amount of light transmitted through the medium S. In this embodiment, in order to stabilize detection variations, the amount of transmitted light is detected multiple times while the medium S is passing, for example 10 times at 5 mm intervals, and the detected amounts are averaged to measure the basis weight of the medium S.

[0040] 4 is an explanatory diagram of the ultrasonic sensor 92 and its arrangement. As described above, the ultrasonic sensor 92 is located between the optical sensor 91 and the timing roller 25, and includes a pair of transmitter 92a and receiver 92b arranged diagonally opposite each other at an angle of about 38° to 45° with respect to the passing direction of the medium S, sandwiching the medium transport path 22 therebetween. Although there are no limitations on the arrangement requirements for the ultrasonic sensor 92, it is desirable to keep the paper passing width within about 2.4 mm in order to stabilize detection variations, similar to the optical sensor 91.

[0041] This ultrasonic sensor 92 is a known sensor that transmits ultrasonic waves from a transmitter 92a to the medium S passing through the ultrasonic sensor 92, receives the ultrasonic waves that have passed through the medium S with a receiver 92b, and measures the basis weight of the medium S based on the amount of ultrasonic waves received. In this embodiment, the basis weight is detected based on the attenuation rate (A' / A) when the peak value A of the ultrasonic waves attenuates to the peak value A' of the wavelength as it passes through the medium S, and it is determined whether or not the medium is an envelope from the basis weight value.

[0042] Figure 5(A) is a diagram showing a schematic diagram of the arrangement positions of the optical sensor 91 and the ultrasonic sensor 92, (B) is a diagram showing the detection voltage (output voltage) of the sensor after the leading edge of the medium S reaches the timing roller 25, and (C) is a diagram showing the detection voltage of the sensor before the leading edge of the medium S reaches the timing roller 25.

[0043] As described above, the optical sensor 91 is disposed near the downstream side of the conveying roller 24, and the ultrasonic sensor 92 is disposed between the optical sensor 91 and the timing roller 25. As shown in the detection voltage diagrams of (B) and (C) in the same figure, the detection voltage of each sensor is not constant, so the medium S is sampled several times and the average value is used. Furthermore, the detection variation of the sensor increases depending on the behavior of the medium S. In particular, in the case of the ultrasonic sensor 92, the detection variation increases when the medium S vibrates, so it is desirable to perform the measurement when the medium S is bitten by both the conveying roller 24 and the timing roller 25. For this reason, in this embodiment, the ultrasonic sensor 92 for determining whether or not it is an envelope is disposed between the optical sensor 91 and the timing roller 25, thereby improving the detection accuracy of the sensor.

[0044] Generally, when considering the usage ratio between envelopes and printing paper (plain paper, thick paper, thin paper, etc.), the number of times printing paper is used is greater. The faster the measurement result of optical sensor 91 that measures the basis weight is obtained, the faster the first copy time becomes, so it is desirable to arrange optical sensor 91 that detects the basis weight of printing paper that is used frequently upstream of ultrasonic sensor 92, as this shortens the total operating time of image forming apparatus 1 and leads to suppression of a decrease in productivity.

[0045] Furthermore, it is desirable to perform measurements using the optical sensor 91 and the ultrasonic sensor 92 when there is a possibility that new media S has been placed in the paper feed cassette 21, the manual feed tray, etc., that is, when measuring the first sheet when the paper feed cassette 21 is opened and closed, or when using the manual feed tray.

[0046] FIG. 6 is a table showing the characteristics of the optical sensor 91 and the ultrasonic sensor 92. The optical sensor 91 is capable of detecting basis weight with high accuracy regardless of thickness, but is not suitable for detecting envelopes. On the other hand, the ultrasonic sensor 92 is unstable in terms of basis weight accuracy, and is not suitable for detecting envelopes with a basis weight of 150 g / mm 2 The accuracy is high for thinner papers below 150g / mm 2 The accuracy drops for thicker paper than this, but the system can accurately identify envelopes.

[0047] The reason for this is that the optical sensor 91 is a transmission type sensor, and therefore determines the basis weight corresponding to the amount of light transmitted through the medium S based on a preset correspondence relationship between the amount of transmitted light and basis weight. In principle, the thicker the paper, the less the amount of transmission. If the optical sensor 91 were to try to detect an envelope, the thickness of the envelope would be the same as that of two sheets of paper, resulting in a smaller amount of transmission and misidentifying it as thick paper. On the other hand, the ultrasonic sensor 92 is able to detect an envelope from the amount of attenuation, since ultrasonic waves are attenuated by the air layer within the envelope. For this reason, if the basis weight of the medium S being conveyed is measured by the optical sensor 91 and the measurement results of the ultrasonic sensor 92 are used simultaneously to perform medium discrimination, a misidentification or inconsistent error will occur.

[0048] Therefore, in this embodiment, it is possible to accurately detect the basis weight of the envelope and the print paper by first using the ultrasonic sensor 92 to detect whether it is an envelope, and when it is detected that it is not an envelope, using the detection result of the optical sensor 91 or continuing the detection of the optical sensor 91. If the detection by the optical sensor 91 has ended when the ultrasonic sensor 92 detects that it is not an envelope, the detection result of the optical sensor 91 will be used, and if the detection by the optical sensor 91 has not ended when the ultrasonic sensor 92 detects that it is not an envelope, the detection by the optical sensor 91 will continue.

[0049] Fig. 7 is a flowchart showing an example of a medium discrimination process executed by the image forming apparatus of Fig. 1. This medium discrimination process and the medium discrimination process shown in the flowchart of Fig. 8 are executed by CPU 101 in control unit 100 of image forming apparatus 1 operating according to an operating program recorded in ROM 102, fixed storage device 110, etc. and loaded into S-RAM 103.

[0050] When paper feeding begins in step S01, medium S is transported along medium transport path 22 by transport rollers 24 and the like. When medium S is transported to the position of optical sensor 91, detection of basis weight by optical sensor 91 begins in step S02, and when medium S is further transported to the position of ultrasonic sensor 92, detection by ultrasonic sensor 92 of whether or not it is an envelope begins in step S03.

[0051] Next, in step S04, it is determined whether detection by the ultrasonic sensor 92 has ended. If it has not ended (NO in step S04), it waits until detection has ended. If it has ended (YES in step S04), in step S05, it is checked whether the detection result of the ultrasonic sensor 92 has determined that the medium S is an envelope. If it has been determined to be an envelope (YES in step S05), it is determined in step S06 that the medium S is an envelope, and then it is determined that the detection result of the optical sensor 91 will not be used, and in step S07, if detection by the optical sensor 91 (including calculation of basis weight) has not ended, detection is stopped. If detection by the optical sensor 91 has ended, the detection result is not used.

[0052] Next, in step S08, the transport of the envelope, which is medium S, is stopped, and then in step S09, it is determined whether the envelope, which is medium S, has been fed from a feed port (including paper feed cassette 21) from which feeding of envelopes is prohibited. The feed ports from which feeding of envelopes is prohibited are set in advance. If the envelope has been fed from a feed port from which feeding is prohibited (YES in step S09), in step S15, a message to that effect is displayed on display 54 of operation panel 50 to notify the user. This notification enables the user to take measures such as resetting the envelope in another feed port that can feed envelopes.

[0053] In step S09, if the sheet has not been fed from a feed port where feeding of envelopes is prohibited (NO in step S09), in step S10, at least one of heating roller 31 and pressure roller 32 is moved in the separating direction to adjust the pressure of fixing unit 30 according to the thickness of the envelope, which is medium S. If the rollers have already been moved in the separating direction, the processing in this step is not performed.

[0054] Thereafter, in step S11, the transport of the envelope, which is the medium S, is resumed, and then in step S12, printing is performed under printing conditions appropriate for the envelope.

[0055] If the medium S is not determined to be an envelope in step S05 (NO in step S05), it is determined that the detection result of the basis weight by the optical sensor 91 is used, and in step S13, it is determined whether detection of the basis weight by the optical sensor 91 has been completed. If it has not been completed (NO in step S13), the process waits until it is completed. If it is completed (YES in step S13), the basis weight of the medium S is determined in step S14, and then the process proceeds to step S12, where printing processing is performed under printing conditions according to the basis weight of the medium S.

[0056] In this embodiment, the detection result of the ultrasonic sensor 92 that detects that the type of the medium S conveyed by the conveying roller 24 or the like is an envelope is first obtained, and based on the detection result, it is determined whether or not to use the detection result of the optical sensor 91. In other words, since whether or not the medium S is an envelope is determined by one ultrasonic sensor 92, it is possible to more reliably determine whether or not the medium S is an envelope compared to a case where the detection results of the optical sensor 91 and the ultrasonic sensor 92 are comprehensively determined. Furthermore, when the ultrasonic sensor 92 detects that the type of the medium S is not an envelope, it is determined that the detection result of the optical sensor 91 is to be used, so that the detection of the basis weight by the optical sensor 91 is not wasted, and efficient determination can be performed. Furthermore, when the ultrasonic sensor 92 detects that the type of the medium S is an envelope, it is determined that the detection result of the optical sensor 91 is not to be used, so that the medium can be quickly determined without waiting for the detection of the basis weight by the optical sensor 91.

[0057] Moreover, because the optical sensor 91 starts detecting the basis weight of the medium S before the ultrasonic sensor 92 starts detecting that the type of the medium S is an envelope, if the ultrasonic sensor 92 detects that the type of the medium S is not an envelope, the detection result of the optical sensor 91 can be acquired and used early. As a result, in the case of printing paper that is used frequently, the start of the printing process can be brought forward, and the overall printing process time can be shortened.

[0058] Fig. 8 is a flow chart showing another example of the medium discrimination process performed in the image forming apparatus of Fig. 1. This example is a medium discrimination process in a continuous printing process.

[0059] When paper feeding begins in step S21, medium S is transported along medium transport path 22 by transport rollers 24 and the like. When medium S is transported to the position of optical sensor 91, detection of basis weight by optical sensor 91 begins in step S22, and when medium S is further transported to the position of ultrasonic sensor 92, detection by ultrasonic sensor 92 of whether or not it is an envelope begins in step S23.

[0060] Next, in step S24, it is determined whether detection by the ultrasonic sensor has ended. If it has not ended (NO in step S24), the process waits until detection has ended. If it has ended (YES in step S24), in step S25, it is checked whether medium S has been determined to be an envelope based on the detection result of ultrasonic sensor 92. If it has been determined to be an envelope (YES in step S25), it is determined in step S26 that medium S is an envelope, and then it is determined that the detection result of optical sensor 91 will not be used. In step S27, if detection by optical sensor 91 (including calculation of basis weight) has not ended, detection is stopped and the process proceeds to step S28.

[0061] On the other hand, if the medium is not determined to be an envelope in step S25 (NO in step S25), it is determined that the detection result of the basis weight by the optical sensor 91 is used, and in step S33, it is determined whether the detection by the optical sensor 91 has ended. If it has not ended (NO in step S33), the process waits until it has ended. If it has ended (YES in step S33), the basis weight of the medium S is determined in step S34, and then the process proceeds to step S28.

[0062] In step S28, the result of whether or not it is an envelope is stored in S-RAM 103, etc. If it is detected by ultrasonic sensor 92 to be an envelope, it is stored as an envelope, and if it is detected to be not an envelope, the basis weight is determined by optical sensor 91 and then it is stored as not an envelope.

[0063] Next, in step S29, it is determined whether the stored result is the same as the previous stored result. If it is the same (YES in step S29), the printing process is executed for the medium S in step S35, and then the process proceeds to step S36. Note that, if there is no previous stored result, such as in the case of the first sheet of medium S, the determination in step S29 is set to YES, and the process proceeds directly to steps S35 and S36.

[0064] In step S36, it is checked whether or not there is the next medium S, and if there is (YES in step S36), the process returns to step S21 to feed the next medium S. If there is not the next medium S (NO in step S36), the process ends.

[0065] If the stored result in step S29 is different from the previous result (NO in step S29), it is determined in step S30 that medium S is a mixture of envelopes and other papers, the printing process is stopped in step S31, and the fact that the papers are mixed is displayed on display unit 54 in step S32 to notify the user. This notification enables the user to take necessary measures to avoid mixing.

[0066] In this manner, in this embodiment, it is possible to detect whether envelopes and other papers are mixed on the medium S, and to prevent printing from being performed in a mixed state.

[0067] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in addition to the optical sensor 91 and the ultrasonic sensor 92, other sensors for detecting the characteristics of the medium S may be arranged.

[0068] Also, although the optical sensor 91 is disposed upstream of the ultrasonic sensor 92 in the transport direction of the medium S, the ultrasonic sensor 92 may be disposed upstream of the optical sensor 91. In this case, when the ultrasonic sensor 92 detects that the medium S is an envelope, if the optical sensor 91 has not started detecting the basis weight, it is determined that the optical sensor 91 will not detect the basis weight and detection of the basis weight is not started, and if the basis weight detection has already started, it is determined that the basis weight detection result by the optical sensor 91 will not be used and detection is stopped. On the other hand, when the ultrasonic sensor 92 detects that the medium S is not an envelope, if the optical sensor 91 has not started detecting the basis weight, it is determined that the optical sensor 91 will detect the basis weight and detection of the basis weight is started. If the basis weight detection has already started, it is determined that the basis weight detection result by the optical sensor 91 will be used. [Explanation of symbols]

[0069] 1. Image forming device 1A Device body 10 Image forming section 17 Secondary transfer roller 20 Paper feed section 21 Paper feed tray 22 Media transport path 23 Paper feed roller 24 Transport roller 24a Coro 24b Guide 25 Transport roller (timing roller) 30 Fixing unit 31 Heating roller 32 Pressure roller 50 Operation panel section 54 Display section 91 Optical sensor (first detection means) 91a Light emitting part 91b Light receiving part 92 Ultrasonic sensor (second detection means) 92a Transmitter 92b Receiving section S medium

Claims

1. An image forming means for forming an image on a medium; a first sensor for detecting an amount of light transmitted through the medium out of light irradiated onto the medium; a first control means for controlling the image forming means based on a detection result of the first sensor; a second sensor for detecting a different media characteristic than the first sensor; a second control means for performing control for an envelope without performing control by the first control means when the second sensor detects characteristics of the medium in an envelope; An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, wherein the first control means has a means for determining the basis weight of the medium based on the amount of transmitted light detected by the first sensor, and controls the image forming means under conditions corresponding to the basis weight.

3. 3. The image forming apparatus according to claim 2, wherein the second control means stops the determination of basis weight by the first control means and performs control for an envelope.

4. 3. The image forming apparatus according to claim 2, wherein the second control means performs control for an envelope without using a result of determination of basis weight by the first control means.

5. The second sensor is an ultrasonic sensor that detects ultrasonic waves transmitted through a medium among ultrasonic waves transmitted to the medium, a determining unit for determining that an envelope characteristic has been detected for the medium based on a detection result by the ultrasonic sensor, An image forming apparatus as described in any one of claims 1 to 4, wherein the second control means performs control for an envelope without performing control by the first control means when the determination means determines that characteristics of an envelope have been detected for the medium.

6. An image forming device as described in any one of claims 1 to 5, wherein the second control means, when detecting characteristics of an envelope for the medium, notifies a user that an envelope has been fed from a paper feed port that cannot feed envelopes, if the medium has been fed from a paper feed port that cannot feed envelopes.

7. a fixing unit that fixes a medium by passing the medium between a pair of heating and pressing bodies that can be adjusted in a contact and separation direction; 7. The image forming apparatus according to claim 1, wherein the second control means performs control to adjust the position of the heating and pressing body of the fixing unit in a separation direction when characteristics of an envelope are detected for the medium.

8. An image forming means for forming an image on a medium; an optical sensor that detects an amount of transmitted light that passes through the medium out of the light irradiated onto the medium; an ultrasonic sensor that detects ultrasonic waves transmitted through the medium among ultrasonic waves transmitted to the medium; a second control means for not performing control based on the detection result of the optical sensor when an attenuation amount of the ultrasonic wave is equal to or greater than a predetermined amount, and for performing control based on the detection result of the optical sensor when the attenuation amount is equal to or less than the predetermined amount, based on the detection result of the ultrasonic sensor; An image forming apparatus comprising:

9. The image forming apparatus of Claim 8, wherein the second control means stops detection by the optical sensor when the attenuation of the ultrasonic wave is greater than or equal to a predetermined value, and performs control for envelopes.

10. The image forming apparatus of Claim 8, wherein the second control means performs control for envelopes without using the detection results of the optical sensor when the attenuation of the ultrasonic waves is greater than or equal to a predetermined value.

11. An image forming device as described in any of claims 8 to 10, wherein the second control means, when the attenuation of the ultrasonic wave is greater than or equal to a predetermined value, notifies a user that an envelope has been fed from a paper feed port that cannot feed envelopes, if the medium has been fed from a paper feed port that cannot feed envelopes.

12. A fixing unit for fixing a medium between a pair of heating and pressing bodies whose positions can be adjusted in a contact and separation direction, 11. The image forming apparatus according to claim 8, wherein the second control means performs control to adjust the position of the heating and pressing body of the fixing unit in a separating direction when an amount of attenuation of the ultrasonic wave is equal to or greater than a predetermined value.

13. An image forming step of forming an image on a medium; detecting an amount of light transmitted through the medium out of the light irradiated onto the medium by a first sensor; a first control step of performing control in the image forming step based on a detection result of the first sensor; detecting a media characteristic with a second sensor different from the first sensor; a second control step of performing control for an envelope without performing control according to the first control step when the second sensor detects characteristics of the medium corresponding to an envelope; The image forming method is carried out by the image forming apparatus.

14. An image forming step of forming an image on a medium; detecting an amount of light transmitted through the medium out of the light irradiated onto the medium by an optical sensor; detecting, by an ultrasonic sensor, ultrasonic waves transmitted through the medium among the ultrasonic waves transmitted to the medium; a second control step of not performing control based on the detection result of the optical sensor when an attenuation amount of the ultrasonic wave is equal to or greater than a predetermined amount based on the detection result of the ultrasonic sensor, and performing control based on the detection result of the optical sensor when the attenuation amount is equal to or less than the predetermined amount based on the detection result of the ultrasonic sensor; The image forming method is carried out by the image forming apparatus.

15. An image forming step of forming an image on a medium; detecting an amount of light transmitted through the medium out of the light irradiated onto the medium by a first sensor; a first control step of performing control in the image forming step based on a detection result of the first sensor; detecting a media characteristic with a second sensor different from the first sensor; a second control step of performing control for an envelope without performing control according to the first control step when the second sensor detects characteristics of the medium corresponding to an envelope; A program for causing a computer of an image forming apparatus to execute the above.

16. An image forming step of forming an image on a medium; detecting an amount of light transmitted through the medium out of the light irradiated onto the medium by an optical sensor; detecting, by an ultrasonic sensor, ultrasonic waves transmitted through the medium among the ultrasonic waves transmitted to the medium; a second control step of not performing control based on the detection result of the optical sensor when an attenuation amount of the ultrasonic wave is equal to or greater than a predetermined amount based on the detection result of the ultrasonic sensor, and performing control based on the detection result of the optical sensor when the attenuation amount is equal to or less than the predetermined amount based on the detection result of the ultrasonic sensor; A program for causing a computer of an image forming apparatus to execute the above.

Images