JP2000063001A - Jam detection device in image forming apparatus - Google Patents

Abstract

(57) [Problem] An image capable of detecting a jam even when a trailing end of a sheet cannot be detected by a detecting means, and capable of detecting that the paper-out state is not jammed accurately even for a short time. Provided is a jam detection device in a forming device. When a paper feed is started, a clock processing unit starts time measurement, and at the same time, a rear end of a first sheet of paper passes from a storage unit to change from a paper present state to a paper end state. The theoretical time T ₁ and the theoretical time T ₂ at which the _second tip passes are extracted. Then, it is determined whether or not it is detected that the paper out state detection means 10 after the counting of clock means 11 has exceeded the time T _1, when detecting the no paper state, it is determined that the normal, there is a paper state when detecting the, because jam might have occurred, detecting means until further continued counting, counting reaches the time T ₂ 10
It is determined that a paper jam has occurred if the detection of the presence of paper continues.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting whether a sheet has jammed (paper jam) on a conveyance path in an image forming apparatus. 2. Description of the Related Art In a conventional image forming apparatus, a detecting means for detecting the presence or absence of a sheet at an installation position is provided on a conveyance path, and after the detecting means detects the trailing end of the sheet, the leading end of a subsequent sheet is detected. Set the required time until the sheet is detected, and start timing after the trailing edge of the preceding sheet is detected by the detecting means. It was detected that a jam had occurred on the road. However, the conventional jam detecting device in the image forming apparatus cannot detect the jam when the trailing edge of the sheet cannot be detected, and the sheet remains on the detecting means. There is a problem that even if a jam occurs in a state where the jam occurs, the jam cannot be detected. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and has a time measuring means for starting time measurement from the start of sheet feeding, and a paper sheet installed on a transport path and provided at an installation position. a detection means for detecting the presence, n th sheet to be fed (n is an integer of 1 or more) time T ₁ that the trailing edge passes between the n +
And calculating means or storing means for calculating and storing the time T ₂ where the first sheet of the tip passes, clocking of the timer means the time T
Immediately after elapse of ₁ , the detecting means detects the presence or absence of paper, and when it is detected that there is no paper, it is determined that the paper is normal. detecting means until it reaches the T ₂ is obtained by the jam detection device in an image forming apparatus equipped with a determination processing unit that determines that a jam has occurred in the case of continued detection with the paper is present. [0005] With such a jam detecting device, even if a jam occurs in a state where the sheet remains in the detecting means, the jam can be detected. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram illustrating a conveyance path of an image forming apparatus according to the present invention. Sheets stored in a sheet feeding cassette 1 are conveyed to a registration roller 4 by a sheet feeding roller 2 and a conveying roller 3, At the timing when the development of the toner on the drum 5 is completed by the developing roller 7, the toner is conveyed and transferred between the photosensitive drum 5 and the transfer roller 6, and after the toner is fixed by the heating roller 8 and the pressure roller 9,
The paper is discharged to a paper discharge tray or the like. [0007] The detecting means 10 of the present invention, in this embodiment,
Although provided near the discharge port to detect a jam near the discharge port, the jam can be detected similarly when provided at another location on the transport path. In addition, the detection means 10
The sensor may be a mechanical sensor that operates when a sheet passes, or may be an optical sensor using a light emitting element and a light receiving element. In this embodiment, a mechanical sensor is used. FIG. 2 is a block diagram showing a unit relating to the jam detection of the image forming apparatus. The detecting unit 10 detects the presence or absence of a sheet, and the timing unit 1 starts counting time from the start of sheet feeding.
1, n th sheet to be fed (n is an integer of 1 or more) storage means 12 for storing the time T ₂ the rear end passes the time T ₁ and the n + 1 th leading end passing the, Judgment processing means 1
It consists of three. In this embodiment, the time T ₁ and the time T ₂ corresponding to various paper sizes are stored in the storage unit 12 in advance, but the time T ₁ and the time T ₂ are calculated from the size of the paper to be fed. It is also possible to provide a calculating means for performing the calculation, and store the calculated time T ₁ and time T ₂ in the storage means 12. FIGS. 3 and 4 are a timing chart and a flowchart for detecting a jam with the configuration shown in FIG. 2, and the operation of the present invention will be described below with reference to FIG. First, when paper feeding is started (step 10).
1), the timing means 11 starts timing (step 10)
2). The paper feed start time may be, for example, a time during which the paper feed roller 2 rotates or a time during which the registration roller 4 rotates. Simultaneously with the start of the time measurement, the determination processing means 13 stores the theoretical time T ₁ from the storage means 12 when the rear end of the first sheet passes and when there is no paper and there is no paper.
2 th tip should take out the theoretical time T ₂ to pass through but the time T ₁ and time T ₂ are different depending on the size of paper to be fed. [0011] Then, the judgment processing means 13 outputs
Timekeeping confirms whether or not the elapsed time T ₁ (step 103), determines whether or not detected the paper out state detecting unit 10 after the elapse (step 104). If a paper-out state is detected, the state is as shown in FIG. 3A, and it is determined that the state is normal (no jam has occurred) (step 10).
5), when detecting the paper present state is a state in FIG. 3 (b), whether there is a possibility that a jam has occurred, further continued for counting or timing has reached the time T ₂ Is confirmed (step 106), and when it reaches,
(B) the state of which determines that a jam has occurred to the detection unit 9 from the time T ₁ to time T ₂ continues to sense the state there the paper (step 108). [0012] As has been described in the foregoing, according to the jam detection device in an image forming apparatus of the present invention, detecting the presence or absence of the detection means the paper immediately after the counting of the timer means is elapsed time T ₁ and further continue the counting of the time counting means when it detects the paper is present, to determine that a jam has occurred if the detection means continues to detect the paper is present to reach the time T _2, the detection Even if the trailing edge of the paper cannot be detected by the means, the jam can be detected, and it can be detected that the paper-out state has not been jammed accurately even in a short time, thereby realizing more accurate jam detection. A jam detection device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a conveyance path of an image forming apparatus according to the present invention. FIG. 2 is a configuration diagram showing means related to the jam detection device of the present invention. FIG. 3 is a timing chart of the detection means of the present invention. FIG. 4 is a flowchart of the detection means of the present invention. [Description of Signs] 1: Paper feed cassette 2: Paper feed roller 3: Conveyance roller 4: Registration roller 5: Photoconductor drum 6: Transfer roller 7: Developing roller 8: Heating roller 9: Pressure roller 10: Detecting means 11 : Clocking means 12: Storage means 13: Judgment processing means

Claims (1)

Claims: 1. A time-measuring means for starting time measurement from the start of sheet feeding, a means for detecting presence or absence of a sheet at a setting position provided on a conveying path, and a number of sheets n to be fed. th (n is an integer of 1 or more) lapse storage means for storing the time T ₂ the tip trailing edge time T ₁ and the n + 1 th passing the passes, the counting time T ₁ of the said timer means Immediately after the detection, the detection means detects the presence or absence of a sheet. If it is detected that there is no sheet, it is determined that the sheet is normal. _2. A jam detecting device in an image forming apparatus, comprising: a judgment processing unit for judging that a jam has occurred when the detecting unit continues to detect that there is a sheet until the sheet reaches ₂ .