JPS62125375A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the unnecessary developing while a photosensitive body is electrostatically charged without being laser-exposed by stopping the charging to the photosensitive body with a signal fed from an optical abnormality detecting means at the time of the abnormality of the optical system. CONSTITUTION:When a recording starting request is inputted from an interface circuit 32, the control signal of a laser lighting-up is sent through a control circuit 31 to a laser driver 33. On the other hand, from a beam position detecting circuit 34, a beam detecting signal is sent to the control circuit 31, the beam detecting signal is inputted even to an optical abnormality detecting circuit 35 as an optical abnormality detecting means, and when the beam detection is stopped, a charging stopping signal is sent from an optical abnormality detecting circuit 35 to an input control circuit 31. When the charging stopping signal is sent from the optical abnormality detecting circuit 35, a high pressure electric power source 36 is turned off and the charging to a photosensitive body 1 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an image recording device using a laser as a light source.
In particular, the present invention relates to a background exposure type image recording apparatus in which a part where no image is to be recorded is exposed to laser light, a part where one image is to be recorded is not exposed to laser light, and a toner image is formed in the unexposed part.

(Prior art) In general, electrophotographic laser beam printers use an image reversal development method that forms toner images on exposed areas, that is, areas where the electrical charge has decreased, and another that forms toner images on unexposed areas. There are two background exposure and positive development methods. In this background exposure positive development method, most of one image area is exposed and becomes a white background.

The laser modulation was turned off and a toner image was formed only when a recording signal was sent out. Therefore, if the laser breaks down or deteriorates during recording, no exposure or insufficient exposure will occur.

(Problems to be Solved by the Invention) By the way, in the above-mentioned conventional laser beam printer, if the laser malfunctions or deteriorates, exposure may not be performed or exposure may be insufficient, resulting in the formation of a pitch-black image, or the so-called There was a problem in that the image was recorded and output with fog remaining.

Furthermore, if a similar failure or malfunction occurs during preparation before or after recording operation, the charged photoreceptor will not be exposed to light, or will pass through the development area with insufficient exposure and be developed. However, there were problems such as unnecessary consumption of developer and contamination of the inside of the machine. Incidentally, even if a scanner such as a polygon mirror that scans a laser beam becomes abnormal, the same problem as above occurs.

Therefore, the present invention has been made to solve the above-mentioned problems of the conventional example, and its purpose is to perform unnecessary development while the photoreceptor remains charged without being exposed to laser light. An object of the present invention is to provide an image recording device capable of preventing wastage of agents and contamination of the inside of the device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an image recording apparatus that records a background, which is a non-recording portion, on a photoreceptor by exposing it to laser light using an optical system. In the present invention, an optical abnormality detection means for detecting an abnormality in the optical system is provided, and when an abnormality occurs in the optical system, charging of the photoreceptor is stopped in response to a signal from the optical abnormality detection means.

(Embodiment) The present invention will be explained below based on the illustrated embodiment. In FIG.
After being uniformly charged, the optical system 3 exposes it to a laser beam 4 that is modulated by an external or internal signal, forming a pattern of charges, that is, a latent image. after that,
A toner image is developed by a developing device 5 to form a toner image on the photoconductor 1.Then, the toner image is transferred by a transfer charger 8 to a transfer material 7 such as paper fed by a paper feed roller 6, and then The transfer material 7 having this toner image is fixed by a fixing device 9 and then discharged onto a paper discharge tray 10 .

On the other hand, the photoreceptor 1 is cleaned by a cleaner 11 to remove residual toner that has not been transferred, and subjected to pre-exposure 12 to uniformly remove static electricity and perform primary image formation.Here, a high voltage is applied to the charger 2. The photoreceptor 1 is uniformly charged by corona discharge, but if an abnormality is detected in the optical system 3, the application of high voltage to the charger 2 is stopped and the photoreceptor 1 is not charged. Since the photoreceptor 1 that does not receive toner is developed, the photoreceptor 1 can be rotated and the transfer material 7 can be discharged outside the machine without toner adhering to it.

Next, the optical system abnormality detection method will be explained based on FIG. A laser beam 22 emitted from a laser beam 21 (exposure) 21 is scanned by a polygon mirror 24 rotated by a scanner motor 23, and then passed through an imaging lens 25.
The light is then scanned and exposed onto the photoreceptor l through the folding mirror 26. On the other hand, a mirror 27 is disposed at the end of the scanning surface of the laser beam 22, and this mirror 27 exposes a part of the beam outside the image area to the beam detection device 28 to detect the beam position. The detection consists of horizontally synchronizing the image by detecting the beam scanning position and detecting an abnormality in the optical system.

FIG. 3 shows sequence control of the image recording apparatus according to the present invention. In the figure, when a recording start request is input from the interface circuit 32, a laser lighting control signal is sent to the laser driver 33 via the control circuit 31. is sent. On the other hand, a beam detection signal is sent from the beam position detection circuit 34 to the control circuit 31, and the beam detection signal is sent to the optical abnormality detection circuit 3 as an optical abnormality detection means.
5, and when beam detection is interrupted, a charging stop signal is sent from the optical abnormality detection circuit 35 to the control circuit 31. When the charging stop signal is sent from the optical abnormality detection circuit 35, the high voltage power supply 36 is turned off and charging of the photoreceptor 1 is stopped.

Furthermore, to explain the optical abnormality detection circuit 35 based on FIG. 4, when a beam position detection signal is input from the beam position detection circuit 34, the flip-flop 41 is set and the counter 42 is reset. When the counter 42 counts a time corresponding to a time slightly longer than the l-scanning time using the clock signal, the flip-flop 41
works to reset. Here, the front optical system 3
If is normal, the beam detection signal from the next scan is input before the counter 42 resets the flip-flop 41, and the counter 42 is cleared, so it does not become a signal to reset the flip-flop 41. In other words, When the optical system 3 is normal, the beam detection signal becomes a charging enable signal.

The operation timing of the optical system having the above configuration will be explained based on FIG. 5. When the control circuit 31 is about to start recording operation, it sends an exposure-on signal to the laser driver 33 as shown in FIG. 5(a). Send out. As a result, as shown in FIG. 6(b), if the optical abnormality detection circuit 35 is normal, it is sent to the control circuit 31, but if the fourth beam detection pulse (break & i) is not sent, the counter 4
2 is a reset signal for the flip-flop 41 after a period of time slightly longer than l scanning as shown in FIG.
That is, a charging-off pulse is sent out. As a result, the charge enable signal, which is the output of the flip-flop 41, is turned off as shown in FIG. 4(d).

On the other hand, when the charging enable signal is turned off while exposure is on, the control circuit 31 shown in FIG. emits. At this time, if an optical abnormality is detected during recording, the transfer material 7 is discharged outside the machine, and then operations such as rotation of the photoreceptor 1 are stopped.

Incidentally, in the above embodiment, the abnormality of the optical system was detected by beam position detection, but the present invention is not limited to the above embodiment. It is also possible to turn off the charging by notifying the rotation abnormality from the driver itself.Also, in a laser driver that monitors the amount of light emitted from the laser and controls the light amount, even if the light amount is controlled, the standard light amount cannot be obtained. If this occurs, an optical abnormality signal may be generated and the charging may be turned off in the same manner as described above.

(Effects of the Invention) The image recording device according to the present invention has the above-described configuration and operation, and is provided with an optical abnormality detection means for detecting an abnormality in the optical system. Since charging of the photoreceptor is stopped by a signal, the photoreceptor is not exposed to laser light and unnecessary development is not performed while the photoreceptor is charged as in the conventional case, which prevents waste of developer and contamination inside the machine. can do. In addition, it is possible to prevent troubles such as paper wrapping around the fixing roller due to poor fixing separation that occurs when an image with abnormally attached toner is sent to the fixing device.
Furthermore, it is possible to prevent poor cleaning and an increase in toner recovery capacity that would otherwise occur due to sending a large amount of toner to the cleaner.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the entire laser beam printer to which the present invention is applied, Fig. 2 is an explanatory diagram showing the optical system of Fig. 1, and Fig. 3 is a block diagram showing an embodiment of the optical system of the present invention. 4 is a circuit diagram of the optical abnormality detection circuit of the same embodiment, and FIG.
The figure is a timing chart diagram showing the operating state of each part in the same embodiment. Explanation of symbols l...Photoconductor 2...Charger 3...Optical system 4.22...Laser beam 7...Transfer material 21...Laser unit 31...-Control circuit 32 ...Interface circuit 33...Laser driver 34...Beam position detection circuit 35...Optical abnormality detection circuit (optical abnormality detection means) 36
...High voltage power supply 41...Flip-flop 42...Counter

Claims (1)

[Claims] In an image recording device that records the background, which is a non-recorded area on a photoreceptor, by exposing it to laser light using an optical system,
providing an optical abnormality detection means for detecting an abnormality in the optical system;
An image recording apparatus characterized in that charging of the photoreceptor is stopped in response to a signal from the optical abnormality detection means when the optical system is abnormal.