JPS60120662A - Laser recorder - Google Patents

Abstract

PURPOSE:To obtain a stable picture with no deterioration of picture quality at each page by providing a laser light intensity control means controlling the luminous intensity of a laser light to a prescribed level just before recording is started at each recording page. CONSTITUTION:When a laserlight of a semiconductor laser 1 is made incident to a luminous intensity detector 16, a luminous intensity signal 22 is obtained. A comparison amplifier 18 compares it with a reference voltage VS and controls a drive bias voltage VB so as to make the luminous intensity signal 22 eqaul to the reference voltage VS. A control timing signal 23 keeps a switch SW1 to the conductive state until this control is applied. The bias voltage VB is stored for its voltage value in a capacitor C1 for a prescribed period even if the control timing signal 23 is turned off and a switch SW1 is interrupted so as to keep the output of the laser light 1 constant. The luminous intensity detector 16 is provided in the inside or fitted on the scanning line turnably.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laser recording apparatus such as a C11 printer that records an image by scanning a photoreceptor with a laser beam modulated by an image signal.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In recent years, laser printers have been widely used as devices that record images such as characters and figures by modulating a laser beam using signals from a computer, word processor, or the like.

Below, the conventional laser recording device is shown in Figures 1 and 2.
This will be explained using figures. FIG. 1 is a schematic configuration diagram of a conventional laser recording device, in which 1 is a semiconductor laser, 2 is a collimator lens, 3 is a deflector, and 4G is an imaging lens.The laser beam emitted from the semiconductor laser 1 is =1 The beam is collimated by a remeter lens 2, converted into a beam by a deflector 3, and made into a specified beam diameter by an imaging lens 4, and then scanned over a -C photoreceptor 6. Reference numeral 7 denotes a reflecting mirror, which reflects a part of the scanning laser beam 5 and passes it to the synchronous detector 8. The signal from the synchronization detector 8 is shaped into a synchronization signal by the comparator amplifier 9, and the control circuit 10 that transmits the image signal creates a timing for transmitting the image signal.Therefore, this synchronization By detecting and adjusting the position of the scanning radiation beam 5 by means of the detector 8, it is possible to perform high-viscosity image recording.1
1 is a drive circuit for the semiconductor laser 1. However, in such a conventional 414 structure, the light intensity output of the semiconductor laser 1 changes with temperature or aging. Figure 2 shows the problem of heat source generation in recorded images or changes in line width of recorded characters. There is C in Otsu, and On 1 stands from 1-1 to Wang 3.
When you go upFll''J, Rayleigh light intensity II comes out]J is a
There was a drawback that the image quality changed as a result. The solution to this problem has conventionally been to use a Bertier element to control the temperature of the semiconductor ray 111 at a constant level. However, this method has the disadvantage that it is necessary to control the temperature of the semiconductor laser with high precision, and that it cannot cope with changes in the optical intensity of the semiconductor laser 1 due to aging.

OBJECTS OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art.
The purpose of this invention is to provide a laser recording device capable of producing stable images without deterioration of image quality by reducing changes in the light intensity output of a body laser.

Arrangement of the Invention - 1 - In order to achieve the object, the laser recording device of the present invention includes a laser light source modulated by an image signal, and a laser light source from the laser light source that scans a photoconductor to record an image. The apparatus is configured to include a scanning means for performing the recording, and a laser light intensity control means for controlling the light intensity of the laser light to a constant level immediately before starting recording for each recording page.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Fig. 3 is an evening/timing diagram in which the light intensity of the laser beam at a laser recording station according to an embodiment of the present invention is controlled to a constant level;
The figure is a schematic configuration diagram of a control circuit of a laser recording apparatus according to an embodiment of the present invention. ; i ノ J ツ] - Using paper - ((13) Because there is a gap between each page, a non-recording area occurs. Within this non-recording time, just before starting recording, the light intensity of the Rayleigh light is 13 is a timing signal for controlling the light intensity, and 14 is a recording (image signal sent out during Ei bow 12) using a detector. It is.

Figure 4 shows how to control the laser light intensity of the semiconductor diagonal relay to one C! An example of 1 path is shown, and 1!1 is a semiconductor laser “
1 drive circuit t1.1G is a light intensity detector, 17 is an amplifier,
Reference numeral 18 denotes a comparison amplifier, and a mixer bold circuit 20 is constituted by a switch SW1 and a buffer amplifier 19 such as a capacitor C1. Vs is the via/sink pressure corresponding to the current that drives the semiconductor laser 1 as a bias voltage, VS
is the reference voltage from the reference power supply 21.

Next, I will explain the operation. When the laser light from the semiconductor laser 1 enters the light intensity detector 16, the light intensity detector 1G outputs a light intensity signal 822 as shown in FIG. 5A according to the laser light intensity.
is obtained. The comparator amplifier 18 compares this light intensity signal 22 with the reference voltage VS, and adjusts the drive bias voltage V of the semiconductor laser 1 so that the light intensity signal 22 has the same value as the reference voltage Vs.
control s. The control timing signal 23 keeps the switch SW+ in a conductive state until this control is applied. Even if the control timing signal 23 is turned off and the switch SW1 is cut off, the bias voltage Vs remains constant across the capacitor C1]! This is maintained during the IJ period, and therefore the output of the live body laser 1 maintains a constant output state. Sunara 2nd
As shown in the figure, for example, when the temperature changes from Go 1 to T3, the drive bias voltage is changed from VB to Va', the drive current is corrected from Is to ■B', and the light intensity output is changed from C to C'. Control over to a constant value.

The above control is performed immediately before recording, and constants such as capacitor capacitance C1 are selected so as to keep the control bias voltage Vl-3 constant during the recording of -pages. Regulation 11
The generation of the timing signal 23 may be performed according to the light intensity 1 and the rising of the signal 22, or may be performed at a predetermined time.

There are several possible specific configurations and arrangements for the light intensity detector 1G, but this is the simplest! As an eleventh method, there is a method of detection using an Al-diode (for monitoring) built into the semiconductor laser 1. In this case, since the light intensity is controlled at least immediately before recording on each member, the photoreceptor is irradiated with Rayleigh light. If the development method of a laser printer is negative development, where the area exposed to the laser beam is turned into a bronze image, it is necessary to cut off the laser beam that irradiates the photoreceptor (using a mechanical shutter, etc.). . In the case of positive development that visualizes areas that are not irradiated with laser light, the photoreceptor can be irradiated as is, so laser-type copper is continuously applied from the end of the recorded page to the beginning of the next page. , to prevent the non-recorded area of the second photoreceptor from being developed.

Semiconductor laser 1 further reduces its output by -1 due to its own heat generation.
Although simple temperature control is necessary to prevent runaway heat generation, conventional high-precision control is unnecessary. If the control temperature is too low, condensation will form on the cover glass of the semiconductor laser 1, so either control the temperature to near room temperature 2!1℃, or detect the air temperature and control the semiconductor laser to a temperature close to air temperature A4. The temperature of the laser 1 is controlled. Condensation can be prevented by keeping the temperature at a temperature of 40°C. It is also effective to prevent dew condensation on the optical elements of the semiconductor laser 1 (= optical path of the snarling Rayleigh light).

Another arrangement of the light intensity detector 1G is to arrange it in the laser beam scanning area near the photoreceptor. FIG. 6 shows an example of this arrangement E(J3), and FIG. 1 shows an example of the J configuration "f!7.
The same constituent threads as the original are given the same number 14 and their explanation will be omitted. That is, the scanning laser beam 5 is arranged so as to cover the light receiving surface of the light intensity detector 16. In FIG. 5, the light intensity detector 16 (it does not need to be placed at the imaging position of the laser beam; the light receiving surface is sufficiently larger than the laser beam diameter and the light receiving time is sufficient for controlling the laser beam). This is a high-speed laser photodetector consisting of a PIN diode, etc., and the width of the light-receiving surface in the scanning direction is increased. If it can be placed in .

The light intensity detector 1G is fixed during image recording.1. In this case, it can be placed near the foul mirror 7 for synchronization detection. Generally, the scanning width of the laser beam is close to the recording width, so the light intensity detector 16 is placed in the recording area of the scanning laser. +
i! Place it. In this case, the light intensity detector 16 is configured to be movable so that the light intensity detector 16 does not block the laser beam during image recording. 3. For example, as shown in the figure, the light intensity detector 16 may be placed in the synchronizing port 1. In addition, a movable reflective mirror is placed in the optical path,
From the reflecting mirror (1) 1 normal light is transmitted to the light intensity detector 1
J being illuminated by G: It's just that J...

In the arrangement shown in FIG. 6, the light intensity of the scanning laser beam 5 irradiated onto the photoreceptor 6 is controlled to a constant 1ffii, so losses in the optical system along the way are also corrected, and more accurate light intensity control is possible. I am an office lady. Also, photoreceptor 6 J3. J: Since the light intensity detector 16 is a semiconductor, the sensitivity of both decreases as the temperature increases. Therefore, the light intensity detector 1G is
Due to the cage 13 placed near the sensor, the sensitivity of the photoreceptor 6 is increased due to the warm polishing, and the sensitivity of the light intensity detector 16 is also increased, thereby correcting the light intensity of the LED light. The problem is that the image quality is 1! '7 can be done.

The control timing signal 23 is generated at the timing of the signal H of the light intensity detector 1G.
Even if you decide between 1 and 1 from the synchronized Gokyu, it is not possible. In the case of the light intensity detection method shown in FIG. 6, the light intensity of the Q'J laser beam directed onto the photoreceptor 6 can be controlled, and at the same time, an abnormal state of the scanning radiation beam 5 can also be detected. Light intensity detection: If the light intensity output of fiIG becomes extremely small due to dirt on the lens, etc., it will notify you of an abnormality in the optical system.

In this case, the first
If the output of the diode is detected and is normal, an abnormality in the optical system or abnormality in the deflector 3 can be confirmed. In addition, when controlling the light intensity output of the semiconductor laser 1, the current driven by the semiconductor laser 1 must be controlled to the maximum level by monitoring with a built-in photodiode so that the laser light output does not exceed the maximum rated value. According to the present invention, the light intensity of the Rayleigh light is controlled to a constant level immediately before starting recording for each recording page. , , - During the recording of pages, it is possible to perform recording while maintaining a constant output of Rayleigh light, so that a stable 1ilii image is always produced 1,

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the IB configuration of a conventional Rayleigh recording device, and FIG.
FIG. 3 shows the lake shown in 1) in one embodiment of the present invention.
(The control timing diagram of the IC device, Figure 4 is the same as the circuit of the light intensity control part of the 1F recording device (1?J diagram, Figure 1)
4. :i', /1 Figure shows the signal waveform diagram of each part of the circuit,
Figure 6 shows an example of the arrangement of light intensity detectors in the same recording device. 3... Deflector, 6
. . . Photoreceptor, 16 . . . Light intensity detector, 17 . figure

Claims (1)

[Claims] 1. A ray light source modulated by an image signal, a scanning means for scanning a photoreceptor with a laser beam from the laser light source to record an image, and recording for each recording page. A laser recording device comprising: a light intensity control means for controlling the light intensity of a laser beam to a constant level immediately before starting. 2. Claim No. 2, wherein a semiconductor laser is used as the laser light source, and the first tie 'A-1-' incorporating the semiconductor laser is used as the light intensity detection section of the laser light intensity control means. The laser recording device according to item 1. 3. A laser recording apparatus according to claim 1 or 2, wherein the light intensity detection section of the laser light intensity control means is arranged near the photoreceptor and within the scanning area of the Lehr light. 4. The laser recording apparatus according to claim 1, wherein a semiconductor laser is used as the lake 2 light source, and a temperature control means is provided for controlling the temperature of the semiconductor laser to i degrees near room temperature.