JPH0398010A - Optical scanning recorder - Google Patents

Abstract

PURPOSE:To prevent the contrast of a recording image from changing and to shorten a recording time by providing a control means which adjusts the light output of a light source other than a light source for image recording according to the outside temperature, and holds the recording spot diameter of the light source for image recording constant. CONSTITUTION:A 1st semiconductor laser 1 and a controller 20 which performs ON-OFF control over the semiconductor laser 1 with a digital image signal constitute the light source for image recording, and the controller 11 controls the intensity of the light output according to the output (t) of an outside temperature detector 15. The controller 11 varies the light output intensity of a 2nd semiconductor laser 12 with a threshold value Th varying with the outside temperature according to the detection signal of the outside temperature detector 15 and varies the intensity of a light spot C to control the peak intensity P of the multiplexed light spot A so that the size of the recording spot diameter D is nearly equal. Consequently, the resolution is not impaired and the recording time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical scanning recording device that uses a rotatable mirror to scan a deflected light beam onto an object to record an image by thermal transfer.

[Prior Art] FIG. 4 is a diagram showing a conventional optical scanning recording device disclosed in, for example, Japanese Patent Application Laid-open No. 167559/1983. In the figure, (l) is a semiconductor laser, (2) is a semiconductor laser (1)
(3) is the light beam emitted from the semiconductor laser (1); (4) is a rotating polygon mirror that is a means for deflecting the light beam (3) to a required angle; (5) is a focusing lens, which is composed of an f/θ lens that has a characteristic that the focal point position is proportional to the deflection angle. (6) is a long mirror for reflecting the light beam from (5) at a predetermined angle; (7) is a sublimation thermal transfer photosensitive film; (8) is an endless belt that conveys the photosensitive film; (9) (10) is a drive device for driving the endless belt (8), and (10) is a semiconductor laser (1) that is turned on and off by a digital image signal S.
It is a control device that controls.

Next, we will explain the operation. A light beam (3) emitted from a semiconductor laser (1) is made into a parallel beam by a collimator lens (2), and then enters a rotating polygon mirror (4). The light beam (3) is reflected and deflected by this rotating polygon mirror (4), passes through a focusing lens (5), is reflected at a long mirror (6), and scans on a photosensitive film (7) in the direction of arrow X. (main scan). At the same time, the endless belt (8) driven by the drive device (9) performs sub-scanning in which the photosensitive film (7) is conveyed in the direction of arrow Y, which is substantially perpendicular to the main scanning direction X, and the photosensitive film (7)
A light beam (3) is illuminated two-dimensionally above. The semiconductor laser (1) is ON-OFF controlled by the control device (10) based on the digital image signal SC, and the light beam (3) is pulse number modulated thereby. An image based on the image signal S is recorded. Next, the relationship between the output power of the semiconductor laser (1) and the recording spot diameter D will be explained. The photosensitive film (7) is a sublimation type thermal transfer film, and consists of a printing substrate (not shown), a dye layer, and a heat generating layer. When the photosensitive film (7) is irradiated with a light spot having a light intensity above a certain level, the heating layer heats up and sublimates the dye, thereby printing on the printing substrate.

The size of this printed one dot (recording spot diameter D)
is determined by the intensity distribution of the light spot on the surface of the photosensitive film (7) and the recorded light intensity (hereinafter referred to as "threshold value") Th. Figure 5 shows the intensity distribution of the light spot and the recording spot diameter D when the temperature of the photosensitive film is a certain temperature.
In this figure, as the threshold value Th becomes higher, the recording spot diameter D becomes smaller, and when the threshold value Th exceeds the peak intensity P of the optical spot, no recording occurs. This threshold Th is determined by (1) the heat-sensitive temperature of the photosensitive film, (2) the main scanning speed, and (2) the temperature of the surface of the photosensitive film. The reason why the threshold value Th changes depending on the main scanning speed in (2) is that this recording method is a thermal transfer method, and the energy absorbed by the photosensitive film (7) per unit area depends on the light intensity per unit time.

[Problems to be Solved by the Invention] Conventional optical scanning recording devices are of the thermal transfer type, so the main scanning speed is limited by the output power of the semiconductor laser. There was a problem that it was not possible to shorten the . This is because increasing the main scanning speed reduces the light energy absorbed per unit time. Further, when the outside temperature, that is, the temperature of the photosensitive film changes, the threshold value Th also changes, so the size of the recording spot diameter D also changes, causing a problem in that the contrast of the recorded image changes. This invention was made to solve the above-mentioned problems, and it is possible to shorten the recording time by increasing the main scanning speed of the light spot, and
It is an object of the present invention to provide an optical scanning recording device capable of recording and scanning with a constant recording spot diameter D even if there is a slight change in threshold due to a change in outside temperature.

[Means for Solving the Problems] The optical scanning recording device according to the present invention includes a means for converging the output lights of at least two light sources to increase the light intensity of a light spot that scans on the surface of a photosensitive film, and The present invention is characterized in that it includes a control means that adjusts the light output of the light source other than for recording according to the outside temperature and maintains the recording spot diameter D of the image recording light source constant.

[Function] The light source of the present invention is provided with a light source for pre-heating in addition to the light source for image recording, so that the light intensity of the light spot focused on the photosensitive film surface can be increased, so that the main scanning speed can be increased.

Further, the recording spot diameter control means adjusts the light output of the light source for pre-heating according to the temperature change of the photosensitive film, and controls the recording spot diameter D of the image recording light spot to always be the same size.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
In the figure, the same components as those in FIG. 3 are designated by the same reference numerals, and the explanation thereof will be omitted.

(l2) is the second semiconductor laser, (13) is the second collimator lens, (11) is the second semiconductor laser (l2
), (14) is a deflection beam splitter, and (15) is an outside temperature detector that detects the temperature near the surface of the photosensitive film (7). Next, we will explain the operation. First semiconductor laser (1) and semiconductor laser (1)
) constitutes an image recording light source, and the polarization direction of the first semiconductor laser (1) is controlled by the polarization beam splitter (
The second semiconductor laser (12) has its optical output adjusted by the control device (1l) according to the output t from the outside temperature sensor (l5). Strength is controlled.

The polarization direction of the second semiconductor laser (12) enters the polarization beam splitter (l4) as S-polarized light, and the polarization direction of the second semiconductor laser (12) is approximately 100%.
% reflected and emitted light from the first semiconductor laser (1) (
3). Next, we will explain the control operation of the intensity distribution of the light spot that illuminates the surface of the photosensitive film (7). In this example,
As shown in FIG. 2, a light spot B for image recording by the semiconductor laser (1) of 'Ii1 and
Since the light spots C obtained by 12) are superimposed on the photosensitive film (7), it is possible to realize a light spot A with a peak intensity P that is at most twice that of the conventional example, and it is possible to significantly increase the light scanning speed.

Further, the control device (1l) controls the second semiconductor laser (12) according to the change in the threshold Th due to the change in the outside air temperature, based on the signal detected by the outside air temperature detector (15).
The peak intensity P of the combined light spot A is controlled by changing the light output intensity of the light spot A and changing the intensity of the light spot C so that the recording spot diameter D is always the same size.

As a result, the recording spot diameter D of the light spot A scanning the surface of the photosensitive film (7) is always kept constant. In this case, the light emitted from the second semiconductor laser (12) may be a signal synchronized with the first semiconductor laser (1) or may be DC light (CW light), and the peak intensity of the light spot C is the threshold value. It is good if it is lower than Th. Further, the recording spot diameter D is controlled by the light intensity distribution of the image recording light spot B,
Since the light spot C is only an auxiliary heating means, the light intensity distribution of the light spot C may have a shape with large aberrations, and furthermore, it may be defocused to some extent on the surface of the photosensitive film (7). In other words, the second semiconductor laser (12)
Since the permissible placement accuracy can be low, mass productivity is not impaired.

In the above embodiment, the light spot B and the light spot C were irradiated to the same position on the surface of the photosensitive film (7), but as shown in FIG. It is also possible to use a configuration in which the light is irradiated at a slightly distant position.
In this embodiment, since the photosensitive film (7) is preheated by the light spot C, the apparent threshold Th for the image recording light spot B can be lowered, and the light scanning speed can be increased.

Furthermore, as in the previous embodiment, the threshold value Th can be controlled by controlling the light intensity of the light spot C, so that the recording spot diameter D can always be kept constant even if the outside temperature changes. In addition, in order to form two light spots at separate positions on the surface of the film (7) as in this example, two semiconductor lasers (1) are connected to a polarized beam splitter ( 14) is not necessary, and can be easily constructed using a well-known two-beam array laser.

Further, in the above embodiment, an example using two semiconductor lasers has been described, but the number of light sources may be three or more, and the same effect can be obtained.

[Effects of the Invention] As described above, according to the present invention, at least one light source is provided in addition to the image recording light source, and the output light of these light sources is condensed into a light spot to transfer the surface of the thermal transfer type photosensitive film. The light output of a light source other than the image recording light source is controlled in accordance with the temperature on the surface of the photosensitive film, so that the recording spot diameter scanning the photosensitive film surface is always the same diameter. Since the IIJ is controlled in such a manner, an optical scanning recording device with a short recording time can be obtained without deteriorating the resolution.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of the present invention.
Fig. s2 is a light intensity distribution diagram of light spots on the photosensitive film surface of this embodiment, Fig. 3 is a diagram showing the arrangement of light spots on the photosensitive film surface of another embodiment of the present invention, and Fig. 4 is a diagram showing the arrangement of light spots on the photosensitive film surface of another embodiment of the present invention. FIG. 5 is a perspective view showing the configuration of an optical scanning recording device, and FIG. 5 is a light intensity distribution diagram of a light spot on the surface of the photosensitive film. (1). (12)...Semiconductor laser, (2).
(13)... Collimator lens, (4)... Rotating polygon mirror, (5)... Focusing lens, (7)... Sublimation thermal transfer type photosensitive film, (8)... Endless belt,
(9)...Drive device, (10), (11)...Control device, (14)...Deflection beam splitter, (l5)
...Outside air temperature detector. In each figure, the same symbols indicate the same or equivalent parts.

Claims (1)

[Claims] (1) The first one in which the intensity of the output light is modulated by the image signal
a light source, at least one second light source whose output light intensity is controlled, and the output light of these light sources is focused to the same point on the surface of the thermal transfer photosensitive film or slightly separated in the main scanning direction. a focusing means for forming a light spot at a position; a means for deflecting these light spots in the main scanning direction; a means for moving the thermal transfer photosensitive film in a direction perpendicular to the main scanning direction; means for detecting the temperature or the outside air temperature in the vicinity thereof; and a means for maintaining the size of the spot diameter recorded by the light spot of the first light source irradiated onto the surface of the thermal transfer type photosensitive film at a constant value. an optical scanning recording device comprising means for controlling the intensity of output light from the second light source based on the detected temperature.