JPH052213B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a light amount adjustment device, and particularly to a device that can adjust the light amount of a light source in a reader or reader printer. (Prior Art) Conventionally, a microfilm reader or reader printer is configured to illuminate a microfilm with a lamp light source and project an image on the microfilm onto a screen via a projection lens. Therefore, the amount of light from the lamp light source is always set constant. (Problem to be Solved by the Invention) However, in the case of such prior art, the light intensity of the lamp light source for projecting the microfilm image onto the screen is always set to a constant value, so the following problems occur. There are problems. That is,
In negative microfilm, the film density in the background area varies by about 0.6 to 1.5 depending on the type of original, film, and development conditions. Furthermore, the density of the image area is greatly influenced by the base density of the film and the original (for example, it differs between pen drawings and pencil drawings). For this reason, even if the same negative microfilm is used, there is a problem in that when the same amount of light is applied to a low-density film and a high-density film, the screen illuminance may be too bright or too dark. Also, with positive film, the screen illuminance differs depending on the difference in density between the background area and the image area, just as with negative film, but especially with positive film, the background area, which makes up most of the image, is higher than the image area. The problem is that the overall screen is brighter than negative film, giving the operator the impression of being dazzling. Therefore, a lamp light source in which the light intensity can be adjusted within a predetermined range has been proposed, but even in this case, the adjustment range of light intensity is limited, so it is sufficient to cope with changes in density between negative and positive films. The problem is that it cannot be done. Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and its purpose is to increase the density of images depending on whether the microfilm used as an information recording medium is a negative film or a positive film. An object of the present invention is to provide a light amount adjustment device that can always adjust the light amount of a light source to a light amount value that is appropriate for an operator even when the widths are different. (Means for Solving the Problems) In order to achieve the above object, the present invention provides a setting means for setting the light intensity of a light source for projecting an image of an information recording medium onto a screen, and a control means for adjusting the light intensity of the light source to a set light intensity; an identification means for identifying whether the image on the information recording medium is a negative image or a positive image; and a switching means for switching the light amount adjustment range. (Function) In the present invention, the identification means identifies whether the image on the information recording medium is a negative image or a positive image, and the light amount adjustment range of the control means is determined by the signal from the identification means. is switched by a switching means. (Example) The present invention will be explained below based on the illustrated example. FIG. 8 shows an optical system of a reader to which the light amount adjusting device according to the present invention can be applied. In the figure, 1 is a lamp for film illumination, and the light beam of this lamp 1 is reflected forward by a reflecting plate 2, and is also reflected by a mirror 3 and a condenser lens 4.
The light is irradiated onto a microfilm F held between a pair of glass plates 5 and 6. The image light transmitted through the microfilm F is projected onto a screen 10 via a projection lens 7 and mirrors 8 and 9. FIG. 1 is a block diagram showing a light amount adjusting device according to the present invention. As a control means and switching means
The CPU 11 includes a display section 12 and a key scanning section 1.
3, and controls the keyboard section shown in FIG. 2 in which the display section 12 and key scanning section 13 are arranged. Further, the CPU 11 is connected to a zero cross circuit 14 and a phase control circuit 15, and controls the light amount of the lamp 1 by phase control, as will be described in detail later. Furthermore, CPU11 has
An N/P switching key 26 is connected as an identification means for identifying whether the microfilm F is a negative film or a positive film. Figure 2 shows the keyboard section, which includes the light intensity up key 1 as a setting means.
6, a key scanning unit 13 consisting of a light intensity down key 17, a numerical key 18, a clear/stop key 19, and a copy key 20; a two-digit 7-segment display 21; a copy number indicator 22; and a light intensity indicator 23 as a display means. , various warning displays 24, the N/P switching key 26, a display section 12 consisting of a negative display 27 and a positive display 28. The number of copies is normally displayed on the 7-segment display 21. When displaying the number of copies, press the 3rd button.
As shown in the figure, the display 22 lights up and the display 2
3 goes out, and the 7-segment display 2
The number of copies is displayed in 1. However, when one of the light quantity up and light quantity down keys 16 and 17 is pressed, the display changes as shown in FIG. 4, the display 22 goes out and the display 23 lights up. and,
The 7-segment display 21 displays a numerical value corresponding to the amount of lamp light. In this embodiment, as a numerical value corresponding to the lamp light quantity, a numerical value proportional to the logarithm value (log L) of the lamp light quantity is used as shown in FIG. This is done by storing the relationship between the phase angle of the phase control circuit 15 and the amount of lamp light in advance in the ROM in the CPU 11.
It is set by writing in 25. Then, as described later, reference data is selected by counting up/down by the program from the reference value, and the reference value + count up/down value is set to 7.
- In addition to displaying on the segment display 21, the amount of light from the lamp 1 is controlled using a phase angle based on reference data. Furthermore, after 10 seconds have elapsed after releasing the light intensity up/down keys 16 and 17, or when the numerical key 18 is pressed, the mode is automatically switched to the copy number display mode (FIG. 3). Also, when the copy key 20 is pressed, the mode also enters the copy number display mode, after which the remaining number of copies is displayed, and after copying is completed, the initially set number of copies is displayed. Next, a phase control method will be explained. First, the zero-crossing circuit 15 extracts the zero-crossing signal from the AC input, and transmits the zero-crossing signal to the CPU.
11. The timer setting time from the zero cross point is obtained by referring to a table written in the ROM 25 in the CPU 11. In this embodiment, two reference tables are set as shown in Tables 1 and 2, and the CPU 11 has N/
When negative film is specified from the P switching key 26, the reference table shown in Table 1 is selected; conversely, when positive film is specified from the N/P switching key 26, the reference table shown in Table 2 is selected. Select. These reference tables are based on the light amount up and down keys 16 and 1, as shown in the respective tables.
7, the data on the relationship between the light amount display value and the timer setting value are made to correspond to each other. For example, when the light amount display value is n, the timer setting value is Tn. The CPU 11 starts the timer from the zero cross point based on the timer setting value obtained by referring to the table, and outputs a pulse to the phase control circuit 15 after the timer elapses. After this pulse is output until the next zero crossing of the AC input is the phase angle, and the amount of light of the lamp 1 is controlled by the power determined by this phase angle. By the way, in the case of a negative film, since the background portion, which occupies most of the image, has a high density, the entire image is dark, and the image on the screen 10 is dark. Therefore, the timer values T ₁ to _{T 90} in the table in Table 1, which are referenced in the case of negative film, are set longer than those in Table 2, and the adjustment area in Table 2 is the same as in Table 1. In comparison, the amount of light from the lamp light source 1 is shifted in the direction of increasing.

【table】

Claims (1)

[Claims] 1. A setting means for setting the light intensity of a light source for projecting an image of an information recording medium onto a screen, a control means for adjusting the light intensity of the light source to the light intensity set by the setting means, and the information recording medium. A light amount adjustment device comprising: identification means for identifying whether the image is a negative image or a positive image; and switching means for switching the light amount adjustment range of the control means based on a signal from the identification means.