SU1327047A1 - Method of correcting signal irregularity of scanning beam device - Google Patents

Abstract

The invention relates to processes for converting photo images using a traveling beam device. The purpose of the invention is raising. Guidance of image conversion accuracy. In plane 1 of scanning the cathode-ray tube 2, the light beam formed by the forming optical system 3 passes line by line: the scanned material 4 is an image carrier, behind which is placed a light filter 5 with a given distribution of optical density that compensates for the inhomogeneity of sensitivity of the photoelectric receiver 6 the focal plane of the collecting optical system 7. The formation of new connections makes it possible to compensate for the non-uniformity of the sensitivity of the photoelectric receiver 6. 2 Il. (L

Description

The invention relates to a photo-cinema technician: and a television technology, and is known to have processes for converting photographic images using a traveling beam device, and can be used in photo printing systems with electronic masking.

The aim of the invention is to improve the accuracy of image conversion by compensating for the sensitivity of the photoelectric converter.

FIG. 1 shows a block diagram of a device that implements the proposed correction method; 2, a generalized structural scheme for scanning a portion of a traveling beam device.

The essence of the method for correcting the irregularity of the signal of the traveling beam devices is as follows.

In the scanning plane 1 of the cathode-ray tube 2, the light beam formed by the forming optical system 3 passes through the lines, the scanned material 4 is depicted as a carrier, behind which is located the light filter 5 with a given distribution of optical density compensating for the inhomogeneity of the photoelectric receiver 6, across the field of the collecting optical system 1 located in the focal plane,

In this case, the light filter 5 is obtained by exposing a positive photosensitive material on a transparent base to a scanning light spot formed by an adjustable device 8 (Fig. 2) containing a scanning light spot sensor 9 with a cathode ray tube 1 and a control unit for brightness and scanning, an operational amplifier 10, a signal sensor 11 in the form of a constant voltage driver, a counter of 12 scanning cycles and

trigger 13. 1

When receiving the light filter 5 with

a predetermined distribution of the transparency coefficient is controlled by a scanning spotlight by modulating its brightness B (x, y) and scanning time t (x, y) of the scanning field element to maintain a constant value of h, the output signal Vi, for example, equal to U reference signal:

. (x, y) -b (x, y) (x, y) Uo, (1)

Where

tn constant value of the scanning element

scan; L (x, y) - unevenness of brightness

light spot in the scanning plane;

F (x, y) is the uneven sensitivity of the photoelectric converter.

15

Uo

 Ltx, y) (x, y)

(2)

0

five

0

In this case, BCxjy is modulated accordingly.

When modulating the scan duration of the element t (x, y), the condition

 t (x, y) (x, y) - (x, y) t (x, y)

 - (3)

t (x, y), /, ° n /. , (four)

В „-Ь (х, у) -9 (х, у)

The brightness of the light spot is kept constant by the same B.

In practice, conditions (2) and (4) can be fulfilled, for example, by feedback from the output of the photoelectric converter 6 to the input of the brightness control of the spot of cathode ray tube 1 or to the input of the control of the scanning speed.

With such an exposure, the exposure distribution H (x, y) of the surface of the photosensitive material of the transducer 6 in the case of a light modulation H., (x, y) B (x, y) -b (x, y) - t,

five

and,

Where

F (x, y) K K F (x, y)

(five)

AT

coefficient of proportionality, the case of time modulation

H (x, y)

В „-Ь (х, у) tCx, y) К

(x, y) P (x, y)

(6-)

(by choosing the parameters U and t one can achieve equality of the proportionality coefficients in both cases).

Then, the exposed positive photosensitive material is subjected to photochemical treatment, i.e.

occurrence, and get a filter, the distribution of transparency t / cp (x, y) which will correspond to the distribution of exposure

H (x, y):

(7)

(.Y)

TO

F (x, y)

Then, the resulting filter 5 (Fig. 1) is placed in the scanning plane behind the scanned material 4 - the image carrier - along the light flux and orient its substrate relative to the axis of the optical system of the device as it was located during exposure.

The traveling beam device 8 (Fig. 1 may be an electron copying device with amplitude modulated exposure or a television image signal sensor with the ability to modulate the brightness of the light spot. All these devices complement the light filter holder 5, providing placement of the light filter 5 or positive photosensitive material on a transparent basis in the sky-plane behind the photo-carrier - the scanned material 4 - fio during the course of the Light flux. The operational amplifier 10 can be made in microcircuit design. The counter 12 scanning cycles can be performed, for example, on the basis of a counter with a controlled division factor, and the trigger 13 can be based on the microcircuit.

The output of the photoelectric converter 6 is connected to the inverting input of the operational amplifier 10, the non-inverting input of which is connected to the output of the sensor 11 of the reference signal. The output of the operational amplifier 10 is connected to the first input (brightness control), the sensor 9 of the scanning light spot. The first input of the counter 12 scan cycles is connected to the first input of the device 8, the second input. - to the output of the sensor 9 scanning light spot, and the third - to the second input of the device 8. The output of the counter 12 is connected to the first input of the trigger 13, the second input of which is connected to the second input of the device 8. The output of the trigger 13 is connected to the second input of the sensor 9.

(7)

,) about t.

.1) o- 5, oo on aa y t, o10

15

20

25

A device that uses located behind the photocarrier 4 light filter 5, works as follows.

In the initial state, trigger 13 is reset. The signal from its output, for example, 7) a logical zero, prohibits scanning in sensor 9. Scanned material 4 is missing. In the holder of the corrective light filter 5 place a positive photosensitive material-on a transparent basis. The first input of the counter 12 is supplied with a code specifying the required counting coefficient, and the sensor 11 of the reference signal is set to the desired value of the reference signal to obtain the setpoint. The average scan field exposure of h, which is determined, for example, by test exposures.

A second start signal is sent to the second input of the device 8, for example, a pulse, the counter 12 is reset and the trigger 13 is set. The output of the trigger 13, for example a logical unit, removes the prohibition of scanning in the sensor 9. A light spot is displayed on the screen of the cathode ray tube 2 image

30 which is formed with the help of the shaping optical system 3 in the scanning plane 1. The luminous flux transmitted by the positive photosensitive material 5 on a transparent axis 35 is not transferred by means of the collecting optical system 7 to the photosensitive surface of the photoelectric converter 6, where it is converted into an electrical signal. The signal from the output of the photoelectric converter 6 is supplied to the inverting input of the operational amplifier 10, in which the difference between the reference signal U at the output is formed

45 of the sensor 11 and the output signal U of the photoelectric converter 6. The amplified difference signal from the output of the operational amplifier 10 is fed to the sensor brightness control input

50 9 scanning light spot. In the operational amplifier 10, covered by negative feedback along the circuit: cathode-ray tube 2, optical system 3-5-7, photoelectric converter 6, the output signal value is automatically set so that the difference of signals at its inputs tends to zero. Thus, by modulating the brightness of the light spot, the amplitude of the output signal of the photoelectric converter 6 is equal to the value of the reference signal in each element of the scanning field. This means that, at a constant scanning speed, the output signal of the converter 6 output signal,

f at the output of converter 6 will be

described by hyphenation

Ucp (x, y) - T (x, y) j (8)

where B is the brightness of the glow in the center of the screen of the cathode ray tube.

The amplified difference sipgal on Biji during an operational amplifier 10 modulates the brightness of the light beam database on the screen of the cathode ray tube 2, i.e.

 AT,

from here

R Up Koj)

° 1 + b (x, y) 9Cx, y) -K

(9)

oa

() Kj ,, (Uj, -Bg-b (x, y) (x, y)) KO. | transducer. Wherein

25 to fully compensate for the irregularity of the signal of a traveling beam device of this type, this method is advisable to be used in conjunction, for example, with a known method that provides compensation for irregularity

B (x, y) of the brightness of the light spot in the scanning plane with the help of an additional light filter 14. In devices of a traveling beam with feedback 35 according to the exposure, taking into account the light filter 5 when operating them with the luminance modulation of the exposure, the brightness of the light spot

(ten)

 Up

 B (x, y) f (x, y)

Exposure reported by photosensitive material located in the scanning plane:

H B, .b (x, y) .t,. )

(eleven)

will be directly proportional to the function F (x, y) of the non-uniformity of sensitivity of the photoelectric converter 6.

At the end of a scan cycle, the transparency of scanning from the output of sensor 9 of the scanning light spot receives a signal, for example, a pulse, and the second input of the counter has 12 scanning cycles. When the numbers

the duration and duration of the scan of an element is inversely proportional to the output signal of the photoelectric converter

In the scan cycles, the exposure light intensity is set to 50, the output of the counter 12 is a signal that resets the trigger 13. The scan in the sensor 9 stops.

The exposed photosensitive material is subjected to photochemical treatment, and the resulting light filter is placed with the help of the holder to the place of exposure to photosensitivity (x, y)

Up ......

B-b (x, y) (x, y). (X, y). F (

Uo

K. B o b (x, y) o (x, y)

vital material. In this case, the distribution of the transparency of the light filter 5 across the scanning field in accordance with the obtained exposure will be the opposite of the non-uniformity of sensitivity of the photoelectric converter 6 and this unevenness will be KONmeHcnpoBaTb.

Taking into account the corrective light filter in the devices of the traveling beam converting the photo image into an electrical signal, the scanned material 4 in this case is a photo image with transparency

 5 (x, y) photoelectric converter output 6

u, b (x, (x, y) -uh, y) - P (x, y)

20

 К В „-Ь (х, у) - t (х, у)

(12)

does not contain a component of the non-uniformity of sensitivity of the photoelectric

B (x, y)

 Uo

b (x, y). , y) -1i- (x, y). P (x, y)

(13)

Uo

K.b (x, y) -)

of the material, and the duration of the element scan remains constant.

When working with time modulation

the duration of the scanning element is inversely proportional to the output of the photoelectric converter

exposure brightness of the light spot

t (x, y)

Up ...... B-b (x, y) (x, y). (X, y). F (x, y)

Uo

K. B o b (x, y) o (x, y)

(14)

The exposure reported to the photosensitive material located in the scanning plane 1, which in this case is the output signal of the device, is equal to:

(x, y) -b (x, y) - o (x, y). t (x, y). (15)

With a fast exposure modulation, the duration of the element scan is constant and equal to, and the output signal is:

H (x, y) B (x, y) -b (x, y) Vx, y) -t

 o- t K

With time modulation, the exposure of the light spot is constant and equal to BO, and the output signal

H (x, y) (x, y) - i (x, y) -t (h, y)

  - (

In the case of photo printing with masking, the scanned material 4 consists of an original with background, transparency nd (x, y) and a photosensitive material superimposed on it. Supporting

the signal Ug in this case is constant. Thus, the suppression of the background image component is achieved with high accuracy, i.e. without the influence of the uneven sensitivity of the photoelectric converter.

In the case of photo registration, the following materials are used as scanned material.

photosensitive material, and the reference signal is modulated by a signal of the recorded image. Thus, the output signal with high accuracy corresponds to the input signal, i.e. without the influence of the uneven sensitivity of the photoelectric converter.

Claims (1)

 About formula of invention and 15 and A method for correcting irregularity of the signal of traveling beam devices, which consists in placing a prefabricated neutral filter with a specified optical density distribution in the scanning plane by exposing the photosensitive material on a transparent basis to a scanning light spot controlled by the corrected device, and then photochemical processing, characterized in that, in order to increase the accuracy of the correction, the scan control etovym n tnom performed modulated luminance its duration or the scanning element scanning the floor while maintaining persistence value a value equal to the product of the length of the scanning output signal of the floor element 20 25 thirty 35 scans, and a neutral filter is obtained by exposing a positive photosensitive material and placing it behind the scanned material. z 3 .mm f t 5 (y) (x, y) FIG. 2