Abstract:
Each correction factor can assume one of a plurality of values and the selected value is to be stored in the printing apparatus. A plurality of input keys is provided, each furnishing a selected value upon activation. Activation of the key applies the input signal signifying the chosen value to the storage inputs of a plurality of storages, one for each correction factor. Further, activation of each key advances a counter by one step. The counter output enables each of the storages in turn.

Description:
BACKGROUND OF THE INVENTION 
     The present invention regards the equipment for entering a determined number of correction factors into photographic printing apparatus. Each of the correction factors may assume one of a predetermined number of values. 
     In photographic printing apparatus, it is necessary to enter values of a number of correction factors such as the density correction factor which may assume any one of the values of -3, -2, -1, 0, +1, +2 or +3, each of these steps of values indicating a change of approximately 35 percent. Similarly correction factors requiring the selection of one of a plurality of values for color correction in the colors blue, green and red are required. In conventional apparatus, a key is provided signifying each correction factor and further an individual key is required for each value of each of these correction factors. In this way the operator may make a visual inspection of the negative and enter correction values corresponding to the particular characteristics of this negative into the apparatus. When the values of all of the correction factors have been entered, a key is depressed which causes the printing process to take place with the so-entered values of the various correction factors. 
     This type of input arrangement has a number of disadvantages. First of all a great number of input keys is required. For example, for four correction factors each being able to assume seven different values, 28 keys are required. This tends to make the equipment somewhat unwieldy and unreliable. Further, the operator must find the correct keys out of a relatively large key field which requires visual concentration. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to decrease the number of input keys required for printing apparatus of the above-described type. 
     The present invention is equipment for entering a selected one of a plurality of values for each of a determined number of correction factors into photographic printing apparatus. It comprises a plurality of input means corresponding in number to said plurality of values, each for furnishing an input signal corresponding to a selected one of said values upon external activation. A plurality of storage means are provided, one for storing each of said correction factors, each having a storage input connected to said input means and an enabling input. Further comprised are gating means for furnishing enabling signals to each of said enabling inputs in turn in a predetermined sequence in response to activation of said input means, whereby the selected values of each of said correction factors is entered in turn into each of said storage means. 
     This type of arrangement has the advantage that the operator utilizes only a single set of keys and that the gating means which in a preferred embodiment of the present invention are a binary counter, automatically enter the selected value of the correction factor into the storage associated with said correction factor. The cost of the equipment is also greatly decreased. 
     The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The single FIGURE is a schematic diagram of the equipment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will now be described with reference to the drawing. 
     A key field having keys 1a-1g is denoted by reference numeral 1. The marking on the keys is -3, -2, -1, 0, +1, +2 and +3 respectively. These designations are the designations conventionally used in printing equipment for the different values of the correction factors. The seven keys have electrical outputs connected to the inputs of a code converter 2 which converts each of the signals into a binary coded signal available at the code converter output lines 3a, 3b and 3c. These lines are connected to the storage inputs of all of the storage means, namely storages 4, 5, 6 and 7. Each of the storages is to store the selected value of a corresponding correction factor. The signals at the output of the code converter are thus continually applied to the storage inputs of all of the storages. Each of the storages may in well-known fashion be constructed of semi-conductor elements such as flip-flops. The storages are also commercially available as individual storage units. 
     Further, a pulse generator 8 has an input connected to the key field (input means). Every activation of a key causes a pulse to be furnished at the output of pulse generator 8. The pulse may be generated either in response to the pressing of the key or in response to the release of the key. The output of pulse generator 8 is connected to the input of gating means, here a binary counter 9. The gating means could of course alternatively be embodied in a shift register, in a mechanical step switch, or various other means. Directly connected to the counter is a code converter 10 which causes the signals at the output of counter 9 to be converted to decimal signals, that is the output lines of the code converter namely lines 10a-10d are energized in turn and in response to each counting output signal furnished by binary counter 9. Lines 10a-10d are respectively applied to the first inputs of AND-gates 11-14. The second input of AND-gates 11-14 is connected in common to a second output of pulse generator 8. The pulse output furnished to gates 11-14 precedes the output furnished to binary counter 9 by some small amount. For example, the pulse advancing binary counter 9 may be derived from the trailing edge of the pulse applied to AND-gates 11-14. 
     The outputs of AND-gates 11-14 are each connected to an enabling input of a corresponding one of storages 4-7. A signal applied to the enabling input of these storages causes the content of these storages to be changed in accordance with the signal at the storage input. The enabling inputs are denoted by reference numerals 4a-7a, respectively. Each of the storages has a further input namely inputs 4b-7b which are connected through a common line 15 to means for furnishing a reset signal. This means may for example be a manually activatable key 16 or alternatively, the reset signal may be derived from the exposure control circuit (17) at the end of the printing process. Counter 9 is also reset to zero by the signal on line 15. 
     The signals furnished by the depression of the keys for each of the correction factors are stored in storages 4-7 in coded form. An indicator is connected to the output of each of the storages (18-21) for indicating the value stored therein. The indicators each contain a decoding network so that the visual indication is furnished in exact correspondence to the indication on the input keys. Further, the storage outputs of each of the storages is connected through a decoder 22 to the actual printing control circuit 17. The latter may be constructed in accordance with the embodiment shown in German patent No. 2,246,466 corresponding to U.S. patent application Ser. No. 399,184. Various color correction potentiometers (43, 65 and 66) are shown in this patent. For purposes of the present invention these are replaced by six resistors which are selectively connectable into the circuit in accordance with the values stored in storages 4-7. 
     The above-described equipment operates as follows: Originally, counter 9 is reset to zero and storages 4-7 are also in a reset state. No indication is shown on indicators 18-21. A negative is now examined and it is determined that a density correction of +2 is required for this negative. The +2 key is pressed. This causes the binary coded representation of +2 to be applied to the storage input of storages 4-7 by means of lines 3a-3c. Since however counter 4 is reset to zero, only AND-gate 11 has an energized second input. Thus the pulse which has been generated at the first output of pulse generator 8 in response to the pressing of the +2 key causes a signal to appear at the output of AND-gate 11 and thereby at the enabling input 4a of storage 4. Thus the +2 value is stored in storage 4 causing indicator 18 to indicate a +2 value. At the end of the pulse furnished by pulse generator 8 to AND-gate 11, a pulse is furnished to binary counter 9 advancing this counter by one count. AND-gate 12 now has a second input which is energized. 
     It it is now determined that the next selected value, namely the value for the correction factor for the color correction in the color blue is zero, the 0 key is pressed. The coded 0 value of course appears on lines 3a-3c and, as previously stated, is applied to all storage inputs of storages 4-7. However, an enabling signal exists at enabling input 5a only since only, AND-gate 12 has an energized second input. This causes the 0 value to be stored in storage 5 and a corresponding indication to appear on indicator 19. Again, binary counter 9 is advanced by one count causing the second input of AND-gate 13 to be energized. The process is thus continued until the selected values for the correction factors for storages 6 and 7 are also entered. The capacity of binary counter 4 is thus exhausted. This causes a blocking signal to be applied through line 23 to a blocking input of pulse generator 8 so that no further signal may be entered into any of the storages since none of the AND-gates 11-14 can be energized by pulse generator 8. 
     At this point in time the correct values for each correction factor have been entered into storages 4-7. All indicators 18-21 are lit and indicate the so-entered correcton value. The printing process can now be started either by pressing a separate key or, alternatively, the pressing of the key for the last correction value is used to initiate the printing process. The printing or exposure control circuit 17 which has been adjusted to the correct values of the various correction factors through the decoder 22 then operates. At the end of the printing process or at the end of the exposure, a signal is furnished which resets counter 9 and storages 4-7 so that new correction values can be entered for the next negative. 
     If the operator has made an error while entering the correction values and wishes to change this value, key 16 must be depressed causing all correction values to be reset and enabling the operator to enter new values. The pushing of reset key 16 also causes the blocking signal for pulse generator 8 to be eliminated. 
     Other constructions of counter 4 are possible. For example, entering of the first correction factor can cause the printing process for the particular negative to commence. Alternatively, an additional key can be provided which allows the printing process to proceed when, during a full counter, only one or two correction values are to be entered at the beginning of the sequence but no further correction values with then be required. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.